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Measurements of the $τ$ Mass and Mass Difference of the $τ^{+}$
and $τ^{-}$} at BaBar: We present the result from a precision measurement of the mass of the $\tau$
lepton, $M_\tau$, based on $423 fb^{-1}$ of data recorded at the $\Upsilon(4S)$
resonance with the BaBar detector. Using a pseudomass endpoint method, we
determine the mass to be $1776.68 \pm 0.12 (stat) \pm 0.41 (syst) MeV$. We also
measure the mass difference between the $\tau^+$ and $\tau^-$, and obtain
$(M_{\tau^{+}}-M_{\tau^{-}})/M^\tau_{AVG} = (-3.4 \pm 1.3 (stat) \pm 0.3
(syst)) \times 10^{-4}$, where $M^\tau_{AVG}$ is the average value of
$M_{\tau^+}$ and $M_{\tau^-}$. | hep-ex |
New results on alpha_s and optimized scales: A summary of the latest alpha_s results at LEP1 and LEP2 from event-shape
predictions at Order(alpha2_s) + NLLA is presented. Later these are compared to
measurements obtained using the Experimentally Optimized Scale method. Finally
the alpha_s measurement from the 4-jet rate is discussed. | hep-ex |
Search for Direct CP Violation in K+-->pi+-pi+pi- Decays by NA48/2: First preliminary measurement of the direct CP-violating parameter Ag by the
NA48/2 experiment at CERN SPS is presented. Using more than 1.6 billions of
charged kaon decays into three charged pions, the charge asymmetry in the
K+-->pi+-pi+pi- Dalitz plot slope, Ag, has been measured to Ag = (0.5 +- 3.8) x
10^-4. This result is more than an order of magnitude more precise than results
of previous experiments. | hep-ex |
Measurement of the leptonic ttbar charge asymmetry in the dilepton
channel with the D0 detector: We present the legacy measurement of the leptonic ttbar charge asymmetry in
the dilepton channel with the D0 detector. | hep-ex |
Rare B0_(s) -> mu+mu- decays: This review summarizes the current experimental results on rare B0_(s) ->
mu+mu- decays of the Tevatron experiments CDF and D0, and the LHC experiments
ATLAS, CMS and LHCb. The experimental branching fraction upper limits for the
B0_s -> mu+mu- are already quite close to the branching fraction predicted by
the Standard Model, and the first observation of the B0_s -> mu+mu- decay is
expected soon. The rare decays B0_(s) -> mu+mu- are highly suppressed in the
Standard Model, and therefore accurate measurements of these branching
fractions provide complementary constraints to the free parameters of various
extensions of the Standard Model. | hep-ex |
A Luminosity Spectrometer for the Zeus Experiment at HERA: The HERA luminosity upgrade is expected to generate two major problems in the
current method of luminosity determination which is based on counting
brehmsstrahlung photons: damage of the calorimeter monitor due to high primary
synchrotron radiation and large multiple event (pile-up) corrections. The
luminosity spectrometer presented in this talk, is a novel method that reduces
the impact of these problems in the luminosity measurement and is expected to
yield a total systematic uncertainty of 1.4%. The spectrometer counts
brehmsstrahlung photon conversions in the beam pipe exit window using two small
calorimeters (former ZEUS beam pipe calorimeters) symmetrically placed away
from the synchrotron radiation plane. The photon conversion rate is measured by
counting electron-positron (ep) coincidences in the calorimeters. The ep
acceptance is measured using a third calorimeter (6 meter tagger) which tags
the brehmsstrahlung electrons. The electron-positron pair is separated by a
small dipole magnet. | hep-ex |
Limits on Majoron-emitting double-beta decays of Xe-136 in the
KamLAND-Zen experiment: We present limits on Majoron-emitting neutrinoless double-beta decay modes
based on an exposure of 112.3 days with 125 kg of Xe-136. In particular, a
lower limit on the ordinary (spectral index n = 1) Majoron-emitting decay
half-life of Xe-136 is obtained as T_{1/2}^{0\nu\chi^{0}} > 2.6 x 10^{24} yr at
90% C.L., a factor of five more stringent than previous limits. The
corresponding upper limit on the effective Majoron-neutrino coupling, using a
range of available nuclear matrix calculations, is <g_{ee}> < (0.8 - 1.6) x
10^{-5}. This excludes a previously unconstrained region of parameter space and
strongly limits the possible contribution of ordinary Majoron emission modes to
0\nu\beta\beta decay for neutrino masses in the inverted hierarchy scheme. | hep-ex |
Searches for the Supersymmetric Partner of the Bottom Quark: We have performed a search for the scalar bottom quark from gluino decays in
an R-parity conserving SUSY scenario with m(gluino) > m(sbottom), by
investigating a final state of large missing transverse energy, with three or
more jets, and some of them from the hadronization of b-quarks. A data sample
of 156pb-1 collected by the Collider Detector at Fermilab at a center-of-mass
energy of 1.96TeV was used. For the final selection, jets containing secondary
displaced vertices were required. This analysis has been performed 'blind', in
that the inspection of the signal region was only made after the standard model
prediction was fina lized. Comparing data with SUSY predictions, we can exclude
masses of the gluino and sbottom of up to 280 and 240GeV/c^2 respectively. | hep-ex |
Measurement of the $B^{\pm}$ production cross-section in pp collisions
at $\sqrt{s} =$ 7 and 13 TeV: The production of $B^{\pm}$ mesons is studied in $pp$ collisions at
centre-of-mass energies of 7 and 13 TeV, using $B^{\pm}\rightarrow J/\psi
K^{\pm}$ decays and data samples corresponding to 1.0 fb$^{-1}$ and 0.3
fb$^{-1}$, respectively. The production cross-sections summed over both charges
and integrated over the transverse momentum range $0<p_{\text{T}}< 40$ GeV/$c$
and the rapidity range $2.0<y<4.5$ are measured to be $\sigma(pp \rightarrow
B^{\pm} X, \sqrt{s} = \text{7 TeV}) = 43.0 \pm 0.2 \pm 2.5 \pm 1.7\mu b,$
$\sigma(pp \rightarrow B^{\pm} X, \sqrt{s} = \text{13 TeV}) = 86.6 \pm 0.5 \pm
5.4 \pm 3.4\mu b,$ where the first uncertainties are statistical, the second
are systematic, and the third are due to the limited knowledge of the
$B^{\pm}\rightarrow J/\psi K^{\pm}$ branching fraction. The ratio of the
cross-section at 13 TeV to that at 7 TeV is determined to be
$2.02\pm0.02\text{(stat)}\pm0.12\text{(syst)}$. Differential cross-sections are
also reported as functions of $p_{\text{T}}$ and $y$. All results are in
agreement with theoretical calculations based on the state-of-art fixed
next-to-leading order quantum chromodynamics. | hep-ex |
Measurement of the flavour-specific CP violating asymmetry asl in B0s
decay: The CP violating asymmetry asl is studied with a sample of Bs0 or Bs0bar
semi-muonic decays in proton-proton collisions at a centre-of-mass energy of 7
TeV at LHCb with an integrated luminosity of 1 fb^-1. The final state studied
is Ds{\mu}, with Ds reconstructed in the final state {\phi}{\pi}. The Ds{\mu}
yields are summed over untagged Bs0 and Bs0bar initial states, and integrated
with respect to decay time. Data driven methods have been developed to measure
all the efficiency ratios needed to determine asl from the measured raw
asymmetry. We obtain asl= (-0.24+/-0.54+/-0.33)%, where the first uncertainty
is statistical and the second systematic. | hep-ex |
Search for the Charged Higgs Boson in the Decays of Top Quark Pairs in
the $eτ$ and $μτ$ Channels at $\sqrt{s}$=1.8 TeV: Top quark production offers the unique opportunity to search for a charged
Higgs boson ($H^\pm$), as the contribution from $t\to H^+b\to \tau^+\nu b$ can
be large in extensions of the Standard Model. We use results from a search for
top quark pair production by the Collider Detector at Fermilab (CDF) in the
e$\tau + \ebar_T$+jets and $\mu\tau +\ebar_T$+jets signatures to set an upper
limit on the branching ratio of ${\cal B} (t \to H^{+} b)$ in 106 pb$^{-1}$ of
data. The upper limit is in the range 0.5 to 0.6 at 95% C.L. for $H^{+}$ masses
in the range 60 to 160 GeV, assuming the branching ratio for {$H^+\to \tau
\nu$} is 100% . The $\tau$ lepton is detected through its 1-prong and 3-prong
hadronic decays. | hep-ex |
KLOE results on f0(980), a0(980) scalars and eta decays: The KLOE experiment running at the phi-factory DAPHNE has collected ~ 450
pb^(-1) in the 2001--2002 data taking. We report preliminary results on light
meson spectroscopy based on this data sample; particles are all produced
through phi radiative decays. The nature of f0(980) and a0(980) is investigated
by studying the shape of the resulting mass spectra, which is sensitive to
their structure. A detailed study of the eta --> pi pi pi dynamics through a
Dalitz plot analysis gives the possibility to extract information on the quark
mass difference. Finally, the branching ratio for the eta --> pi0 gamma gamma
decay is compared with previous measurements and with the expectations from
Chiral Perturbation Theory. | hep-ex |
Study of $K^+ \rightarrow π^{0} e^{+} νγ$ decay with OKA
setup: Results of a study of the $K^+ \rightarrow \pi^{0} e^{+} \nu \gamma $ decay
at OKA setup are presented. More than 32000 events of this decay are observed.
The differential spectra over the photon energy and the photon-electron opening
angle in kaon rest frame are presented. The branching ratios, normalized to
that of $K_{e3}$ decay are calculated for different cuts in $E^*_\gamma$ and
$cos\Theta^{*}_{e\gamma}$. In particular, the branching ratio for
$E^{*}_{\gamma}>30$ MeV and $\Theta^{*}_{e \gamma}>20^{\circ}$ is measured R =
$\frac{Br(K^+ \rightarrow \pi^{0} e^{+} \nu_{e} \gamma) } {Br(K^+ \rightarrow
\pi^{0} e^{+} \nu_{e})} $ =
=(0.587$\pm$0.010($stat.$)$\pm$0.015($syst.$))$\times10^{-2}$, which is in a
good agreement with ChPT $O(p^{4})$ calculations. | hep-ex |
Measurements of branching fraction ratios and CP asymmetries in B+/-
->D_CP K+/- decays in hadron collisions: We reconstruct B+/- -> D K+/- decays in a data sample collected by the CDF II
detector at the Tevatron collider corresponding to 1 fb-1 of integrated
luminosity. We select decay modes where the D meson decays to either K- pi+
(flavor eigenstate) or K- K+, pi- pi+ (CP-even eigenstates), and measure the
direct CP asymmetry A_CP+ = 0.39 +/- 0.17(stat) +/- 0.04(syst), and the double
ratio of CP-even to flavor eigenstate branching fractions R_CP+ = 1.30 +/-
0.24(stat) +/- 0.12(syst). These measurements will improve the determination of
the CKM angle gamma. They are performed here for the first time using data from
hadron collisions. | hep-ex |
Search for Dark Matter Annihilation in the Earth using the ANTARES
Neutrino Telescope: A search for a neutrino signal from WIMP pair annihilations in the centre of
the Earth has been performed with the data collected with the ANTARES neutrino
telescope from 2007 to 2012. The event selection criteria have been developed
and tuned to maximise the sensitivity of the experiment to such a neutrino
signal. No significant excess of neutrinos over the expected background has
been observed. Upper limits at $90\%$ C.L. on the WIMP annihilation rate in the
Earth and the spin independent scattering cross-section of WIMPs to nucleons
$\sigma^{SI}_p$ were calculated for WIMP pair annihilations into either
$\tau^{+}\tau^{-}$, $W^+W^-$, $b\overline{b}$ or the non-SUSY
$\nu_{\mu}\bar{\nu}_{\mu}$ as a function of the WIMP mass (between
$25\,\mathrm{GeV/c^2}$ and $1000\,\mathrm{GeV/c^2}$) and as a function of the
thermally averaged annihilation cross section times velocity $\langle\sigma_{A}
v\rangle_{Earth}$ of the WIMPs in the centre of the Earth. For masses of the
WIMP close to the mass of iron nuclei ($50\,\mathrm{GeV/c^2}$), the obtained
limits on $\sigma^{SI}_p$ are more stringent than those obtained by other
indirect searches. | hep-ex |
Search for charged-lepton flavor violation in top quark production and
decay in pp collisions at $\sqrt{s} =$ 13 TeV: Results are presented from a search for charged-lepton flavor violating
(CLFV) interactions in top quark production and decay in pp collisions at a
center-of-mass energy of 13 TeV. The events are required to contain one
oppositely charged electron-muon pair in the final state, along with at least
one jet identified as originating from a bottom quark. The data correspond to
an integrated luminosity of 138 fb$^{-1}$, collected by the CMS experiment at
the LHC. This analysis includes both the production (q $\to$ e$\mu$t) and decay
(t $\to$ e$\mu$q) modes of the top quark through CLFV interactions, with q
referring to a u or c quark. These interactions are parametrized using an
effective field theory approach. With no significant excess over the standard
model expectation, the results are interpreted in terms of vector-, scalar-,
and tensor-like CLFV four-fermion effective interactions. Finally, observed
exclusion limits are set at 95% confidence levels on the respective branching
fractions of a top quark to an e$\mu$ pair and an up (charm) quark of 0.13
$\times$ 10$^{-6}$ (1.31 $\times$ 10$^{-6}$), 0.07 $\times$ 10$^{-6}$ (0.89
$\times$ 10$^{-6}$), and 0.25 $\times$ 10$^{-6}$ (2.59 $\times$ 10$^{-6}$) for
vector, scalar, and tensor CLFV interactions, respectively. | hep-ex |
Measurement of the Transverse Single-Spin Asymmetry for Mid-rapidity
Production of Neutral Pions in Polarized p+p Collisions at 200 GeV
Center-of-Mass Energy: The spin structure of the proton has revealed itself to be extremely complex
and is an area of ongoing research. The Relativistic Heavy Ion Collider (RHIC)
at Brookhaven National Laboratory (BNL) inaugurated its operation as the first
polarized-proton collider during the 2001-2002 run, marking the beginning of a
new era in the study of proton spin structure.
From the data collected in this run, the PHENIX experiment measured the
transverse single-spin asymmetry (A_N) for neutral pion production at x_F~0.0
over a transverse momentum range of 1 to 5 GeV/c from polarized proton-proton
interactions at a center-of-mass energy of 200 GeV and found it to be zero
within a few percent. Interest in these measurements arises from the
observation of large (~30%) transverse single-spin asymmetries in pion
production at forward angles by the E704 collaboration at Fermilab (sqrt{s} =
19.4 GeV), found by the STAR and BRAHMS experiments to persist at RHIC
energies, as well as single-spin, azimuthal asymmetries observed recently in
semi-inclusive deep-inelastic scattering experiments. Such large asymmetries
were initially surprising because at leading order, pQCD predicted only small
effects.
Several possible origins of these large asymmetries have been proposed.
Despite great theoretical progress in recent years, no single, clear formalism
has emerged in which to interpret the available data. Further theoretical work
and a variety of additional experimental measurements will be necessary to
understand current results and elucidate the transverse spin structure of the
proton. | hep-ex |
Search for Cosmic-ray Boosted Sub-GeV Dark Matter using Recoil Protons
at Super-Kamiokande: We report a search for cosmic-ray boosted dark matter with protons using the
0.37 megaton$\times$years data collected at Super-Kamiokande experiment during
the 1996-2018 period (SKI-IV phase). We searched for an excess of proton
recoils above the atmospheric neutrino background from the vicinity of the
Galactic Center. No such excess is observed, and limits are calculated for two
reference models of dark matter with either a constant interaction
cross-section or through a scalar mediator. This is the first experimental
search for boosted dark matter with hadrons using directional information. The
results present the most stringent limits on cosmic-ray boosted dark matter and
exclude the dark matter-nucleon elastic scattering cross-section between
$10^{-33}\text{ cm}^{2}$ and $10^{-27}\text{ cm}^{2}$ for dark matter mass from
10 MeV/$c^2$ to 1 GeV/$c^2$. | hep-ex |
Correlated inclusive /\bar production in e+e- annihilations at
sqrt(s)~10.5 GeV: Using a 13.7/fb sample of continuum two-jet e+e- -> qqbar events collected
with the CLEO detector, we have searched for correlations between / and /\bar
particles, specifically in cases where the opening angle between the two
particles is large and each has momentum $>$1 GeV/c. Such correlations may
indicate the presence of baryon number conservation at the primary quark level.
A previous CLEO study of /\c/\cbar correlations indicated direct, associated
production of primary charmed baryons /\c: e+e- -> ccbar -> /\c/\cbar. That
effect was not observed in Monte Carlo simulations. Our current search for
similar direct, associated production of / baryons at the primary quark level
(e+e- -> ssbar -> /\bar, e.g.) qualitatively indicates a similar effect,
although it relies on a Monte Carlo dependent subtraction of background /\bar
production (based on the default JETSET 7.4 event generator). | hep-ex |
Feasibility, engineering aspects and physics reach of microwave cavity
experiments searching for hidden photons and axions: Using microwave cavities one can build a resonant
``light-shining-through-walls'' experiment to search for hidden sector photons
and axion like particles, predicted in many extensions of the standard model.
In this note we make a feasibility study of the sensitivities which can be
reached using state of the art technology. | hep-ex |
Performance of the CMS Zero Degree Calorimeters in pPb collisions at the
LHC: The two Zero Degree Calorimeters (ZDCs) of the CMS experiment are located at
$\pm 140~$m from the collision point and detect neutral particles in the
$|\eta| > 8.3$ pseudorapidity region. This paper presents a study on the
performance of the ZDC in the 2016 pPb run. The response of the detectors to
ultrarelativistic neutrons is studied using in-depth Monte Carlo simulations. A
method of signal extraction based on template fits is presented, along with a
dedicated calibration procedure. A deconvolution technique for the correction
of overlapping collision events is discussed. | hep-ex |
Recent Results from the Tevatron Fixed Target and Collider Experiments: We present a review of recent QCD related results from the Fermilab Tevatron
fixed target and collider experiments. Topics include jet and boson production,
W boson and top quark mass measurements, and studies of CP violation. | hep-ex |
Study of charmless hadronic B decays into the final states $Kπ,
ππ$, and KK, with the first observation of $B \to π^+ π^-$ and $B\to
K^0π^0$: We have studied charmless hadronic decays of B mesons into two-body final
states with kaons and pions. We present preliminary results based on 9.66
million $B\bar{B}$ pairs collected with the CLEO detector. We have made the
first observation of the decay $B \to \pi^+\pi^-$, with the branching fraction
of $Br(B \to \pi^+ \pi^-) = (4.7^{+1.8}_{-1.5} \pm 0.6) \times 10^{-6}$. We
have also observed for the first time the decay $B \to K^0\pi^0$ with the
branching fraction of $Br(B \to K^0 \pi^0) = (14.8^{+5.9+2.4}_{-5.1-3.3})
\times 10^{-6}$, thus completing the set of four $K\pi$ branching fraction
measurements. We present improved measurements for the decays $B\to
K^{\pm}\pi^{\mp}$, $B^{\pm}\to K^0\pi^{\pm}$, and $B^{\pm}\to K^{\pm}\pi^0$. We
use these and other charmless hadronic B decays to make a first determination
of the value of the weak phase ${\rm Arg}(V^*_{ub})=\gamma =
{113^\circ}^{+25^\circ}_{-23^\circ}$. | hep-ex |
Top properties (excluding mass) and ancillary measurements: A review on recent top quark properties measurements by the ATLAS and CMS
Collaborations in pp collisions at the LHC is presented. | hep-ex |
Search for Dark Matter at CMS: The results are presented from searches with the CMS experiment for
directly-produced dark matter particles. All these searches use the full LHC
Run-I dataset of ~20/fb of proton-proton collisions at 8TeV centre-of-mass
energy. Final states with a monojet, monophoton, and monolepton signature are
considered, as well as processes with dark-matter particles produced in
association with top quarks. Most of these results have been interpreted using
an effective field theory approach, while first results are also reported with
simplified models. | hep-ex |
Interpretation of Scalar and axial mesons in LHCb from an historical
perspective: LHCb measurements of $B_{d,s} \to J/\psi + X$ are shown to be consistent with
historical data on scalar and axial mesons below 2 GeV. This is in contrast to
some recent interpretations of these data. Further tests of our hypotheses in
other $B_{u,d,s} \to J/\psi + X$ decay modes are suggested. | hep-ex |
Search for supersymmetric particles in events with lepton pairs and
large missing transverse momentum in sqrt{s} = 7 TeV proton-proton collisions
with the ATLAS experiment: Results are presented of searches for the production of supersymmetric
particles decaying into final states with missing transverse momentum and
exactly two isolated leptons in sqrt{s}=7 TeV proton-proton collisions at the
Large Hadron Collider. Search strategies requiring lepton pairs with identical
sign or opposite sign electric charges are described. In a data sample
corresponding to an integrated luminosity of 35 pb-1 collected with the ATLAS
detector, no significant excesses are observed. Based on specific benchmark
models, limits are placed on the squark mass between 450 and 690 GeV for
squarks approximately degenerate in mass with gluinos, depending on the
supersymmetric mass hierarchy considered. | hep-ex |
Investigation of the $e^+e^- \to ωπ^0 \to π^0 π^0 γ$
reaction in the energy domain near the $φ$-meson: The $e^+e^- \to \omega \pi^0 \to \pi^0 \pi^0 \gamma$ process was investigated
in the SND experiment at the VEPP-2M collider. A narrow energy interval near
the $\phi$-meson was scanned. The observed cross-section reveals, at the level
of three standard deviation, the interference effect caused by $\phi \to
\pi^0\pi^0\gamma$ decay. The cross-section parameters, as well as the real and
imaginary parts of the $\phi$-meson related amplitude, were measured. | hep-ex |
Measurements of top-quark pair differential cross-sections in the $eμ$
channel in $pp$ collisions at $\sqrt{s} = 13$ TeV using the ATLAS detector: This article presents measurements of $t\bar{t}$ differential cross-sections
in a fiducial phase-space region, using an integrated luminosity of 3.2
fb$^{-1}$ of proton--proton data at a centre-of-mass energy of $\sqrt{s} = 13$
TeV recorded by the ATLAS experiment at the LHC in 2015. Differential
cross-sections are measured as a function of the transverse momentum and
absolute rapidity of the top quark, and of the transverse momentum, absolute
rapidity and invariant mass of the $t\bar{t}$ system. The $t\bar{t}$ events are
selected by requiring one electron and one muon of opposite electric charge,
and at least two jets, one of which must be tagged as containing a $b$-hadron.
The measured differential cross-sections are compared to predictions of
next-to-leading order generators matched to parton showers and the measurements
are found to be consistent with all models within the experimental
uncertainties with the exception of the POWHEG-Box + HERWIG++ predictions,
which differ significantly from the data in both the transverse momentum of the
top quark and the mass of the $t\bar{t}$ system. | hep-ex |
Inclusive and exclusive measurements of $B$ decays to $χ_{c1}$ and
$χ_{c2}$ at Belle: We report inclusive and exclusive measurements for $\chi_{c1}$ and
$\chi_{c2}$ production in $B$ decays. We measure $\mathcal{B}(B \to \chi_{c1}
X)$= $(3.03 \pm 0.05(\mbox{stat}) \pm 0.24(\mbox{syst})) \times 10^{-3}$ and
$\mathcal{B}(B \to \chi_{c2} X)$= $(0.70 \pm 0.06(\mbox{stat}) \pm
0.10(\mbox{syst})) \times 10^{-3}$. For the first time, $\chi_{c2}$ production
in exclusive $B$ decays in the modes $B^0 \to \chi_{c2}\pi^- K^+$ and $B^+ \to
\chi_{c2} \pi^+ \pi^- K^+$ has been observed, along with first evidence for the
$B^+ \to \chi_{c2} \pi^+ K_S^0$ decay mode. For $\chi_{c1}$ production, we
report the first observation in the $B^+ \to \chi_{c1} \pi^+ \pi^- K^+$, $B^0
\to \chi_{c1} \pi^+ \pi^- K_S^0$ and $B^0 \to \chi_{c1} \pi^0 \pi^- K^+$ decay
modes. Using these decay modes, we observe a difference in the production
mechanism of $\chi_{c2}$ in comparison to $\chi_{c1}$ in $B$ decays. In
addition, we report searches for $X(3872)$ and $\chi_{c1}(2P)$ in the $B^+ \to
(\chi_{c1} \pi^+ \pi^-) K^+$ decay mode. The reported results use $772 \times
10^{6}$ $B\overline{B}$ events collected at the $\Upsilon(4S)$ resonance with
the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. | hep-ex |
Forward pi^0-meson production at HERA: The production of high transverse momentum piz^0-mesons has been measured in
deep-inelastic e-p scattering events at low Bjorken-$x$ taken with the
H1 detector at HERA. The production of high p_T particles is strongly
correlated to the emission of hard partons in QCD and is therefore sensitive to
the dynamics of the strong interaction. For the first time the measurement of
single particles has been extended to the region of small angles w.r.t. the
proton remnant (forward region) and down to very low values of x ~ 5x10^-5.
This region is expected to be particularly sensitive to QCD evolution effects
in final states. Differential cross sections of inclusive pi^0-meson production
have been measured as a function of Bjorken-x and the four-momentum transfer
Q^2, and also as a function of the transverse momentum and the polar angle of
the pi^0-mesons. A recent BFKL calculation and QCD models based on the DGLAP
splitting functions are compared to the data. The best description of the data
is achieved by the BFKL calculation. | hep-ex |
Recent Results on $ψ(3770)$ Physics at BES-II: About 33, 6.5 and 1.0 pb$^{-1}$ of $e^+e^-$ annihilation data were,
respectively, taken around the center-of-mass energies of $\sqrt s=$ 3.773 GeV,
at $\sqrt s=$ 3.650 GeV and at $\sqrt s=$ 3.6648 GeV with the BES-II detector
at the BEPC collider. By analyzing these data sets, we measure the branching
fraction for $\psi(3770)\to$ non-$D\bar D$; observe an anomalous line shape of
the cross section for $e^+e^-\to$ hadrons in the energy region from 3.650 to
3.872 GeV; and measure the line shapes of the $D^+D^-$, $D^0\bar D^0$ and
$D\bar D$ production and the ratios of the production rates of $D^+D^-$ and
$D^0\bar D^0$ in $e^+e^-$ annihilation at $\psi(3770)$ resonance. We also
search for $\psi(3770)$ decay into exclusive light hadron processes containing
$K^0_S$ or $\pi^0\pi^0$ mesons in the final states. | hep-ex |
Measurement of the top quark pair production cross-section with ATLAS in
the single lepton channel: A measurement of the production cross-section for top quark pairs (t tbar) in
pp collisions at sqrt{s} = 7 TeV is presented using data recorded with the
ATLAS detector at the Large Hadron Collider. Events are selected in the single
lepton topology by requiring an electron or muon, large missing transverse
momentum and at least three jets. With a data sample of 35/pb, two different
multivariate methods, one of which uses b-quark jet identification while the
other does not, use kinematic variables to obtain cross-section measurements of
sigma (t tbar) = 187 +/- 11 (stat.) +18-17 (syst.) +/- 6 (lumi.) pb and sigma
(t tbar) = 173 +/- 17 (stat.) +18-16 (syst.) +/- 6 (lumi.) pb} respectively.
The two measurements are in agreement with each other and with QCD
calculations. The first measurement has a better a priori sensitivity and
constitutes the main result of this Letter. | hep-ex |
Measurement of Mw from LEP2: In 1997 each LEP experiment collected approximately 55 inv. pb of data at a
center-of-mass energy of 183 GeV. These data yield a sample of candidate e+e-
-> WW events from which the mass of the W boson, Mw, is measured. The LEP
combined result, including data taken at roots = 161 and 172 GeV and assuming
the Standard Model relation between the W decay width and mass, is
Mw = 80.35 +/- 0.07 (exp) +/- 0.04 (CR) +/- 0.03 (E_beam) GeV, where the
errors correspond to experimental, colour-reconnection/Bose-Einstein, and LEP
beam energy uncertainties respectively. | hep-ex |
The search for solar axions in the CAST experiment: The CAST (CERN Axion Solar Telescope) experiment at CERN searches for solar
axions with energies in the keV range. It is possible that axions are produced
in the core of the sun by the interaction of thermal photons with virtual
photons of strong electromagnetic fields. In this experiment, the solar axions
can be reconverted to photons in the transversal field of a 9 Tesla
superconducting magnet. At both ends of the 10m-long dipole magnet three
different X-ray detectors were installed, which are sensitive in the
interesting photon energy range. Preliminary results from the analysis of the
2004 data are presented: g$_{a\gamma}<0.9\times10^{-10}$ GeV$^{-1}$ at 95% C.L.
for axion masses m$_{a} <$ 0.02 eV. At the end of 2005, data started to be
taken with a buffer gas in the magnet pipes in order to extend the sensitivity
to axion masses up to 0.8 eV. | hep-ex |
Measurement of inclusive jet and dijet cross sections in proton-proton
collisions at 7 TeV centre-of-mass energy with the ATLAS detector: Jet cross sections have been measured for the first time in proton-proton
collisions at a centre-of-mass energy of 7 TeV using the ATLAS detector. The
measurement uses an integrated luminosity of 17 nb-1 recorded at the Large
Hadron Collider. The anti-kt algorithm is used to identify jets, with two jet
resolution parameters, R = 0.4 and 0.6. The dominant uncertainty comes from the
jet energy scale, which is determined to within 7% for central jets above 60
GeV transverse momentum. Inclusive single-jet differential cross sections are
presented as functions of jet transverse momentum and rapidity. Dijet cross
sections are presented as functions of dijet mass and the angular variable
$\chi$. The results are compared to expectations based on next-to-leading-order
QCD, which agree with the data, providing a validation of the theory in a new
kinematic regime. | hep-ex |
High Energy Muon Momentum Estimation from Multiple Coulomb Scattering in
Dense Detectors: A method is described for estimating muon track momentum from the
distribution of hits along tracks in dense calorimeters due to multiple Coulomb
scattering (MCS). The method requires only well-aligned conventional drift
chambers or similar tracking devices and can be implemented with or without a
magnetic field present. Neutrino experiments can use this technique to increase
acceptance for large angle charged-current scattering events. Resolutions in a
typical detector geometry vary from ~10% at p=20 GeV/c to ~50% for p=500 GeV/c,
if the number of hits on the track is sufficient. | hep-ex |
Extraction of F_2^c(x,Q^2) from D* cross sections at H1: The charm contribution to the proton structure, F_2^c(x,Q^2), is determined
using the inclusive cross sections of D*(2010) meson production in
deep-inelastic scattering. The cross section measurement covers the region 5 <
Q2 < 1000 GeV2 in photon virtuality and 0.02 < y < 0.70 in the inelasticity of
the scattering process. The D* meson is measured in transverse momentum and
pseudo-rapidity down to p_T > 1.5 GeV and up to |eta| < 1.5. The data were
taken with the H1 detector corresponding to an integrated luminosity of 347
pb-1. F_2^c is determined from the D* production cross sections and compared to
leading and next-to-leading order perturbative QCD predictions. | hep-ex |
The experimental future of Neutrino Oscillations: After the recent experimental results on neutrino oscillations, some shape
starts to emerge from the puzzle. However, the situation is still far from
being clarified. First of all, accommodating all experimental results in a
single and simple framework is not possible, and the possibility of sterile
neutrinos entering the oscillation process has not been ruled out. Moreover,
new questions arise that the presently-available data, nor those that will be
available in a near future, will be able to answer. In this paper some of these
problems will be discussed, as well as the experimental guidelines for their
clarification. | hep-ex |
The program of research at hadronic beams of ITEP accelerator.
(Collection of experimental proposals): This is a collection of proposals of experiments at hadronic beams of 10 GeV
accelerator, situated at the Institute of Theoretical and Experimental Physics
(Moscow, Russia). The proposals were presented by the leaders of several ITEP
experimental groups and include selected problems of hadron-hadron (exotic
states, scalar mesons, electomagnetic form factors, polarization phenomena
etc.) and hadron-nucleon interactions (flucton and nuclear matter properties,
hadron properties inside nuclei, interactions at small distances). Most of
proposals are united by an idea of a common magnetic spectrometer with LiH(D)
and polarized targets, wich could be built on the base of an existing 3m
magnet. Some of them also refer to the intrinsic accelerator beam and to the
new ion ring. | hep-ex |
Direct determination of Neutrino Mass from Tritium Beta Spectrum: The investigation of the endpoint region of the tritium beta decay spectrum
is still the most sensitive direct method to determine the neutrino mass scale.
In the nineties and the beginning of this century the tritium beta decay
experiments at Mainz and Troitsk have reached a sensitivity on the neutrino
mass of 2 eV/c^2 . They were using a new type of high-resolution spectrometer
with large sensitivity, the MAC-E-Filter, and were studying the systematics in
detail. Currently, the KATRIN experiment is being set up at Forschungszentrum
Karlsruhe, Germany. KATRIN will improve the neutrino mass sensitivity by one
order of magnitude down to 0.2 eV/c^2, sufficient to cover the degenerate
neutrino mass scenarios and the cosmologically relevant neutrino mass range. | hep-ex |
An Experimentalist's View of Neutrino Oscillations: Neutrinos, and primarily neutrino oscillations, have undoubtedly been one of
the most exciting topics in the field of high-energy physics over the past few
years. The existence of neutrino oscillations would require an extension of the
currently accepted description of sub-nuclear phenomena beyond the Standard
Model. Compelling evidence of new physics, which seems to be pointing towards
neutrino oscillations, is coming from the solar neutrino deficit and from the
atmospheric neutrino anomaly. More controversial effects have been observed
with artificially produced neutrinos. The present experimental status of
neutrino oscillations is reviewed, as well as the planned future experimental
programme, which, it is hoped, will solve most of the outstanding puzzles. | hep-ex |
Discovery of Single Top Quark Production: The first observation of electroweak single top quark production was recently
reported by the the D0 and CDF collaborations based on 2.3 and 3.2 fb-1 of
ppbar collision data collected at \sqrt{s}=1.96 TeV from the Fermilab Tevatron
collider. Several multivariate techniques are used to separate the single top
signal from backgrounds, and both collaborations present measurements of the
single top cross section and the CKM matrix element |Vtb|. | hep-ex |
Search for $CP$ violation with kinematic asymmetries in the $D^0 \to K^+
K^- π^+ π^-$ decay: We search for $CP$ violation in the singly-Cabibbo-suppressed decay
$D^{0}\rightarrow K^{+}K^{-}\pi^{+}\pi^{-}$ using data corresponding to an
integrated luminosity of $988\text{ }{\rm fb}^{-1}$ collected by the Belle
detector at the KEKB $e^{+}e^{-}$ collider. We measure a set of five
kinematically dependent $CP$ asymmetries, of which four asymmetries are
measured for the first time. The set of asymmetry measurements can be sensitive
to $CP$ violation via interference between the different partial-wave
contributions to the decay and performed on other pseudoscalar decays. We find
no evidence of $CP$ violation. | hep-ex |
Search for high-mass Z-gamma resonances in e+e-gamma and mu+mu-gamma
final states in proton-proton collisions at sqrt(s) = 8 and 13 TeV: This paper describes the search for a high-mass narrow-width scalar particle
decaying into a Z boson and a photon. The analysis is performed using
proton-proton collision data recorded with the CMS detector at the LHC at
center-of-mass energies of 8 and 13 TeV, corresponding to integrated
luminosities of 19.7 and 2.7 inverse femtobarns, respectively. The Z bosons are
reconstructed from opposite-sign electron or muon pairs. No statistically
significant deviation from the standard model predictions has been found in the
200-2000 GeV mass range. Upper limits at 95% confidence level have been derived
on the product of the scalar particle production cross section and the
branching fraction of the Z decaying into electrons or muons, which range from
280 to 20 fb for resonance masses between 200 and 2000 GeV. | hep-ex |
Proton structure and elastic scattering amplitudes: Three main statements are advocated in this talk:
1. Protons become more active at the periphery with increase of their
collision energy as follows from comparison of ISR and LHC data.
2. The geometric scaling is violated even in the diffraction region as
follows from comparison of lower energy and LHC data.
3. The problem of the ratio of real to imaginary parts of the elastic
scattering amplitude at non-zero transferred momenta is very crucial.
The talk is based on arXiv:1206.5474 (review), 1202.2016, 1204.1914,
1204.4866, 1208.3073, 1209.1935, 1212.3313, 1304.5345, 1306.5384. All papers
have been published already. | hep-ex |
The LHCb ultra-fast simulation option, Lamarr: design and validation: Detailed detector simulation is the major consumer of CPU resources at LHCb,
having used more than 90% of the total computing budget during Run 2 of the
Large Hadron Collider at CERN. As data is collected by the upgraded LHCb
detector during Run 3 of the LHC, larger requests for simulated data samples
are necessary, and will far exceed the pledged resources of the experiment,
even with existing fast simulation options. An evolution of technologies and
techniques to produce simulated samples is mandatory to meet the upcoming needs
of analysis to interpret signal versus background and measure efficiencies. In
this context, we propose Lamarr, a Gaudi-based framework designed to offer the
fastest solution for the simulation of the LHCb detector. Lamarr consists of a
pipeline of modules parameterizing both the detector response and the
reconstruction algorithms of the LHCb experiment. Most of the parameterizations
are made of Deep Generative Models and Gradient Boosted Decision Trees trained
on simulated samples or alternatively, where possible, on real data. Embedding
Lamarr in the general LHCb Gauss Simulation framework allows combining its
execution with any of the available generators in a seamless way. Lamarr has
been validated by comparing key reconstructed quantities with Detailed
Simulation. Good agreement of the simulated distributions is obtained with
two-order-of-magnitude speed-up of the simulation phase. | hep-ex |
First study of the CP-violating phase and decay-width difference in
$B_s^0\toψ(2S)φ$ decays: A time-dependent angular analysis of $B_s^0\to\psi(2S)\phi$ decays is
performed using data recorded by the LHCb experiment. The data set corresponds
to an integrated luminosity of 3.0\invfb collected during Run 1 of the LHC. The
CP-violating phase and decay-width difference of the $B_s^0$ system are
measured to be $\phi_s = 0.23^{+0.29}_{-0.28} \pm 0.02$ rad and $\Delta\Gamma_s
= 0.066^{+0.041}_{-0.044} \pm 0.007$ ps$^{-1}$, respectively, where the first
uncertainty is statistical and the second systematic. This is the first time
that $\phi_s$ and $\Delta\Gamma_s$ have been measured in a decay containing the
$\psi(2S)$ resonance. | hep-ex |
Measurement of Baryon Electromagnetic Form Factors at BESIII: The Beijing $e^+e^-$-collider (BEPCII) is a double-ring symmetric collider
running at center-of-mass energies between 2.0 and 4.6 GeV. This energy range
allows the BESIII-experiment to measure baryon electromagnetic form factors in
direct $e^+e^-$-annihilation and in initial state radiation processes. In this
paper, results on $e^+e^-\rightarrow p\bar{p}$ and $e^+e^-\rightarrow \Lambda
\bar{\Lambda}$ based on data collected by BESIII in 2011 and 2012 are
presented. Expectations from the BESIII high luminosity energy scan from 2015
and from radiative return at different center-of-mass energies are also
reported. | hep-ex |
First measurement of low intensity fast neutron background from rock at
the Boulby Underground Laboratory: A technique to measure low intensity fast neutron flux has been developed.
The design, calibrations, procedure for data analysis and interpretation of the
results are discussed in detail. The technique has been applied to measure the
neutron background from rock at the Boulby Underground Laboratory, a site used
for dark matter and other experiments, requiring shielding from cosmic ray
muons. The experiment was performed using a liquid scintillation detector. A
6.1 litre volume stainless steel cell was filled with an in-house made liquid
scintillator loaded with Gd to enhance neutron capture. A two-pulse signature
(proton recoils followed by gammas from neutron capture) was used to identify
the neutron events from much larger gamma background from PMTs. Suppression of
gammas from the rock was achieved by surrounding the detector with high-purity
lead and copper. Calibrations of the detector were performed with various gamma
and neutron sources. Special care was taken to eliminate PMT afterpulses and
correlated background events from the delayed coincidences of two pulses in the
Bi-Po decay chain. A four month run revealed a neutron-induced event rate of
1.84 +- 0.65 (stat.) events/day. Monte Carlo simulations based on the GEANT4
toolkit were carried out to estimate the efficiency of the detector and the
energy spectra of the expected proton recoils. From comparison of the measured
rate with Monte Carlo simulations the flux of fast neutrons from rock was
estimated as (1.72 +- 0.61 (stat.) +- 0.38 (syst.))*10^(-6) cm^(-2) s^(-1)
above 0.5 MeV. | hep-ex |
Differential Z + jet cross section measurements at 8 TeV: The measurement of differential cross section of a Z boson produced in
association with jets is presented. The cross section is presented with respect
to various jet kinematic variables where the Z bosons are reconstructed from
opposite sign lepton pairs. The analysis is based on data of proton proton
collisions with the centre of mass energy of 8 TeV collected in 2012 by the CMS
experiment at LHC corresponding to 19.8 /fb of integrated luminosity. Obtained
results are compared with different generators and are shown to be consistent
with the Standard Model predictions. | hep-ex |
Measurements of the mass and width of the eta_c using psi' -> gamma
eta_c: The mass and width of the lowest lying S-wave spin singlet charmonium state,
the eta_c, are measured using a data sample of 1.06x10^8 psi' decays collected
with the BESIII detector at the BEPCII storage ring. We use a model that
incorporates interference between the signal reaction, psi' -> gamma eta_c, and
a non-resonant radiative background to successfully describe the line shape of
the eta_c. We measure the eta_c mass to be 2984.3 +- 0.6 +- 0.6 MeV/c^2 and the
total width to be 32.0 +- 1.2 +- 1.0 MeV, where the first errors are
statistical and the second are systematic. | hep-ex |
Searches for leptoquarks and excited fermions at HERA: Recent results on searches for new particles at the electron-proton collider
HERA are reported. Based on roughly 100pb-1 of e^+p data and 16pb-1 of e^-p
data per experiment, taken in the years 1994-2000, the H1 and ZEUS
collaborations have derived new exclusion limits for the direct production of
excited fermion states and leptoquarks. The latter are searched for in
different decay channels, including lepton-flavor violating decays. The
production of R_P-violating squarks followed by leptoquark-like decays to
lepton and quark is studied, as are cascade decays yielding multi-jet plus
lepton signatures. New limits from indirect searches are also reported. Several
of the searches obtain sensitivities of the same order or exceeding those of
other experiments, indicating the substantial discovery potential of future
HERA running. | hep-ex |
Measurement of Branching Fractions for $B\to η_c K^{(*)}$ Decays: We report measurements of branching fractions for charged and neutral $B\to
\eta_c K$ decays where the $\eta_c$ meson is reconstructed in the $K_S^0
K^{\pm}\pi^{\mp}, K^+ K^- \pi^0, K^{*0} K^-\pi^+$ and $p \bar{p}$ decay
channels. The neutral $B^0$ channel is a CP eigenstate and can be used to
measure the CP violation parameter $\sin 2\phi_1$. We also report the first
observation of the $B^0\to \eta_c K^{*0}$ mode. The results are based on an
analysis of 29.1 fb$^{-1}$ of data collected by the Belle detector at KEKB. | hep-ex |
Search for a massless dark photon in $Λ^{+}_{c}\to p
γ^{\prime}$ decay: A search for a massless dark photon $\gamma^{\prime}$ is conducted using 4.5
$\mathrm{fb}^{-1}$ of $e^+e^-$ collision data collected at center-of-mass
energies between 4.600 and 4.699 $\mathrm{GeV}$ with the BESIII detector at
BEPCII. No significant signal is observed, and the upper limit on the branching
fraction $\mathcal{B}(\Lambda^{+}_{c}\to p \gamma^{\prime})$ is determined to
be $8.0\times 10^{-5}$ at 90% confidence level. | hep-ex |
Spin Physics with the PHENIX Detector System: The PHENIX experiment at RHIC has extended its scope to cover spin physics
using polarized proton beams. The major goals of the spin physics at RHIC are
elucidation of the spin structure of the nucleon and precision tests of the
symmetries. Sensitivities of the spin physics measurements with the PHENIX
detector system are reviewed. | hep-ex |
Measurement of the forward-backward asymmetry of electron and muon
pair-production in $pp$ collisions at $\sqrt{s}$ = 7 TeV with the ATLAS
detector: This paper presents measurements from the ATLAS experiment of the
forward-backward asymmetry in the reaction $pp\rightarrow
Z/\gamma^{*}\rightarrow l^{+}l^{-}$, with $l$ being electrons or muons, and the
extraction of the effective weak mixing angle. The results are based on the
full set of data collected in 2011 in $pp$ collisions at the LHC at $\sqrt{s}$
= 7 TeV, corresponding to an integrated luminosity of 4.8 fb$^{-1}$. The
measured asymmetry values are found to be in agreement with the corresponding
Standard Model predictions. The combination of the muon and electron channels
yields a value of the effective weak mixing angle of $0.2308 \pm 0.0005
\mathrm{(stat.)} \pm 0.0006 \mathrm{(syst.)} \pm 0.0009\mathrm{(PDF)}$, where
the first uncertainty corresponds to data statistics,the second to systematic
effects and the third to knowledge of the parton density functions. This result
agrees with the current world average from the Particle Data Group fit. | hep-ex |
$Υ$ Production in Heavy-Ion Collisions from the STAR Experiment: In these proceedings, we present recent results of $\Upsilon$ measurements in
heavy-ion collisions from the STAR experiment at RHIC. Nuclear modification
factors ($R_{AA}$) for $\Upsilon(1S)$ and $\Upsilon(1S+2S+3S)$ in U+U
collisions at \sqrtsNN\ = 193 GeV are measured through the di-electron channel
and compared to those in Au+Au collisions at \sqrtsNN\ = 200 GeV and Pb+Pb
collisions at \sqrtsNN\ = 2.76 TeV. The ratio between the $\Upsilon(2S+3S)$ and
$\Upsilon(1S)$ yields in Au+Au collisions at \sqrtsNN\ = 200 GeV is measured in
the di-muon channel and compared to those in p+p collisions and in Pb+Pb
collisions at \sqrtsNN\ = 2.76 TeV. Prospects for future $\Upsilon$
measurements with the STAR experiment are also discussed. | hep-ex |
Search for a CP-odd Higgs boson decaying into a heavy CP-even Higgs
boson and a $Z$ boson in the $\ell^+\ell^- t\bar{t}$ and
$ν\barνb\bar{b}$ final states using 140 fb$^{-1}$ of data collected
with the ATLAS detector: A search for a heavy CP-odd Higgs boson, $A$, decaying into a $Z$ boson and a
heavy CP-even Higgs boson, $H$, is presented. It uses the full LHC Run 2
dataset of $pp$ collisions at $\sqrt{s}=13$ TeV collected with the ATLAS
detector, corresponding to an integrated luminosity of $140$ fb$^{-1}$. The
search for $A\to ZH$ is performed in the $\ell^+\ell^- t\bar{t}$ and
$\nu\bar{\nu}b\bar{b}$ final states and surpasses the reach of previous
searches in different final states in the region with $m_H>350$ GeV and
$m_A>800$ GeV. No significant deviation from the Standard Model expectation is
found. Upper limits are placed on the production cross-section times the decay
branching ratios. Limits with less model dependence are also presented as
functions of the reconstructed $m(t\bar{t})$ and $m(b\bar{b})$ distributions in
the $\ell^+\ell^- t\bar{t}$ and $\nu\bar{\nu}b\bar{b}$ channels, respectively.
In addition, the results are interpreted in the context of two-Higgs-doublet
models. | hep-ex |
UV Irradiation Facility for Solar Effects Simulations: We describe an experimental setup developed aiming to irradiate samples under
UV radiation for accelerated test for solar effects according to the relevant
ECSS-ESA standards. This facility has been already used for projects belonging
to large space programs (Cosmic Vision, Artes) for simulations up to 3500
equivalent sun hours. In particular, we detail the calculation of the UV dose
delivered by Sun, the calibration of the detectors, the spatial distribution of
the UV radiation on samples, the remote control of both samples temperature and
lamp radiation, the samples heat dissipation and operation in a helium
atmosphere. | hep-ex |
The Double Chooz reactor neutrino experiment: The Double Chooz reactor neutrino experiment will be the next detector to
search for a non vanishing theta13 mixing angle with unprecedented sensitivity,
which might open the way to unveiling CP violation in the leptonic sector. The
measurement of this angle will be based in a precise comparison of the
antineutrino spectrum at two identical detectors located at different distances
from the Chooz nuclear reactor cores in France. Double Chooz is particularly
attractive because of its capability to measure sin2(2theta13) to 3 sigmas if
sin2(2theta13) > 0.05 or to exclude sin2(2theta13) down to 0.03 at 90% C.L. for
Dm2 = 2.5 x 10-3 eV2 in three years of data taking with both detectors. The
construction of the far detector starts in 2008 and the first neutrino results
are expected in 2009. The current status of the experiment, its physics
potential and design and expected performance of the detector are reviewed. | hep-ex |
Development of time-of-flight particle identification for future Higgs
factories: With the emergence of advanced Silicon (Si) sensor technologies such as
LGADs, it is now possible to achieve exceptional time measurement precision
below 50 ps. As a result, the implementation of time-of-flight (TOF) particle
identification (PID) for charged hadrons at future $e^{+}e^{-}$ Higgs factory
detectors has gained increasing attention. Other PID techniques require a
gaseous tracker with excellent dE/dx resolution, or a Ring-imaging Cherenkov
detector (RICH), which adds additional material in front of the calorimeter.
TOF measurements can be implemented either in the outer layers of the tracker
or in the electromagnetic calorimeter, and are thus particularly interesting as
a PID method for detector concepts based on all-silicon trackers and optimised
for particle-flow reconstruction. In this study, we will explore potential
integration scenarios of a TOF measurement in a future Higgs factory detector,
using the International Large Detector (ILD) as an example. We will focus on
the challenges associated with crucial components of TOF PID, namely track
length reconstruction and TOF measurements. The subsequent discussion will
highlight the vital impact of precise track length reconstruction and various
TOF measurement techniques, including recently developed machine learning
approaches. We will evaluate the performance in terms of $\pi/K$ and $K/p$
separation as a function of momentum, and discuss potential physics
applications. | hep-ex |
Search for contact interactions in opposite-sign dimuon events in pp
collisions at sqrt(s) = 7 TeV: Results are reported from a search for the effects of contact interactions
using events with a high-mass, oppositely charged muon pair. The events are
collected in proton-proton collisions at sqrt(s) = 7 TeV using the Compact Muon
Solenoid detector at the Large Hadron Collider. The data sample corresponds to
an integrated luminosity of 5.3 inverse femtobarns. The observed dimuon mass
spectrum is consistent with that expected from the standard model. The data are
interpreted in the context of a quark- and muon-compositeness model with a
left-handed isoscalar current and an energy scale parameter Lambda. The 95%
confidence level lower limit on Lambda is 9.5 TeV under the assumption of
destructive interference between the standard model and contact-interaction
amplitudes. For constructive interference, the limit is 13.1 TeV. These limits
are comparable to the most stringent ones reported to date. | hep-ex |
Measurement of the charge asymmetry in top quark pair production in pp
collisions at sqrt(s) = 8 TeV using a template method: The charge asymmetry in the production of top quark and antiquark pairs is
measured in proton-proton collisions at a center-of-mass energy of 8 TeV. The
data, corresponding to an integrated luminosity of 19.6 inverse femtobarns,
were collected by the CMS experiment at the LHC. Events with a single isolated
electron or muon, and four or more jets, at least one of which is likely to
have originated from hadronization of a bottom quark, are selected. A template
technique is used to measure the asymmetry in the distribution of differences
in the top quark and antiquark absolute rapidities. The measured asymmetry is
A[c,y] = [0.33 +/- 0.26 (stat) +/- 0.33 (syst)]%, which is the most precise
result to date. The results are compared to calculations based on the standard
model and on several beyond-the-standard-model scenarios. | hep-ex |
Why is the Conclusion of the GERDA Experiment not Justified ?: The first results of the GERDA double beta experiment in Gran Sasso were
recently presented. They are fully consistent with the Heidelberg-Moscow
experiment, but because of its low statistics cannot proof anything at this
moment. It is no surprise that the statistics is still far from being able to
test the signal claimed by the HEIDELBERG-MOSCOW experiment. The energy
resolution of the coaxial detectors is a factor of 1.5 worse than in the
HEIDELBERG-MOSCOW experiment. The original goal of background reduction to
10^{-2}counts/kgykeV, or by an order of magnitude compared to the
HEIDELBERG-MOSCOW experiment, has not been reached. The background is only a
factor 2.3 lower if we refer it to the experimental line width, i.e. in units
counts/kgy energy resolution.
With pulse shape analysis (PSA) the background in the HEIDELBERG-MOSCOW
experiment around Q_{\beta\beta} is 4x10^{-3} counts/kgykeV
\cite{HVKK-IVK-MPhLA2006}, which is a factor of 4 (5 referring to the line
width) lower than that of GERDA with pulse shape analysis.
The amount of enriched material used in the GERDA measurement is 14.6kg, only
a factor of 1.34 larger than that used in the HM experiment. The background
model is oversimplified and not yet adequate. It is not shown that the lines of
their background can be identified. GERDA has to continue the measurement
further ~5years, until they can responsibly present an understood background.
The present half life limit presented by GERDA of T_{1/2}^{0\nu} > 2.1 x
10^{25} y (90% confidence level, i.e. 1.6sigma)) is still lower than the
half-life of T_{1/2}^{0\nu} = 2.23^{{+0.44}_{-0.31}} x 10^{25} y
\cite{HVKK-IVK-MPhLA2006} determined in the HEIDELBERG-MOSCOW experiment. | hep-ex |
Precision Measurement of CP Violation in D0->pi+pi- at CDF: We report a preliminary measurement of the CP violating asymmetry in
D0->pi+pi- using approximately 215,000 decays reconstructed in about 5.94/fb of
CDF data. We use the strong D*+->D0pi+ decay ("D* tag") to identify the flavor
of the charmed meson at production time and exploit CP-conserving strong c-cbar
pair-production in p-pbar collisions. Higher statistic samples of
Cabibbo-favored D0->K-pi+ decays with and without D* tag are used to highly
suppress systematic uncertainties due to detector effects. The result is the
world's most precise measurement to date. | hep-ex |
Search for Single Top Production at the Tevatron: Searches for the electroweak production of single top quarks have been
started at the Fermilab Tevatron proton-antiproton collider using Run II data
by both the D0 and CDF collaborations. Using a dataset of approximately
160pb^-1, neither experiment finds evidence for Single Top production and sets
95% C.L. upper limits on the production cross section. The D0 limits are 19pb
on the s-channel production, 25pb on the t-channel production, and 23pb on the
combined s+t-channel production. The CDF limits are 8.5pb on the t-channel
production and 13.7pb on the combined s+t-channel production. | hep-ex |
Study of Hadronic Five-Body Decays of Charmed Mesons: We study the decay of D+ and Ds+ mesons into charged five body final states,
and report the discovery of the decay mode D+ -> K+K-Pi+Pi+Pi-, as well as
measurements of the decay modes D+ -> K-Pi+Pi+Pi+Pi-, Ds+ -> K+K-Pi+Pi+Pi-, Ds+
-> PhiPi+Pi+Pi- and D+/Ds+ -> Pi+Pi+Pi+Pi-Pi-. An analysis of the resonant
substructure is also included, with evidence suggesting that both decays
proceed primarily through an a1 vector resonance. | hep-ex |
Measurement of the production cross section of an isolated photon
associated with jets in proton-proton collisions at sqrt(s) = 7 TeV with the
ATLAS detector: A measurement of the cross section for the production of an isolated photon
in association with jets in proton-proton collisions at a center-of-mass energy
sqrt(s) = 7 TeV is presented. Photons are reconstructed in the pseudorapidity
range |eta(gamma)|<1.37 and with a transverse energy E_T(gamma)>25 GeV. Jets
are reconstructed in the rapidity range |y(jet)|<4.4 and with a transverse
momentum p_T(jet)>20 GeV. The differential cross section dsigma/dE_T(gamma) is
measured, as a function of the photon transverse energy, for three different
rapidity ranges of the leading-p_T jet: |y(jet)|<1.2, 1.2<=|y(jet)|<2.8 and
2.8<=|y(jet)|< 4.4. For each rapidity configuration the same-sign
(eta(gamma)y(jet)>=0) and opposite-sign (eta(gamma)y(jet)<0) cases are studied
separately. The results are based on an integrated luminosity of 37 pb^-1,
collected with the ATLAS detector at the LHC. Next-to-leading order
perturbative QCD calculations are found to be in fair agreement with the data,
except for E_T(gamma)<~45 GeV, where the theoretical predictions overestimate
the measured cross sections. | hep-ex |
Search for narrow resonances using the dijet mass spectrum in pp
collisions at sqrt(s) = 8 TeV: Results are presented of a search for the production of new particles
decaying to pairs of partons (quarks, antiquarks, or gluons), in the dijet mass
spectrum in proton-proton collisions at sqrt(s) = 8 TeV. The data sample
corresponds to an integrated luminosity of 4.0 inverse femtobarns, collected
with the CMS detector at the LHC in 2012. No significant evidence for narrow
resonance production is observed. Upper limits are set at the 95% confidence
level on the production cross section of hypothetical new particles decaying to
quark-quark, quark-gluon, or gluon-gluon final states. These limits are then
translated into lower limits on the masses of new resonances in specific
scenarios of physics beyond the standard model. The limits reach up to 4.8 TeV,
depending on the model, and extend previous exclusions from similar searches
performed at lower collision energies. For the first time mass limits are set
for the Randall-Sundrum graviton model in the dijet channel. | hep-ex |
Search for Free Fractional Electric Charge Elementary Particles: We have carried out a direct search in bulk matter for free fractional
electric charge elementary particles using the largest mass single sample ever
studied - about 17.4 mg of silicone oil. The search used an improved and highly
automated Millikan oil drop technique. No evidence for fractional charge
particles was found. The concentration of particles with fractional charge more
than 0.16e (e being the magnitude of the electron charge) from the nearest
integer charge is less than $4.71\times10^{-22}$ particles per nucleon with 95%
confidence. | hep-ex |
Prospects at Future B Factories: Proceedings of CKM 2012, the 7th International Workshop on the CKM Unitarity
Triangle, University of Cincinnati, USA, 28 September - 2 October 2012.
A concise overview of the possibilities offered by high-luminosity B
Factories in mixing and mixing-related CP violating processes in B decays is
presented. | hep-ex |
Muon reconstruction and identification with the Run II D0 detector: We present an overview of the muon reconstruction and identification methods
employed by the D0 Collaboration to analyze the Run II (2001-2011) ppbar data
of the Fermilab Tevatron collider at sqrt s = 1.96 TeV. We discuss the
performance of these methods, how it is measured using D0 data, and how it is
properly modeled by the D0 simulation program. In its pseudorapidity
acceptance, eta< 2, the muon system identifies high-pT muons (pT>10 GeV) with
efficiencies ranging from 72% to 89%. Muons tracks are reconstructed in the D0
central tracking system with efficiencies ranging from 85% to 92% and with a
typical relative momentum resolution of 10% for pT = 40 GeV. Isolation criteria
reject multijet background with efficiencies of 87% to 99%. | hep-ex |
$\mathrm{t\bar{t}H}$ production at $\mathrm{13\,TeV}$: In this paper, the latest results of searches for the standard model Higgs
boson produced in association with a top quark-antiquark pair
($\mathrm{t\bar{t}H}$), where Higgs decays into photons, bottom quark-antiquark
pair or leptons via $\mathrm{WW^*}$, $\mathrm{ZZ^*}$ and $\mathrm{\tau\tau}$
will be presented. The analyses have been performed using the
$\mathrm{13\,TeV}$ pp collisions data recorded by the CMS experiment in 2015
and part of 2016. The results are presented in the form of the best fit to the
signal strength ($\mathrm{\mu=\sigma/\sigma_{SM}}$) measured with respect to
the Standard Model prediction and its expected and observed $\mathrm{95\%}$
C.L. upper limits. | hep-ex |
Status Report of the MACRO Experiment for the year 2001: In this 2001 status report of the MACRO experiment, results are presented on
atmospheric neutrinos and neutrino oscillations, high energy neutrino
astronomy, searches for WIMPs, search for low energy stellar gravitational
collapse neutrinos, stringent upper limits on GUT magnetic monopoles,
nuclearites and lightly ionizing particles, high energy downgoing muons,
primary cosmic ray composition and shadowing of primary cosmic rays by the Moon
and the Sun. | hep-ex |
Observation of $K^*(892)^0\bar K^*(892)^0$ in $χ_{cJ}$ Decays: $K^*(892)^0\bar K^*(892)^0$ signals from $\chi_{cJ} (J=0,1,2)$ decays are
observed for the first time using a data sample of 14 million $\psi(2S)$ events
accumulated at the BES II detector. The branching fractions ${\cal
B}(\chi_{cJ}\to K^*(892)^0\bar K^*(892)^0)$ $(J = 0,1,2)$ are determined to be
$(1.55 \pm 0.35 \pm 0.30)\times 10^{-3}$, $(1.58 \pm 0.32 \pm 0.29)\times
10^{-3}$, and $(4.67 \pm 0.55 \pm 0.85)\times 10^{-3}$ for the $\chi_{c0}$,
$\chi_{c1}$ and $\chi_{c2}$ decays, respectively, where the first errors are
statistical and the second are systematic. The significances of these signals
are about 4.2$\sigma$, 4.3$\sigma$, and 7.5$\sigma$, respectively. | hep-ex |
Search for a light charged Higgs boson decaying to c s-bar in pp
collisions at sqrt(s) = 8 TeV: A search for a light charged Higgs boson, originating from the decay of a top
quark and subsequently decaying into a charm quark and a strange antiquark, is
presented. The data used in the analysis correspond to an integrated luminosity
of 19.7 inverse femtobarns recorded in proton-proton collisions at sqrt(s) = 8
TeV by the CMS experiment at the LHC. The search is performed in the process t
t-bar to W+/- b H-/+ b-bar, where the W boson decays to a lepton (electron or
muon) and a neutrino. The decays lead to a final state comprising an isolated
lepton, at least four jets and large missing transverse energy. No significant
deviation is observed in the data with respect to the standard model
predictions, and model-independent upper limits are set on the branching
fraction B(t to H+ b), ranging from 1.2 to 6.5% for a charged Higgs boson with
mass between 90 and 160 GeV, under the assumption that B(H+ to c s-bar) = 100%. | hep-ex |
The monitoring system for the aerogel Cherenkov counter of the BELLE
detector: We report on a design and performances of a monitoring system developed for
the aerogel Cherenkov counters (ACC) of the BELLE detector. The system consists
of blue LEDs, a diffuser box, and optical distributors which distribute the LED
light to the ACC modules. The employed LED (NSPB series) has been observed to
have high reliability on the long term stability and the temprature dependence.
The diffuser box is employed to reduce the intrinsic non-uniformity of the LED
light intensity. The overall performances of the present monitoring system on
uniformity and intensity of the light output have been found to satisfy all the
requirements for the monitoring. | hep-ex |
Transverse Polarization of Lambda and Lambda-bar Hyperons in Quasireal
Photoproduction: The HERMES experiment has measured the transverse polarization of Lambda and
Lambda-bar hyperons produced inclusively in quasireal photoproduction at a
positron beam energy of 27.6 GeV. The transverse polarization of the Lambda
hyperon is found to be positive while the observed Lambda-bar polarization is
compatible with zero. The transverse polarization values averaged over the
kinematic acceptance of HERMES are 0.078 +/- 0.006(stat) +/- 0.012(syst) and
-0.025 +/- 0.015(stat) +/- 0.018(syst) for Lambda and Lambda-bar hyperons,
respectively. The dependences of Lambda and Lambda-bar polarizations on the
fraction $\zeta$ of the beam's light-cone momentum carried by the hyperon and
on the hyperon's transverse momentum $p_T$ were investigated. The measured
Lambda polarization rises linearly with $p_T$ and exhibits a different behavior
for low and high values of $\zeta$, which approximately correspond to the
backward and forward regions in the center-of-mass frame of the $\gamma^*N$
reaction. | hep-ex |
Top quark and W/Z results from the Tevatron: We summarize results of some crucial measurements of the top quark and W/Z
boson properties carried out by the D0 and the CDF collaborations at the
Tevatron collider at Fermilab based on data collected during Run 1 (1992-96).
Among the interesting properties measured are the pair-production cross section
and the mass of the top quark, and the mass and the width of the W boson.
Searches for singly produced top quarks and for certain non-standard production
and decays of the top quark, as well as studies of angular correlations in the
production and decay of the top quarks are also presented. Expectations from
the ongoing Run 2 of the Tevatron, presently in its second year, are discussed. | hep-ex |
Neutrino Characterisation using Convolutional Neural Networks in CHIPS
water Cherenkov detectors: This work presents a novel approach to water Cherenkov neutrino detector
event reconstruction and classification. Three forms of a Convolutional Neural
Network have been trained to reject cosmic muon events, classify beam events,
and estimate neutrino energies, using only a slightly modified version of the
raw detector event as input. When evaluated on a realistic selection of
simulated CHIPS-5kton prototype detector events, this new approach
significantly increases performance over the standard likelihood-based
reconstruction and simple neural network classification. | hep-ex |
Search for Lepton Flavor Violation in $Υ(3S)\rightarrow
e^{\pm}μ^{\mp}$: We report on the first search for electron-muon lepton flavor violation (LFV)
in the decay of a $b$~quark and $b$~antiquark bound state. We look for the LFV
decay $\Upsilon (3S)\rightarrow e^{\pm}\mu^{\mp}$ in a sample of 118~million
$\Upsilon (3S)$ mesons from 27~fb$^{-1}$ of data collected with the \babar\
detector at the SLAC PEP-II $e^+e^-$ collider operating with a 10.36~GeV
center-of-mass energy. No evidence for a signal is found and we set a limit on
the branching fraction $\mathcal{B}(\Upsilon(3S)\rightarrow
e^{\pm}\mu^{\mp})<3.6\times10^{-7}\mathrm{at~ 90\%~ CL}$. This result can be
interpreted as a limit $\Lambda_{NP}/g^2_{NP} > 80~$TeV on the energy scale
$\Lambda_{NP}$ divided by the coupling-squared $g^2_{NP}$ of relevant new
physics. | hep-ex |
Dalitz plot analysis of the D^+ -> K^-pi^+pi^+ decay: We perform a Dalitz plot analysis of D^+ -> K^-pi^+pi^+ decay with the CLEO-c
data set of 572 pb^-1 of e^+e^- collisions accumulated at the psi(3770). This
corresponds to 1.6 million D^+D^- pairs from which we select 140793 candidate
events with a small background of 1.1%. We compare our results with previous
measurements using the isobar model. We modify the isobar model with improved
description of some of the contributing resonances, and get better agreement
with our data. We also consider a quasi-model-independent approach and measure
the magnitude and phase of the contributing K pi S wave in the range of
invariant masses from the threshold to the maximum in this decay. This gives an
improved descriptions of our data over the isobar model. Finally we allow for
an isospin-two pi^+pi^+ S-wave contribution, and find that adding this to both
the isobar model and quasi-model-independent approach gives the best
description of our data. | hep-ex |
Searches for exclusive Higgs and $Z$ boson decays into $J/ψγ$,
$ψ(2S)γ$, and $Υ(nS)γ$ at $\sqrt{s}=13$ TeV with the
ATLAS detector: Searches for the exclusive decays of the Higgs and $Z$ bosons into a
$J/\psi$, $\psi(2S)$, or $\Upsilon(nS)$ ($n=1,2,3$) meson and a photon are
performed with a $pp$ collision data sample corresponding to an integrated
luminosity of 36.1 fb$^{-1}$ collected at $\sqrt{s}=13$ TeV with the ATLAS
detector at the CERN Large Hadron Collider. No significant excess of events is
observed above the expected backgrounds, and 95% confidence-level upper limits
on the branching fractions of the Higgs boson decays to $J/\psi\gamma$,
$\psi(2S)\gamma$, and $\Upsilon(nS)\gamma$ of $3.5\times10^{-4}$,
$2.0\times10^{-3}$, and $(4.9,5.9,5.7)\times10^{-4}$, respectively, are
obtained assuming Standard Model production. The corresponding 95%
confidence-level upper limits for the branching fractions of the $Z$ boson
decays are $2.3\times10^{-6}$, $4.5\times10^{-6}$ and
$(2.8,1.7,4.8)\times10^{-6}$, respectively. | hep-ex |
Measurement of the Absolute Branching Fraction of D0 -> K- pi+: We measure the absolute branching fraction for $D0 \to K^{-} \pi^{+}$ using
partial reconstruction of $B0bar \to D^{*+} X \ell^{-} \bar{\nu}_{\ell}$
decays. Only the charged lepton and the soft pion from the decay $D^{*+} \to
D^{0} \pi^{+}$ are used. Based on a data sample of 230 million BBbar pairs
collected at the $\Upsilon(4S)$ resonance with the \babar detector at the
PEP-II asymmetric-energy $B$ Factory at SLAC, we obtain ${\cal B}(\Dz \to \Km
\pip) = (4.025 \pm 0.038 \pm 0.098)%$, where the first error is statistical and
the second error is systematic. | hep-ex |
Search for production of single top quarks via flavor-changing neutral
currents at the Tevatron: We search for the production of single top quarks via flavor-changing neutral
current couplings of a gluon to the top quark and a charm (c) or up (u) quark.
We analyze 230 pb^{-1} of lepton+jets data from \ppbar collisions at a center
of mass energy of 1.96 TeV collected by the D0 detector at the Fermilab
Tevatron Collider. We observe no significant deviation from standard model
predictions, and hence set upper limits on anomalous coupling parameters
\kappa^c_g/\Lambda and \kappa^u_g/\Lambda, where the \kappa_g define the
strength of the tcg and tug couplings, and \Lambda defines the scale of new
physics. The limits at 95% C.L. are: \kappa^c_g/\Lambda < 0.15 TeV^{-1} and
\kappa^u_g/\Lambda < 0.037 TeV^{-1}. | hep-ex |
Heavy quark meson spectroscopy at CDF: From a study of the X(3872) mass and width based on the world's largest
sample of $X(3872)\to J/\psi\pi^+\pi^-$ decays, we find that our X(3872) signal
is consistent with a single state, and leads to the most precise measurement of
the X(3872) mass. We also report the recent evidence for a new narrow
structure, Y(4140), decaying to the $J/\psi \phi$ final state, in exclusive
$B^+\to J/\psi\phi K^+$ decays in a data sample corresponding to an integrated
luminosity of 2.7 \ifb collected at the CDF II detector. This narrow structure
with its mass well above open charm pairs is unlikely to be a candidate for a
conventional charmonium state. | hep-ex |
Production of Slow Protonium in Vacuum: We describe how protonium, the quasi-stable antiproton-proton bound system,
has been synthesized following the interaction of antiprotons with the
molecular ion H$_2^+$ in a nested Penning trap environment. From a careful
analysis of the spatial distributions of antiproton annihilation events in the
ATHENA experiment, evidence is presented for protonium production with sub-eV
kinetic energies in states around $n$ = 70, with low angular momenta. This work
provides a new 2-body system for study using laser spectroscopic techniques. | hep-ex |
Evidence for the decay B0 --> K+K-pi0: We report a search for charmless hadronic decays of neutral B mesons to the
final state K+K-pi0. The results are based on a 711 fb^-1 data sample that
contains 772x10^6 BB-bar pairs, and was collected at the Y(4S) resonance with
the Belle detector at the KEKB asymmetric-energy e+e- collider. We find the
first evidence for this decay with a significance of 3.5 standard deviations
and measure its branching fraction as BF(B0 --> K+K-pi0) = [2.17 +/- 0.60(stat)
+/- 0.24 (syst)]x10^-6. | hep-ex |
Measurement of the centrality dependence of the charged-particle
pseudorapidity distribution in proton--lead collisions at
$\sqrt{s_{_{\rm{NN}}}} = 5.02$ TeV with the ATLAS detector: The centrality dependence of the mean charged-particle multiplicity as a
function of pseudorapidity is measured in approximately 1 $\mu$b$^{-1}$ of
proton--lead collisions at a nucleon--nucleon centre-of-mass energy of
$\sqrt{s_{_{\rm{NN}}}} = 5.02$ TeV using the ATLAS detector at the Large Hadron
Collider. Charged particles with absolute pseudorapidity less than 2.7 are
reconstructed using the ATLAS pixel detector. The $p$+Pb collision centrality
is characterised by the total transverse energy measured in the Pb-going
direction of the forward calorimeter. The charged-particle pseudorapidity
distributions are found to vary strongly with centrality, with an increasing
asymmetry between the proton-going and Pb-going directions as the collisions
become more central. Three different estimations of the number of nucleons
participating in the $p$+Pb collision have been carried out using the Glauber
model as well as two Glauber--Gribov inspired extensions to the Glauber model.
Charged-particle multiplicities per participant pair are found to vary
differently for these three models, highlighting the importance of including
colour fluctuations in nucleon--nucleon collisions in the modelling of the
initial state of $p$+Pb collisions. | hep-ex |
Evidence for the decay $B^0\to J/ψω$ and measurement of the
relative branching fractions of $B^0_s$ meson decays to $J/ψη$ and
$J/ψη^{'}$: First evidence of the $B^0\to J/\psi\omega$ decay is found and the
$B_{s}^0\to J/\psi\eta$ and $B_{s}^0\to J/\psi\eta^{\prime}$ decays are studied
using a dataset corresponding to an integrated luminosity of 1.0
$\mathrm{fb}^{-1}$ collected by the LHCb experiment in proton-proton collisions
at a centre-of-mass energy of $\sqrt{s} = 7$ TeV. The branching fractions of
these decays are measured relative to that of the $\mathrm{B}^0\to
J/\psi\rho^0$ decay: $$\frac{Br(B^0\to J/\psi\omega)}{Br(B^0\to J/\psi\rho^0)}
= 0.89 \pm0.19(stat)^{+0.07}_{-0.13}(syst)$$ $$\frac{Br(B^0_s\to
J/\psi\eta)}{Br(B^0\to J/\psi\rho^0)} = 14.0 \pm
1.2(stat)^{+1.1}_{-1.5}(syst)^{+1.1}_{-1.0}(\frac{f_d}{f_s}),$$
$$\frac{Br(B^0_s\to J/\psi\eta^{\prime})}{Br(B^0\to J/\psi\rho^0)} =
12.7\pm1.1(stat)^{+0.5}_{-1.3}(syst)^{+1.0}_{-0.9}(\frac{f_d}{f_s}),$$ where
the last uncertainty is due to the knowledge of $f_d/f_s$, the ratio of b-quark
hadronization factors that accounts for the different production rate of $B^0$
and $B^0_s$ mesons. The ratio of the branching fractions of $B^0_s\to
J/\psi\eta^{\prime}$ and $B^0_s\to J/\psi\eta$ decays is measured to be $$
\frac{Br(B^0_s\to J/\psi\eta^{\prime})}{Br(B^0_s\to J/\psi\eta)} =
0.90\pm0.09(stat)^{+0.06}_{-0.02}(syst).$$ | hep-ex |
Prospects for X(3872) Detection at Panda: Monte-Carlo simulations for a resonance scan of the charmonium-like state
X(3872) at Panda are performed. Final state radiation hadronic background
reactions are taken into account. The signal reconstruction uses a realistic
pattern recognition (track finder and track fitter) and electron/pion
discrimination. | hep-ex |
Neutrino Physics Opportunities with the IsoDAR Source at Yemilab: IsoDAR seeks to place a high-power-cyclotron and target combination, as an
intense source of $\bar{\nu}_e$ at the level of $\sim 10^{23}$/year, close to a
kiloton-scale neutrino detector in order to gain sensitivity to very
short-baseline neutrino oscillations ($\bar{\nu}_e \rightarrow \bar{\nu}_{e}$)
and perform precision tests of the weak interaction, among other physics
opportunities. Recently, IsoDAR has received preliminary approval to be paired
with the 2.26~kton target volume liquid scintillator detector at the Yemi
Underground Laboratory (Yemilab) in Korea, at a 17~m center-to-center baseline,
and cavern excavation for IsoDAR is now complete. In this paper, we present the
physics capabilities of IsoDAR@Yemilab in terms of sensitivity to oscillations
(via inverse beta decay, IBD; $\bar{\nu}_e+p \rightarrow e^+ + n$), including
initial-state wavepacket effects, and the weak mixing angle (via elastic
scattering off atomic electrons, $\bar{\nu}_e + e^- \rightarrow \bar{\nu}_e +
e^-$). We also introduce a study of IsoDAR sensitivity to new particles, such
as a light $X$ boson, produced in the target that decays to $\nu_e \bar \nu_e$. | hep-ex |
Precision Top Quark Mass Measurement in the Lepton + Jets Topology in
ppbar Collisions at sqrt(s) = 1.96 TeV: We report two measurements of the top quark mass M_top using the CDF II
detector at the Fermilab Tevatron in a 318 pb^-1 data sample observed in the
lepton + jets final state. One method uses an event-based likelihood technique
resulting in M_top = 173.2 +2.6/-2.4 (stat.) +/- 3.2 (syst.) GeV/c^2 or 173.2
+4.1/-4.0 GeV/c^2. The second method reconstructs a top quark mass in each
event using the measured invariant mass of the hadronically decaying W boson to
constrain the jet energy scale to obtain a value for M_top of 173.5 +3.7/-3.6
(stat.) +/- 1.3 (syst.) GeV/c^2 or 173.5 +3.9/-3.8 GeV/c^2. We take the latter,
which is more precise, as our result. | hep-ex |
Inclusive Charged Hadron Production in Two-Photon Collisions at LEP: Inclusive charged hadron production, e+e- -> e+e- h+- X, is studied using 414
pb-1 of data collected at LEP with the L3 detector at centre-of-mass energies
between 189 and 202 GeV. Single particle inclusive differential cross sections
are measured as a function of the particle transverse momentum, pt, and
pseudo-rapidity, eta. For p_t < 1.5 GeV, the data are well described by an
exponential, typical of soft hadronic processes. For higher pt, the onset of
perturbative QCD processes is observed. The pi+- production cross section for
pt > 5 GeV is much higher than the NLO QCD predictions. | hep-ex |
Study of the Baryon-Antibaryon Low-Mass Enhancements in Charmless
Three-body Baryonic B Decays: The angular distributions of the baryon-antibaryon low-mass enhancements seen
in the charmless three-body baryonic B decays B+ -> p pbar K+, B0 -> p pbar Ks,
and B0 -> p Lambdabar pi- are reported. A quark fragmentation interpretation is
supported, while the gluonic resonance picture is disfavored. Searches for the
Theta+ and Theta++ pentaquarks in the relevant decay modes and possible
glueball states G with 2.2 GeV/c2 < M-ppbar < 2.4 GeV/c2 in the ppbar systems
give null results. We set upper limits on the products of branching fractions,
B(B0 -> Theta+ p)\times B(Theta+ -> p Ks) < 2.3 \times 10^{-7}, B(B+ -> Theta++
pbar) \times B(Theta++ -> p K+) < 9.1 \times 10^{-8}, and B(B+ -> G K+) \times
B(G -> p pbar) < 4.1 \times 10^{-7} at the 90% confidence level. The analysis
is based on a 140 fb^{-1} data sample recorded on the Upsilon(4S) resonance
with the Belle detector at the KEKB asymmetric-energy e+e- collider. | hep-ex |
Observation of Two New N* Peaks in J/psi -> $p pi^- \bar n$ and $\bar
pπ^+n$ Decays: The $\pi N$ system in decays of $J/\psi\to\bar NN\pi$ is limited to be
isospin 1/2 by isospin conservation. This provides a big advantage in studying
$N^*\to \pi N$ compared with $\pi N$ and $\gamma N$ experiments which mix
isospin 1/2 and 3/2 for the $\pi N$ system. Using 58 million $J/\psi$ decays
collected with the Beijing Electron Positron Collider, more than 100 thousand
$J/\psi \to p \pi^- \bar n + c.c.$ events are obtained. Besides two well known
$N^*$ peaks at 1500 MeV and 1670 MeV, there are two new, clear $N^*$ peaks in
the $p\pi$ invariant mass spectrum around 1360 MeV and 2030 MeV. They are the
first direct observation of the $N^*(1440)$ peak and a long-sought "missing"
$N^*$ peak above 2 GeV in the $\pi N$ invariant mass spectrum. A simple
Breit-Wigner fit gives the mass and width for the $N^*(1440)$ peak as $1358\pm
6 \pm 16$ MeV and $179\pm 26\pm 50$ MeV, and for the new $N^*$ peak above 2 GeV
as $2068\pm 3^{+15}_{-40}$ MeV and $165\pm 14\pm 40$ MeV, respectively. | hep-ex |
Excess Electronic Recoil Events in XENON1T: We report results from searches for new physics with low-energy electronic
recoil data recorded with the XENON1T detector. With an exposure of 0.65 t-y
and an unprecedentedly low background rate of $76\pm2$ events/(t y keV) between
1 and 30 keV, the data enables sensitive searches for solar axions, an enhanced
neutrino magnetic moment, and bosonic dark matter. An excess over known
backgrounds is observed at low energies and most prominent between 2 and 3 keV.
The solar axion model has a 3.4$\sigma$ significance, and a 3D 90% confidence
surface is reported for axion couplings to electrons, photons, and nucleons.
This surface is inscribed in the cuboid defined by $g_{ae}<3.8 \times
10^{-12}$, $g_{ae}g_{an}^{eff}<4.8\times 10^{-18}$, and
$g_{ae}g_{a\gamma}<7.7\times10^{-22} GeV^{-1}$, and excludes either $g_{ae}=0$
or $g_{ae}g_{a\gamma}=g_{ae}g_{an}^{eff}=0$. The neutrino magnetic moment
signal is similarly favored over background at 3.2$\sigma$ and a confidence
interval of $\mu_{\nu} \in (1.4,2.9)\times10^{-11}\mu_B$ (90% C.L.) is
reported. Both results are in strong tension with stellar constraints. The
excess can also be explained by $\beta$ decays of tritium at 3.2$\sigma$ with a
trace amount that can neither be confirmed nor excluded with current knowledge
of its production and reduction mechanisms. The significances of the solar
axion and neutrino magnetic moment hypotheses are reduced to 2.0$\sigma$ and
0.9$\sigma$, respectively, if an unconstrained tritium component is included in
the fitting. With respect to bosonic dark matter, the excess favors a
monoenergetic peak at ($2.3\pm0.2$) keV (68% C.L.) with a 3.0$\sigma$ global
(4.0$\sigma$ local) significance. We also consider the possibility that
$^{37}$Ar may be present in the detector and yield a 2.82 keV peak. Contrary to
tritium, the $^{37}$Ar concentration can be tightly constrained and is found to
be negligible. | hep-ex |
Measurement of indirect CP-violating asymmetries in $D^0\to K^+K^-$ and
$D^0\to π^+π^-$ decays at CDF: We report a measurement of the indirect CP-violating asymmetries
($A_{\Gamma}$) between effective lifetimes of anticharm and charm mesons
reconstructed in $D^0\to K^+ K^-$ and $D^0\to \pi^+\pi^-$ decays. We use the
full data set of proton-antiproton collisions collected by the Collider
Detector at Fermilab experiment and corresponding to $9.7$~fb$^{-1}$ of
integrated luminosity. The strong-interaction decay $D^{*+}\to D^0\pi^+$ is
used to identify the meson at production as $D^0$ or $\overline{D}^0$. We
statistically subtract $D^0$ and $\overline{D}^0$ mesons originating from
$b$-hadron decays and measure the yield asymmetry between anticharm and charm
decays as a function of decay time. We measure $A_\Gamma (K^+K^-) = (-0.19 \pm
0.15 (stat) \pm 0.04 (syst))\%$ and $A_\Gamma (\pi^+\pi^-)= (-0.01 \pm 0.18
(stat) \pm 0.03 (syst))\%$. The results are consistent with the hypothesis of
CP symmetry and their combination yields $A_\Gamma = (-0.12 \pm 0.12)\%$. | hep-ex |
Precision Electroweak Physics at the Z: A review of the decade of Z-pole electroweak physics is presented. Although
all experimental work has been completed, it represents a ``Golden Age'' in our
understanding of the Minimal Electroweak Standard Model (MSM). The latest (and
nearly final) results from the LEP and SLC experiments are presented. The
remaining inconsistencies are discussed and and their effects upon the MSM
interpretation are explored. | hep-ex |
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