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Linac*LHC Based ep, Gamma-p, eA, Gamma-A and FEL Gamma-A Colliders:
Luminosity and Physics: Main parameters and physics goals of different colliders, which can be
realized if a special 1 TeV energy linear electron accelerator or corresponding
linear collider is constructed tangential to LHC, are discussed. It is shown
that L_(ep)=10^(32)cm^(-2)s^(-1) at sqrt(s_(ep))=5.29 TeV can be achieved
within moderate upgrade of LHC parameters. Then, Gamma-p collider with he same
luminosity and sqrt(s)=4.82 TeV can be realized using Compton backscattering of
laser beam off the electron beam. Concerning the nucleus beam,
L*A=10^(31)cm^(-2)s^(-1) can be achieved at least for light and medium nuclei
for both eA and Gamma-A options. Finally, colliding of FEL beam from an
electron linac and nucleus beam from LHC will give a new opportunity to
investigate nuclear spektroscopy and photo-nuclei reactions. | hep-ex |
Testing CPT and Lorentz Invariance with the Anomalous Spin Precession of
the Muon: This article discusses tests of CPT and Lorentz invariance with data from the
muon g-2 experiment at Brookhaven National Laboratory. According to an
extension of the Standard Model by Kostelecky et al., CPT/Lorentz violating
terms in the Lagrangian induce a shift of the anomaly frequency omega_a of
muons in a magnetic field. This shift is predicted to be different for positive
and negative muons and to oscillate with the Earth's sidereal frequency. We
discuss the sensitivity of the g-2 experiment to different parameters of this
Standard Model extension and propose an analysis method to search for sidereal
variations of omega_a. | hep-ex |
Exclusive $J/ψ$ and $ψ(2S)$ production in $pp$ collisions at
$\sqrt{s}=7$ TeV: Exclusive $J/\psi$ and $\psi(2S)$ vector meson production has been observed
in the dimuon channel using the LHCb detector. The cross-section times
branching fractions to two muons with pseudorapidities between 2.0 and 4.5 are
measured to be $ \sigma_{pp\rightarrow J/\psi (\rightarrow \mu^{+} \mu^{-})}
(2.0 <\eta_{\mu^{\pm}}< 4.5) = 307 \pm 21 \pm 36 \text{pb},
\sigma_{pp\rightarrow \psi(2S) (\rightarrow \mu^{+} \mu^{-})} (2.0
<\eta_{\mu^{\pm}}< 4.5) = 7.8 \pm 1.3 \pm 1.0 \text{pb}, $ where the first
uncertainties are statistical and the second are systematic. The measurements
are found to be in good agreement with results from previous experiments and
theoretical predictions. The $J/\psi$ photoproduction cross-section has been
measured as a function of the photon-proton centre-of-mass energy. The results
are consistent with measurements obtained at HERA and confirm a similar power
law behaviour for the photoproduction cross-section. | hep-ex |
Recent results on $B \to μ^+ μ^-$ decays with the CMS experiment: Results on $B \to \mu^+ \mu^-$ decays with the CMS experiment are reported,
using 61 fb$^{-1}$ of data recorded during LHC Run 1 and 2016. With an improved
muon identification algorithm and refined unbinned maximum likelihood fitting
methods, the decay $B_s^0 \to \mu^+ \mu^-$ is observed with a significance of
5.6 standard deviations. Its branching fraction is measured to be BF($B^0_s \to
\mu^+ \mu^-$) = [2.9+/-0.7(exp)+/-0.2(frag)]$\times 10^{-9}$, where the first
error is the combined statistical and systematic uncertainty and the second
error quantifies the uncertainty of the $B^0_s$ and $B^+$ fragmentation
probability ratio. The $B^0_s \to \mu^+ \mu^-$ effective lifetime is
$\tau_{\mu^+ \mu^-} =1.70^{+0.61}_{-0.44}$ps. No evidence for the decay $B^0
\to \mu^+ \mu^-$ is found and an upper limit of BF($B^0 \to \mu^+ \mu^-$) <
3.6$\times 10^{-10}$ (at 95% confidence level) is determined. All results are
consistent with the standard model of particle physics. | hep-ex |
Search for the Rare Leptonic Decay B- -> tau- nubar: We present a search for the decay $B^{-} \to \tau^{-} \bar{\nu}_{\tau}$ in a
sample of $88.9 \times 10^{6}$ $B\bar{B}$ pairs recorded with the BaBar
detector at the SLAC $B$-Factory. One of the two $B$ mesons from the
$\Upsilon(4S)$ is reconstructed in a hadronic or a semileptonic final state and
the decay products of the other $B$ in the event are analyzed for consistency
with a $B^{-} \to \tau^{-} \bar{\nu}_{\tau}$ decay. We find no evidence of a
signal and set an upper limit on the branching fraction of $\mathcal{B}(B^{-}
\to \tau^{-} \bar{\nu}_{\tau}) < 4.2 \times 10^{-4}$ at the 90% confidence
level. | hep-ex |
Measurement of jet fragmentation in Pb+Pb and $pp$ collisions at
$\sqrt{s_\mathrm{NN}} = 2.76$ TeV with the ATLAS detector: The distributions of transverse momentum and longitudinal momentum fraction
of charged particles in jets are measured in Pb+Pb and pp collisions with the
ATLAS detector at the LHC. The distributions are measured as a function of jet
transverse momentum and rapidity. The analysis utilises an integrated
luminosity of 0.14 nb$^{-1}$ of Pb+Pb data and 4.0 pb$^{-1}$ of pp data
collected in 2011 and 2013, respectively, at the same centre-of-mass energy of
2.76 TeV per colliding nucleon pair. The distributions measured in pp
collisions are used as a reference for those measured in Pb+Pb collisions in
order to evaluate the impact on the internal structure of jets from the jet
energy loss of fast partons propagating through the hot, dense medium created
in heavy-ion collisions. Modest but significant centrality-dependent
modifications of fragmentation functions in Pb+Pb collisions with respect to
those in pp collisions are seen. No significant dependence of modifications on
jet $p_{\mathrm{T}}$ and rapidity selections is observed except for the
fragments with the highest transverse momenta for which some reduction of
yields is observed for more forward jets. | hep-ex |
Top Quark Current Experimental Status: Ten years after its discovery at the Tevatron collider, we still know little
about the top quark. Its large mass suggests it may play a key role in the
mechanism of Electroweak Symmetry Breaking (EWSB), or open a window of
sensitivity to new physics related to EWSB and preferentially coupled to it. To
determine whether this is the case, precision measurements of top quark
properties are necessary. The high statistics samples being collected by the
Tevatron experiments during Run II start to incisively probe the top quark
sector. This report summarizes the experimental status of the top quark,
focusing in particular on the recent measurements from the Tevatron. | hep-ex |
D meson nuclear modification factors in Pb-Pb collisions at {\surd}sNN =
2.76 TeV, measured with the ALICE detector: The ALICE experiment has measured the D meson production in pp and Pb-Pb
collisions at the LHC at {\surd}s = 7 and 2.76 TeV and {\surd}sNN = 2.76 TeV
respectively, via the exclusive reconstruction of hadronic decay channels. The
analyses of the D0{\to}K-pi+ and D+{\to}K-pi+pi+ channels will be described and
the preliminary results for the D0 and D+ nuclear modification factor will be
presented. | hep-ex |
High-purity germanium detector ionization pulse shapes of nuclear
recoils, gamma interactions and microphonism: Nuclear recoil measurements with high-purity Germanium detectors are very
promising to directly detect dark matter candidates. The main background
sources in such experiments are natural radioactivity and microphonic noise.
Digital pulse shape analysis is an encouraging approach to reduce the
background originating from the latter. To study the pulse shapes of nuclear
recoil events we performed a neutron scattering experiment, which covered the
ionization energy range from 20 to 80 keV. We have measured ionization
efficiencies as well and found an excellent agreement with the theory of
Lindhard. In a further experiment we measured pulse shapes of a radioactive
gamma-source and found no difference to nuclear recoil pulse shapes. Pulse
shapes originating from microphonics of a HPGe-detector are presented for the
first time. A microphonic noise suppression method, crucial for dark matter
direct detection experiments, can therefore be calibrated with pulse shapes
from gamma-sources. | hep-ex |
Measurement of the underground atmospheric muon charge ratio using the
MINOS Near Detector: The magnetized MINOS Near Detector, at a depth of 225 meters of water
equivalent (mwe), is used to measure the atmospheric muon charge ratio. The
ratio of observed positive to negative atmospheric muon rates, using 301 days
of data, is measured to be 1.266+/-0.001(stat.)+0.015/-0.014(syst.). This
measurement is consistent with previous results from other shallow underground
detectors, and is 0.108+/-0.019(stat. + syst.) lower than the measurement at
the functionally identical MINOS Far Detector at a depth of 2070 mwe. This
increase in charge ratio as a function of depth is consistent with an increase
in the fraction of muons arising from kaon decay for increasing muon surface
energies. | hep-ex |
Point Cloud Generation using Transformer Encoders and Normalising Flows: Data generation based on Machine Learning has become a major research topic
in particle physics. This is due to the current Monte Carlo simulation approach
being computationally challenging for future colliders, which will have a
significantly higher luminosity. The generation of collider data is similar to
point cloud generation, but arguably more difficult as there are complex
correlations between the points which need to be modelled correctly. A
refinement model consisting of normalising flows and transformer encoders is
presented. The normalising flow output is corrected by a transformer encoder,
which is adversarially trained against another transformer encoder
discriminator/critic. The model reaches state-of-the-art performance while
yielding a stable training. | hep-ex |
Measurement of the branching fractions of the singly Cabibbo-suppressed
decays $Λ_{c}^{+}\to pη$ and $Λ_{c}^{+}\to pω$: Based on 4.5 $\mbox{fb$^{-1}$}$ $e^{+}e^{-}$ collision data collected with
BESIII detector at seven energy points between 4.600 and 4.699 GeV, the
branching fractions for $\Lambda_{c}^{+}\to p\eta$ and $\Lambda_{c}^{+}\to
p\omega$ were measured by means of single-tag method. The branching fractions
of $\Lambda_{c}^{+}\to p\eta$ and $\Lambda_{c}^{+}\to p\omega$ are determined
to be $(1.57\pm0.11_{\rm {stat}}\pm0.04_{\rm{syst}})\times10^{-3}$ and
$(1.11\pm0.20_{\rm{stat}}\pm0.07_{\rm{syst}})\times10^{-3}$, with a statistical
significance of greater than 10 $\sigma$ and 5.7 $\sigma$, respectively. These
results are consistent with the previous measurements by BESIII, LHCb and
Belle, and the result of $\Lambda_{c}^{+}\to p\eta$ is the most precise to
date. | hep-ex |
Observation of Y(2175) in $J/ψ\to ηφf_0(980)$: The decays of $J/\psi\to \eta\phi f_0(980) (\eta\to \gamma\gamma, \phi \to
K^+K^-, f_0(980)\to\pi^+\pi^-)$ are analyzed using a sample of $5.8 \times
10^{7}$ $J/\psi$ events collected with the BESII detector at the Beijing
Electron-Positron Collider (BEPC). A structure at around $2.18 $GeV/$c^2$ with
about $5\sigma$ significance is observed in the $\phi f_0(980)$ invariant mass
spectrum. A fit with a Breit-Wigner function gives the peak mass and width of
$m=2.186\pm 0.010 (stat)\pm 0.006 (syst) $GeV/$c^2$ and $\Gamma=0.065\pm 0.023
(stat)\pm 0.017 (syst) $GeV/$c^2$, respectively, that are consistent with those
of Y(2175), observed by the BABAR collaboration in the initial-state radiation
(ISR) process $e^+e^-\to\gamma_{ISR}\phi f_0(980)$. The production branching
ratio is determined to be $Br(J/\psi\to\eta Y(2175))\cdot Br(Y(2175)\to\phi
f_0(980))\cdot Br(f_0(980)\to\pi^+\pi^-)=(3.23\pm 0.75 (stat)\pm0.73
(syst))\times 10^{-4}$, assuming that the Y(2175) is a $1^{--}$ state. | hep-ex |
KARMEN: Present Neutrino-Oscillation Limits and Perspectives after the
Upgrade: The neutrino experiment KARMEN is situated at the beam stop neutrino source
ISIS. It provides nu_mu's, nu_e's and nu_mu_bar's in equal intensities from the
pi+ mu+ decay at rest. The oscillation channels nu_mu->nu_e and
nu_mu_bar->nu_e_bar are investigated with a 56t liquid scintillation
calorimeter at a mean distance of 17.6m from the nu source. No evidence for
oscillations could be found with KARMEN, resulting in 90% CL exclusion limits
of sin(2th) < 8.5 10^-3 (nu_mu_bar->nu_e_bar) and sin(2th) < 4.0 10^-2
(nu_mu->nu_e) for Delta m^2 > 100eV^2. In 1996, the KARMEN neutrino experiment
has been upgraded by an additional veto system. Vetoing of cosmic muons passing
the 7000t massive iron shielding of the detector suppresses energetic neutrons
from deep inelastic scattering of muons as well as from mu-capture in iron. Up
to 1996, these neutrons penetrating into the detector represented the main
background for the nu_mu_bar->nu_e_bar oscillation search. With an expected
reduction of the background rate by a factor of 40 the experimental sensitivity
for nu_mu_bar->nu_e_bar will be significantly enhanced towards sin(2th) = 10^-3
for large Delta m^2. | hep-ex |
Improved Measurement of CP Violation in Neutral B Decays to c cbar s: We present updated measurements of time-dependent CP asymmetries in
fully-reconstructed neutral B decays to several CP eigenstates containing a
charmonium meson. The measurements use a data sample of (383 +/- 4) x 10^6
Y(4S)-> BBbar decays collected with the BABAR detector at the PEP-II B factory.
We determine sin2beta = 0.714 +/- 0.032 (stat) +/- 0.018 (syst) and |lambda| =
0.952 +/- 0.022 (stat) +/- 0.017 (syst). | hep-ex |
Search for $B^0 \to p \bar{p}$, $Λ\barΛ$ and $B^+ \to p
\barΛ$ at Belle: We report results of a search for the charmless two-body baryonic decays B^0
\to p \bar{p}, B^0 \to \Lambda \bar{\Lambda}, and B^+\to p \bar{\Lambda} based
on the analysis of a 140 fb^{-1} data sample. We set 90% confidence level upper
limits on their branching fractions: B(B^0 \to p \bar{p}) < 4.1 x 10^{-7},
B(B^0 \to \Lambda \bar{\Lambda}) < 6.9 x 10^{-7}$, and B(B^+ \to p
\bar{\Lambda}) < 4.9 x 10^{-7}. | hep-ex |
Search for pair production of second-generation leptoquarks at $\sqrt{s}
=$ 13 TeV: A search for pair production of second-generation leptoquarks is performed
using proton-proton collision data collected at $\sqrt{s}=$ 13 TeV in 2016 with
the CMS detector at the CERN LHC, corresponding to an integrated luminosity of
35.9 fb$^{-1}$. Final states with two muons and two jets, or with one muon, two
jets, and missing transverse momentum are considered. Second-generation scalar
leptoquarks with masses less than 1530 (1285) GeV are excluded for $\beta =$
1.0 (0.5), where $\beta$ is the branching fraction for the decay of a
leptoquark to a charged lepton and a quark. The results of the search are also
interpreted as limits on the pair production of long-lived top squarks in an
$R$-parity violating supersymmetry model that has a final state with two muons
and two jets. These limits represent the most stringent limits to date on these
models. | hep-ex |
Search for the Flavor Changing Neutral Current Decay t $\to Zq$ in $p
\bar{p}$ Collisions at $\sqrt{s}=1.96$: We report a search for the flavor changing neutral current (FCNC) decay of
the top quark \tZq ($q=u,c$) in \ppbar collisions at $\sqrt{s} = 1.96\tev$
using a data sample corresponding to an integrated luminosity of 1.9\invfb
collected by the CDF II detector. This decay is strongly suppressed in the
standard model (SM) and an observation of a signal at the Tevatron would be an
indication of physics beyond the SM. Using $Z+\ge4$ jet final state candidate
events, both with and without an identified bottom quark jet, we discriminate
signal from background by exploiting kinematic constraints present in FCNC
events and obtain an upper limit of $\btZq < 3.7%$ at 95% C.L. | hep-ex |
The NA62 experiment at CERN: status and perspectives: The future program of the NA62 experiment at CERN SPS is currently in
advanced stage of development. The main goal of the experiment is to measure
the branching ratio of the ultra-rare decay K^+ -> pi+\nu\nubar, by detecting
approximately 80 events with a background on the order of 10%. In the present
paper, the motivation behind this measurement and the overall design strategy
of the experiment are briefly outlined. The experiment's construction status is
discussed and perspectives are given for the first runs with the new detector. | hep-ex |
Review on low and high mass spectroscopy: We review the most recent experimental progress in the hadron spectroscopy,
up to bottomonium mass. This covers the search for the J^PC=1^-+ exotic state,
the states in J/psi decays, the spin-singlets of heavy quarkonium, and the
charmoniumlike XYZ states. | hep-ex |
Search for charged Higgs bosons in decays of top quarks in p-pbar
collisions at sqrt(s) = 1.96 TeV: We report the recent charged Higgs search in top quark decays in 2.2/fb CDF
data. This is the first attempt to search for charged Higgs using fully
reconstructed mass assuming H->c-sbar in small tan beta region. No evidence of
a charged Higgs is observed in the CDF data, hence 95% upper limits are placed
at B(t->H+b) < 0.1-0.3. The upper limits can be used to limit the generic
non-SM charged boson production in top quark decays. | hep-ex |
The ZEPLIN-III Anti-Coincidence Veto Detector: The design, optimisation and construction of an anti-coincidence veto
detector to complement the ZEPLIN-III direct dark matter search instrument is
described. One tonne of plastic scintillator is arranged into 52 bars
individually read out by photomultipliers and coupled to a gadolinium-loaded
passive polypropylene shield. Particular attention has been paid to
radiological content. The overall aim has been to achieve a veto detector of
low threshold and high efficiency without the creation of additional background
in ZEPLIN-III, all at a reasonable cost. Extensive experimental measurements of
the components have been made, including radioactivity levels and performance
characteristics. These have been used to inform a complete end-to-end Monte
Carlo simulation that has then been used to calculate the expected performance
of the new instrument, both operating alone and as an anti-coincidence detector
for ZEPLIN-III. The veto device will be capable of rejecting over 65% of
coincident nuclear recoil events from neutron background in the energy range of
interest in ZEPLIN-III. This will reduce the background in ZEPLIN-III from ~0.4
to ~0.14 events per year in the WIMP acceptance region, a significant factor in
the event of a non-zero observation. Furthermore, in addition to providing
valuable diagnostic capabilities, the veto is capable of tagging over 15% for
gamma-ray rejection, all whilst contributing no significant additional
background. In conjunction with the replacement of the internal ZEPLIN-III
photomultiplier array, the new veto is expected to improve significantly the
sensitivity of the ZEPLIN-III instrument to dark matter, allowing spin
independent WIMP-nucleon cross sections below 1E-8 pb to be probed. | hep-ex |
First Observation of the $Σ_{c}^{*+}$ Baryon and a New Measurement
of the $Σ_{c}^{+}$ Mass: Using data recorded with the CLEO II and CLEO II.V detector configurations at
the Cornell Electron Storage Rings, we report the first observation and mass
measurement of the $\Sigma_c^{*+}$ charmed baryon, and an updated measurement
of the mass of the $\Sigma_c^+$ baryon. We find
$M(\Sigma_c^{*+})-M(\Lambda_c^+)$= 231.0 +- 1.1 +- 2.0 MeV, and
$M(\Sigma_c^{+})-M(\Lambda_c^+)$= 166.4 +- 0.2 +- 0.3 MeV, where the errors are
statistical and systematic respectively. | hep-ex |
Search for Deconfinement in NA49 at the CERN SPS: Experiment NA49 at the Cern SPS uses a large acceptance detector for a
systematic study of particle yields and correlations in nucleus-nucleus,
nucleon-nucleus and nucleon-nucleon collisions. Preliminary results for Pb+Pb
collisions at 40, 80 and 158 A*GeV beam energy are shown and compared to
measurements at lower and higher energies. | hep-ex |
Search for nearly mass-degenerate higgsinos using low-momentum
mildly-displaced tracks in $pp$ collisions at $\sqrt{s}$ = 13 TeV with the
ATLAS detector: Higgsinos with masses near the electroweak scale can solve the hierarchy
problem and provide a dark matter candidate, while detecting them at the LHC
remains challenging if their mass-splitting is $\mathcal{O}$(1 GeV). This
Letter presents a novel search for nearly mass-degenerate higgsinos in events
with an energetic jet, missing transverse momentum, and a low-momentum track
with a significant transverse impact parameter using 140 fb$^{-1}$ of
proton-proton collision data at $\sqrt{s}$ = 13 TeV collected by the ATLAS
experiment. For the first time since LEP, a range of mass-splittings between
the lightest charged and neutral higgsinos from 0.3 GeV to 0.9 GeV is excluded
at 95% confidence level, with a maximum reach of approximately 170 GeV in the
higgsino mass. | hep-ex |
Quarkonia production in ultra-peripheral PbPb collisions at LHCb: Measurements of coherent charmonium production cross sections together with
their ratio in ultra-peripheral PbPb collisions are studied at a
nucleon-nucleon centre-of-mass energy of $5.02\,\mathrm{TeV}$, the differential
cross-sections are measured as a function of rapidity and transverse momentum,
separately. The photo-production of \jpsi mesons at low transverse momentum is
studied in peripheral PbPb collisions, which confirms coherent \jpsi production
in hadronic collisions. These latest results significantly improve previous
measurements and are compared with some theoretical predictions. | hep-ex |
Storage Ring to Search for Electric Dipole Moments of Charged Particles
-- Feasibility Study: The proposed method exploits charged particles confined as a storage ring
beam (proton, deuteron, possibly $^3$He) to search for an intrinsic electric
dipole moment (EDM) aligned along the particle spin axis. Statistical
sensitivities could approach 10$^{-29}$ e$\cdot$cm. The challenge will be to
reduce systematic errors to similar levels. The ring will be adjusted to
preserve the spin polarisation, initially parallel to the particle velocity,
for times in excess of 15 minutes. Large radial electric fields, acting through
the EDM, will rotate the polarisation from the longitudinal to the vertical
direction. The slow rise in the vertical polarisation component, detected
through scattering from a target, signals the EDM.
The project strategy is outlined. A stepwise plan is foreseen, starting with
ongoing COSY activities that demonstrate technical feasibility. Achievements to
date include reduced polarization measurement errors, long horizontal plane
polarization lifetimes, and control of the polarization direction through
feedback from scattering measurements. The project continues with a
proof-of-capability measurement (precursor experiment; first direct deuteron
EDM measurement), an intermediate prototype ring (proof-of-principle;
demonstrator for key technologies), and finally a high-precision electric-field
storage ring. | hep-ex |
Measurement of CP Asymmetry in B0 to Ks pi0 pi0 Decays: We present a measurement of the time-dependent CP asymmetry for the neutral
B-meson decay into the CP = +1 final state Ks pi0 pi0, with Ks -> pi+ pi-. We
use a sample of approximately 227 million B-meson pairs recorded at the
Upsilon(4S) resonance with the BABAR detector at the PEP-II B-Factory at SLAC.
From an unbinned maximum likelihood fit we extract the mixing-induced
CP-violation parameter S = 0.72 +/- 0.71 +/- 0.08 and the direct CP-violation
parameter C = 0.23 +/- 0.52 +/- 0.13, where the first uncertainty is
statistical and the second systematic. | hep-ex |
Atmospheric Neutrino Physics with the MACRO detector: We present the measurement of the the flux and angular distribution of
atmospheric muon neutrinos using the MACRO detector. Three different event
topologies are detected in two different energy ranges. High energy neutrinos
(E~80 GeV) via the identification of upward throughgoing muons. Lower energy
neutrinos (E~ 4 GeV) via the upgoing stopping and partially contained downgoing
muons (ID+UGS), or via the partially contained upgoing muons (IU). The measured
flux is reduced with respect to the predictions. For the high energy sample,
globally the flux reduction is $0.74\pm 0.054_{stat+sys} \pm 0.12_{th}$ and
varies with the zenith angle. The ratio of measured to expected events is
almost constant with the zenith angle for the low energy events, and is $0.57
\pm 0.08_{stat+sys} \pm 0.14_{theor}$ for the IU sample, and $0.71 \pm
0.09_{stat+sys} \pm 0.17_{theor}$ for the (ID+UGS). All the data sets are
consistent within a scenario of neutrino oscillations, with maximum mixing and
$\Delta m^2 \sim 10^{-3}\div 10^{-2} eV^2$. | hep-ex |
The Strangeness Physics Program at CLAS: An extensive program of strange particle production off the nucleon is
currently underway with the CEBAF Large Acceptance Spectrometer (CLAS) in Hall
B at Jefferson Laboratory. This talk will emphasize strangeness
electroproduction in the baryon resonance region between W=1.6 and 2.4 GeV,
where indications of s-channel structure are suggestive of high-mass baryon
resonances coupling to kaons and hyperons in the final state. Precision
measurements of cross sections and polarization observables are being carried
out with highly polarized electron and real photon beams at energies up to 6
GeV. The near-term and longer-term future of this program will also be
discussed. | hep-ex |
Search for supersymmetry with a compressed mass spectrum in the vector
boson fusion topology with 1-lepton and 0-lepton final states in
proton-proton collisions at $\sqrt{s} =$ 13 TeV: A search for supersymmetric particles produced in the vector boson fusion
topology in proton-proton collisions is presented. The search targets final
states with one or zero leptons, large missing transverse momentum, and two
jets with a large separation in rapidity. The data sample corresponds to an
integrated luminosity of 35.9 fb$^{-1}$ of proton-proton collisions at
$\sqrt{s} =$ 13 TeV collected in 2016 with the CMS detector at the LHC. The
observed dijet invariant mass and lepton-neutrino transverse mass spectra are
found to be consistent with the standard model predictions. Upper limits are
set on the cross sections for chargino ($\widetilde\chi_1^\pm$) and neutralino
($\widetilde\chi_2^0$) production with two associated jets. For a compressed
mass spectrum scenario in which the $\widetilde\chi_1^\pm$ and
$\widetilde\chi_2^0$ decays proceed via a light slepton and the mass difference
between the lightest neutralino $\widetilde\chi_1^0$ and the mass-degenerate
particles $\widetilde\chi_1^\pm$ and $\widetilde\chi_2^0$ is 1 (30) GeV, the
most stringent lower limit to date of 112 (215) GeV is set on the mass of these
latter two particles. | hep-ex |
Study of the inclusive production of charged pions, kaons, and protons
in pp collisions at sqrt(s) = 0.9, 2.76, and 7 TeV: Spectra of identified charged hadrons are measured in pp collisions at the
LHC for sqrt(s) = 0.9, 2.76, and 7 TeV. Charged pions, kaons, and protons in
the transverse-momentum range pt approximately 0.1-1.7 GeV and for rapidities
abs(y) < 1 are identified via their energy loss in the CMS silicon tracker. The
average pt increases rapidly with the mass of the hadron and the event
charged-particle multiplicity, independently of the center-of-mass energy. The
fully corrected pt spectra and integrated yields are compared to various tunes
of the PYTHIA6 and PYTHIA8 event generators. | hep-ex |
Evidence for D0-D0bar Mixing at Babar: We present evidence for D0-D0bar mixing in $D^0 \to K^{+}\pi^{-}$ decays from
384 fb^{-1} of e+e- colliding-beam data recorded near sqrt(s)=10.6 GeV with the
Babar detector at the PEP-II storage rings at SLAC. We find the mixing
parameters ${x^{\prime}}^2 = [-0.22 \pm 0.30 (stat.) \pm 0.21 (syst.)] \times
10^{-3}$ and $y^{\prime} = [9.7 \pm 4.4 (stat.) \pm 3.1 (syst.)] \times
10^{-3}$, and a correlation between them of -0.94. This result is inconsistent
with the no-mixing hypothesis with a significance of 3.9 standard deviations.
We measure $R_{\rm D}$, the ratio of doubly Cabibbo-suppressed to
Cabibbo-favored decay rates, to be $[0.303 \pm 0.016 (stat.) \pm 0.010 (syst.)]
%$. We find no evidence for CP violation. | hep-ex |
Gamma Factory high-intensity muon and positron source: Exploratory
studies: One of the fundamental challenges for future leptonic colliders and neutrino
factories as well as for high-sensitivity studies of lepton universality is to
design and construct new high-intensity sources of muons and positrons. The
next-generation sources should increase the intensity of the presently
operating ones by at least three orders of magnitude and include an important
option of producing longitudinally polarized leptons. The main effort to
achieve this goal has been focused, so far, on the proton-beam-driven muon
sources and electron-beam-driven positron sources. In this paper, we present
exploratory studies of an alternative scheme which is based on high-intensity
megawatt-class photon beams. Such beams could be delivered in the future by the
Gamma Factory (GF) project. One of the GF multiple goals is to increase the
energy range (by more than one order of magnitude) and the intensity (by more
than six orders of magnitude) of presently operating photon sources. Such a
leap can be achieved by extending the present hadron-collider modus operandi of
the LHC with a new GF-operation-mode, allowing the collisions of beams with
laser pulses. The exploratory studies presented in this paper demonstrate that
more than 10$^{13}$ muons of both signs and more than 10$^{16}$
electrons/positrons per second can be produced by a GF source. | hep-ex |
W asymmetries at CDF and D0: We present recent W and charged lepton asymmetry measurements from the CDF
and D0 experiments. Theoretical predictions agree with the CDF W asymmetry,
measured using a new matrix element technique. These theoretical predictions
are less consistent with the latest lepton asymmetry measurements from D0 and
CDF, especially for high charged lepton transverse momentum. | hep-ex |
The KM3NeT Neutrino Telescope and the potential of a neutrino beam from
Russia to the Mediterranean Sea: KM3NeT is a new generation neutrino telescope currently under construction at
two sites in the Mediterranean Sea. At the Capo Passero site, 100 km off-shore
Sicily, Italy, a volume of more than one cubic kilometre of water will be
instrumented with optical sensors. This instrument, called ARCA, is optimized
for observing cosmic sources of TeV and PeV neutrinos. The other site, 40 km
off-shore Toulon, France, will host a much denser array of optical sensors,
ORCA. With an energy threshold of a few GeV, ORCA will be capable to determine
the neutrino mass hierarchy through precision measurements of atmospheric
neutrino oscillations. In this contribution, we review the scientific goals of
KM3NeT and the status of its construction. We also discuss the scientific
potential of a neutrino beam from Protvino, Russia to ORCA. We show that such
an experiment would allow for a measurement of the CP-violating phase in the
neutrino mixing matrix. To achieve a sensitivity competitive with that of the
other planned long-baseline neutrino experiments such as DUNE and T2HK, an
upgrade of the Protvino accelerator complex will be necessary. | hep-ex |
Experimental review of Lepton Flavor Violation searches: A review of the experimental status in searches for charged Lepton Flavor
Violation (LFV) is presented. Searches for LFV in decays of leptons, heavy
mesons, and bosons are explored, with an emphasis on the experiments providing
the best constraints in each sector. In addition, prospects for upper limits by
current and upcoming experiments in the next decade are discussed. | hep-ex |
Performance of the ALICE secondary vertex b-tagging algorithm in p-Pb
collisions: The hot and dense nuclear matter, that is produced in heavy-ion collisions,
could be studied by jets originating from beauty quarks. In-medium energy loss
of these quarks provides information on several properties of the quark-gluon
plasma, produced in ultra-relativistic heavy-ion collisions. Reconstructed jets
are powerful tools, since they offer access to kinematics of these
hard-scattered partons. Beauty hadrons are specific for their long lifetime,
large mass and large-multiplicity decays. Due to the long lifetime beauty
hadrons decay at displaced secondary vertices. In the ALICE experiment,
secondary vertex properties are used to tag b-jets. The study of Monte Carlo
based performance of the b-tagging algorithm for charged jets in p-Pb
collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV is discussed in proceedings. | hep-ex |
Measurements of $J/ψ$ and $ψ(2S)$ decays into $Λ
\barΛπ^0$ and $Λ\barΛη$: Using 58 million $J/\psi$ and 14 million $\psi(2S)$ events collected by the
BESII detector at the BEPC, branching fractions or upper limits for the decays
$J/\psi$ and $\psi(2S) \to \Lambda \bar{\Lambda}\pi^0$ and $\Lambda
\bar{\Lambda}\eta$ are measured. For the isospin violating decays, the upper
limits are determined to be ${\cal B}(J/\psi \to \Lambda
\bar{\Lambda}\pi^0)<6.4\times 10^{-5}$ and ${\cal B}(\psi(2S) \to \Lambda
\bar{\Lambda}\pi^0)<4.9\times 10^{-5}$ at the 90% confidence level. The isospin
conserving process $J/\psi \to \Lambda \bar{\Lambda}\eta$ is observed for the
first time, and its branching fraction is measured to be ${\cal B}(J/\psi \to
\Lambda \bar{\Lambda}\eta)=(2.62\pm 0.60\pm 0.44)\times 10^{-4}$, where the
first error is statistical and the second one is systematic. No $\Lambda
\bar{\Lambda}\eta$ signal is observed in $\psi(2S)$ decays, and ${\cal
B}(\psi(2S) \to \Lambda \bar{\Lambda}\eta)<1.2\times 10^{-4}$ is set at the 90%
confidence level. Branching fractions of $J/\psi$ decays into $\Sigma^+ \pi^-
bar{\Lambda}$ and $\bar{\Sigma}^- \pi^+ \Lambda$ are also reported, and the sum
of these branching fractions is determined to be ${\cal B}(J/\psi \to
\Sigma^+\pi^- \bar{\Lambda} + c.c.)=(1.52\pm 0.08\pm 0.16)\times 10^{-3}$. | hep-ex |
Top and Higgs Physics at the Tevatron: We present a summary of our experimental understanding of the top quark and
discuss the significant improvements expected in Run II at the Fermilab
Tevatron Collider. We also discuss prospects for a Higgs boson discovery at the
Tevatron. | hep-ex |
$CP$-violating triple-product asymmetries in Charm decays: The use of triple-product correlations is described in relation to the search
for $CP$ violation in 4-body charm meson decays. The latest results from the
LHCb and BaBar Collaborations are reported. A novel interpretation of the
asymmetries from triple-product correlations is used for the BaBar results,
which enables the extraction of information on the properties of $D$ decays
under parity and charge-conjugation transformations. | hep-ex |
The Inclusive Jet Cross Section in ppbar Collisions at sqrt{s}=1.8 TeV
using the kT Algorithm: The central inclusive jet cross section has been measured using a
successive-combination algorithm for reconstruction of jets. The measurement
uses 87.3 pb^{-1} of data collected with the D0 detector at the Fermilab
Tevatron ppbar Collider during 1994-1995. The cross section, reported as a
function of transverse momentum (pT>60 GeV) in the central region of
pseudorapidity (|\eta|<0.5), exhibits reasonable agreement with next-to-leading
order QCD predictions, except at low pT where the agreement is marginal. | hep-ex |
Search for $B^{+}\to K^{+}ν\barν$ decays using an inclusive
tagging method at Belle II: A search for the flavor-changing neutral-current decay $B^{+}\to
K^{+}\nu\bar{\nu}$ is performed at the Belle II experiment at the SuperKEKB
asymmetric energy electron-positron collider. The results are based on a data
sample corresponding to an integrated luminosity of $63\,\mbox{fb}^{-1}$
collected at the $\Upsilon{(4S)}$ resonance and a sample of $9\,\mbox{fb}^{-1}$
collected at an energy $60\mathrm{\,Me\kern -0.1em V}$ below the resonance. A
novel measurement method is employed, which exploits topological properties of
the $B^{+}\to K^{+}\nu\bar{\nu}$ decay that differ from both generic
bottom-meson decays and light-quark pair production. This inclusive tagging
approach offers a higher signal efficiency compared to previous searches. No
significant signal is observed. An upper limit on the branching fraction of
$B^{+}\to K^{+}\nu\bar{\nu}$ of $4.1 \times 10^{-5}$ is set at the 90%
confidence level. | hep-ex |
Axion Haloscope Using an 18 T High Temperature Superconducting Magnet: We report details on the axion dark matter search experiment that uses the
innovative technologies of a High-Temperature Superconducting (HTS) magnet and
a Josephson Parametric Converter (JPC). An 18 T HTS solenoid magnet is
developed for this experiment. The JPC is used as the first stage amplifier to
achieve a near quantum-limited low-noise condition. The first dark matter axion
search was performed with the 18 T axion haloscope. The scan frequency range is
from 4.7789 GHz to 4.8094 GHz (30.5 MHz range). No significant signal
consistent with Galactic dark matter axion is observed. Our results set the
best limit of the axion-photon-photon coupling ($g_{a\gamma\gamma}$) in the
axion mass range of 19.764 to 19.890 $\mu$eV. Using the Bayesian method, the
upper bounds of $g_{a\gamma\gamma}$ are set at
0.98$\times|g_{a\gamma\gamma}^{\text{KSVZ}}|$
(1.11$\times|g_{a\gamma\gamma}^{\text{KSVZ}}|$) in the mass ranges of 19.764 to
19.771 $\mu$eV (19.863 to 19.890 $\mu$eV), and at 1.76
$\times|g_{a\gamma\gamma}^{\text{KSVZ}}|$ in the mass ranges of 19.772 to
19.863 $\mu$eV with 90\% confidence level, respectively. We report design,
construction, operation, and data analysis of the 18 T axion haloscope
experiment. | hep-ex |
Search for Supersymmetry with Photon at CMS: We present the searches for supersymmetry (SUSY) in two channels, two photons
plus missing transverse energy and a photon plus a lepton plus missing
transverse energy with the CMS detector using approximately 36 $\rm{pb}^{-1}$
of pp collision at 7 TeV. No excess of events above the standard model
predictions is found. Limits are set for the squark, gluino and wino masses in
the general gauge-mediated SUSY context. | hep-ex |
Search for a light charged Higgs boson decaying into $c\bar{s}$ at CMS: We present results on the search for a light charged Higgs boson that can be
produced in the decay of a top quark and later decays into a charm and an
antistrange quark. The analysis is performed using $19.7\invfb$ pp collison
data recorded with the CMS detector at LHC. | hep-ex |
Photon Events with Missing Energy at sqrt(s) = 183 to 189 GeV: The production of single photons has been studied in the reaction e+e- ->
gamma + invisible particles at centre-of-mass energies of 183 GeV and 189 GeV.
A previously published analysis of events with multi-photon final states
accompanied by missing energy has been updated with 189 GeV data. The data were
collected with the DELPHI detector and correspond to integrated luminosities of
about 51 pb^{-1} and 158 pb^{-1} at the two energies. The number of light
neutrino families is measured to be 2.84 +/- 0.15(stat) +/- 0.14(syst). The
absence of an excess of events beyond that expected from Standard Model
processes is used to set limits on new physics as described by supersymmetric
and composite models. A limit on the gravitational scale is also determined. | hep-ex |
First Results from ABRACADABRA-10 cm: A Search for Sub-$μ$eV Axion
Dark Matter: The axion is a promising dark matter candidate, which was originally proposed
to solve the strong-CP problem in particle physics. To date, the available
parameter space for axion and axion-like particle dark matter is relatively
unexplored, particularly at masses $m_a\lesssim1\,\mu$eV. ABRACADABRA is a new
experimental program to search for axion dark matter over a broad range of
masses, $10^{-12}\lesssim m_a\lesssim10^{-6}$ eV. ABRACADABRA-10 cm is a
small-scale prototype for a future detector that could be sensitive to the QCD
axion. In this Letter, we present the first results from a 1 month search for
axions with ABRACADABRA-10 cm. We find no evidence for axion-like cosmic dark
matter and set 95% C.L. upper limits on the axion-photon coupling between
$g_{a\gamma\gamma}<1.4\times10^{-10}$ GeV$^{-1}$ and
$g_{a\gamma\gamma}<3.3\times10^{-9}$ GeV$^{-1}$ over the mass range
$3.1\times10^{-10}$ eV - $8.3\times10^{-9}$ eV. These results are competitive
with the most stringent astrophysical constraints in this mass range. | hep-ex |
Hashing and metric learning for charged particle tracking: We propose a novel approach to charged particle tracking at high intensity
particle colliders based on Approximate Nearest Neighbors search. With hundreds
of thousands of measurements per collision to be reconstructed e.g. at the High
Luminosity Large Hadron Collider, the currently employed combinatorial track
finding approaches become inadequate. Here, we use hashing techniques to
separate measurements into buckets of 20-50 hits and increase their purity
using metric learning. Two different approaches are studied to further resolve
tracks inside buckets: Local Fisher Discriminant Analysis and Neural Networks
for triplet similarity learning. We demonstrate the proposed approach on
simulated collisions and show significant speed improvement with bucket
tracking efficiency of 96% and a fake rate of 8% on unseen particle events. | hep-ex |
Determination of Solar Neutrino Oscillation Parameters using 1496 Days
of Super-Kamiokande-I Data: A number of different fits to solar neutrino mixing and mass square
difference were performed using 1496 days of Super-Kamiokande-I's solar
neutrino data. These data select two allowed areas at large neutrino mixing
when combined with either the solar $^8$B flux prediction of the standard solar
model or the SNO interaction rate measurements. A global fit combining SK data
with the solar neutrino interaction rates measured by Homestake, SNO,
Gallex/GNO and SAGE prefers a single allowed area, the Large Mixing Angle
solution, at the 98.9% confidence level. The mass square difference $\Delta
m^2$ between the two mass eigenstates ranges from about 3 to
$19\times10^{-5}$eV$^2$, while the mixing angle $\theta$ is in the range of
$\tan^2\theta\approx$0.25--0.65. | hep-ex |
Leptonic Charm Decays: We review the recent experimental results on D and Ds meson leptonic decays
from CLEO-c, Belle, and BABAR, which results in the decay constants f_D= (206.7
+- 8.9) MeV and f_Ds= (257.3 +- 5.3) MeV. The latter is an average obtained by
the Heavy Flavor Averaging Group (HFAG). Comparisons with Lattice QCD (LQCD)
calculations are discussed. | hep-ex |
Measurement of $σ(Λ_b)/σ(B^0) \times
BR(Λ_b\toΛ_cπ^-) / BR(B^0\to D^+π^-)$ in $p\bar{p}$
Collisions at $\sqrt{s}=1.96$ TeV: We present the first observation of the baryon decay
$\Lambda_b\to\Lambda_c\pi^-$ followed by $\Lambda_c\to p K^-\pi^+$ in 106 pb-1
of $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV in the CDF experiment. In
order to reduce systematic error, the measured rate for $\Lambda_b$ decay is
normalized to the kinematically similar meson decay $B^0\to D^+\pi^-$ followed
by $D^+\to\pi^+K^-\pi^+$. We report the ratio of production cross sections
($\sigma$) times the ratio of branching fractions (BR) for the momentum region
integrated above $p_T > 6$ GeV/c and pseudorapidity range $|\eta| < 1.3$:
$\sigma(p\bar{p}\to \Lambda_b X) / \sigma (p\bar{p}\to B^0 X) \times
BR(\Lambda_b\to\Lambda_c\pi^-) / BR(B^0\to D^+\pi^-) = 0.82 \pm 0.08(stat) \pm
0.11(syst) \pm 0.22 (BR(\Lambda_c\to p K^-\pi^+))$. | hep-ex |
Measurements of Absolute Hadronic Branching Fractions of D Mesons: Using e+e- collisions recorded at the psi(3770) resonance with the CLEO-c
detector at the Cornell Electron Storage Ring, we determine absolute hadronic
branching fractions of charged and neutral D mesons. Among measurements for
both Cabibbo-favored and Cabibbo-suppressed modes, we obtain reference
branching fractions B(D0 -> K-pi+)=(3.91 +- 0.08 +- 0.09)% and B(D+ ->
K-pi+pi+)=(9.5 +- 0.2 +- 0.3)%, where the uncertainties are statistical and
systematic, respectively. Using a determination of the integrated luminosity,
we also extract the e+e- -> DDbar cross sections. | hep-ex |
Study of B --> pi l nu and B --> rho l nu decays and determination of
|Vub|: We present an analysis of exclusive charmless semileptonic B-meson decays
based on 83 million BBbar pairs recorded with the BABAR detector at the
Upsilon(4S) resonance. Using isospin symmetry, we measure branching fractions
B(B0 --> pi- l+ nu) = (1.38 +- 0.10 +- 0.16 +- 0.08) x 10^-4 and B(B0 --> rho-
l+ nu) = (2.14 +- 0.21 +- 0.48 +- 0.28) x 10^-4, where the errors are
statistical, experimental systematic, and due to form-factor shape
uncertainties. We compare the measured distribution in q^2, the
momentum-transfer squared, with theoretical predictions for the form factors
from lattice QCD and light-cone sum rules, and extract the
Cabibbo-Kobayashi-Maskawa (CKM) matrix element |V_{ub}| = (3.82 +- 0.14 +- 0.22
+- 0.11 +0.88 -0.52) x 10^-3 from B --> pi l nu, where the fourth error
reflects the uncertainty of the form-factor normalization. | hep-ex |
Physics of CP Violation and Rare Decays: Lectures note for Cargese 99 Summer School Particle Physics: Ideas and Recent
Development NATO Advanced Institute, Corsica, July 26-August 7, 1999 | hep-ex |
Measurement of the Top Quark Mass in the Dilepton Channel: We report a measurement of the top quark mass using six candidate events for
the process pbarp->ttbar->l^+ nu l^- nubar b bbar + X, observed in the D0
experiment at the Fermilab ppbar collider. Using maximum likelihood fits to the
dynamics of the decays, we measure a mass for the top quark of m(top) = 168.4
+- 12.3 (stat) +- 3.6 (syst) GeV/c^2. We combine this result with our previous
measurement in the ttbar->l+jets channel to obtain m(top) = 172.1 +- 7.1
GeV/c^2 as the best value of the mass of the top quark measured by D0. | hep-ex |
Recent results on charmonium-like (exotic) XYZ states at the
BESIII/BEPCII experiment in Beijing/China: With about 12 fb$^{-1}$ collected XYZ data sets, BESIII continues the
exploration of the exotic charmonium-like states. In this talk, recent results
on the measurements of the spin-parity determination of $Z_{\rm c}(3900)$, as
well as on line-shapes of $e^+e^- \rightarrow J/\psi\,\pi\pi, h_{\rm c}\pi\pi,
\psi(2S)\,\pi^0\pi^0/\pi^+\pi^-$, and $\pi^+ D^0 D^{*-}$ from open charm are
discussed. Also, the recent observation of $e^+ e^- \rightarrow \phi
\chi_{c1/2}$ at $\sqrt(s)=4.6$ GeV is reported. | hep-ex |
NA48: Rare Decay Results: Recent results on the kaon rare decays measured in NA48 experiment at CERN
are presented. | hep-ex |
Lorentz Angle Measurement for CO2/Isobutane Gas Mixtures: We have developed a Lorentz angle measurement system for cool gas mixtures in
the course of our R&D for a proposed JLC central drift chamber (JLC-CDC). The
measurement system is characterized by the use of two laser beams to produce
primary electrons and flash ADCs to read their signals simultaneously. With
this new system, we have measured Lorentz angles for CO2/isobutane gas mixtures
with different proportions (95:5, 90:10, and 85:15), varying drift field from
0.6 to 2.0 kV/cm and magnetic field up to 1.5 T. The results of the measurement
are in good agreement with GARFIELD/MAGBOLTZ simulations. | hep-ex |
Branching Fraction Measurements of Charged B Decays to K*+K+K-,
K*+pi+K-, K*+K+pi- and K*+pi+pi- Final States: Branching fraction and asymmetry measurements of charmless $B^+\to
K^{*+}h^+_1h^-_2$ (where $h_{1,2}$ = $K$, $\pi$) decays are presented, using a
data sample of 232 million $\Upsilon(4S) \to$ $BB$ decays collected with the
BaBar detector at the SLAC PEP-II asymmetric-energy $B$ factory. Using a
maximum likelihood fit, the following branching fraction results were obtained:
${\cal B}$($B^+ \to K^{*+}K^+ K^-)$ = (36.2 $\pm$ 3.3 $\pm$ 3.6) $\times$
10$^{-6}$ and ${\cal B}$($B^+$ $\to$ $K^{*+}\pi^+\pi^-$) = (75.3 $\pm$ 6.0
$\pm$ 8.1) $\times$ 10$^{-6}$. Upper limits were set for ${\cal B}$($B^+$ $\to$
$K^{*+}\pi^+ K^-$) $<$ 11.8 $\times$ 10$^{-6}$ and ${\cal B}$($B^+$ $\to$
$K^{*+}K^+ \pi^-$) $<$ 6.1 $\times$ 10$^{-6}$ at 90% confidence level. The
charge asymmetries for the decays $B^+ \to K^{*+}K^+ K^-$ and $B^+$ $\to$
$K^{*+}\pi^+\pi^-$ were measured to be ${\cal A}_{K^*KK} = 0.11 \pm 0.08 \pm
0.03$ and ${\cal A}_{K^*\pi\pi} = 0.07 \pm 0.07 \pm 0.04$, respectively. The
first error quoted on branching fraction and asymmetry measurements is
statistical and the second systematic. | hep-ex |
Search for Lepton Flavor Violating tau Decays at B-factories: Lepton flavor violations in charged lepton give good signatures for the new
physics. We review recent searches for lepton flavor violation in tau decays at
B-factories. In these searches, optimization for background reduction is
important to obtain high sensitivity. No evidence for these decays is observed
and 90% confidence level upper limits have been set on the branching fractions
at the O(10^{-8}) level. | hep-ex |
Measuring the CP properties of the Higgs sector at electron-positron
colliders: The violation of CP symmetry at the electro-weak scale is one of the
essential ingredients for electro-weak baryogenesis. It is therefore of great
interest to map the CP properties of the Higgs sector in as much detail as
possible. A linear electron-positron Higgs factory collider will provide many
opportunities to probe the CP nature of the Higgs sector, thanks to access to
several Higgs production processes at a wide range of centre-of-mass energies.
In this paper we report on two studies based on full simulation of detector
response and realistic reconstruction algorithms: 1) a study of $h \to \tau
\tau$ at ILC-250, in which mixing of CP eigenstates can be measured to a
precision of 75~mrad; and 2) the current status of an ongoing study of the
$ZZ$--fusion process at 1.4 TeV CLIC and 1 TeV ILC, for which we expect to
achieve concrete results during the Snowmass study period. | hep-ex |
Work on the interplay among $h^+$, $h^{-}$ and hadron pair transverse
spin asymmetries in SIDIS: In the fragmentation of a transversely polarized quark a left-right
asymmetry, the Collins asymmetry, is expected for each hadron produced in the
process $\mu N \rightarrow \mu ' h^{+} h^{-} X$. Similarly, an asymmetry is
also expected for the hadron pair, the dihadron asymmetry. Both asymmetries
have been measured to be different from zero on transversely polarised proton
targets and have allowed for first extractions of the transversity
distributions. From the high statistics COMPASS data we have further
investigated these asymmetries getting strong indications that the two
mechanisms are driven by a common physical process. | hep-ex |
Observation of the radiative decays of $Υ(1S)$ to $χ_{c1}$: We report the first observation of the radiative decay of the $\Upsilon(1S)$
into a charmonium state. The statistical significance of the observed signal of
$\Upsilon(1S) \to \gamma \chi_{c1}$ is 6.3 standard deviations including
systematics. The branching fraction is calculated to be Br($\Upsilon(1S) \to
\gamma \chi_{c1}$) = (4.7^{+2.4}_{-1.8} (stat) ^{+0.4}_{-0.5} (sys)) * 10^{-5}.
We also searched for $\Upsilon(1S)$ radiative decays into $\chi_{c0,2}$ and
$\eta_c(1S,2S)$ and set upper limits on their branching fractions. These
results are obtained from a 24.9 fb^{-1} data sample collected with the Belle
detector at the KEKB asymmetric-energy $e^+e^-$ collider at a center-of-mass
energy equal to the $\Upsilon(2S)$ mass using $\Upsilon(1S)$ tagging by the
$\Upsilon(2S) \to \Upsilon(1S) \pi^+\pi^-$ transitions. | hep-ex |
Search for $D^0\toγγ$ and improved measurement of the
branching fraction for $D^0 \to π^0π^0$: Using $2.92$ fb$^{-1}$ of electron-positron annihilation data collected at
$\sqrt{s} = 3.773$~GeV with the BESIII detector, we report the results of a
search for the flavor-changing neutral current process $D^0\to\gamma\gamma$
using a double-tag technique. We find no signal and set an upper limit at
$90\%$ confidence level for the branching fraction of $B(D^0\to\gamma\gamma) <
3.8\times10^{-6}$. We also investigate $D^0$-meson decay into two neutral
pions, obtaining a branching fraction of $B(D^0\to\pi^0\pi^0) =
(8.24\pm0.21(\text{stat.})\pm0.30(\text{syst.}))\times10^{-4}$, the most
precise measurement to date and consistent with the current world average | hep-ex |
Search for a standard model-like Higgs boson in the mass range between
70 and 110 GeV in the diphoton final state in proton-proton collisions at
$\sqrt{s} =$ 8 and 13 TeV: The results of a search for a standard model-like Higgs boson in the mass
range between 70 and 110 GeV decaying into two photons are presented. The
analysis uses the data set collected with the CMS experiment in proton-proton
collisions during the 2012 and 2016 LHC running periods. The data sample
corresponds to an integrated luminosity of 19.7 (35.9) fb$^{-1}$ at $\sqrt{s}
=$8 (13) TeV. The expected and observed 95% confidence level upper limits on
the product of the cross section and branching fraction into two photons are
presented. The observed upper limit for the 2012 (2016) data set ranges from
129 (161) fb to 31 (26) fb. The statistical combination of the results from the
analyses of the two data sets in the common mass range between 80 and 110 GeV
yields an upper limit on the product of the cross section and branching
fraction, normalized to that for a standard model-like Higgs boson, ranging
from 0.7 to 0.2, with two notable exceptions: one in the region around the Z
boson peak, where the limit rises to 1.1, which may be due to the presence of
Drell-Yan dielectron production where electrons could be misidentified as
isolated photons, and a second due to an observed excess with respect to the
standard model prediction, which is maximal for a mass hypothesis of 95.3 GeV
with a local (global) significance of 2.8 (1.3) standard deviations. | hep-ex |
A study of the nuclear medium influence on neutral strange particle
production in deep inelastic neutrino scattering: The influence of nuclear effects on the production of neutral strange
particles ($V^{\circ}$) is investigated using the data obtained with SKAT
propane-freon bubble chamber irradiated in the neutrino beam (with $E_{\nu}$ =
3-30 GeV) at Serpukhov accelerator. The measured mean multiplicity of
$V^{\circ}$ particles in nuclear interactions, ${<n_{V^{\circ}}>}_A$ =
0.096$\pm$0.011, is found to exceed significantly that in 'quasinucleon'
interactions, ${<n_{V^{\circ}}>}_N$ = 0.059$\pm$0.012. The ratio of
${\rho}_{V^{\circ}}$ =${<n_{V^{\circ}}>}_A/{<n_{V^{\circ}}>}_N$ =1.61$\pm$0.23
is larger than that for $\pi^{-}$ mesons, ${\rho}_{\pi^-}$ = 1.10$\pm$0.03. It
is shown that a dominant part of the multiplicity gain of $V^{\circ}$ particles
can be explained by intranuclear interactions of produced pions. | hep-ex |
Measurement of Open Beauty Production at HERA: The first observation of open b production in ep collisions is reported. An
event sample containing muons and jets has been selected which is enriched in
semileptonic b quark decays. The visible cross section \sigma(ep -> b \bar{b}X
-> \mu X') for Q^2 < 1 GeV^2, 0.1 < y < 0.8 is measured to be
0.176+-0.016(stat.)+0.026-0.017(syst.) nb for the muons to be detected in the
range 35 deg < \theta^\mu < 130 deg and \pt^\mu > 2.0 GeV in the laboratory
frame. The expected visible cross section based on a NLO QCD calculation is
0.104+-0.017 nb. The cross sections for electroproduction with Q^2<1 GeV^2 and
photoproduction are derived from the data and found to be \sigma(ep-> e
b\bar{b}X) = 7.1+-0.6(stat.)+1.5-1.3(syst.) nb and \sigma(\gamma p-> b\bar{b}
X) = 111+-10(stat.)+23-20(syst.) at an average <W_{\gamma p}> \sim 180 GeV,
respectively. | hep-ex |
Measurement of the intrinsic electron neutrino component in the T2K
neutrino beam with the ND280 detector: The T2K experiment has reported the first observation of the appearance of
electron neutrinos in a muon neutrino beam. The main and irreducible background
to the appearance signal comes from the presence in the neutrino beam of a
small intrinsic component of electron neutrinos originating from muon and kaon
decays. In T2K, this component is expected to represent 1.2% of the total
neutrino flux. A measurement of this component using the near detector (ND280),
located 280 m from the target, is presented. The charged current interactions
of electron neutrinos are selected by combining the particle identification
capabilities of both the time projection chambers and electromagnetic
calorimeters of ND280. The measured ratio between the observed electron
neutrino beam component and the prediction is 1.01+-0.10 providing a direct
confirmation of the neutrino fluxes and neutrino cross section modeling used
for T2K neutrino oscillation analyses. Electron neutrinos coming from muons and
kaons decay are also separately measured, resulting in a ratio with respect to
the prediction of 0.68+-0.30 and 1.10+-0.14, respectively. | hep-ex |
Search for Higgs boson decays into two new low-mass spin-0 particles in
the 4$b$ channel with the ATLAS detector using $pp$ collisions at $\sqrt{s}=
13$ TeV: This paper describes a search for beyond the Standard Model decays of the
Higgs boson into a pair of new spin-0 particles subsequently decaying into
$b$-quark pairs, $H \rightarrow aa \rightarrow (b\bar{b})(b\bar{b})$, using
proton-proton collision data collected by the ATLAS detector at the Large
Hadron Collider at center-of-mass energy $\sqrt{s}=13$ TeV. This search focuses
on the regime where the decay products are collimated and in the range $15 \leq
m_a \leq 30$ GeV and is complementary to a previous search in the same final
state targeting the regime where the decay products are well separated and in
the range $20 \leq m_a \leq 60$ GeV. A novel strategy for the identification of
the $a \rightarrow b\bar{b}$ decays is deployed to enhance the efficiency for
topologies with small separation angles. The search is performed with 36
fb$^{-1}$ of integrated luminosity collected in 2015 and 2016 and sets upper
limits on the production cross-section of $H \rightarrow aa \rightarrow
(b\bar{b})(b\bar{b})$, where the Higgs boson is produced in association with a
$Z$ boson. | hep-ex |
Search for microscopic black holes in pp collisions at sqrt(s) = 8 TeV: A search for microscopic black holes and string balls is presented, based on
a data sample of pp collisions at sqrt(s) = 8 TeV recorded by the CMS
experiment at the Large Hadron Collider and corresponding to an integrated
luminosity of 12 inverse femtobarns. No excess of events with energetic
multiparticle final states, typical of black hole production or of similar new
physics processes, is observed. Given the agreement of the observations with
the expected standard model background, which is dominated by QCD multijet
production, 95% confidence limits are set on the production of semiclassical or
quantum black holes, or of string balls, corresponding to the exclusions of
masses below 4.3 to 6.2 TeV, depending on model assumptions. In addition,
model-independent limits are set on new physics processes resulting in
energetic multiparticle final states. | hep-ex |
Search for admixture of scalar top quarks in the ttbar lepton+jets final
state at sqrt(s)=1.96 TeV: A search for pair production of the lightest supersymmetric partner of the
top quark is performed in the lepton+jets channel using 0.9 fb-1 of data
collected by the D0 experiment. Kinematic differences between scalar top quark
pair production and the dominant top quark pair production background are used
to separate the two processes. First limits from Run II of the Fermilab
Tevatron Collider for the scalar top quark decaying to a chargino and a b quark
are obtained for scalar top quark masses of 130-190 GeV and chargino masses of
90-150 GeV. | hep-ex |
Electrons and Heavy Quark at PHENIX Detector: Measurement of heavy quark production is one of the tools used to investigate
the matter produced in extremely hot and dense conditions in heavy ion
collisions at RHIC. The PHENIX experiment has measured mid-rapidity transverse
momentum spectra of electrons. After subtracting the photonic background
contribution, the electron spectra are mainly due to semileptonic decays of
hadrons containing heavy quarks and therefore provide a measurement of heavy
quark production and its energy loss in hot and dense matter. This paper will
present the technique used by the PHENIX experiment and recent results on heavy
quark production in p+p, d+Au and Au+Au collisions at sqrt{s_NN}=200 GeV. | hep-ex |
A Review of Charmed Baryon Experimental Data: A review of the experimental results on charmed baryons, with an accent on
those reported most recently. Talk given at FPCP conference, U. Penn, May 2002. | hep-ex |
Search for Magnetic Monopoles Trapped in Matter: There have been many searches for magnetic monopoles in flight, but few for
monopoles in matter. We have searched for magnetic monopoles in meteorites,
schists, ferromanganese nodules, iron ores and other materials. The detector
was a superconducting induction coil connected to a SQUID (Superconducting
Quantum Interference Device) with a room temperature bore 15 cm in diameter. We
tested a total of more than 331 kg of material including 112 kg of meteorites.
We found no monopole and conclude the overall monopole/nucleon ratio in the
samples is $<1.2 \times 10^{-29}$ with a 90\% confidence level. | hep-ex |
Strategies for precision measurements of the charge asymmetry of the W
boson mass at the LHC within the ATLAS experiment: This thesis dissertation presents a prospect for a measurement of the charge
asymmetry of the W boson mass (MW+ - MW-) at the LHC within the ATLAS
experiment. This measurement is of primordial importance for the LHC
experimental program, both as a direct test of the charge sign independent
coupling of the W bosons to the fermions and as a mandatory preliminary step
towards the precision measurement of the charge averaged W boson mass. This
last pragmatic point can be understood since the LHC specific collisions will
provide unprecedented kinematics for the positive and negative channels while
the SPS and Tevatron collider produced W+ and W- on the same footing. For that
reason, the study of the asymmetries between W+ and W- in Drell--Yan like
processes (production of single W decaying into leptons), studied to extract
the properties of the W boson, is described thoroughly in this document. Then,
the prospect for a measurement of MW+ - MW- at the LHC is addressed in a
perspective intending to decrease as much as possible the systematic errors
that will inevitably comes from the misunderstanding of both phenomenological
and apparatus modeling. For that matter strategies have been devised
specifically for the present measurement to display robustness with respect to
the main uncertainties. These strategies consist of introducing new observables
along with considering specific LHC running modes and configurations of the
ATLAS tracker. Eventually we show that the present (2009) precision can be
improved at the LHC by a factor of 20 and argue that such a precision is beyond
the reach of the standard measurement and calibration methods imported to the
LHC from the Tevatron program. | hep-ex |
The European Spallation Source neutrino Super Beam: After measuring in 2012 a relatively large value of the neutrino mixing angle
$\theta_{13}$, the door is now open to observe for the first time a possible CP
violation in the leptonic sector. The measured value of $\theta_{13}$ also
privileges the 2nd oscillation maximum for the discovery of CP violation
instead of the usually used 1st maximum. The sensitivity at this 2nd
oscillation maximum is about three times higher, with a lower influence of
systematic errors, than for the 1st maximum. Going to the 2nd oscillation
maximum necessitates a very intense neutrino beam with the appropriate energy.
The world's most intense pulsed spallation neutron source, the European
Spallation Source, will have a proton linac with 5 MW power and 2 GeV energy.
This linac, under construction, also has the potential to become the proton
driver of the world's most intense neutrino beam with high probability to
discover a neutrino CP violation. The physics performance of that neutrino
Super Beam in conjunction with a megaton underground Water Cherenkov neutrino
detector installed at a distance of about 500~km from ESS has been evaluated.
In addition, the choice of such detector will extent the physics program to
proton-decay and astrophysics searches. The ESS proton linac upgrades, the
accumulator ring needed for proton pulse compression, the target station, the
far detector and the physics potential are described. In addition to neutrinos,
this facility will also produce at the same time a copious number of muons
which could be used by a low energy neutrino facility for sterile neutrino
searches, a future Neutrino Factory or a Muon Collider. The ESS neutron
facility will be fully ready by 2023 at which moment the upgrades for the
neutrino facility could start. | hep-ex |
A Measurement of the Ratio of the W + 1 Jet to Z + 1 Jet Cross Sections
with ATLAS: The measurement of hadronic activity recoiling against W and Z vector bosons
provides an important test of perturbative QCD, as well as a method of
searching for new physics in a model independent fashion. We present a study of
the cross-section ratio for the production of W and Z gauge bosons in
association with exactly one jet Rjet = {\sigma}(W + 1jet)/{\sigma}(Z + 1jet),
in pp collisions at \surds = 7 TeV. The study is performed in the electron and
muon channels with data collected with the ATLAS detector at the LHC. The ratio
Rjet is studied as a function of the cumulative transverse momentum
distribution of the jet. This result can be compared to NLO pQCD calculations
and the prediction from LO matrix element + parton shower generators. | hep-ex |
On the Relation between the True Directions of Neutrinos and the
Reconstructed Directions of Neutrinos in L/E Analysis Performed by
Super-Kamiokande Collaboration Part2: In the previous paper (Part1), we have verified that the SK assumption on the
direction does not hold in the analysis of neutrino events occurred inside the
SK detector, which is the cornerstone for their analysis of zenith angle
distributions of neutrino events. Based on the correlation between L_nu and
L_mu (Figures~16 to 18 in Part1) and the correlation between E_nu and E_mu
(Figure19 in Part1), we have made four possible L/E analyses, namely L_nu/E_nu,
L_nu/E_mu, L_mu/E_mu and L_mu/E_nu. Among four kinds of L/E analyses, we have
shown that only L_nu/E_nu analysis can give the signature of maximum
oscillations clearly, not only the first maximum oscillation but also the
second and third maximum oscillation and etc., as they should be, while the
L_mu/E_mu analysis which are really done by Super-Kamiokande Collaboration
cannot give any maximum oscillation at all. It is thus concluded from those
results that the experiments with the use of the cosmic-ray beam for neutrino
oscillation, such as Super-Kamiokande type experiment, are unable to lead the
maximum oscillation from their L/E analysis, because the incident neutrino
cannot be observed due to its neutrality. Therefore, we would suggest
Super-Kamiokande Collaboration to re-analyze the zenith angle distribution of
the neutrino events which occur inside the detector carefully, since L_nu and
L_mu are alternative expressions of the cosine of the zenith angle for the
incident neutrino and that for the emitted muon, respectively. | hep-ex |
Search for higher mass resonances via KK decay channel in pp collisions
with ALICE at the LHC: The quark model has proven successful in describing the basic building blocks
of strongly interacting particles in the Standard Model, where hadronic states
consist of quarks and gluons. At the same time, Lattice QCD predicts the
possibility of glueball candidates in the mass range \mbox{1550--1750}
MeV/$c^2$, which have never been observed. The experimental search for the
existence of mesons with no quark content is both interesting and challenging
as the glueball is very likely to mix with surrounding quark-antiquark scalar
meson states with the same quantum numbers. The large statistics data sample
collected by ALICE in pp collisions at the highest LHC center-of-mass energy
provides an opportunity to measure high mass resonances, whose characteristics
and internal structure are still unknown. In this article, we report on the
measurements of invariant mass distributions of higher mass resonances using
the decay channels of K$^{0}_\mathrm{S}\mathrm{K}^{0}_\mathrm{S}$ and
K$^{+}$K$^{-}$ pairs in pp collisions at $\sqrt{s}$ = 13 TeV using ALICE
detector at midrapidity. | hep-ex |
Measurement of Time-Dependent CP Asymmetries and the CP-odd Fraction in
the Decay B^0 --> D^{*+}D^{*-}: We present a measurement of time-dependent CP asymmetries and an updated
determination of the CP-odd fraction in the decay B^0 --> D^{*+}D^{*-}. The
measurements are derived from a data sample of 88 times 10^{6} B bar{B} pairs
collected by the BaBar detector at the PEP-II energy asymmetric B Factory at
SLAC. All results are preliminary. | hep-ex |
Measurements of $\mathrm{J/ψ\rightarrow e^{+}e^{-}}$ with ALICE at
the LHC: The ALICE detector provides excellent capabilities to study quarkonium
production at the Large Hadron Collider (LHC). Heavy quarkonia, bound states of
charm or beauty quark anti-quark pairs such as the $\mathrm{J/\psi}$, are
expected to be produced by initial hard processes. Thus they will provide
insight into the earliest and hottest stages of AA collisions where the
formation of a Quark-Gluon Plasma (QGP) is expected. Furthermore,
high-precision data from pp collisions represent an essential baseline for the
measurement of nuclear modifications in heavy-ions and serve also as a crucial
test for several models of quarkonium hadroproduction. In addition, the study
of pA collisions allows to investigate nuclear modifications due to Cold
Nuclear Matter (CNM) effects. In ALICE, $\mathrm{J/\psi}$ were measured in pp
and Pb--Pb collisions down to $p_{\mathrm T}$ = 0 via their di-electron decay
channel in the central barrel ($|y| <$ 0.8). Results on the nuclear
modification factor ($R_{\mathrm{AA}}$) at central rapidities in Pb--Pb
collisions at $\sqrt{s_{\mathrm{NN}}} = 2.76$ TeV will be shown and their
implications discussed. A separation of the prompt and non-prompt components is
also possible down to $p_{\mathrm T}$ of the $\mathrm{J/\psi}$ of 2 GeV/$c$. | hep-ex |
New Physics Effects in $B$ Decays: The two $B$-factories, Belle and BaBar, has been played major roles in the B
decays study. Their wonderful design and excellent operation enables their
fruitful analysis results. Also recently the Tevatron experiments, CDF and DO,
join the game with their $B_S$ studies. From the experimental results of $B$
decay studies, we learn that most of measurements are consistent with the
Standard Model (SM). Some discrepancies from the SM has been found in the
measurements of the phases and magnitudes of CKM unitary triangle. There are
also various theoretical models that possibly give the contributions. These
will relay on further validation with new experimental results. | hep-ex |
Evidence for a neutral near-threshold structure in the $K^{0}_{\rm S}$
recoil-mass spectra in $e^+e^-\rightarrow K^{0}_{\rm S}D_s^+D^{*-}$ and
$e^+e^-\rightarrow K^{0}_{\rm S}D_s^{*+}D^{-}$: We study the processes $e^+e^-\rightarrow K^{0}_{\rm S}D_s^+D^{*-}$ and
$e^+e^-\rightarrow K^{0}_{\rm S}D_s^{*+}D^{-}$, as well as their charge
conjugated processes, at five center-of-mass energies between 4.628~GeV and
4.699~GeV, using data samples corresponding to an integrated luminosity of
$3.8~\rm{fb^{-1}}$ collected by the BESIII detector at the BEPCII storage ring.
Based on a partial reconstruction technique, we find evidence of a structure
near the thresholds for $D_s^+D^{*-}$ and $D_s^{*+}D^{-}$ production in the
$K^{0}_{\rm S}$ recoil-mass spectrum, which we refer to as the $
Z_{cs}(3985)^0$. Fitting with a Breit-Wigner line shape, we find the mass of
the structure to be $(3992.2\pm{1.7}\pm{1.6})~\rm{MeV}/c^2$ and the width to be
$(7.7_{-3.8}^{+4.1}\pm{4.3})~\rm{MeV}$, where the first uncertainties are
statistical and the second are systematic. The significance of the $
Z_{cs}(3985)^0$ signal is found to be $4.6\sigma$ including both the
statistical and systematic uncertainty. We report the Born cross section
multiplied by the branching fraction at different energy points. The mass of
the $Z_{cs}(3985)^0$ is close to that of the $Z_{cs}(3985)^+$. Assuming SU(3)
symmetry, the cross section of the neutral channel is consistent with that of
the charged one. Hence, we conclude that the $Z_{cs}(3985)^0$ is the isospin
partner of the $Z_{cs}(3985)^+$. | hep-ex |
HFLAV $τ$ branching fractions fit and measurements of Vus with $τ$
lepton data: We report the status of the Heavy Flavour Averaging Group (HFLAV) averages of
the $\tau$ lepton measurements We then update the latest published HFLAV global
fit of the $\tau$ lepton branching fractions (Spring 2017) with recent results
by BABAR. We use the fit results to update the Cabibbo-Kobayashi-Maskawa (CKM)
matrix element Vus measurements with the $\tau$ branching fractions. We combine
the direct $\tau$ branching fraction measurements with indirect predictions
using kaon branching fractions measurements to improve the determination of Vus
using $\tau$ branching fractions. The Vus determinations based on the inclusive
branching fraction of $\tau$ to strange final states are about $3\sigma$ lower
than the Vus determination from the CKM matrix unitarity. | hep-ex |
Recent charm results at Belle: We present the selected recent charm results at Belle: (1) the $CP$
asymmetries and branching fractions for the decays of charm mesons, i.e.
$D^{0}\to\pi^{+}\pi^{-}\eta,\,K^{+}K^{-}\eta$ and $D^{0}\to\phi\eta$;
$D_{s}^{+}\to K^{+}\pi^{0},\,K^{+}\eta$ and
$D_{s}^{+}\to\pi^{+}\pi^{0},\,\pi^{+}\eta$. (2) the branching fractions for the
decays of charmed baryons, i.e. $\Lambda_{c}^{+}\to p\pi^{0},\,p\eta$;
$\Lambda_{c}^{+}\to\Lambda\pi^{+}\eta,\,\Sigma^0\pi^{+}\eta$ and intermediate
processes $\Lambda_{c}^{+}\to\Lambda(1670)\pi^{+},\,\eta\Sigma(1385)^+$;
$\Xi_c^0\to\Lambda\bar{K}^{*0},\,\Sigma^0\bar{K}^{*0}$ and $\Sigma^+K^{*-}$.
(3) properties of excited charmed baryons, i.e. search for electromagnetic
transition $\Xi_c(2790,2815)^{+,0}\to\Xi_c^{+,0}\gamma$; and determination of
spin-parity of $\Xi_c(2970)^+$. | hep-ex |
Search for the Decay tau to seven pion (pizero): A search for the decay of the tau lepton to seven charged pions and one or
zero pizero mesons was performed using the BaBar detector at the PEP-II
asymmetric-energy e+e- collider.
The analysis uses 232.2 fb-1 of data at center-of-mass energies on or near
the Y(4S) resonance. We observe 24 events with an expected background of
21.6+-1.3 events. Without evidence for a signal, we calculate an upper limit of
BR(tau- --> 4pi- 3pi+ (pizero) nu_tau) < 3.0*10^-7 at 90 % confidence level.
This is an improvement by nearly an order of magnitude over the previously
established limit. In addition, we set upper limits for the exclusive decays
tau- --> 4pi- 3pi+ nu_tau and tau- --> 4pi- 3pi+ pizero nu_tau. | hep-ex |
Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF
Data Set: We report a measurement of the bottom-strange meson mixing phase \beta_s
using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays
in which the quark-flavor content of the bottom-strange meson is identified at
production. This measurement uses the full data set of proton-antiproton
collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment
at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity.
We report confidence regions in the two-dimensional space of \beta_s and the
B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2,
-1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in
agreement with the standard model expectation. Assuming the standard model
value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +-
0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +-
0.009 (syst) ps, which are consistent and competitive with determinations by
other experiments. | hep-ex |
Mixed higher-order anisotropic flow and nonlinear response coefficients
of charged particles in PbPb collisions at $\sqrt{s_\mathrm{NN}} =$ 2.76 and
5.02 TeV: Anisotropies in the initial energy density distribution of the quark-gluon
plasma created in high energy heavy ion collisions lead to anisotropies in the
azimuthal distributions of the final-state particles known as collective flow.
Fourier harmonic decomposition is used to quantify these anisotropies. The
higher-order harmonics can be induced by the same order anisotropies (linear
response) or by the combined influence of several lower order anisotropies
(nonlinear response) in the initial state. The mixed higher-order anisotropic
flow and nonlinear response coefficients of charged particles are measured as
functions of transverse momentum and centrality in PbPb collisions at
nucleon-nucleon center-of-mass energies $\sqrt{s_\mathrm{NN}} =$ 2.76 and 5.02
TeV with the CMS detector. The results are compared with viscous hydrodynamic
calculations using several different initial conditions, as well as microscopic
transport model calculations. None of the models provides a simultaneous
description of the mixed higher-order flow harmonics and nonlinear response
coefficients. | hep-ex |
Measurement of the $D^*(2010)^+ - D^+$ mass difference: We measure the mass difference, $\Delta m_+$, between the $D^{*}(2010)^+$ and
the $D^+$ using the decay chain $D^{*}(2010)^+\to D^+ \pi^0$ with $D^+\to
K^-\pi^+\pi^+$. The data were recorded with the BABAR detector at
center-of-mass energies at and near the $\Upsilon(4S)$ resonance, and
correspond to an integrated luminosity of approximately 468 ${\rm fb}^{-1}$. We
measure $\Delta m_+ = \left(140\,601.0 \pm 6.8[{\rm stat}] \pm 12.9[{\rm
syst}]\right)$ keV. We combine this result with a previous BABAR measurement of
$\Delta m_0\equiv m(D^{*}(2010)^+) - m (D^0)$ to obtain $\Delta m_D = m(D^+) -
m(D^0) = \left(4\,824.9 \pm 6.8[{\rm stat}] \pm 12.9[{\rm syst}]\right)$ keV.
These results are compatible with and approximately five times more precise
than the Particle Data Group averages. | hep-ex |
High Power Testing Results of the X-Band Mixed-Mode RF Windows for
Linear Colliders: In this paper, we summarize the high power testing results of the X-band
mixed-mode RF windows at KEK and SLAC for linear colliders. The main feature of
these windows is that the combination of modes on the surface of the ceramic
significantly decreases the electric and magnetic fields in the junction
between the ceramic and the metal. So far two types of high power windows (with
the diameter of 53 mm and 64 mm) have been fabricated. A high power model of
the smaller type window was fabricated and tested in a resonant ring at KEK. A
maximum circulating power of 81 MW with 300 ns duration or 66 MW with 700 ns
duration was achieved. Light emission was observed for a power level of over 10
MW. Later, both windows were shipped to SLAC for even higher power testing
using combined power from two klystrons. The first window (53 mm diameter)
achieved a transmitted power of 80 MW with 1.5 microsec duration at 30 Hz
repetition. It was not destroyed during the testing. The testing of the second
window was carried out next to the small type and achieved 62 MW with 1.5
maicrosec duration with 10 Hz repetition. The final results of both windows are
presented in this report. | hep-ex |
Statistical combination of searches for the $\rm{X^{\pm}(5568)}$ state
decaying into $\rm{B^0_s π^\pm}$: A statistical combination of the search results for the narrow
$\rm{X^{\pm}(5568)}$ resonance decaying into $\rm{B_s^0 \pi^+}$ is reported,
based on published results from the ATLAS, CMS, CDF and LHCb Collaborations. A
structure in the invariant mass distribution of $\rm{B_s^0 \pi^+}$ has been
observed by the D0 Collaboration with a mass value of 5568 MeV but not
confirmed by any of the latest searches from the other Collaborations. Limits
have been set on the relative production rate $\rm{\rho_X}$ of the
$\rm{X^{\pm}(5568)}$ and $\rm{B^0_s}$ states, times the branching ratio for the
decay $\rm{X^{\pm}(5568) \rightarrow B^0_s\pi^\pm}$.
By applying a statistical combination of limits set by the three LHC
experiments, we derive a limit at 95\% Confidence Level of $\rho_X < 0.0092$
for $p_T(B^0_s)>$ 10 GeV, and $\rho_X < 0.0091$ for $p_T(B^0_s)>$ 15 GeV,
superseding the previous most stringent upper limits. The effect of including
the CDF result in the combination is also discussed. | hep-ex |
Hanohano:A Deep Ocean Antineutrino Observatory: This paper presents the science potential of a deep ocean antineutrino
observatory being developed at Hawaii and elsewhere. The observatory design
allows for relocation from one site to another. Positioning the observaory some
60 km distant from a nuclear reactor complex enables preecision measurement of
neutrino mixing parameters, leading to a determination of neutrino mass
hierarchy and theta_13. At a mid-Pacific location, the observatory measures the
flux of uranium and thorium decay series antineutrinos from earth's mantle and
performs a sensitive search for a hypothetical natural fission reactor in
earth's core. A subequent deployment at another mid-ocean location would test
lateral homogeneity of uranium and thorium in earth's mantle. These
measurements have significance for earth energy studies. | hep-ex |
Radiative decays of the Sigma0(1385) and Lambda(1520) hyperons: The electromagnetic decays of the Sig0(1385) and Lambda(1520) hyperons were
studied in photon-induced reactions gamma p -> K+ Lambda(1116)gamma in the CLAS
detector at the Thomas Jefferson National Accelerator Facility. We report the
first observation of the radiative decay of the Sig0(1385) and a measurement of
the Lambda(1520) radiative decay width. For the Sig0(1385) -> Lambda(1116)gamma
transition, we measured a partial width of 479+/-120(stat)+81-100(sys) keV,
larger than all of the existing model predictions. For the Lambda(1520) ->
Lambda(1116)gamma transition, we obtained a partial width of
167+/-43(stat)+26-12(sys) keV. | hep-ex |
Transverse Spin Effects at COMPASS: Single spin asymmetries in semi-inclusive deep-inelastic scattering off
transversely polarized nucleon targets have been under intense experimental
investigation over the past few years. They provide new insights into QCD and
the nucleon structure. For instance, they allow the determination of the third
yet-unknown leading-twist quark distribution function $\Delta_{T}q(x)$, the
transversity distribution. Additionally, they give insight into the parton
transverse momentum distribution and angular momentum.
The measurement of transverse spin effects in semi-inclusive deep-inelastic
scattering is an important part of the COMPASS physics program. In the years
2002-2004 data were collected scattering a 160 GeV muon beam on a transversely
polarized deuteron target. In 2007, additional data were collected on a
transversely polarized proton target. New results from the analysis of the
proton data will be presented. A different but not less important insight into
the nucleon structure might be given by the Sivers asymmetry. This angular
dependence of the cross-section arises from an intrinsic asymmetry in the
parton transverse momentum distribution. The Sivers function is tightly related
to the total angular momentum carried by the quarks in the nucleon. New COMPASS
results for the Sivers asymmetry of the proton will be shown. | hep-ex |
Search for CP Violation in B0B0bar Mixing using Partial Reconstruction
of B0-->D*-Xl+ nu and a Kaon Tag: We present results of a search for CP violation in B0B0bar mixing with the
BABAR detector. We select a sample of B0-->D*-Xl+ nu decays with a partial
reconstruction method and use kaon tagging to assess the flavor of the other B
meson in the event. We determine the CP violating asymmetry
ACP = (N(B0B0) - N(B0bar B0bar))/(N(B0B0) + N(B0bar
B0bar))=(0.06+-0.17+0.38-0.32)%, corresponding to delta_CP =1 - |q/p|
=(0.29+-0.84+1.88 -1.61)*10^-3. | hep-ex |
Search for light mediators in the low-energy data of the CONNIE reactor
neutrino experiment: The CONNIE experiment is located at a distance of 30 m from the core of a
commercial nuclear reactor, and has collected a 3.7 kg-day exposure using a CCD
detector array sensitive to an $\sim$1 keV threshold for the study of coherent
neutrino-nucleus elastic scattering. Here we demonstrate the potential of this
low-energy neutrino experiment as a probe for physics Beyond the Standard
Model, by using the recently published results to constrain two simplified
extensions of the Standard Model with light mediators. We compare the new
limits with those obtained for the same models using neutrinos from the
Spallation Neutron Source. Our new constraints represent the best limits for
these simplified models among the experiments searching for CE$\nu$NS for a
light vector mediator with mass $M_{Z^{\prime}}<$ 10 MeV, and for a light
scalar mediator with mass $M_{\phi}<$ 30 MeV. These results constitute the
first use of the CONNIE data as a probe for physics Beyond the Standard Model. | hep-ex |
Measurement of Diffractive Scattering of Photons with Large Momentum
Transfer at HERA: The first measurement of diffractive scattering of quasi-real photons with
large momentum transfer gamma p -> gamma Y, where Y is the proton dissociative
system, is made using the H1 detector at HERA. The measurement is performed for
initial photon virtualities Q^2 < 0.01 GeV^2. Cross sections are measured as a
function of W, the incident photon-proton entre of mass energy, and t, the
square of the four-momentum transferred at the proton vertex, in the range 175
< W < 247 GeV and 4<|t|<36 GeV^2. The W dependence is well described by a model
based on perturbative QCD using a leading logarithmic approximation of the BFKL
evolution. The measured |t| dependence is harder than that predicted by the
model and those observed in exclusive vector meson production. | hep-ex |
Study of fermion pair events at the 250 GeV ILC: Precise measurements of electroweak processes at the International Linear
Collider (ILC) will provide unique opportunities to explore new physics beyond
the Standard Model. Fermion pair production events are sensitive to new
interactions involving a new heavy gauge boson or an electroweak interacting
massive particle (EWIMP).We studied the mass reach of new particles at the ILC
with $\sqrt{s}=250$ GeV by using $e^+ e^-\to e^+ e^-$and $e^+ e^-\to \mu^+
\mu^-$ events. We show that a mass reach for BSM particles can be determined
with 90% confidence level using a toy Monte Carlo technique. | hep-ex |
Measurement of the ratio of branching fractions
$\mathcal{B}(B_c^+\,\to\,J/ψτ^+ν_τ)$/$\mathcal{B}(B_c^+\,\to\,J/ψμ^+ν_μ)$: A measurement is reported of the ratio of branching fractions
$\mathcal{R}(J/\psi)=\mathcal{B}(B_c^+\,\to\,J/\psi\tau^+\nu_\tau)/\mathcal{B}(B_c^+\,\to\,J/\psi
\mu^+\nu_\mu)$, where the $\tau^+$ lepton is identified in the decay mode
$\tau^+\,\to\,\mu^+\nu_\mu\overline{\nu}_\tau$. This analysis uses a sample of
proton-proton collision data corresponding to 3.0$\mathrm{\,fb}^{-1}$ of
integrated luminosity recorded with the LHCb experiment at center-of-mass
energies $7\,\mathrm{TeV}$ and $8\,\mathrm{TeV}$. A signal is found for the
decay $B_c^+\,\to\,J/\psi \tau^+\nu_\tau$ at a significance of 3 standard
deviations, corrected for systematic uncertainty, and the ratio of the
branching fractions is measured to be $\mathcal{R}(J/\psi) = 0.71 \pm 0.17
\mathrm{\,(stat)} \pm 0.18\mathrm{\,(syst)}$. This result lies within 2
standard deviations above the range of existing predictions in the Standard
Model. | hep-ex |
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