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Search for exotic neutrino-electron interactions using solar neutrinos
in XMASS-I: We have searched for exotic neutrino-electron interactions that could be
produced by a neutrino millicharge, by a neutrino magnetic moment, or by dark
photons using solar neutrinos in the XMASS-I liquid xenon detector. We observed
no significant signals in 711 days of data. We obtain an upper limit for
neutrino millicharge of 5.4$\times$10$^{-12} e$ at 90\% confidence level
assuming all three species of neutrino have common millicharge. We also set
flavor dependent limits assuming the respective neutrino flavor is the only one
carrying a millicharge, $7.3 \times 10^{-12} e$ for $\nu_e$, $1.1 \times
10^{-11} e$ for $\nu_{\mu}$, and $1.1 \times 10^{-11} e$ for $\nu_{\tau}$.
These limits are the most stringent yet obtained from direct measurements. We
also obtain an upper limit for the neutrino magnetic moment of
1.8$\times$10$^{-10}$ Bohr magnetons. In addition, we obtain upper limits for
the coupling constant of dark photons in the $U(1)_{B-L}$ model of
1.3$\times$10$^{-6}$ if the dark photon mass is 1$\times 10^{-3}$ MeV$/c^{2}$,
and 8.8$\times$10$^{-5}$ if it is 10 MeV$/c^{2}$. | hep-ex |
Searches for New Physics with leptons in the final state at the LHC: Final states including leptons are most promising to detect early signs of
new physics processes when the Large Hadron Collider will start proton-proton
collisions at the centre of mass energy of 14\TeV. The reach for Supersymmetry
and Extra Dimension models for integrated luminosities ranging from 1 to 10/fb
is reported. Preliminary results indicate that already with 1/fb of data new
phenomena can be detected. | hep-ex |
Searches for Point-like and extended neutrino sources close to the
Galactic Centre using the ANTARES neutrino Telescope: A search for cosmic neutrino sources using six years of data collected by the
ANTARES neutrino telescope has been performed. Clusters of muon neutrinos over
the expected atmospheric background have been looked for. No clear signal has
been found. The most signal-like accumulation of events is located at
equatorial coordinates RA=$-$46.8$^{\circ}$ and Dec=$-$64.9$^{\circ}$ and
corresponds to a 2.2$\sigma$ background fluctuation. In addition, upper limits
on the flux normalization of an E$^{-2}$ muon neutrino energy spectrum have
been set for 50 pre-selected astrophysical objects. Finally, motivated by an
accumulation of 7 events relatively close to the Galactic Centre in the
recently reported neutrino sample of the IceCube telescope, a search for point
sources in a broad region around this accumulation has been carried out. No
indication of a neutrino signal has been found in the ANTARES data and upper
limits on the flux normalization of an E$^{-2}$ energy spectrum of neutrinos
from point sources in that region have been set. The 90% confidence level upper
limits on the muon neutrino flux normalization vary between 3.5 and
5.1$\times$10$^{-8}$ GeV$\,$cm$^{-2}$s$^{-1}$, depending on the exact location
of the source. | hep-ex |
Projected Sensitivity of DMRadio-m$^3$: A Search for the QCD Axion Below
$1\,μ$eV: The QCD axion is one of the most compelling candidates to explain the dark
matter abundance of the universe. With its extremely small mass ($\ll
1\,\mathrm{eV}/c^2$), axion dark matter interacts as a classical field rather
than a particle. Its coupling to photons leads to a modification of Maxwell's
equations that can be measured with extremely sensitive readout circuits.
DMRadio-m$^3$ is a next-generation search for axion dark matter below
$1\,\mu$eV using a $>4$ T static magnetic field, a coaxial inductive pickup, a
tunable LC resonator, and a DC-SQUID readout. It is designed to search for QCD
axion dark matter over the range $20\,\mathrm{neV}\lesssim m_ac^2\lesssim
800\,\mathrm{neV}$ ($5\,\mathrm{MHz}<\nu<200\,\mathrm{MHz}$). The primary
science goal aims to achieve DFSZ sensitivity above $m_ac^2\approx 120$ neV (30
MHz), with a secondary science goal of probing KSVZ axions down to
$m_ac^2\approx40\,\mathrm{neV}$ (10 MHz). | hep-ex |
Measurement of W-Boson Helicity Fractions in Top-Quark Decays Using
costheta*: Fully reconstructed top-antitop-events are used to determine the fractions of
right-handed and longitudinally polarized W bosons produced in top-quark
decays. The helicity fractions are sensitive to the couplings and the Dirac
structure of the Wtb vertex. This paper reports measurements of the W-boson
helicity fractions from two different methods using data corresponding to an
integrated luminosity of 1.9 fb-1 of proton-antiproton collisions collected by
the CDF II detector operating at the Fermilab Tevatron. | hep-ex |
DsTau: Study of tau neutrino production with 400 GeV protons from the
CERN-SPS: In the DsTau experiment at the CERN SPS, an independent and direct way to
measure tau neutrino production following high energy proton interactions was
proposed. As the main source of tau neutrinos is a decay of Ds mesons, produced
in proton-nucleus interactions, the project aims at measuring a differential
cross section of this reaction. The experimental method is based on a use of
high resolution emulsion detectors for effective registration of events with
short lived particle decays. Here we present the motivation of the study,
details of the experimental technique, and the first results of the analysis of
the data collected during test runs, which prove feasibility of the full scale
study of the process in future. | hep-ex |
Recent Progress on Charmonium Decays at BESIII: In 2009, the BESIII experiment has collected about 225M $\jpsi$ and 106M
$\psip$ samples, both of which are the world largest on-peak charmonium
production. Based on these dataset, BESIII has made great effort on the study
of the charmonium decays, some important of which have been reviewed in this
proceeding. In addition, a searching for new physics through the $CP/P$
violation process is reported. | hep-ex |
Partial Wave Analysis of $J/ψ\rightarrow γγφ$: Using a sample of $(10087\pm44)\times10^{6}$ $J/\psi$ events collected with
the BESIII detector at the BEPCII collider, a partial wave analysis on the
decay $\gamma\gamma\phi$ is performed to investigate the intermediate
resonances in $J/\psi\rightarrow\gamma X, X\rightarrow\gamma\phi$. The
resonances $f_{1}(1285)$, $\eta(1405)$, $f_{1}(1420)$, $f_{1}(1510)$,
$f_{2}(1525)$, $X(1835)$, $f_{2}(1950)$, $f_{2}(2010)$, $f_{0}(2200)$ and
$\eta_{c}$ are observed with statistical significance greater than 5$\sigma$.
The product branching fractions $\mathcal{B}(J/\psi\rightarrow\gamma X,
X\rightarrow \gamma \phi)$ are reported. The resonance parameters of
$\eta(1405)$ and $X(1835)$ are also measured. | hep-ex |
Amplitude analysis of e+e- => Y(nS)pi+pi- at sqrt(s)=10.865 GeV: We report results on studies of the e+e- annihilation into three-body
Y(nS)pi+pi- (n=1,2,3) final states including measurements of cross sections and
the full amplitude analysis. The cross sections measured at sqrt(s)=10.865 GeV
and corrected for the initial state radiation are
sigma(e+e-=>Y(1S)pi+pi-)=(2.27+-0.12+-0.14) pb,
sigma(e+e-=>Y(2S)pi+pi-)=(4.07+-0.16+-0.45) pb, and
sigma(e+e-=>Y(3S)pi+pi-)=(1.46+-0.09+-0.16) pb. Amplitude analysis of the
three-body Y(nS)pi+pi- final states strongly favors I^G(J^P)=1^+(1^+)
quantum-number assignments for the two bottomonium-like Zb+- states, recently
observed in the Y(nS)pi+- and hb(mP)pi+- (m=1,2) decay channels. The results
are obtained with a $121.4 1/fb data sample collected with the Belle detector
at the KEKB asymmetric-energy e+e- collider. | hep-ex |
Key4hep, a framework for future HEP experiments and its use in FCC: The road map to the FCC Feasibility Study Report, for submission to the next
Update of the European Strategy for Particle Physics, will require detailed
simulation and advanced reconstruction algorithms to explore and maximise the
physics reach of proposed detector solutions. The optimisation process will
require maximal flexibility in changing detector geometries, materials and
sensitive areas, and efficient tools to quantify the overall performance. To
synergise such developments the CEPC, CLIC, FCC, ILC and SCT communities have
engaged in the commissioning of a `Turnkey Software Stack' (Key4hep), which
would provide all the necessary ingredients, from simulation to analysis, for
future experiments. This approach is based on the positive experience of the
linear collider projects ILC and CLIC, which have developed and used a common
software stack (iLCSoft) over the last decade. Key4hep aims to cover most, if
not all, future linear and circular machines colliding leptons (electrons,
muons), and hadrons. The common software ecosystem will facilitate writing
specific components for experiments ensuring coherency and maximising the
re-use of established solutions. Project-specific software frameworks will
require adaptation to fully profit from the common software base. In this essay
we present the status and plans for re-framing the FCC software framework,
FCCSW, around Key4hep and discuss the challenges associated with the
transition. | hep-ex |
Tau Lepton Production in ep Collisions at HERA: The production of tau leptons in ep collisions is investigated using data
recorded by the H1 detector at HERA in the period 1994-2000. Tau leptons are
identified by detecting their decay products, using leptonic and hadronic decay
modes. The cross section for the production of tau lepton pairs is measured for
the first time at HERA. Furthermore, a search for events with an energetic
isolated tau lepton and with large missing transverse momentum is performed.
The results are found to be in agreement with the Standard Model predictions. | hep-ex |
The Q^2-dependence of the Generalised Gerasimov-Drell-Hearn Integral for
the Proton: The dependence on Q^2 (the negative square of the 4-momentum of the exchanged
virtual photon) of the generalised Gerasimov-Drell-Hearn integral for the
proton has been measured in the range 1.2 GeV^2 < Q^2 < 12 GeV^2 by scattering
longitudinally polarised positrons on a longitudinally polarised hydrogen gas
target. The contributions of the nucleon-resonance and deep-inelastic regions
to this integral have been evaluated separately. The latter has been found to
dominate for Q^2 > 3 GeV^2, while both contributions are important at low Q^2.
The total integral shows no significant deviation from a 1/Q^2 behaviour in the
measured Q^2 range, and thus no sign of large effects due to either
nucleon-resonance excitations or non-leading twist. | hep-ex |
Search for inclusive charmless B->K+X and B->K0X decays: We present preliminary results from a search for inclusive charmless B->KX
decays. These decays occur dominantly via one-loop b->s penguin transitions,
and can provide useful information about these processes. Using a sample of
288.5/fb collected with the BABAR detector at the PEP-II asymmetric-energy e+e-
B Factory at SLAC, we search for high-energy kaons recoiling against fully
reconstructed B decays. We measure the partial branching fractions for kaons
with momentum p*(K)>2.34GeV in the B rest frame, and obtain (in units of
10^-6): B(B->K+X, p*>2.34GeV) = 196^{+37}_{-34}(stat.)^{+31}_{-30}(syst.) and
B(B->K0X, p*>2.34GeV) = 154^{+55}_{-48}(stat.)^{+55}_{-41}(syst.) (<266 at 90%
C.L.). | hep-ex |
Semileptonic B / Bs decays at Belle: The Belle experiment at the KEKB asymmetric energy e+e- collider recorded
large data sets of both, B and Bs decays. Semileptonic decays B(s) -> X l nu (l
= electron or muon) constitute approximately one fifth of the total decay width
of B(s) mesons and play an important role in the determination of the CKM
matrix elements V_ub and V_cb. Recent results from Belle are presented,
including the study of B- -> Ds(*) K l nu, the first measurements of
semi-inclusive modes B -> D(*) X l nu and the measurement of the inclusive
branching fraction Bf(Bs -> X l nu). | hep-ex |
Search for exotic resonances decaying into WZ/ZZ in pp collisions at
sqrt(s) = 7 TeV: A search for new exotic particles decaying to the VZ final state is
performed, where V is either a W or a Z boson decaying into two overlapping
jets and the Z decays into a pair of electrons, muons or neutrinos. The
analysis uses a data sample of pp collisions corresponding to an integrated
luminosity of 5 inverse femtobarns collected by the CMS experiment at the LHC
at sqrt(s) = 7 TeV in 2011. No significant excess is observed in the mass
distribution of the VZ candidates compared with the background expectation from
standard model processes. Model-dependent upper limits at the 95% confidence
level are set on the product of the cross section times the branching fraction
of hypothetical particles decaying to the VZ final state as a function of mass.
Sequential standard model W' bosons with masses between 700 and 940 GeV are
excluded. In the Randall-Sundrum model for graviton resonances with a coupling
parameter of 0.05, masses between 750 and 880 GeV are also excluded. | hep-ex |
A biased MC for muon production for beam-dump experiments: The search for feebly-interacting new-physics particles in the MeV-GeV mass
range often involves high-intensity beams dumped into thick heavy targets. The
challenge of evaluating the expected backgrounds for these searches from first
principles is limited by the CPU time needed to generate the shower induced by
the primary beam. We present a Monte Carlo biasing method allowing a three
orders of magnitude increase in the efficiency for the simulation of the muon
production in a 400 GeV$/c$ proton beam-dump setup. At the same time, this
biasing method is maintaining nearly every feature of a simulation from first
principles. | hep-ex |
Topological heavy-flavor tagging and intrinsic bottom at the
Electron-Ion Collider: Heavy-flavor hadron production, in particular bottom hadron production, is
difficult to study in deep-inelastic scattering (DIS) experiments due to small
production rates and branching fractions. To overcome these limitations, a
method for identifying heavy-flavor DIS events based on event topology is
proposed. Based on a heavy-flavor jet tagging strategy developed for the LHCb
experiment, this algorithm uses displaced vertices to identify decays of
heavy-flavor hadrons. The algorithm's performance at the Electron-Ion Collider
is demonstrated using simulation, and it is shown to provide discovery
potential for non-perturbative intrinsic bottom quarks in the proton. | hep-ex |
Prompt Photon Production at HERA and LEP: Results on isolated prompt photon production are presented. The measurements
were performed at HERA in deep inelastic ep scattering and photoproduction, as
well as at LEP in photon photon collisions. Differential cross sections are
shown for inclusive prompt photons and those accompanied by a jet. The results
are compared to predictions of perturbative QCD calculations in next to leading
order and to predictions of the event generators PYTHIA and HERWIG. | hep-ex |
Results on Charmonium-like States at BaBar: We present recent results on charmonium and charmonium-like states from the
BaBar B-factory located at the PEP-II asymmetric energy $e^{+}e^{-}$ storage
ring at the SLAC National Accelerator Laboratory. | hep-ex |
Measuring the W boson mass at the Tevatron: The measurement of the mass of the W boson is one of the prime goals of the
Tevatron experiments. In this contribution, a review is given of the most
recent determinations of the W boson mass (mW) at the Tevatron. The combined
Tevatron result, mW = 80.420 +/- 0.031 GeV, is now more precise than the
combined LEP result, leading to a world average value of mW = 80.399 +/- 0.023
GeV. | hep-ex |
Direct Measurements of the Branching Fractions for the Semileptonic
Decays $D^0 \to K^-μ^+ν_μ$ and $D^0 \to π^-μ^+ν_μ$: Based on the data sample of 33 pb$^{-1}$ collected at and around 3.773 GeV
with the BES-II detector at the BEPC collider, the absolute branching fractions
for the semileptonic decays $D^0\to K^-\mu^+\nu_\mu$ and
$D^0\to\pi^-\mu^+\nu_\mu$ have been measured. In the system recoiling against
$7584\pm198\pm341$ singly tagged $\bar D^0$ mesons, $87.2\pm13.6$ events for
$D^0\to K^-\mu^+\nu_\mu$ and $9.3\pm7.4$ events for $D^0\to\pi^-\mu^+\nu_\mu$
are observed. These yield the absolute branching fractions to be $BF(D^0\to
K^-\mu ^+\nu_\mu)= (3.55\pm0.56\pm0.59)%$ and $BF(D^0\to\pi^-\mu^+\nu_\mu)=
(0.38\pm0.30\pm0.10)%$. The measured branching fraction for $D^0\to K^-\mu
^+\nu_\mu$ was previously used to determine the ratio $\Gamma(D^0\to
K^-\mu^+\nu_\mu)/ \Gamma(D^+\to \bar K^0\mu^+\nu_\mu)$ combining the previously
measured branching fraction for $D^+\to \bar K^0\mu^+\nu_\mu$ by the BES
Collaboration. | hep-ex |
Experimental Search for Chargino and Neutralino Production in
Supersymmetry Models with a Light Gravitino: We search for inclusive high $E_T$ diphoton events with large missing
transverse energy in $p\bar{p}$ collisions at $\sqrt{s}$=1.8 TeV. Such events
are expected from pair production of charginos and neutralinos within the
framework of the minimal supersymmetric standard model with a light gravitino.
No excess of events is observed. In that model, and assuming gaugino mass
unification at the GUT scale, we obtain a 95% CL exclusion region in the
supersymmetry parameter space and lower mass bounds of 150 GeV/c$^2$ for the
lightest chargino and 75 GeV/c$^2$ for the lightest neutralino. | hep-ex |
New Search for tau -> mu gamma and tau -> e gamma Decays at Belle: We report on a search for the lepton flavor violating tau- -> mu- gamma and
tau- -> e- gamma decays based on 535/fb of data accumulated at the Belle
experiment. No signal is found and we set 90% confidence level upper limits on
the branching ratios Br(tau- -> mu- gamma) < 4.5x10^-8 and Br(tau- -> e- gamma)
< 1.2x10^-7. | hep-ex |
CLEO Results on Transitions in Heavy Quarkonia: Recent CLEO results on electromagnetic and hadronic transitions in charmonium
and bottomonium systems are reviewed. | hep-ex |
Measurement of the ttbar cross section using high-multiplicity jet
events: We present a measurement of the ttbar cross section using high-multiplicity
jet events produced in ppbar collisions at sqrt{s}=1.96 TeV. These data were
recorded at the Fermilab Tevatron collider with the D0 detector. Events with at
least six jets, two of them identified as b jets, were selected from a 1 fb-1
data set. The measured cross section, assuming a top quark mass of 175 GeV/c^2,
is 6.9 \pm 2.0 pb, in agreement with theoretical expectations. | hep-ex |
Electron - Dark Matter Scattering in an Evacuated Tube: The light dark matter model can explain both the primordial abundance of dark
matter and the anomalous 511 keV gamma-ray signal from the galactic center.
This model posits a light neutral scalar, \chi, with a mass in the range 1 MeV
< Mchi < 10 MeV, as well as a light neutral spin-1 boson, U, which mediates the
annihilation channel \chi\chi -> e+e-. Since the dark matter particle is light,
its number density is relatively large if it accounts for a local dark matter
density of 0.3 GeV/cm^3. We consider an experiment in which a low-energy,
high-current electron beam is passed through a long evacuated tube, and elastic
scattering of electrons off dark matter particles is observed. The kinematics
of this process allow a clean separation of the signal process from scattering
off residual gas in the tube, and also a direct measurement of Mchi. | hep-ex |
Observation of a vector charmoniumlike state at 4.7 ${\rm GeV}/c^2$ and
search for $Z_{cs}$ in $e^+e^-\to K^+K^-J/ψ$: Using data samples with an integrated luminosity of 5.85~fb$^{-1}$ collected
at center-of-mass energies from 4.61 to 4.95 GeV with the BESIII detector
operating at the BEPCII storage ring, we measure the cross section for the
process $e^+e^-\to K^+K^-J/\psi$. A new resonance with a mass of $M =
4708_{-15}^{+17}\pm21$ MeV/$c^{2}$ and a width of $\Gamma =
126_{-23}^{+27}\pm30$ MeV is observed in the energy-dependent line shape of the
$e^+e^-\to K^+K^-J/\psi$ cross section with a significance over $5\sigma$. The
$K^{+}J/\psi$ system is also investigated to search for charged charmoniumlike
states, but no significant $Z_{cs}^+$ states are observed. Upper limits on the
Born cross sections for $e^+e^-\to K^{-} Z_{cs}(3985)^{+}/K^{-}
Z_{cs}(4000)^{+} + c.c.$ with $Z_{cs}(3985)^{\pm}/Z_{cs}(4000)^{\pm}\to K^{\pm}
J/\psi$ are reported at 90\% confidence levels. The ratio of branching
fractions $\frac{\mathcal{B}(Z_{cs}(3985)^{+}\to K^+
J/\psi)}{\mathcal{B}(Z_{cs}(3985)^{+}\to (\bar{D}^{0}D_s^{*+} +
\bar{D}^{*0}D_s^+))}$ is measured to be less than 0.03 at 90\% confidence
level. | hep-ex |
Top quark mass and properties in ATLAS and CMS: For standard model (SM) processes involving top quarks, such as top
quark-antiquark pair production or single top quark production, the theoretical
predictions depend on fundamental parameters of the SM like the top quark mass.
Using the large data sample collected at the CERN LHC in the second data-taking
period by the ATLAS and CMS experiments, these parameters can be extracted in
experimental measurements with high precision. Furthermore, properties of the
production processes such as quark polarization or asymmetries can be measured.
Exploiting the large luminosity of the data set, new kinematic regimes and
methods are explored, as for events in which the top quarks have a very large
transverse momentum. In these proceedings, recent measurements of SM parameters
and top quark properties are presented. Individual results are also interpreted
in terms of effective field theory extensions of the SM. | hep-ex |
Direct Measurement of the Pseudoscalar Decay Constant fD+: The absolute branching fraction of $D^+ \to \mu^+ \nu$ has been directly
measured by an analysis of a data sample of about 33 ${\rm pb^{-1}}$ collected
around $\sqrt{s}=3.773$ GeV with the BES-II at the BEPC. At these energies,
$D^-$ meson is produced in pair as $e^+e^-\to D^{+} D^{-}$. A total of $5321
\pm 149 \pm 160$ $D^-$ mesons are reconstructed from this data set. In the
recoil side of the tagged $D^-$ mesons, $2.67\pm1.74$ purely leptonic decay
events of $D^+ \to \mu^+ \nu$ are observed. This yields a branching fraction of
$BF(D^+ \to \mu^+ \nu_{\mu}) = (0.122^{+0.111}_{-0.053}\pm 0.010)%$, and a
corresponding pseudoscalar decay constant $f_{D^+}=(371^{+129}_{-119}\pm 25)$
MeV. | hep-ex |
Experimental study of direct photon emission in K- --> pi- pi0 gamma
decay using ISTRA+ detector: The branching ratio in the charged-pion kinetic energy region of 55 to 90 MeV
for the direct photon emission in the K- --> pi- pi0 gamma decay has been
measured using in-flight decays detected with the ISTRA+ setup operating in the
25 GeV/c negative secondary beam of the U-70 PS. The value
Br(DE)=[0.37+-0.39(stat)+-0.10(syst)]*10^(-5) obtained from the analysis of 930
completely reconstructed events is consistent with the average value of two
stopped-kaon experiments, but it differs by 2.5 standard deviations from the
average value of three in-flight-kaon experiments. The result is also compared
with recent theoretical predictions. | hep-ex |
Search for Light Dark Matter-Electron Scatterings in the PandaX-II
Experiment: We report constraints on light dark matter through its interactions with
shell electrons in the PandaX-II liquid xenon detector with a total 46.9
tonne$\cdot$day exposure. To effectively search for these very low energy
electron recoils, ionization-only signals are selected from the data. 1821
candidates are identified within ionization signal range between 50 to 75
photoelectrons, corresponding to a mean electronic recoil energy from 0.08 to
0.15 keV. The 90% C.L. exclusion limit on the scattering cross section between
the dark matter and electron is calculated based on Poisson statistics. Under
the assumption of point interaction, we provide the world's most stringent
limit within the dark matter mass range from 15 to 30 $\rm MeV/c^2$, with the
corresponding cross section from $2.5\times10^{-37}$ to $3.1\times10^{-38}$
cm$^2$. | hep-ex |
Hidden Charm Spectroscopy from Tevatron: The observation of a narrow structure near the J/psi phi threshold in
exclusive B+ to J/psi phi K+ decays produced in p-pbar collisions at sqrt(s) =
1.96 TeV is reported. A signal of 19 +- 6(stat) +- 3(syst) events, with
statistical significance of 5.0 standard deviations, is seen in a data sample
corresponding to an integrated luminosity of 6.0 invfb, collected by the CDF II
detector. The mass and natural width of the structure are determined to be m =
4143.4 + 2.9 - 3.0(stat) +- 0.6(syst) MeV and Gamma = 15.3 + 10.4 - 6.1(stat)
+- 2.5(syst) MeV, consistent with the previous measurements reported as
evidence of the Y(4140). | hep-ex |
Exclusive $ρ^{0}$ Production in Polarized DIS at SMC: Preliminary spin cross section asymmetries for exclusive $\rho^{0}$
lepto-production, $\vec{\mu} + \vec{N} \to \mu' + N + \rho^{0} (\rho^{0} \to
\pi^{+} \pi^{-})$, are reported. These asymmetries have been determined for the
first time by the Spin Muon Collaboration (SMC) at low Q^2 (photoproduction)
and at large Q^2 (DIS) for different $p_T^2$ intervals in the kinematic range
$0.01 <Q^2< 60 GeV^2$ and $140 < W^2 < 310 GeV^2$ (<W> \simeq 15 GeV) for the
full SMC data set. About 100 K $\rho^{0}$'s have been selected for $0.62 < m
(\pi^{+} \pi^{-}) < 1.07 GeV/c^2$ and $|I|< 0.05$. Within the statistical
precision, no significant asymmetries have been observed at low $Q^{2}$ in the
preliminary results. | hep-ex |
Resonances in the System of Pi+Pi- -- Mesons from the Reaction
np->npPi+Pi- at Pn=5.20GeV/c: Search, Results of Direct Observations,
Interpretation: Ten resonances were found in the mass spectrum of pi+pi- -system from the
reaction np->nppi+pi- in np-interactions at Pn=5.20 GeV/c in the 1-m HBC of LHE
JINR by using the criterion cos(teta)[c.m.c.] p>0. Such effects were not found
in pi-pi0 - combinations from the reaction np->pppi-pi0. Therefore, it is
necessary to attribute the value of isotopic spin I = 0 to the resonances found
in the mass spectrum of the pi+pi- -system. The spin was estimated for the most
statistically provided resonances. We determine with a high degree of
confidence that J = 0 for the resonances at MR = 757 MeV/c^2 and MR = 418
MeV/c^2. Therefore, it can be affirmed that at least 3 states with quantum
numbers of sigma0-meson 0+(0++) have been found at masses of 418, 511 and 757
MeV/c^2. The fact low-mass sigma0-mesons are glueballs is one of the possible
interpretations. The comparison with the data of other papers has also been
made. The investigation has been performed at the Veksler and Baldin Laboratory
of High Energies,JINR. | hep-ex |
First Probe of Sub-GeV Dark Matter Beyond the Cosmological Expectation
with the COHERENT CsI Detector at the SNS: The COHERENT collaboration searched for scalar dark matter particles produced
at the Spallation Neutron Source with masses between 1 and 220~MeV/c$^2$ using
a CsI[Na] scintillation detector sensitive to nuclear recoils above
9~keV$_\text{nr}$. No evidence for dark matter is found and we thus place
limits on allowed parameter space. With this low-threshold detector, we are
sensitive to coherent elastic scattering between dark matter and nuclei. The
cross section for this process is orders of magnitude higher than for other
processes historically used for accelerator-based direct-detection searches so
that our small, 14.6~kg detector significantly improves on past constraints. At
peak sensitivity, we reject the flux consistent with the cosmologically
observed dark-matter concentration for all coupling constants $\alpha_D<0.64$,
assuming a scalar dark-matter particle. We also calculate the sensitivity of
future COHERENT detectors to dark-matter signals which will ambitiously test
multiple dark-matter spin scenarios. | hep-ex |
The Nuclear Emulsion Technology and the Analysis of the OPERA Experiment
Data: OPERA is an experiment that aims at detecting the appearance of tau-neutrino
in an almost pure mu-neutrino beam (the CNGS neutrino beam) through
oscillation. OPERA is a hybrid detector that associates nuclear emulsions to
electronic detectors. The nuclear emulsion provides the resolution necessary to
detect tau-neutrino CC interactions. The first physics run started in July and
ended in November 2008. In this presentation, the status of the emulsion
technology and of the analysis of its data is reported. | hep-ex |
Charmless B Decays Involving Vector Mesons in Belle: Using the data sample of 10.5 fb-1 collected by the Belle detector, we
searched for two-body charmless decays involving vector mesons. The clear
signal signature of B+ -> phi K+ is seen and its branching fraction is measured
to be (1.39+.32-.30 +- 0.2) X 10-5. The evidence for B+ -> rho pi+, B0 -> rho-
pi+ and B+ -> phi K*+ is reported and their branching fractions are determined.
No significant signals are observed for B0 -> phi K0S, -> phi K*0, -> rho- K+,
B+ -> rho K+, -> omega pi+ and -> omega K+ only the 90% C.L. upper limits are
given. | hep-ex |
Determination of the strong coupling constant using subjet
multiplicities in Neutral Current Deep Inelastic Scattering: The internal structure of the jets produced in neutral current interactions
for Q^2>125 GeV^2 has been studied using the subjet multiplicity with the ZEUS
detector at HERA. Jets are identified in the laboratory frame by applying the
longitudinally invariant k_T-cluster algorithm. Next-to-leading order QCD
calculations have been obtained and compared to the data; a good agreement has
been observed in the region where hadron-to-parton corrections are small,
E_{T,jet}> 25 GeV. In this region, the strong coupling constant is extracted
and the resulting value is alpha_s (M_Z)=0.1185 +/- 0.0016 (stat.)
^{+0.0067}_{-0.0048} (syst.) ^{+0.0089}_{-0.0071} (th.). | hep-ex |
Measurement of the Ratio of Partial Branching Fractions of Inclusive
$\overline{B} \to X_u \ell \overlineν$ to $\overline{B} \to X_{c} \ell
\overlineν$ and the Ratio of their Spectra with Hadronic Tagging: We present a measurement of the ratio of partial branching fractions of the
semi-leptonic inclusive decays, $\overline{B} \to X_{u} \ell \overline{\nu}$ to
$\overline{B} \to X_{c} \ell \overline{\nu}$, where $\ell = (e, \mu)$, using
the full Belle sample of $772 \times 10^{6}$ $B \kern 0.18em\overline{\kern
-0.18em B}$ pairs collected at the $\Upsilon(4S)$ resonance. The ratio is
measured via a two-dimensional fit to the squared four-momentum transfer to the
lepton pair, and the charged lepton energy in the $B$ meson rest frame, where
the latter must be larger than $1$ Ge\kern -0.1em V, covering approximately
$86\%$ and $78\%$ of the $\overline{B} \to X_{u} \ell \overline{\nu}$ and
$\overline{B} \to X_{c} \ell \overline{\nu}$ phase space, respectively. We find
$\Delta \mathcal{B}(\overline{B} \to X_{u} \ell \overline{\nu})/ \Delta
\mathcal{B}(\overline{B} \to X_{c} \ell \overline{\nu}) = 0.0196(1 \pm
8.4\%_{\rm stat} \pm 7.9\%_{\rm syst})$ where the uncertainties are statistical
and systematic, respectively. In addition, we report the partial branching
fractions separately for charged and neutral $B$ meson decays, and for electron
and muon decay channels. We place a limit on isospin breaking in $\overline{B}
\to X_{u} \ell \overline{\nu}$ decays, and find no indication of lepton flavor
universality violation in either the charmed or charmless mode. Furthermore, we
unfold the $\overline{B} \to X_{u} \ell \overline{\nu}$ and $\overline{B} \to
X_{c} \ell \overline{\nu}$ yields and report the differential ratio in lepton
energy and four-momentum transfer squared. | hep-ex |
Search for Single Top Production in e+e- Collisions at sqrt(s) up to
209GeV: Single top production via the flavour changing neutral current reactions e+e-
-> \bar{t}c, \bar{t}u is searched for within the 214 pb-1 of data collected by
ALEPH at centre-of-mass energies between 204 and 209 GeV. No deviation from the
Standard Model expectation is observed and upper limits on the single top
production cross sections are derived. The combination with data collected at
lower centre-of-mass energies yields an upper limit on the branching ratio BR(t
-> Zc)+BR(t -> Zu) 14%, for BR(t -> \gamma c)+BR(t -> \gamma u)= 0 and mt=174
GeV/c2. | hep-ex |
Search for a heavy charged boson in events with a charged lepton and
missing transverse momentum from $pp$ collisions at $\sqrt{s} = 13$ TeV with
the ATLAS detector: A search for a heavy charged-boson resonance decaying into a charged lepton
(electron or muon) and a neutrino is reported. A data sample of 139 fb$^{-1}$
of proton-proton collisions at $\sqrt{s} = 13$ TeV collected with the ATLAS
detector at the LHC during 2015-2018 is used in the search. The observed
transverse mass distribution computed from the lepton and missing transverse
momenta is consistent with the distribution expected from the Standard Model,
and upper limits on the cross section for $pp \to W^\prime \to \ell\nu$ are
extracted ($\ell = e$ or $\mu$). These vary between 1.3 pb and 0.05 fb
depending on the resonance mass in the range between 0.15 and 7.0 TeV at 95%
confidence level for the electron and muon channels combined. Gauge bosons with
a mass below 6.0 TeV and 5.1 TeV are excluded in the electron and muon
channels, respectively, in a model with a resonance that has couplings to
fermions identical to those of the Standard Model $W$ boson. Cross-section
limits are also provided for resonances with several fixed $\Gamma / m$ values
in the range between 1% and 15%. Model-independent limits are derived in
single-bin signal regions defined by a varying minimum transverse mass
threshold. The resulting visible cross-section upper limits range between 4.6
(15) pb and 22 (22) ab as the threshold increases from 130 (110) GeV to 5.1
(5.1) TeV in the electron (muon) channel. | hep-ex |
Evidence for the decay $Υ(4S) \to Υ(1S) π^{+} π^{-} $: A study of transitions between $\Upsilon$ states with the emission of charged
pions using 398 fb$^{-1}$ of data collected with the Belle detector at the KEKB
asymmetric energy $e^+e^-$ collider is presented. A clear peak from the decay
$\Upsilon(1S)\to\mu^+\mu^-$ is observed in the invariant mass distribution of
$(\mu^+ \mu^-)$ pairs from the $(\mu^+ \mu^- \pi^+ \pi^- X)$ event sample. The
mass difference distribution ($M_{\mu^+\mu^-\pi^+\pi^-}-M_{\mu^+\mu^-}$) for
$M_{\mu^+\mu^-}$ from the $\Upsilon(1S)$ mass region has two peaks from
$\Upsilon(2S,3S)\to \Upsilon(1S)\pi^+\pi^-$ decays, with no background. A third
peak at $\Delta M = (1119.0\pm 1.4)$~MeV/$c^2$ can be interpreted as evidence
of a signal from the decay $\Upsilon(4S)\to \Upsilon(1S)\pi^+\pi^-$ with a
subsequent $ \Upsilon(1S) \to \mu^+ \mu^-$ transition. This is the first
example of a non-$B \bar{B}$ decay of the $\Upsilon(4S)$ resonance. The
preliminary estimated branching fraction is equal to
$\mathcal{B}(\Upsilon(4S)\to \Upsilon(1S)\pi^+\pi^-) = (1.1 \pm
0.2(\mathrm{stat.}) \pm 0.4(\mathrm{sys.}))\times 10^{-4}.$ | hep-ex |
Combined search for electroweak production of winos, binos, higgsinos,
and sleptons in proton-proton collisions at $\sqrt{s}$ = 13 TeV: A combination of the results of several searches for the electroweak
production of the supersymmetric partners of standard model bosons, and of
charged leptons, is presented. All searches use proton-proton collision data at
$\sqrt{s}$ = 13 TeV recorded with the CMS detector at the LHC in 2016-2018. The
analyzed data correspond to an integrated luminosity of up to 137 fb$^{-1}$.
The results are interpreted in terms of simplified models of supersymmetry. Two
new interpretations are added with this combination: a model spectrum with the
bino as the lightest supersymmetric particle together with mass-degenerate
higgsinos decaying to the bino and a standard model boson, and the
compressed-spectrum region of a previously studied model of slepton pair
production. Improved analysis techniques are employed to optimize sensitivity
for the compressed spectra in the wino and slepton pair production models. The
results are consistent with expectations from the standard model. The
combination provides a more comprehensive coverage of the model parameter space
than the individual searches, extending the exclusion by up to 125 GeV, and
also targets some of the intermediate gaps in the mass coverage. | hep-ex |
Measurement of Orbitally Excited D-Mesons at CDF II: Measurement of Orbitally Excited D-Mesons at CDF II Igor V. Gorelov (For the
CDF Collaboration)
Talk given on behalf of the CDF Collaboration at the First Meeting of the APS
Topical Group on Hadronic Physics, GHP 2004, 24-26 October 2004, FERMILAB.
Results on the first measurement of orbitally excited neutral D-meson states,
D*_2 and D_1, produced in hadron collisions at Tevatron are presented. Using
data from the displaced track trigger, CDF II collects the largest world sample
of these states in decay modes D*+ pi-, D+ pi-. Masses and widths of both
states have been measured with precision better than or comparable to the world
average. | hep-ex |
Particle Correlations in Z and WW Events: Important information about the dynamics of hadron production can be obtained
by the study of particle correlations. More than 16 million hadronic Z0 decays
and several thousand W+W- events have been recorded from the four LEP
collaborations between 1989 and 2000. Recently, in Z0 decays, new results of
Bose-Einstein correlations in pairs of pions and Fermi-Dirac correlations for
antiproton pairs were reported. In fully-hadronic W+W- decays particle
correlations were used to study whether the two W bosons decay independently. | hep-ex |
Measurement of the production of neighbouring jets in lead-lead
collisions at $\sqrt{s_{\mathrm{NN}}} = 2.76$ TeV with the ATLAS detector: This Letter presents measurements of correlated production of nearby jets in
Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 2.76$ TeV using the ATLAS
detector at the Large Hadron Collider. The measurement was performed using 0.14
${\rm nb}^{-1}$ of data recorded in 2011. The production of correlated jet
pairs was quantified using the rate, $R_{\Delta R}$, of "neighbouring" jets
that accompany "test" jets within a given range of angular distance, $\Delta
R$, in the pseudorapidity--azimuthal angle plane. The jets were measured in the
ATLAS calorimeter and were reconstructed using the anti-$k_{t}$ algorithm with
radius parameters $d = 0.2$, $0.3$, and $0.4$. $R_{\Delta R}$ was measured in
different Pb+Pb collision centrality bins, characterized by the total
transverse energy measured in the forward calorimeters. A centrality dependence
of $R_{\Delta R}$ is observed for all three jet radii with $R_{\Delta R}$ found
to be lower in central collisions than in peripheral collisions. The ratios
formed by the $R_{\Delta R}$ values in different centrality bins and the values
in the 40-80 % centrality bin are presented. | hep-ex |
Top-quark pair production in association with a $Z$ boson in the 4$\ell$
channel with the ATLAS experiment: The cross section of the $t\bar{t}Z$~and $t\bar{t}W$~processes are measured
in a simultaneous fit using 36.1 $\text{fb}^{-1}$ of of proton--proton
collisions at a centre-of-mass energy of $\sqrt{s}=13$ TeV recorded by the
ATLAS experiment at the LHC. In addition, a fit is performed in the 4$\ell$
channel only, resulting in a cross section of $\sigma_{t\bar{t}Z} = 1.07 \pm
0.26 \,\text{pb}$. This result is consistent with the combined fit and agrees
with the prediction by the Standard Model. | hep-ex |
Fraction Constraint in Partial Wave Analysis: To resolve the non-convex optimization problem in partial wave analysis, this
paper introduces a novel approach that incorporates fraction constraints into
the likelihood function. This method offers significant improvements in both
the efficiency of pole searching and the reliability of resonance selection
within partial wave analysis. | hep-ex |
Indirect CP violation results and HFAG averages: The current status of the search for indirect CP violation in the neutral D
meson system at the B-factories and at LHCb is reported. The indirect CP
asymmetry search is performed by the measurement of the proper-time asymmetry
($A_{\Gamma}$) in decays of $D^0-\bar{D^0}$ mesons to CP eigenstates, $K^-K^+$
and $\pi^- \pi^+$, and by $y_{CP}$, the ratio between the effective lifetime
measured in decay to a CP eigenstate and that to the mixed eigenstate $K \pi$.
All results are consistent with the no CP violation hypothesis. The latest
world averages for mixing and CP asymmetry in the charm sector evaluated by the
Heavy Flavour Averaging Group are presented. The no mixing hypothesis is
excluded at more than 12 standard deviations. The search for direct and
indirect CP violation in the charm sector is consistent with no CP violation at
2.0% confident level. | hep-ex |
Machine Learning Solutions for High Energy Physics: Applications to
Electromagnetic Shower Generation, Flavor Tagging, and the Search for
di-Higgs Production: This thesis demonstrate the efficacy of designing and developing machine
learning (ML) algorithms to selected use cases that encompass many of the
outstanding challenges in the field of experimental high energy physics.
Although simple implementations of neural networks and boosted decision trees
have been used in high energy physics for a long time, the field of ML has
quickly evolved by devising more complex, fast and stable implementations of
learning algorithms. The complexity and power of state-of-the-art deep learning
far exceeds those of the learning algorithms implemented in the CERN-developed
\texttt{ROOT} library. All aspects of experimental high energy physics have
been and will continue being revolutionized by the software- and hardware-based
technological advances spearheaded by both academic and industrial research in
other technical disciplines, and the emergent trend of increased
interdisciplinarity will soon reframe many scientific domains. This thesis
exemplifies this spirit of versatility and multidisciplinarity by bridging the
gap between ML and particle physics, and exploring original lines of work to
modernize the reconstruction, particle identification, simulation, and analysis
workflows. This contribution documents a collection of novel approaches to
augment traditional domain-specific methods with modern, automated techniques
based on industry-standard, open-source libraries. Specifically, it contributes
to setting the state-of-the-art for impact parameter-based flavor tagging and
di-Higgs searches in the $\gamma \gamma b\bar{b} $ channel with the ATLAS
detector at the LHC, it introduces and lays the foundations for the use of
generative adversarial networks for the simulation of particle showers in
calorimeters. These results substantiate the notion of ML powering particle
physics in the upcoming years and establish baselines for future applications. | hep-ex |
$C\!P$ violation in beauty and charm quarks at LHCb: The LHCb experiment has been reporting remarkable $C\!P$-violation (CPV)
measurements concerning the sectors of $b$ and $c$ quarks. Recently, the new
measurements of time-integrated CPV with $D^0\to K^+ K^-$ decays led to the
first evidence ($3.8\sigma$) of CPV in a single charmed decay. The first search
for CPV in the $D_{(s)}^+\to K^+K^+K^-$ decays was executed. The knowledge of
the CKM parameter $\gamma$ was improved by new results; the current combination
of the LHCb measurements is: $\left(63.8^{+3.5}_{-3.7}\right)^\circ$. The study
of $B_s^0\to\phi\phi$ decays resulted in the most precise measurement of
time-dependent CPV in any penguin-dominated $B$ meson decay. All the results
are consistent with the Standard-Model predictions. | hep-ex |
Search for new particles decaying to a jet and an emerging jet: A search is performed for events consistent with the pair production of a new
heavy particle that acts as a mediator between a dark sector and normal matter,
and that decays to a light quark and a new fermion called a dark quark. The
search is based on data corresponding to an integrated luminosity of 16.1
fb$^{-1}$ from proton-proton collisions at $\sqrt{s} =$ 13 TeV collected by the
CMS experiment at the LHC in 2016. The dark quark is charged only under a new
quantum-chromodynamics-like force, and forms an "emerging jet" via a parton
shower, containing long-lived dark hadrons that give rise to displaced vertices
when decaying to standard model hadrons. The data are consistent with the
expectation from standard model processes. Limits are set at 95% confidence
level excluding dark pion decay lengths between 5 and 225 mm for dark mediators
with masses between 400 and 1250 GeV. Decay lengths smaller than 5 mm and
greater than 225 mm are also excluded in the lower part of this mass range. The
dependence of the limit on the dark pion mass is weak for masses between 1 and
10 GeV. This analysis is the first dedicated search for the pair production of
a new particle that decays to a jet and an emerging jet. | hep-ex |
Precise Neutron Lifetime Measurement Using Pulsed Neutron Beams at
J-PARC: A neutron decays into a proton, an electron, and an anti-neutrino through the
beta-decay process. The decay lifetime ($\sim$880 s) is an important parameter
in the weak interaction. For example, the neutron lifetime is a parameter used
to determine the |$V_{\rm ud}$| parameter of the CKM quark mixing matrix. The
lifetime is also one of the input parameters for the Big Bang Nucleosynthesis,
which predicts light element synthesis in the early universe. However,
experimental measurements of the neutron lifetime today are significantly
different (8.4 s or 4.0$\sigma$) depending on the methods. One is a bottle
method measuring surviving neutron in the neutron storage bottle. The other is
a beam method measuring neutron beam flux and neutron decay rate in the
detector. There is a discussion that the discrepancy comes from unconsidered
systematic error or undetectable decay mode, such as dark decay. A new type of
beam experiment is performed at the BL05 MLF J-PARC. This experiment measured
neutron flux and decay rate simultaneously with a time projection chamber using
a pulsed neutron beam. We will present the world situation of neutron lifetime
and the latest results at J-PARC. | hep-ex |
Measurement of the branching fraction for $ψ(3770) \to
γχ_{c0}$: By analyzing a data set of 2.92 fb$^{-1}$ of $e^+e^-$ collision data taken at
$\sqrt s= 3.773~\rm GeV$ and 106.41$\times 10^{6}$ $\psi(3686)$ decays taken at
$\sqrt s= 3.686~\rm GeV$ with the BESIII detector at the BEPCII collider, we
measure the branching fraction and the partial decay width for
$\psi(3770)\to\gamma\chi_{c0}$ to be ${\mathcal
B}(\psi(3770)\to\gamma\chi_{c0})=(6.88\pm0.28\pm0.67)\times 10^{-3}$ and
$\Gamma[\psi(3770)\to\gamma\chi_{c0}]=(187\pm8\pm19)~\rm keV$, respectively.
These are the most precise measurements to date. | hep-ex |
Precision Analysis of the $^{136}$Xe Two-Neutrino $ββ$ Spectrum
in KamLAND-Zen and Its Impact on the Quenching of Nuclear Matrix Elements: We present a precision analysis of the $^{136}$Xe two-neutrino $\beta\beta$
electron spectrum above 0.8 MeV, based on high-statistics data obtained with
the KamLAND-Zen experiment. An improved formalism for the two-neutrino
$\beta\beta$ rate allows us to measure the ratio of the leading and subleading
$2\nu\beta\beta$ nuclear matrix elements (NMEs), $\xi^{2\nu}_{31} =
-0.26^{+0.31}_{-0.25}$. Theoretical predictions from the nuclear shell model
and the majority of the quasiparticle random-phase approximation (QRPA)
calculations are consistent with the experimental limit. However, part of the
$\xi^{2\nu}_{31}$ range allowed by the QRPA is excluded by the present
measurement at the 90% confidence level. Our analysis reveals that predicted
$\xi^{2\nu}_{31}$ values are sensitive to the quenching of NMEs and the
competing contributions from low- and high-energy states in the intermediate
nucleus. Since these aspects are also at play in neutrinoless $\beta\beta$
decay, $\xi^{2\nu}_{31}$ provides new insights towards reliable neutrinoless
$\beta\beta$ NMEs. | hep-ex |
Measurement of isolated-photon plus two-jet production in $pp$
collisions at $\sqrt{s}=13$ TeV with the ATLAS detector: The dynamics of isolated-photon plus two-jet production in $pp$ collisions at
a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the
LHC using a dataset corresponding to an integrated luminosity of 36.1
fb$^{-1}$. Cross sections are measured as functions of a variety of
observables, including angular correlations and invariant masses of the objects
in the final state, $\gamma+jet+jet$. Measurements are also performed in
phase-space regions enriched in each of the two underlying physical mechanisms,
namely direct and fragmentation processes. The measurements cover the range of
photon (jet) transverse momenta from 150 GeV (100 GeV) to 2 TeV. The tree-level
plus parton-shower predictions from SHERPA and PYTHIA as well as the
next-to-leading-order QCD predictions from SHERPA are compared with the
measurements. The next-to-leading-order QCD predictions describe the data
adequately in shape and normalisation except for regions of phase space such as
those with high values of the invariant mass or rapidity separation of the two
jets, where the predictions overestimate the data. | hep-ex |
Search for neutral MSSM Higgs bosons decaying into a pair of bottom
quarks: A search for neutral Higgs bosons decaying into a b-bbar quark pair and
produced in association with at least one additional b quark is presented. This
signature is sensitive to the Higgs sector of the minimal supersymmetric
standard model (MSSM) with large values of the parameter tan(beta). The
analysis is based on data from proton-proton collisions at a center-of-mass
energy of 8 TeV collected with the CMS detector at the LHC, corresponding to an
integrated luminosity of 19.7 inverse femtobarns. The results are combined with
a previous analysis based on 7 TeV data. No signal is observed. Stringent upper
limits on the cross section times branching fraction are derived for Higgs
bosons with masses up to 900 GeV, and the results are interpreted within
different MSSM benchmark scenarios, m[h,max], m[h,mod+], m[h,mod-], light-stau
and light-stop. Observed 95% confidence level upper limits on tan(beta),
ranging from 14 to 50, are obtained in the m[h,mod+] benchmark scenario. | hep-ex |
Measurement of dijet azimuthal decorrelations in $pp$ collisions at
$\sqrt{s}=8$ TeV with the ATLAS detector and determination of the strong
coupling: A measurement of the rapidity and transverse momentum dependence of dijet
azimuthal decorrelations is presented, using the quantity $R_{\Delta \phi}$.
The quantity $R_{\Delta \phi}$ specifies the fraction of the inclusive dijet
events in which the azimuthal opening angle of the two jets with the highest
transverse momenta is less than a given value of the parameter $\Delta
\phi_\mathrm{max}$. The quantity $R_{\Delta \phi}$ is measured in
proton--proton collisions at $\sqrt{s}=$8 TeV as a function of the dijet
rapidity interval, the event total scalar transverse momentum, and $\Delta
\phi_\mathrm{max}$. The measurement uses an event sample corresponding to an
integrated luminosity of 20.2 fb$^{-1}$ collected with the ATLAS detector at
the CERN Large Hadron Collider. Predictions of a perturbative QCD calculation
at next-to-leading order in the strong coupling with corrections for
non-perturbative effects are compared to the data. The theoretical predictions
describe the data in the whole kinematic region. The data are used to determine
the strong coupling $\alpha_{\mathrm{S}}$ and to study its running for momentum
transfers from 260 GeV to above 1.6 TeV. An analysis that combines data at all
momentum transfers results in $\alpha_{\mathrm{S}}(m_{Z}) =
0.1127^{+0.0063}_{-0.0027}$. | hep-ex |
Search for the process $e^+e^-\to η^\prime(958)$ with the CMD-3
detector: A search for the process $\epem\to \eta^\prime(958)$ in the
$\pipi\eta\to\pipi\gamma\gamma$ final state has been performed with the CMD-3
detector at the VEPP-2000 $e^+e^-$ collider. Using an integrated luminosity of
2.69 pb$^{-1}$ collected at the center-of-mass energy \Ecm = 957.68 MeV we set
an upper limit for the product of electronic width and branching fractions
$\Gamma_{\eta^\prime(958)\to\epem}\cdot\BR_{\eta^\prime(958)\to\pipi\eta}\cdot\BR_{\eta\to\gamma\gamma}<0.00041$
eV at 90\% C.L. | hep-ex |
Tau lepton reconstruction at collider experiments using impact
parameters: We present a novel method for the reconstruction of events containing pairs
of hadronically decaying tau leptons at collider experiments. This method
relies on accurate knowledge of the tau production vertex and precise
measurement of its charged decay products. The method makes no assumptions
about the centre-of-mass or invariant mass of the tau pair, and is insensitive
to momentum loss along the beam direction. We demonstrate the method using e+e-
-> mu+ mu- tau+ tau- events fully simulated in the ILD detector. | hep-ex |
An Improved Measurement of Neutrino Oscillation Parameters by the NOvA
Experiment: We present new $\nu_\mu\rightarrow\nu_e$, $\nu_\mu\rightarrow\nu_\mu$,
$\overline{\nu}_\mu\rightarrow\overline{\nu}_e$, and
$\overline{\nu}_\mu\rightarrow\overline{\nu}_\mu$ oscillation measurements by
the NOvA experiment, with a 50% increase in neutrino-mode beam exposure over
the previously reported results. The additional data, combined with previously
published neutrino and antineutrino data, are all analyzed using improved
techniques and simulations. A joint fit to the $\nu_e$, $\nu_\mu$,
$\overline{\nu}_e$, and $\overline{\nu}_\mu$ candidate samples within the
3-flavor neutrino oscillation framework continues to yield a best-fit point in
the normal mass ordering and the upper octant of the $\theta_{23}$ mixing
angle, with $\Delta m^{2}_{32} = (2.41\pm0.07)\times 10^{-3}$ eV$^2$ and
$\sin^2\theta_{23} = 0.57^{+0.03}_{-0.04}$. The data disfavor combinations of
oscillation parameters that give rise to a large asymmetry in the rates of
$\nu_e$ and $\overline{\nu}_e$ appearance. This includes values of the
CP-violating phase in the vicinity of $\delta_\text{CP} = \pi/2$ which are
excluded by $>3\sigma$ for the inverted mass ordering, and values around
$\delta_\text{CP} = 3\pi/2$ in the normal ordering which are disfavored at
2$\sigma$ confidence. | hep-ex |
Search for dark matter in events with missing transverse momentum and a
Higgs boson decaying into two photons in $pp$ collisions at $\sqrt{s} = 13$
TeV with the ATLAS detector: A search for dark-matter particles in events with large missing transverse
momentum and a Higgs boson candidate decaying into two photons is reported. The
search uses $139$ fb$^{-1}$ of proton-proton collision data collected at
$\sqrt{s}=13$ TeV with the ATLAS detector at the CERN LHC between 2015 and
2018. No significant excess of events over the Standard Model predictions is
observed. The results are interpreted by extracting limits on three simplified
models that include either vector or pseudoscalar mediators and predict a final
state with a pair of dark-matter candidates and a Higgs boson decaying into two
photons. | hep-ex |
Differential cross section measurements for the production of a W boson
in association with jets in proton-proton collisions at sqrt(s) = 7 TeV: Measurements are reported of differential cross sections for the production
of a W boson, which decays into a muon and a neutrino, in association with
jets, as a function of several variables, including the transverse momenta (pt)
and pseudorapidities of the four leading jets, the scalar sum of jet transverse
momenta (HT), and the difference in azimuthal angle between the directions of
each jet and the muon. The data sample of pp collisions at a centre-of-mass
energy of 7 TeV was collected with the CMS detector at the LHC and corresponds
to an integrated luminosity of 5.0 inverse femtobarns. The measured cross
sections are compared to predictions from Monte Carlo generators, MADGRAPH +
PYTHIA and SHERPA, and to next-to-leading-order calculations from BLACKHAT +
SHERPA. The differential cross sections are found to be in agreement with the
predictions, apart from the pt distributions of the leading jets at high pt
values, the distributions of the HT at high-HT and low jet multiplicity, and
the distribution of the difference in azimuthal angle between the leading jet
and the muon at low values. | hep-ex |
New measurement of $θ_{13}$ via neutron capture on hydrogen at Daya
Bay: This article reports an improved independent measurement of neutrino mixing
angle $\theta_{13}$ at the Daya Bay Reactor Neutrino Experiment. Electron
antineutrinos were identified by inverse $\beta$-decays with the emitted
neutron captured by hydrogen, yielding a data-set with principally distinct
uncertainties from that with neutrons captured by gadolinium. With the final
two of eight antineutrino detectors installed, this study used 621 days of data
including the previously reported 217-day data set with six detectors. The
dominant statistical uncertainty was reduced by 49%. Intensive studies of the
cosmogenic muon-induced $^9$Li and fast neutron backgrounds and the
neutron-capture energy selection efficiency, resulted in a reduction of the
systematic uncertainty by 26%. The deficit in the detected number of
antineutrinos at the far detectors relative to the expected number based on the
near detectors yielded $\sin^22\theta_{13} = 0.071 \pm 0.011$ in the
three-neutrino-oscillation framework. The combination of this result with the
gadolinium-capture result is also reported. | hep-ex |
Observation of the semi-muonic decay $D^+\to ωμ^+ν_μ$: We report the first observation of the semi-muonic decay $D^+\to \omega
\mu^+\nu_\mu$ using an $e^+e^-$ collision data sample corresponding to an
integrated luminosity of $2.93~\mathrm{fb}^{-1}$ collected with the BESIII
detector at a center-of-mass energy of 3.773 GeV. The absolute branching
fraction of the $D^+\to \omega \mu^+\nu_\mu$ decay is measured to be ${\mathcal
B}_{D^+\to \omega\mu^+\nu_\mu}=(17.7\pm1.8_{\rm stat}\pm1.1_{\rm syst})\times
10^{-4}$. Its ratio with the world average value of the branching fraction of
the $D^+\to \omega e^+\nu_e$ decay probes lepton flavor universality and it is
determined to be ${\mathcal B}_{D^+\to \omega \mu^+\nu_\mu}/{\mathcal B}^{\rm
PDG}_{D^+\to \omega e^+\nu_e}=1.05\pm0.14$, in agreement with the standard
model expectation within one standard deviation. | hep-ex |
Exploring coherent elastic neutrino-nucleus scattering using reactor
electron antineutrinos in the NEON experiment: Neutrino elastic scattering observation with NaI (NEON) is an experiment
designed to detect neutrino-nucleus coherent scattering using reactor electron
antineutrinos. NEON is based on an array of six NaI(Tl) crystals with a total
mass of 13.3 kg, located at the tendon gallery that is 23.7 m away from a
reactor core with a thermal power of 2.8 GW in the Hanbit nuclear power
complex. The installation of the NEON detector was completed in December 2020,
and since May 2021, the detector has acquired data at full reactor power. Based
on the observed light yields of the NaI crystals of approximately 22, number of
photoelectrons per unit keV electron-equivalent energy (keVee), and 6
counts/kg/keV/day background level at 2-6 keVee energy, coherent elastic
neutrino-nucleus scattering observation sensitivity is evaluated as more than
3$\sigma$ assuming one-year reactor-on and 100 days reactor-off data, 0.2 keVee
energy threshold, and 7 counts/keV/kg/day background in the signal region of
0.2-0.5 keVee. This paper describes the design of the NEON detector, including
the shielding arrangement, configuration of NaI(Tl) crystals, and associated
operating systems. The initial performance and associated sensitivity of the
experiment are also presented. | hep-ex |
Extracting TMDs from CLAS12 data: We present studies of double longitudinal spin asymmetries in semi-inclusive
deep inelastic scattering using a new dedicated Monte Carlo generator, which
includes quark intrinsic transverse momentum within the generalized parton
model based on the fully differential cross section for the process.
Additionally we employ Bessel-weighting to the MC events to extract transverse
momentum dependent parton distribution functions and also discuss possible
uncertainties due to kinematic correlation effects. | hep-ex |
Study of the $ρ$ and $ω$ meson decays into pseudoscalar meson
and $e^+e^-$ pair with the CMD-2 detector: Using 3.3 pb$^{-1}$ of data collected with the CMD-2 detector in the 720 --
840 MeV c.m. energy range, the branching fraction of the conversion decay
$\omega\to\pi^0e^+e^-$ has been measured:
$\mathcal{B}(\omega\to\pi^0e^+e^-)=(8.19\pm0.71\pm0.62)\cdot10^{-4}$. The upper
limits for the branching fractions of the following conversion decays have been
obtained at the 90% confidence level:
$\mathcal{B}(\rho\to\pi^0e^+e^-)<1.6\cdot10^{-5}$, $\mathcal{B}(\rho\to\eta
e^+e^-)<0.7\cdot10^{-5}$ and $\mathcal{B}(\omega\to\eta
e^+e^-)<1.1\cdot10^{-5}$. | hep-ex |
Snowmass Neutrino Frontier: Neutrino Interaction Cross Sections (NF06)
Topical Group Report: A thorough understanding of neutrino cross sections in a wide range of
energies is crucial for the successful execution of the entire neutrino physics
program. In order to extract neutrino properties, long-baseline experiments
need an accurate determination of neutrino cross sections within their
detector(s). Since very few of the needed neutrino cross sections across the
energy spectrum are directly measured, we emphasize the need for theoretical
input and indirect measurements such as electron scattering, which would
complement direct measurements. In this report we briefly summarize the current
status of our knowledge of the neutrino cross sections and articulate needs of
the experiments, ongoing and planned, at energies ranging from CEvNS and
supernova neutrino energies to the DUNE and atmospheric neutrino energies. | hep-ex |
A new parameterization of the nucleon elastic form factors: The nucleon elastic form factors are generally interpreted as a mapping of
the charge and magnetic current distributions of the proton and neutron. New
high Q^2 measurements have opened up fundamental questions about G_ep that
remain to be answered. This talk will summarize current developments
surrounding the nucleon form factors and explain why they are important to
neutrino physicists. New parameterizations of the nucleon form factors,
suitable for use by neutrino physicists, will be introduced and discussed. | hep-ex |
Search for decays of stopped long-lived particles produced in
proton-proton collisions at sqrt(s) = 8 TeV: A search has been performed for long-lived particles that could have come to
rest within the CMS detector, using the time intervals between LHC beam
crossings. The existence of such particles could be deduced from observation of
their decays via energy deposits in the CMS calorimeter appearing at times that
are well separated from any proton-proton collisions. Using a data set
corresponding to an integrated luminosity of 18.6 inverse femtobarns of 8 TeV
proton-proton collisions, and a search interval corresponding to 281 hours of
trigger livetime, 10 events are observed, with a background prediction of 13.2
+3.6 -2.5 events. Limits are presented at 95% confidence level on gluino and
top squark production, for over 13 orders of magnitude in the mean proper
lifetime of the stopped particle. Assuming a cloud model of R-hadron
interactions, a gluino with mass < 1000 GeV and a top squark with mass < 525
GeV are excluded, for lifetimes between 1 microsecond and 1000 s. These results
are the most stringent constraints on stopped particles to date. | hep-ex |
Universality of the underlying event in pp collisions: In this paper we study ATLAS results on underlying event in pp collisions at
$\sqrt{s}$=0.9, 7 and 13 TeV. We show that the center-of-mass energy
dependences of the charged-particle production sensitive to the underlying
event ("transverse" region) and to the hardest partonic interaction ("towards"
and "away" regions) in pp collisions can be both understood in terms of the
change of the inclusive average multiplicity. Within uncertainties, the
corresponding particle production as a function of the leading charged particle
shows no significant $\sqrt{s}$-dependence for the three regions once they are
scaled according to the relative change in multiplicity. The scaling properties
reported here are well reproduced by PYTHIA 8.212 tune Monash 2013 and suggest
an universality of the underlying event in hadronic interactions at high
$\sqrt{s}$. Based on the simulations, we observed that the same scaling
properties are also present in the average number of multi-partonic
interactions as a function of the leading charged particle. Moreover, the
multiplicity distributions associated to the underlying event exhibit a KNO
scaling. | hep-ex |
Measurements of the branching fractions of $Λ_c^+ \to p η$ and
$Λ_c^+ \to p π^0$ decays at Belle: We report measurements of the branching fractions of singly
Cabibbo-suppressed decays $\Lambda_c^+ \to p \eta$ and $\Lambda_c^+ \to p
\pi^0$ using the full Belle data sample corresponding to an integrated
luminosity of 980.6 $\rm fb^{-1}$. The data were collected by the Belle
detector at the KEKB $e^{+}$$e^{-}$ asymmetric-energy collider. A clear
$\Lambda_c^+$ signal is seen in the invariant mass distribution of $p \eta$.
The signal yield of the $\Lambda_c^+ \to p \eta$ process is $7734 \pm 263$;
from this, we measure the ratio of branching fractions ${\cal B}(\Lambda_c^+
\to p \eta)/{\cal B}(\Lambda_c^+ \to p K^- \pi^+) = (2.258 \pm 0. 077(\rm stat.
) \pm 0.136(\rm syst. ))\times 10^{-2}$, from which we infer the branching
fraction ${\cal B}(\Lambda_c^+ \to p \eta) = (1.42 \pm 0.05(\rm stat.) \pm
0.11(\rm syst.)) \times 10^{-3}$. In addition, no significant signal for
$\Lambda_c^+ \to p \pi^0$ is found so an upper limit on the branching fraction
of ${\cal B}(\Lambda_c^+ \to p \pi^0)<8.0 \times 10^{-5}$ at 90\% credibility
level is set, more than three times better than the best current upper limit. | hep-ex |
Long-term temporal stability of the DarkSide-50 dark matter detector: The stability of a dark matter detector on the timescale of a few years is a
key requirement due to the large exposure needed to achieve a competitive
sensitivity. It is especially crucial to enable the detector to potentially
detect any annual event rate modulation, an expected dark matter signature. In
this work, we present the performance history of the DarkSide-50 dual-phase
argon time projection chamber over its almost three-year low-radioactivity
argon run. In particular, we focus on the electroluminescence signal that
enables sensitivity to sub-keV energy depositions. The stability of the
electroluminescence yield is found to be better than 0.5%. Finally, we show the
temporal evolution of the observed event rate around the sub-keV region being
consistent to the background prediction. | hep-ex |
Measurement of neutral-current $K^+$ production by neutrinos using
MINERvA: Neutral-current production of $K^{+}$ by atmospheric neutrinos is a
background in searches for the proton decay $p \rightarrow K^{+} \bar{\nu}$.
Reactions such as $\nu p \rightarrow \nu K^{+} \Lambda$ are indistinguishable
from proton decays when the decay products of the $\Lambda$ are below detection
threshold. Events with $K^{+}$ are identified in MINERvA by reconstructing the
timing signature of a $K^{+}$ decay at rest. A sample of 201 neutrino-induced
neutral-current $K^{+}$ events is used to measure differential cross sections
with respect to the $K^{+}$ kinetic energy, and the non-$K^{+}$ hadronic
visible energy. An excess of events at low hadronic visible energy is observed
relative to the prediction of the NEUT event generator. Good agreement is
observed with the cross section prediction of the GENIE generator. A search for
photons from $\pi^{0}$ decay, which would veto a neutral-current $K^{+}$ event
in a proton decay search, is performed, and a 2$\sigma$ deficit of detached
photons is observed relative to the GENIE prediction. | hep-ex |
Status of Dual-Readout Calorimetry for Future High-Energy Physics
Experiments: Future experiments at high energy $e^+e^-$ colliders will focus on extremely
precise Standard Model measurements. Among the most important physics
benchmarks, there is the capability to resolve the Higgs decays into W or Z
pairs, in their completely hadronic decay modes (4 jets in the final state),
only based on the invariant mass of the jet pair coming from decay of the
on-shell boson. This translates into a relative energy resolution target of
$30\%/\sqrt{E}$, well beyond current detector performances. Dual-readout
calorimetry is a technique which aims to improve the energy resolution, for
single hadrons and hadronic jets, exploiting the information produced by two
different physical processes, namely scintillation and Cerenkov light emission.
The IDEA detector, whose concept has been included in both the FCC and CEPC
Conceptual Design Reports, is based on a dual-readout fibre calorimeter with
independent fibre readout exploiting Silicon PhotoMultipliers (SiPMs). The
individual SiPM information will be beneficial for a highly granular
calorimeter design, opening up to advanced reconstruction techniques such as
Particle Flow and a variety of neural network algorithms. In this paper the
status of calorimeter prototypes that have been developed to demonstrate the
feasibility of the dual-readout method in association with the high granularity
feature is illustrated. The specific choice for the design of each prototype is
presented, together with the performances achieved at high-energy test beams or
through simulations. | hep-ex |
LHC experiments for long-lived particles of the dark sector: Dark matter scenarios are being tested at the LHC in the general-purpose
experiments through promptly decaying states. In parallel, new dedicated
detectors have been proposed for the LHC to probe dark matter portal theories
predicting long-lived particles that decay away from the interaction point:
MoEDAL-MAPP, MoEDAL-MALL, FASER, SND@LHC, CODEX-b, MATHUSLA, AL3X, ANUBIS,
FACET, milliQan, FORMOSA. In addition, the SHiP beam-dump experiment is planned
to operate with the SPS beam to extend the discovery reach for such particles.
The detector design and expected physics sensitivity of these experiments is
presented with emphasis on scenarios explaining the nature of dark matter. | hep-ex |
Top physics in ATLAS: These proceedings summarize the latest measurements on top production, top
properties and searches using the ATLAS detector at the LHC. The measurements
are performed on $pp$ collision data with a center of mass energy $\sqrt{s} =
7, 8$ and $13$ TeV. | hep-ex |
Measurement of $ν_μ$ and $\barν_μ$ Neutral Current
$π^{0} \rightarrow γγ$ Production in the ArgoNeuT Detector: The ArgoNeuT collaboration reports the first measurement of neutral current
$\pi^{0}$ production in $\nu_{\mu}$-argon and $\bar{\nu}_{\mu}$-argon
scattering. This measurement was performed using the ArgoNeuT liquid argon time
projection chamber deployed at Fermilab's NuMI neutrino beam with an exposure
corresponding to 1.2$\times 10^{20}$ protons-on-target from the Fermilab Main
Injector and a mean energy for $\nu_{\mu}$ of 9.6~GeV and for $\bar{\nu}_{\mu}$
of 3.6~GeV. We compare the measured cross section and kinematic distributions
to predictions from the GENIE and NuWro neutrino interaction event generators. | hep-ex |
Search for stop production in R-parity-violating supersymmetry at HERA: A search for stop production in R-parity-violating supersymmetry has been
performed in $e^{+}p$ interactions with the ZEUS detector at HERA, using an
integrated luminosity of 65 pb$^{-1}$. At HERA, the R-parity-violating coupling
$\lambda'$ allows resonant squark production, $e^+d\to\tilde{q}$. Since the
lowest-mass squark state in most supersymmetry models is the light stop,
$\tilde{t}$, this search concentrated on production of $\tilde{t}$, followed
either by a direct R-parity-violating decay, or by the gauge decay to
$b\tilde{\chi}^+_{1}$. No evidence for stop production was found and limits
were set on $\lambda'_{131}$ as a function of the stop mass in the framework of
the Minimal Supersymmetric Standard Model. The results have also been
interpreted in terms of constraints on the parameters of the minimal
Supergravity model. | hep-ex |
Heavy Flavour results from Tevatron: The CDF and D0 experiments finalize the analysis of their full statistics
collected in the $p \bar p$ collisions at a center-of-mass energy of $\sqrt{s}
= 1.96$ TeV at the Fermilab Tevatron collider. This paper presents several new
results on the properties of hadrons containing heavy $b$- and $c$-quarks
obtained by both collaborations. These results include the search for the rare
decays $B^0, B^0_s \to \mu^+ \mu^-$ (CDF), the study of CP asymmetry in $B_s
\to J\psi \phi$ decay (CDF, D0), the measurement of the like-sign dimuon charge
asymmetry (D0), the measurement of CP asymmetry in $D^0 \to K^+K^-$ and $D^0
\to \pi^+\pi^-$ decays (CDF), and the new measurement of the $B_s \to
D_s^{(*)+} D_s^{(*)-}$ branching fraction (CDF). Both experiments still expect
to produce more results on the properties of heavy flavours. | hep-ex |
Measurement of F_2^{c\bar{c}} and F_2^{b\bar{b}} at Low Q^2 and x using
the H1 Vertex Detector at HERA: Measurements are presented of inclusive charm and beauty cross sections in
e^+p collisions at HERA for values of photon virtuality 12 \le Q^2 \le 60 GeV^2
and of the Bjorken scaling variable 0.0002 \le x \le 0.005. The fractions of
events containing charm and beauty quarks are determined using a method based
on the impact parameter, in the transverse plane, of tracks to the primary
vertex, as measured by the H1 vertex detector. Values for the structure
functions F_2^{c\bar{c}} and F_2^{b\bar{b}} are obtained. This is the first
measurement of F_2^{b\bar{b}} in this kinematic range. The results are found to
be compatible with the predictions of perturbative quantum chromodynamics and
withprevious measurements of F_2^{c\bar{c}}. | hep-ex |
Observation of the decay $ψ(3686)$ $\rightarrow$
$Λ\barΣ^{\pm}π^{\mp}+c.c.$: Using a sample of $1.06\times10^{8}$ $\psi(3686)$ events collected with the
BESIII detector, we present the first observation of the decays of $\psi(3686)$
$\rightarrow$ $\Lambda\bar\Sigma^{+}\pi^{-}+c.c.$ and $\psi(3686)$
$\rightarrow$ $\Lambda\bar\Sigma^{-}\pi^{+}+c.c.$. The branching fractions are
measured to be $\mathcal{B}(\psi(3686) \rightarrow \Lambda\bar\Sigma^{+}\pi^{-}
+ c.c.)=(1.40\pm 0.03 \pm 0.13)\times10^{-4}$ and $\mathcal{B}(\psi(3686)
\rightarrow \Lambda\bar\Sigma^{-}\pi^{+}+c.c.)=(1.54\pm 0.04 \pm
0.13)\times10^{-4}$, where the first errors are statistical and the second ones
systematic. | hep-ex |
Observation of the Decay \bar{B0}-> Ds+ Lambda \bar{p}: We report the first observation of the decay \bar{B0} -> D_s^+ Lambda \bar{p}
with a statistical significance of 6.6 sigma. We measure Br(\bar{B0} -> Ds+
Lambda \bar{p}) = (2.9 \pm 0.7\pm 0.5 \pm 0.4)* 10^{-5}, where the first error
is statistical, the second is systematic and the third error comes fr\om the
uncertainty in Br(Ds+ -> phi pi+). The data used for this analysis was
accumulated at the Upsilon(4S) resonance, using the Belle detector at the KEKB
asymmetric-energy e+e- collider. The integrated luminosity of the data sample
is 414 fb-1, corresponding to 449*10^{6} B{\bar B} pairs. | hep-ex |
Measurement of the branching fraction and search for CP violation in
$D^0\rightarrow K^0_S\,K^0_S\,π^+π^-$ decays at Belle: We measure the branching fraction for the Cabibbo-suppressed decay
$D^0\rightarrow K^0_S\,K^0_S\,\pi^+\pi^-$ and search for $CP$ violation via a
measurement of the $CP$ asymmetry $A_{\rm CP}$ as well as the $T$-odd
triple-product asymmetry $a^T_{\rm CP}$. We use 922 fb$^{-1}$ of data recorded
by the Belle experiment, which ran at the KEKB asymmetric-energy $e^+e^-$
collider. The branching fraction is measured relative to the Cabibbo-favored
normalization channel $D^0\rightarrow K^0_S\,\pi^+\pi^-$; the result is
$\mathcal{B}(D^0\rightarrow K^0_S\,K^0_S\,\pi^+\pi^-) = [4.79 \pm 0.08\,({\rm
stat}) \pm 0.10\,({\rm syst}) \pm 0.31\,({\rm norm})]\times 10^{-4}$, where the
first uncertainty is statistical, the second is systematic, and the third is
from uncertainty in the normalization channel. We also measure $A_{\rm CP} =
[-2.51\,\pm 1.44\,({\rm stat})\,^{+0.11}_{-0.10}\,({\rm syst})]\%$, and
$a^T_{\rm CP} = [-1.95\,\pm 1.42\,({\rm stat})\,^{+0.14}_{-0.12}\,({\rm
syst})]\%$. These results show no evidence of CP violation. | hep-ex |
Search for charged Higgs bosons in decays of top quarks: We present a search for charged Higgs bosons in decays of top quarks, in the
mass range $80 < m_{H^{\pm} < 155$ GeV, assuming the subsequent decay $H^{+}
\to \tau^{+} \nu_\tau$ (and its charge conjugate). Using 0.9 fb$^{-1}$ of
lepton+jets data collected with the D0 detector at the Fermilab Tevatron
$p\bar{p}$ collider, operating at a center of mass energy $\sqrt{s}=1.96$ TeV,
we find no evidence for a $H^{\pm}$ signal. Hence, we exclude branching ratios
$B(t \to H^+b) > 0.24$ for $m_{H^{\pm}=80$ GeV, and $B(t \to H^+b) > 0.19$ for
$m_{H^{\pm}=155$ GeV, at the 95% C.L. | hep-ex |
Recent Results from KTeV: The implications of the published KTeV $K^0_L \to \pi^0\mu^+\mu^-$ result for
interpreting recent $\Sigma^+ \to p\mu^+\mu^-$ results are discussed. The
status of the KTeV $\Xi^0 \to \Sigma^+\mu^-\nu$ analysis is given. The KTeV
$|V_{us}|$ result is also given. | hep-ex |
Measurement of the top pair production cross-section in 8 TeV
proton-proton collisions using kinematic information in the lepton+jets final
state with ATLAS: A measurement is presented of the $t\bar{t}$ inclusive production
cross-section in $pp$ collisions at a center-of-mass energy of $\sqrt{s}=8$ TeV
using data collected by the ATLAS detector at the CERN Large Hadron Collider.
The measurement was performed in the lepton+jets final state using a data set
corresponding to an integrated luminosity of 20.3 fb$^{-1}$. The cross-section
was obtained using a likelihood discriminant fit and $b$-jet identification was
used to improve the signal-to-background ratio. The inclusive $t\bar{t}$
production cross-section was measured to be $260\pm 1{\textrm{(stat.)}}
^{+22}_{-23} {\textrm{(syst.)}}\pm 8{\textrm{(lumi.)}}\pm 4{\mathrm{(beam)}}$
pb assuming a top-quark mass of 172.5 GeV, in good agreement with the
theoretical prediction of $253^{+13}_{-15}$ pb. The $t\bar{t}\to
(e,\mu)+{\mathrm{jets}}$ production cross-section in the fiducial region
determined by the detector acceptance is also reported. | hep-ex |
Early Search for Supersymmetry at ATLAS: The search for physics beyond the Standard Model (BSM) is one of the most
important goals for the general purpose detector ATLAS at the Large Hadron
Collider at CERN. Supersymmetry search strategies based on generic event
signatures of high jet multiplicity and large missing transverse momentum,
optionally including leptons in the final state with R-parity conservation are
discussed in this document. We review the results for above SUSY search
strategies with first data up to 305 $nb^{-1}$ of integrated luminosity
collected by ATLAS during 2010 at a centre-of-mass energy of 7 TeV. | hep-ex |
Prospects for Measuring B_s->mu mu with the CMS Detector: The flavor-changing neutral current decay B_s->mu mu is highly suppressed in
the standard model, but its branching fraction of 3.4*10^-9 could be
significantly enhanced through contributions from new physics. At the LHC, this
rare decay could be observed for the first time. In this contribution, the
prospects for measuring B_s->mu mu with the CMS detector are presented. In
particular, some aspects of the experimental setup, the first and high level
trigger selections, and the offline analysis are discussed. | hep-ex |
Double Chooz: results towards the near detector phase: Since the first indication in 2011 of a non-vanishing value of $\theta_{13}$
using reactor neutrinos by Double Chooz, this collaboration has developed new
analyses leading to an increased precision on $\theta_{13}$ and different
cross-checks of the oscillation results. Beyond the update of the analysis
based on neutron captures on Gd in 2012, Double Chooz has also released a
consistent measurement of $\theta_{13}$ by means of neutron captures on H. The
combination of the n-Gd and n-H data samples, as well as 7.23 days of reactor
off data, in a global rate+shape analysis yields $\sin^22\theta_{13} = 0.109\pm
0.035$. This measurement has been validated with a new
background-model-independent approach, which compares the observed and expected
neutrino rates as a function of reactor power. This Reactor Rate Modulation
analysis yields $\sin^22\theta_{13} = 0.102\pm 0.043$ when combining the n-Gd
and n-H samples. The Double Chooz collaboration is currently developing a new
analysis increasing the signal-to-background ratio while reducing the
background and detection systematics. This new approach is being prepared as a
first step of the new phase of the experiment that will begin in summer 2014
with the operation of a near detector. | hep-ex |
Measurements of $t\bar{t}$ spin correlations in CMS: We present an overview of the measurements of $t\bar{t}$ spin correlations in
the CMS Collaboration. We present two analyses both in the dilepton channel
using proton-proton collisions at $\sqrt{s}\, =\, 7$ TeV based on an integrated
luminosity of 5.0 fb$^{-1}$. The spin correlations and polarization are
measured using angular asymmetries. The results are consistent with unpolarized
top quarks and Standard Model spin correlation. The second analysis sets a
limit on the real part of the top-quark chromo-magnetic dipole moment of
$-0.043\, <\, Re({\hat{\mu}}_{t})\, <\, 0.117$ at $95\,%$ confidence level
through the measured azimuthal angle difference between the two charged leptons
from $t\bar{t}$ production. | hep-ex |
Strangeness Production in Deep-Inelastic Positron-Proton Scattering at
HERA: Measurements are presented of $K^0$ meson and $\Lambda$ baryon production in
deep-inelastic positron-proton scattering (DIS) in the kinematic range $10 <
Q^2 < 70 $GeV$^2$ and $10^{-4} < x < 10^{-2}$. The measurements, obtained using
the H1 detector at the HERA collider, are discussed in the light of possible
mechanisms for increased strangeness production at low Bjorken-$x$. Comparisons
of the $x_F$ spectra, where $x_F$ is the fractional longitudinal momentum in
the hadronic centre-of-mass frame, with results from electron-positron
annihilation are made. The $x_F$ spectra and the $K^0$ ``seagull'' plot are
compared with previous DIS results. The mean $K^0$ and $\Lambda$ multiplicities
are studied as a function of the centre-of-mass energy $W$ and are observed to
be consistent with a logarithmic increase with $W$ when compared with previous
measurements. A comparison of the levels of strangeness production in
diffractive and non-diffractive DIS is made. An upper limit of $0.9 $nb, at the
95% confidence level, is placed on the cross-section for QCD instanton induced
events. | hep-ex |
Spin Physics Progress with the STAR Detector at RHIC: Progress in STAR over the last two years and projections for the coming two
years are discussed. Important technical developments have been the completion
of the barrel and endcap electromagnetic calorimeters. Measurement of inclusive
pi_0 and jet A_LL over the next two years are expected to answer whether
$\Delta$G is a major contributor to the proton's spin. Transverse effects such
as Collins and Sivers functions at mid-rapidity will also be investigated. | hep-ex |
Muon identification using multivariate techniques in the CMS experiment
in proton-proton collisions at $\sqrt{s}$ = 13 TeV: The identification of prompt and isolated muons, as well as muons from
heavy-flavour hadron decays, is an important task. We developed two
multivariate techniques to provide highly efficient identification for muons
with transverse momentum greater than 10 GeV. One provides a continuous
variable as an alternative to a cut-based identification selection and offers a
better discrimination power against misidentified muons. The other one selects
prompt and isolated muons by using isolation requirements to reduce the
contamination from nonprompt muons arising in heavy-flavour hadron decays. Both
algorithms are developed using 59.7 fb$^{-1}$ of proton-proton collisions data
at a centre-of-mass energy of $\sqrt{s}$ = 13 TeV collected in 2018 with the
CMS experiment at the CERN LHC. | hep-ex |
Search for transitions from $Υ(4S)$ and $Υ(5S)$ to
$η_b(1S)$ and $η_b(2S)$ with emission of an $ω$ meson: Using data collected in the Belle experiment at the KEKB asymmetric-energy
$e^+e^-$ collider we search for transitions $\Upsilon(4S) \rightarrow
\eta_b(1S)\omega$, $\Upsilon(5S) \rightarrow \eta_b(1S)\omega$ and
$\Upsilon(5S) \rightarrow \eta_b(2S)\omega$. No significant signals are
observed and we set 90\% confidence level upper limits on the corresponding
visible cross sections: $0.2 ~\textrm{pb}, 0.4 ~\textrm{pb}$ and $1.9
~\textrm{pb}$, respectively. | hep-ex |
T Violation and CPT Tests in Neutral-Meson Systems: The review covers transitions between M0 and M0bar in all four systems M0 =
K0, D0, B0 and Bs. These systems are ideal laboratories for studying the
discrete symmetries T and CPT. The properties of time reversal T are discussed
in classical and quantum mechanics. T violation in K0 K0bar transitions has
been observed in 1970 independent of assuming CPT symmetry by using the
Bell-steinberger unitarity relation. Improvements of this observation are
reviewed including the latest results in 2013. They show with high significance
that CP violation in K0 K0bar transitions is only T violation without any CPT
violation. Transitions in the other three systems do not show CP violation so
far and therefore neither T nor CPT violation. The large observed CP violation
in B0 -> J/psi K0 decays is presented to be compatible with only T and no CPT
violation, the same for the very small but significant CP violation in decays
K0 -> pi pi with isospin 2. | hep-ex |
Heavy quark production at HERA and the LHC: Measurements of heavy quark production, particularly from HERA, their
theoretical understanding and their relevance for the LHC are reviewed. The
status of beauty and charm production is discussed in the context of the
different components of the production process: the parton density function of
the colliding hadrons; the hard scatter; and the fragmentation of the quarks
into hadrons. The theory of QCD at next-to-leading order generally describes
well the hadronic structure and the production of heavy quarks although
sometimes fails in details which are highlighted. The fragmentation of heavy
quarks measured at HERA is consistent with that at LEP and hence supports the
notion of universality. | hep-ex |
OPERA neutrino oscillation search: status and perspectives: OPERA is a long-baseline experiment at the Gran Sasso laboratory (LNGS)
designed to search for $\nu_\mu \rightarrow \nu_\tau$ oscillations in
appearance mode. OPERA took data from 2008 to 2012 with the CNGS neutrino beam
from CERN. The data analysis is ongoing, with the goal of establishing
$\nu_\tau$ appearance with high significance and improving the sensitivity to
the sterile neutrino search in the $\nu_\mu$ $\rightarrow$ $\nu_e$ appearance
channel. Current results will be presented and perspectives discussed. | hep-ex |
Search for eta_b in two-photon collisions at LEP II with the DELPHI
detector: The pseudoscalar meson eta_b has been searched for in two-photon interactions
at LEP II. The data sample corresponds to a total integrated luminosity of 617
pb^{-1} at centre-of-mass energies ranging from 161 to 209 GeV. Upper limits at
a confidence level of 95% on the product Gamma_{\gamma\gamma}(eta_b) x
BR(eta_b) are 190, 470 and 660 eV/c^2 for the eta_b decaying into 4, 6 and 8
charged particles, respectively. | hep-ex |
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