text
stringlengths 89
2.49k
| category
stringclasses 19
values |
|---|---|
Experimental review of unpolarised nucleon structure functions: Recent results are reviewed on unpolarised structure functions from fixed
target experiments at JLAB, NuTeV and from the HERA ep collider experiments H1
and ZEUS. | hep-ex |
Measurement of B+ -> K+ tau- tau+, B -> K* l+ l- and B -> K pi+ pi-
gamma decays at BABAR: We present some recent measurements of rare flavor-changing neutral current B
decays, using data collected with the BABAR detector at the PEP-II e+e-
collider at SLAC. First, we search for the rare process B+ -> K+ tau- tau+ and
we do not find evidence for signal. The measured branching fraction is
(1.31+0.66-0.61(stat.)+0.35-0.25(sys.)) x 10-3 with an upper limit, at the 90%
confidence level, of B(B+ -> K+ tau+ tau-) < 2.25 x 10-3. We then study the
lepton forward-backward asymmetry AFB and the longitudinal K* polarization FL
in the rare decays B -> K* l+ l-, where l+ l- is either e+ e- or mu+ mu-. We
report results for both the K*(892)0l+l- and K*(892)+l+l- final states, as well
as their combination K*l+l-, in five disjoint dilepton mass-squared bins.
Finally, we measure the time-dependent CP asymmetry in the radiative-penguin
decay B0 -> KS0 pi- pi+ gamma. The Kpipi resonant structure is extracted by an
amplitude analysis of the m_Kpipi and m_Kpi spectra in B+ -> K+ pi- pi+ gamma
decays. We use these results to extract the mixing-induced CP parameters of the
process B0 -> KS rho gamma from the time-dependent analysis of B0 -> KS0 pi+
pi- gamma decays and obtain S = -0.18 pm 0.32(stat.) +0.06 -0.05(syst.). | hep-ex |
Muon identification using multivariate techniques in the CMS experiment
in proton-proton collisions at $\sqrt{s}$ = 13 TeV: The identification of prompt and isolated muons, as well as muons from
heavy-flavour hadron decays, is an important task. We developed two
multivariate techniques to provide highly efficient identification for muons
with transverse momentum greater than 10 GeV. One provides a continuous
variable as an alternative to a cut-based identification selection and offers a
better discrimination power against misidentified muons. The other one selects
prompt and isolated muons by using isolation requirements to reduce the
contamination from nonprompt muons arising in heavy-flavour hadron decays. Both
algorithms are developed using 59.7 fb$^{-1}$ of proton-proton collisions data
at a centre-of-mass energy of $\sqrt{s}$ = 13 TeV collected in 2018 with the
CMS experiment at the CERN LHC. | hep-ex |
Observation of $Z_c(3900)^{0}$ in $e^+e^-\toπ^0π^0 J/ψ$: Using a data sample collected with the BESIII detector operating at the
BEPCII storage ring, we observe a new neutral state $Z_c(3900)^{0}$ with a
significance of $10.4\sigma$. The mass and width are measured to be
$3894.8\pm2.3\pm3.2$ MeV/$c^2$ and $29.6\pm8.2\pm8.2$~MeV, respectively, where
the first error is statistical and the second systematic. The Born cross
section for $e^+e^-\to\pi^0\pi^0 J/\psi$ and the fraction of it attributable to
$\pi^0 Z_c(3900)^{0}\to\pi^0\pi^0 J/\psi$ in the range $E_{cm}=4.19-4.42$ GeV
are also determined. We interpret this state as the neutral partner of the
four-quark candidate $Z_c(3900)^\pm$. | hep-ex |
Measurement of branching fractions for
$ψ(3686)\rightarrowγη',γη$ and $γπ^{0}$: Using a data sample of $448\times10^{6}$ $\psi(3686)$ events collected with
the BESIII detector operating at the BEPCII storage ring, the decays
$\psi(3686)\rightarrow\gamma\eta$ and $\psi(3686)\rightarrow\gamma\pi^{0}$ are
observed with a statistical significance of $7.3\sigma$ and $ 6.7\sigma$,
respectively. The branching fractions are measured to be
$\mathcal{B}(\psi(3686)\rightarrow\gamma\eta)=(0.85\pm0.18\pm0.05)\times10^{-6}$
and
$\mathcal{B}(\psi(3686)\rightarrow\gamma\pi^{0})=(0.95\pm0.16\pm0.05)\times10^{-6}$.
In addition, we measure the branching fraction of
$\psi(3686)\rightarrow\gamma\eta'$ to be
$\mathcal{B}(\psi(3686)\rightarrow\gamma\eta')=(125.1\pm2.2\pm6.2)\times
10^{-6}$, with improved precision compared to previous results. | hep-ex |
TAU 98 Conference Summary: I very briefly review the highlights of the fifth workshop on the physics of
the tau lepton and its neutrino. There has been much progress in many
sub-fields, which I touch upon in this review: the couplings of the tau to the
$Z^0$ and $W^\pm$; the leptonic branching fractions, lifetime, and tests of
universality; the Lorentz structure of tau decays; searches for neutrinoless
decays; limits on weak and electromagnetic dipole moments and CP violation;
inclusive semi-hadronic decays, spectral functions, sum rules, QCD, and
applications; substructure in tau decays to three pseudoscalars; tau decays to
kaons; limits on the mass of the tau neutrino; tau neutrinos from solar,
atmospheric, and AGN sources; accelerator searches for neutrino oscillations;
and prospects for the future. | hep-ex |
Search for the Standard Model Higgs Boson Produced in Association with a
$Z$ Boson in $p\bar{p}$ Collisions at $\sqrt{s} = 1.96$ TeV: We present a search for the standard model Higgs boson produced in
association with a $Z$ boson, using up to 7.9 fb$^{-1}$ of integrated
luminosity from $p\bar{p}$ collisions collected with the CDF II detector. We
utilize several novel techniques, including multivariate lepton selection,
multivariate trigger parametrization, and a multi-stage signal discriminant
consisting of specialized functions trained to distinguish individual
backgrounds. By increasing acceptance and enhancing signal discrimination,
these techniques have significantly improved the sensitivity of the analysis
above what was expected from a larger dataset alone. We observe no significant
evidence for a signal, and we set limits on the $ZH$ production cross section.
For a Higgs boson with mass 115 GeV/$c^2$, we expect (observe) a limit of 3.9
(4.8) times the standard model predicted value, at the 95% credibility level. | hep-ex |
Performance of b-tagging algorithms at the CMS experiment with pp
collision data at $\sqrt s$=8 TeV: The identification of jets originating from b quarks is crucial both for the
searches for new physics and for the measurement of standard model processes.
The Compact Muon Solenoid (CMS) collaboration at the Large Hadron Collider
(LHC) has developed a variety of algorithms to select b-quark jets based on
variables such as the impact parameter of charged particle tracks, properties
of reconstructed secondary vertices from heavy hadron decays, and the presence
or absence of a lepton in the jet, or combinations thereof. Performance
measurements of these b-jet identification algorithms are presented, using
multijet and $t\overline{t}$ events recorded in proton-proton collision data at
$\sqrt s$=8 TeV with the CMS detector during the LHC Run 1. | hep-ex |
Study of the mass and spin-parity of the Higgs boson candidate via its
decays to Z boson pairs: A study is presented of the mass and spin-parity of the new boson recently
observed at the LHC at a mass near 125 GeV. An integrated luminosity of 17.3
inverse femtobarns, collected by the CMS experiment in proton-proton collisions
at center-of-mass energies of 7 and 8 TeV, is used. The measured mass in the ZZ
channel, where both Z bosons decay to e or mu pairs, is 126.2 +/- 0.6 (stat.)
+/- 0.2 (syst.) GeV. The angular distributions of the lepton pairs in this
channel are sensitive to the spin-parity of the boson. Under the assumption of
spin 0, the present data are consistent with the pure scalar hypothesis, while
disfavoring the pure pseudoscalar hypothesis. | hep-ex |
Analysis of the $Wtb$ vertex from the measurement of triple-differential
angular decay rates of single top quarks produced in the $t$-channel at
$\sqrt{s}$ = 8 TeV with the ATLAS detector: The electroweak production and subsequent decay of single top quarks in the
$t$-channel is determined by the properties of the $Wtb$ vertex, which can be
described by the complex parameters of an effective Lagrangian. An analysis of
a triple-differential decay rate in $t$-channel production is used to
simultaneously determine five generalised helicity fractions and phases, as
well as the polarisation of the produced top quark. The complex parameters are
then constrained. This analysis is based on 20.2 fb$^{-1}$ of proton-proton
collision data at a centre-of-mass energy of 8 TeV collected with the ATLAS
detector at the LHC. The fraction of decays containing transversely polarised
$W$ bosons is measured to be $f_1=0.30 \pm 0.05$. The phase between amplitudes
for transversely and longitudinally polarised $W$ bosons recoiling against
left-handed $b$-quarks, is measured to be $\delta_- =
0.002\pi^{+0.016\pi}_{-0.017\pi}$, giving no indication of CP violation. The
fraction of longitudinal or transverse $W$ bosons accompanied by right-handed
$b$-quarks are also constrained. Based on these measurements, limits are placed
at 95% C.L. on the ratio of the complex coupling parameters
Re$[g_\mathrm{R}/V_\mathrm{L}] \in [-0.12,0.17]$ and
Im$[g_\mathrm{R}/V_\mathrm{L}] \in [-0.07,0.06]$. Constraints are also placed
on the ratios $|V_\mathrm{R}/V_\mathrm{L}|$ and $|g_\mathrm{L}/V_\mathrm{L}|$.
In addition, the polarisation of single top quarks in the $t$-channel is
constrained to be $P > 0.72$ (95% C.L.). None of the above measurements make
assumptions on the value of any of the other parameters or couplings and all of
them are in agreement with the Standard Model. | hep-ex |
AMANDA: Status and latest Results: We briefly review some of the recent AMANDA results emphasizing the all
flavor capabilities of the high energy neutrino telescope, important in the
context of equal neutrino mixing from distant sources at Earth. Together with a
report on a preliminary UHE neutrino flux limit, the course of our progress in
the quest for point sources is described. Finally, a 1 year preliminary limit
of AMANDA-II to neutralino cold dark matter (CDM) candidates, annihilating in
the center of the Sun, for various MSSM parameter choices is presented and
discussed. | hep-ex |
Neutrino Reconstruction in TRIDENT Based on Graph Neural Network: TRopIcal DEep-sea Neutrino Telescope (TRIDENT) is a next-generation neutrino
telescope to be located in the South China Sea. With a large detector volume
and the use of advanced hybrid digital optical modules (hDOMs), TRIDENT aims to
discover multiple astrophysical neutrino sources and probe all-flavor neutrino
physics. The reconstruction resolution of primary neutrinos is on the critical
path to these scientific goals. We have developed a novel reconstruction method
based on graph neural network (GNN) for TRIDENT. In this paper, we present the
reconstruction performance of the GNN-based approach on both track- and
shower-like neutrino events in TRIDENT. | hep-ex |
First Measurement of θ_13 from Delayed Neutron Capture on Hydrogen
in the Double Chooz Experiment: The Double Chooz experiment has determined the value of the neutrino
oscillation parameter $\theta_{13}$ from an analysis of inverse beta decay
interactions with neutron capture on hydrogen. This analysis uses a three times
larger fiducial volume than the standard Double Chooz assessment, which is
restricted to a region doped with gadolinium (Gd), yielding an exposure of
113.1 GW-ton-years. The data sample used in this analysis is distinct from that
of the Gd analysis, and the systematic uncertainties are also largely
independent, with some exceptions, such as the reactor neutrino flux
prediction. A combined rate- and energy-dependent fit finds $\sin^2
2\theta_{13}=0.097\pm 0.034(stat.) \pm 0.034 (syst.)$, excluding the
no-oscillation hypothesis at 2.0 \sigma. This result is consistent with
previous measurements of $\sin^2 2\theta_{13}$. | hep-ex |
B Physics (Experiment): In past few years the flavor physics made important transition from the work
on confirmation the standard model of particle physics to the phase of search
for effects of a new physics beyond standard model. In this paper we review
current state of the physics of b-hadrons with emphasis on results with a
sensitivity to new physics. | hep-ex |
CP violation results from CDF: We present world-leading results on CP-violating asymmetries and branching
fractions of several decay modes of B0, B0s, and {\Lambda}b hadrons into
charmless two-body, and of B\pm into charm, final states collected by the CDF
detector. We also report a new measurement of CP-violating asymmetries in
D\ast\pm-tagged D0 \rightarrow h+h- (h = K or {\pi}) decays, where any
enhancement from the Standard Model prediction would be unambiguous evidence
for New Physics. | hep-ex |
Probing Dark Universe with Exceptional Points: It is demonstrated that detection of putative particles such as paraphotons
and axions constituting the dark sector of the universe can be reduced to
detection of extremely weak links or couplings between cavities and modes. This
method allows utilisation of extremely sensitive frequency metrology methods
that are not limited by traditional requirements on ultra low temperatures,
strong magnetic fields and sophisticated superconducting technology. We show
that exceptional points in the eigenmode structure of coupled modes may be used
to boost the sensitivity of dark matter mediated weak links. We find
observables that are proportional to fractional powers of fundamental coupling
constants. Particularly, in the case of axion detection, it is demonstrated
that resonance frequency scaling with $\sim \sqrt{g_{a\gamma\gamma}\theta}$ and
$\sim \sqrt[3]{g_{a\gamma\gamma}\theta}$ dependencies can be realised in a
ternary photonic cavity system, which is beneficial as these coupling constants
are extremely small. | hep-ex |
Search for a new pseudoscalar decaying into a pair of muons in events
with a top-quark pair at $\sqrt{s} = 13$ TeV with the ATLAS detector: A search for a new pseudoscalar $a$-boson produced in events with a top-quark
pair, where the $a$-boson decays into a pair of muons, is performed using
$\sqrt{s} = 13$ TeV $pp$ collision data collected with the ATLAS detector at
the LHC, corresponding to an integrated luminosity of $139\, \mathrm{fb}^{-1}$.
The search targets the final state where only one top quark decays to an
electron or muon, resulting in a signature with three leptons $e\mu\mu$ and
$\mu\mu\mu$. No significant excess of events above the Standard Model
expectation is observed and upper limits are set on two signal models: $pp
\rightarrow t\bar{t}a$ and $pp \rightarrow t\bar{t}$ with $t \rightarrow H^\pm
b$, $H^\pm \rightarrow W^\pm a$, where $a\rightarrow\mu\mu$, in the mass ranges
$15$ GeV $ < m_a < 72$ GeV and $120$ GeV $ \leq m_{H^{\pm}} \leq 160$ GeV. | hep-ex |
Search for heavy resonances decaying to WW, WZ, or WH boson pairs in a
final state consisting of a lepton and a large-radius jet in proton-proton
collisions at $\sqrt{s}$ = 13 TeV: A search for new heavy resonances decaying to pairs of bosons (WW, WZ, or WH)
is presented. The analysis uses data from proton-proton collisions collected
with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an
integrated luminosity of 137 fb$^{-1}$. One of the bosons is required to be a W
boson decaying to an electron or muon and a neutrino, while the other boson is
required to be reconstructed as a single jet with mass and substructure
compatible with a quark pair from a W, Z, or Higgs boson decay. The search is
performed in the resonance mass range between 1.0 and 4.5 TeV and includes a
specific search for resonances produced via vector boson fusion. The signal is
extracted using a two-dimensional maximum likelihood fit to the jet mass and
the diboson invariant mass distributions. No significant excess is observed
above the estimated background. Model-independent upper limits on the
production cross sections of spin-0, spin-1, and spin-2 heavy resonances are
derived as functions of the resonance mass and are interpreted in the context
of bulk radion, heavy vector triplet, and bulk graviton models. The reported
bounds are the most stringent to date. | hep-ex |
Inclusive production of D*+- mesons in photon-photon collisions at
sqrt(s) = 183 and 189 GeV and a first measurement of the the charm structure
function of the photon: The inclusive production of D*+- mesons in photon-photon collisions has been
measured using the OPAL detector at LEP at e+e- centre-of-mass energies of 183
and 189GeV. The D* mesons are reconstructed in their decay to D0pi+ with the D0
observed in the two decay modes Kpi+ and Kpi+pi-pi+. After background
subtraction, 100.4+-12.6(stat) D*+- mesons have been selected in events without
observed scattered beam electron ("anti-tagged") and 29.8+-5.9 (stat) D*+-
mesons in events where one beam electron is scattered into the detector
("single-tagged"). Direct and single-resolved events are studied separately.
Differential cross-sections as functions of the D* transverse momentum p_t and
pseudorapidity \eta are presented in the kinematic region 2<p_t<12GeV and
\eta<1.5. They are compared to next-to-leading order (NLO) perturbative QCD
calculations. The total cross-section for the process (e+e- to e+e-ccbar),
where the charm quarks are produced in the collision of two quasi-real photons,
is measured to be 842+-97(stat)+-75(syst)+-196(extrapolation)pb. A first
measurement of the charm structure function F2 of the photon is performed in
the kinematic range 0.0014<x<0.87 and 5<Q^2<100 GeV^2, and the result is
compared to a NLO perturbative QCD calculation. | hep-ex |
Search for charged Higgs bosons through the violation of lepton
universality in ttbar events using pp collision data at sqrt(s) = 7 TeV with
the ATLAS experiment: In several extensions of the Standard Model, the top quark can decay into a
bottom quark and a light charged Higgs boson H+, t to bH+, in addition to the
Standard Model decay t to bW. Since W bosons decay to the three lepton
generations equally, while H+ may predominantly decay into tau+nu, charged
Higgs bosons can be searched for using the violation of lepton universality in
top quark decays. The analysis in this paper is based on 4.6/fb of
proton-proton collision data at sqrt(s) = 7 TeV collected by the ATLAS
experiment at the Large Hadron Collider. Signatures containing leptons (e or
mu) and/or a hadronically decaying tau (tau_had) are used. Event yield ratios
between e+tau_had and e+mu, as well as between mu+tau_had and mu+e, final
states are measured in the data and compared to predictions from simulations.
This ratio-based method reduces the impact of systematic uncertainties in the
analysis. No significant deviation from the Standard Model predictions is
observed. With the assumption that the branching fraction B(H+ to tau+nu) is
100%, upper limits in the range 3.2%-4.4% can be placed on the branching
fraction B(t to bH+) for charged Higgs boson masses m(H+) in the range 90-140
GeV. After combination with results from a search for charged Higgs bosons in
ttbar decays using the tau_had+jets final state, upper limits on B(t to bH+)
can be set in the range 0.8%-3.4%, for m(H+) in the range 90-160 GeV. | hep-ex |
Measurement of sin2thetaW from Neutrino-Nucleon Scattering at NuTeV: We report the measurement of sin2thetaW in neutrino-nucleon deep inelastic
scattering from the NuTeV experiment. Using separate neutrino and anti-neutrino
beams, NuTeV is able to determine sin2thetaW with low systematic errors by
measuring the Paschos-Wolfenstein variable R-minus, a ratio of differences of
neutrino and anti-neutrino neutral-current and charged-current cross-sections.
NuTeV measures sin2thetaW(on-shell)= 0.2253+/-0.0019(stat)+/-0.0010(syst),
which implies a W mass of 80.26+/-0.11 GeV. | hep-ex |
Measurement of the Quasi-Two-Body B Decays: We study the contributions of the $B\rightarrow
\psi(3770)K[\psi(3770)\rightarrow D\bar{D}]$, $B\rightarrow
K^*(1410)\pi[K^*(1410)\rightarrow K\pi]$ and $B\rightarrow
X(3872)K[X(3872)\rightarrow J/\psi\gamma, \psi(2S)\gamma, D\bar{D}\pi,
J/\psi\omega, J/\psi\pi\pi$ and $D\bar{D}^*\pi]$ quasi-two-body decays. There
are no existing previous measurement of the three-body branching fractions for
three final states of the $X(3872)\rightarrow J/\psi\gamma$, $\psi(2S)\gamma$
and $D\bar{D}\pi$ but several quasi-two-body modes that can decay to this final
state have been seen. | hep-ex |
Search for B_{s}^{0}->hh Decays at the $Υ(5S)$ Resonance: We have searched for B_{s}^{0}->hh decays, where h stands for a charged or
neutral kaon, or a charged pion. These results are based on a 23.6 fb^{-1} data
sample collected with the Belle detector on the \Upsilon(5S) resonance at the
KEKB asymmetric-energy e^{+}e^{-} collider, containing 1.25x10^6
B_{s}^{(*)}\bar{B}_{s}^{(*)} events. We observe the decay B_{s}^{0}->K^{+}K^{-}
and measure its branching fraction, \mathcal{B}(B_{s}^{0}->K^{+}K^{-}) =
[3.8_{-0.9}^{+1.0}(\mathrm{stat})\pm 0.5(\mathrm{syst})\pm 0.5(f_s)] \times
10^{-5}. The first error is statistical, the second is systematic, and the
third error is due to the uncertainty in the B^0_s production fraction in
$e^+e^-\to b\bar{b}$ events. No significant signals are seen in other decay
modes, and we set upper limits at 90% confidence level:
\mathcal{B}(B_{s}^{0}->K^-\pi^{+})< 2.6 \times 10^{-5},
\mathcal{B}(B_{s}^{0}->\pi^{+}\pi^{-})< 1.2 \times 10^{-5} and
\mathcal{B}(B_{s}^{0}->K^0\bar{K}^0) < 6.6\times 10^{-5}. | hep-ex |
Experimental overview of charmonium spectroscopy: In this talk, I review the recent experimental results on charmonium
spectroscopy from BESIII, Belle, BaBar and CLEOc. Below the open-charm
threshold, the masses and widths of spin-singlet states eta_c, eta_c(2S), h_c
are measured with high precision. Above the threshold, chi_{c2}(2P) is
identified in the process gamma gamma -> chi_{c2}(2P) -> gamma D bar{D};
Evidence of X(3823) is found in the M(chi_{c1} gamma) invariant-mass
distribution for B -> gamma chi_{c1} K decays, the measured properties are
consistent with the missing psi_2(1^{2}D_2) state. | hep-ex |
Search for heavy neutrinos at CERN SPS: The phenomenology in the neutrino sector requires physics beyond the Standard
Model. One possibility is the existence of new massive leptonic states which
could be probed at the high intensity machines. The present results on heavy
neutral leptons from the study of kaon decays in flight with the NA48/2 and
NA62 experiments are presented and the future prospects for such searches at
CERN SPS are discussed. | hep-ex |
Status of LHCb: The status of the LHCb experiment is presented. The experiment has been
taking data since the LHC startup. The performances of the various
sub-detectors are discussed and a preliminary measurement of the b
cross-section is reported. The value is in agreement with expectations. | hep-ex |
DM+$b\bar b$ simulations with DMSimp: an update: Searches for dark matter (DM) produced using collider data probe wide regions
of the allowed parameter space of many models and have become competitive with
more traditional searches. The interpretations of the results can be
efficiently performed in simplified models, which feature only a mediator and a
DM candidate together with the interactions among them and the standard model
particles. The DMSimp model in FeynRules currently features a wide set of
$s$-channel simplified models and can be exploited by the MadGraph5_aMC@NLO
framework to produce event samples including NLO QCD corrections for realistic
simulations. Higher-order corrections typically have a sizeable impact on the
total production rate and lead to a reduction of the theoretical uncertainties.
In this short note we report on a recent update of the DMSimp model, which
makes it possible to simulate dark matter production in association with bottom
quarks in a mixed four-flavour scheme, where the $\overline{\rm MS}$
renormalisation for the bottom-quark Yukawa is employed, while the bottom quark
mass is on shell. By comparing with five-flavour scheme, we show that the mixed
four-flavor scheme provides reliable predictions for DM+$b\bar b$ final states
in a wide range of DM masses. | hep-ex |
Measurements of branching fractions, rate asymmetries, and angular
distributions in the rare decays B --> Kl+l- and B --> K*l+l-: We present measurements of the flavor-changing neutral current decays B -->
Kl+l- and B --> K*l+l-, where l+l- is either an e+e- or mu+mu- pair. The data
sample comprises 229 x 10^6 Y(4s) -->to BBbar decays collected with the BaBar
detector at the PEP-II e+e- storage ring. Flavor-changing neutral current
decays are highly suppressed in the Standard Model and their predicted
properties could be significantly modified by new physics at the electroweak
scale. We measure the branching fractions B(B --> Kll) = (0.34 +- 0.07 +- 0.02)
x 10^{-6}, B(B --> K*ll) = (0.78^{+0.19}_{-0.17} +- 0.11) x 10^{-6}, the direct
CP asymmetries of these decays, and the relative abundances of decays to
electrons and muons. For two regions in l+l- mass, above and below m(Jpsi), we
measure partial branching fractions and the forward-backward angular asymmetry
of the lepton pair. In these same regions we also measure the K* longitudinal
polarization in B --> K*l+l- decays. Upper limits are obtained for the lepton
flavor-violating decays B --> Kemu and B --> K*emu. All measurements are
consistent with Standard Model expectations. | hep-ex |
Vector Boson + Heavy Flavor Jets Production at the Tevatron: Recent measurements on the vector boson plus heavy-flavor jets production by
the CDF and D0 experiments are presented in comparisons with recent theoretical
predictions. Good understanding of such processes is important to improve our
understanding of QCD and also to enhance the potential to search for
yet-to-be-discovered new physics phenomena which lead to similar final states. | hep-ex |
First measurement of charm production in fixed-target configuration at
the LHC: The first measurement of heavy-flavour production by the LHCb experiment in
its fixed-target mode is presented. The production of $J/\psi$ and $D^0$ mesons
is studied with beams of protons of different energies colliding with gaseous
targets of helium and argon with nucleon-nucleon centre-of-mass energies of
$\sqrt{s_{NN}} = 86.6 $ and $ 110.4$ ${\rm GeV}$, respectively. The $J/\psi$
and $D^0$ (including charge conjugate) production cross sections in $p{\rm He}$
collisions in the rapidity range $[2,4.6]$ are found to be $\sigma_{J/\psi} =
652 \pm 33$ (stat) $\pm 42$ (syst) nb$/$nucleon and $\sigma_{D^0} = 80.8 \pm
2.4$ (stat) $\pm 6.3$ (syst) $\mu$b$/$nucleon, where the first uncertainty is
statistical and the second is systematic. No evidence for a substantial
intrinsic charm content of the nucleon is observed in the large Bjorken-$x$
region. | hep-ex |
Measurements of the CKM angle gamma using B^+ --> D K^+ decays at LHCb: Of the three angles that make up the CKM matrix, the least well known is
gamma. A precision measurement of this quantity is highly desirable as it forms
one of the arbitrary parameters in the Standard Model. Moreover, this is the
one angle of the CKM triangle that can be determined in channels that occur via
tree-level decays. While loop-level processes could have sensitivity to physics
beyond the standard model, tree level processes are expected to be unaltered.
Hence a measurement of gamma in tree level processes leads to a standard model
benchmark measurement against which other loop-driven measurements can be
compared. The measurements described here are the latest developments from LHCb
involving the decay B^+ --> D K^+, where the D meson is either a D^0 or a
anti-D^0 and the final state of the D meson is accessible from either flavour
state. | hep-ex |
Discovery potential for heavy t-tbar resonances in dilepton+jets final
states: We examine the prospects for probing heavy top quark-antiquark (t-tbar)
resonances at the upgraded LHC in pp collisions at $\root_s = 14 TeV. Heavy
t-tbar resonances (Z' bosons) are predicted by several theories that go beyond
the standard model. We consider scenarios in which each top quark decays
leptonically, either to an electron or a muon, and the data sets correspond to
integrated luminosities of \int L dt = 300 /fb and \int L dt = 3000 /fb. We
present the expected 5-sigma discovery potential for a Z' resonance as well as
the expected upper limits at 95% C.L. on the Z' production cross section and
mass in the absence of a discovery. | hep-ex |
Measurement of neutrino source activity in the experiment BEST by
calorimetric method: Experiments to study non-standard properties of neutrinos using
high-intensity artificial neutrino sources require high accuracy in determining
their activity. A calorimetric system to determine the activity of a 51Cr
neutrino source in the experiment BEST with an accuracy better than 1% was
created. The design of the calorimetric system and the main factors affecting
the accuracy of measurements are considered. The results of measurements of the
activity of the source made for the BEST experiment are presented. The value of
the source activity from calorimetric measurements was 3.41 MCi at the
beginning of the experiment. | hep-ex |
Observation of Time-Dependent CP Violation in B0 -> eta' K0 Decays and
Improved Measurements of CP Asymmetries in B0 -> phiK0, KsKsKs and B0 ->
J/psi K0 Decays: We present improved measurements of CP-violation parameters in B0->phiK0,
eta'K0, KsKsKs decays based on a sample of 535x10^6 BBbar pairs collected at
the Y(4S) resonance with the Belle detector at the KEKB energy-asymmetric e+e-
collider. We obtain sin2phi_1^eff=+0.64+-0.10(stat)+-0.04(syst) for B0->eta'K0,
+0.50+-0.21(stat)+-0.06(syst) for B0->phiK0, and +0.30+-0.32(stat) +-0.08(syst)
for B0->KsKsKs decays. We have observed CP violation in the B0->eta'K0 decay
with a significance of 5.6 standard deviations. We also perform an improved
measurement of CP asymmetries in B0->J/psiK0 decays and obtain
sin2phi_1=+0.642+- 0.031(stat)+-0.017(syst). | hep-ex |
Recent Studies of Exotic Hadrons at the LHCb Experiment: Recent results on studies of exotic hadrons at the LHCb experiment are
summarised. These are the observation of new resonances decaying to J/$\psi
K^{+}$ and J/$\psi\phi$, evidence of a J/$\psi\Lambda$ structure and
observation of excited $\Xi^{-}$ states in the $\Xi_{b}^{-}\to J/\psi \Lambda
K^{-}$ decay and the study of $B_{s}^{0}\to J/\psi\pi^{+}\pi^{-}K^{+}K^{-}$
decays. | hep-ex |
Measurements of the Higgs boson production and decay rates and
constraints on its couplings from a combined ATLAS and CMS analysis of the
LHC $pp$ collision data at $\sqrt{s}=$ 7 and 8 TeV: Combined ATLAS and CMS measurements of the Higgs boson production and decay
rates, as well as constraints on its couplings to vector bosons and fermions,
are presented. The combination is based on the analysis of five production
processes, namely gluon fusion, vector boson fusion, and associated production
with a $W$ or a $Z$ boson or a pair of top quarks, and of the six decay modes
$H \to ZZ, WW$, $\gamma\gamma, \tau\tau, bb$, and $\mu\mu$. All results are
reported assuming a value of 125.09 GeV for the Higgs boson mass, the result of
the combined measurement by the ATLAS and CMS experiments. The analysis uses
the CERN LHC proton--proton collision data recorded by the ATLAS and CMS
experiments in 2011 and 2012, corresponding to integrated luminosities per
experiment of approximately 5 fb$^{-1}$ at $\sqrt{s}=7$ TeV and 20 fb$^{-1}$ at
$\sqrt{s} = 8$ TeV. The Higgs boson production and decay rates measured by the
two experiments are combined within the context of three generic
parameterisations: two based on cross sections and branching fractions, and one
on ratios of coupling modifiers. Several interpretations of the measurements
with more model-dependent parameterisations are also given. The combined signal
yield relative to the Standard Model prediction is measured to be 1.09 $\pm$
0.11. The combined measurements lead to observed significances for the vector
boson fusion production process and for the $H \to \tau\tau$ decay of $5.4$ and
$5.5$ standard deviations, respectively. The data are consistent with the
Standard Model predictions for all parameterisations considered. | hep-ex |
Search for Violation of CPT and Lorentz Invariance in $B^0_s$ Meson
Oscillations using the D0 Detector: A search is presented for CPT-violating effects in the mixing of $B^0_s$
mesons using the D0 detector at the Fermilab Tevatron Collider. The
CPT-violating asymmetry in the decay $B^0_s \rightarrow \mu^{\pm} D_s^{\mp} X$
as a function of sidereal phase is measured. No evidence for CPT-violating
effects is observed and limits are placed on CPT- and Lorentz-invariance
violating coupling coefficients. | hep-ex |
Experimental Review of Structures in the $J/ψφ$ Mass Spectrum: The discovery of numerous new charmonium-like structures since 2003 have
revitalized interest in exotic meson spectroscopy. These structures do not fit
easily into the conventional charmonium model, and proposals like four-quark
states, hybrids, and re-scattering effects have been suggested as explanations.
Since 2009, several new structures were reported in the $J/\psi\phi$ mass
spectrum with the following characteristics: they are the first ones reported
decaying into two heavy mesons which contain both a $c\bar{c}$ pair and a
$s\bar{s}$ pair; and their masses are well beyond the open charm pair
threshold. Conventional $c\bar{c}$ states with a mass beyond the $J/\psi\phi$
threshold are not expected to decay into this channel and the width is expected
to be large, thus they are good candidates for exotic mesons. My focus in this
article is to review the recent developments on the structures in the
$J/\psi\phi$ mass spectrum from CDF, Belle and LHCb. | hep-ex |
Precision measurement of the top-quark mass in lepton+jets final states: We measure the mass of the top quark in lepton$+$jets final states using the
full sample of $p\bar{p}$ collision data collected by the D0 experiment in Run
II of the Fermilab Tevatron Collider at $\sqrt s=1.96 $TeV, corresponding to
$9.7 {\rm fb}^{-1}$ of integrated luminosity. We use a matrix element technique
that calculates the probabilities for each event to result from $t\bar t$
production or background. The overall jet energy scale is constrained in situ
by the mass of the $W$ boson. We measure $m_t=174.98\pm0.76$ GeV. This
constitutes the most precise single measurement of the top-quark mass. | hep-ex |
A Review of chi_cJ Decays at BESIII and CLEO-c: The latest results on chi_cJ(1P) decays from BESIII and CLEO-c are reviewed
and compared to theoretical predictions. The experimental results use the final
samples of chi_cJ(1P) decays from CLEO-c, obtained from 26 million psi(2S)
decays, and the most recent samples from BESIII, from a starting sample of 106
million psi(2S) decays. | hep-ex |
Search for the exotic $Ξ^{--}(1860)$ Resonance in 340GeV/c
$Σ^-$-Nucleus Interactions: We report on a high statistics search for the $\Xi^{--}(1860)$ resonance in
$\Sigma^-$-nucleus collisions at 340GeV/c. No evidence for this resonance is
found in our data sample which contains 676000 $\Xi^-$ candidates above
background. For the decay channel $\Xi^{--}(1860) \to \Xi^-\pi^-$ and the
kinematic range 0.15$<x_F<$0.9 we find a 3$\sigma$ upper limit for the
production cross section of 3.1 and 3.5 $\mu$b per nucleon for reactions with
carbon and copper, respectively. | hep-ex |
A simulation-based study of the neutron backgrounds for NaI dark matter
experiments: Among the direct search experiments for weakly interacting massive particle
(WIMP) dark matter, the DAMA experiment observed an annual modulation signal
interpreted as WIMP interactions with a significance of 9.2$\sigma$. Recently,
Jonathan Davis claimed that the DAMA modulation may be interpreted on the basis
of the neutron scattering events induced by the muons and neutrinos together.
We tried to simulate the neutron backgrounds at the Gran Sasso and Yangyang
laboratory with and without the polyethylene shielding to quantify the effects
of the ambient neutrons on the direct detection experiments based on the
crystals. | hep-ex |
Measurement of the residual energy of muons in the Gran Sasso
underground Laboratories: The MACRO detector was located in the Hall B of the Gran Sasso underground
Laboratories under an average rock overburden of 3700 hg/cm^2. A transition
radiation detector composed of three identical modules, covering a total
horizontal area of 36 m^2, was installed inside the empty upper part of the
detector in order to measure the residual energy of muons. This paper presents
the measurement of the residual energy of single and double muons crossing the
apparatus. Our data show that double muons are more energetic than single ones.
This measurement is performed over a standard rock depth range from 3000 to
6500 hg/cm^2. | hep-ex |
Measurement of $WW/WZ \to \ell νq q^{\prime}$ production with the
hadronically decaying boson reconstructed as one or two jets in $pp$
collisions at $\sqrt{s}=8$ TeV with ATLAS, and constraints on anomalous gauge
couplings: This paper presents a study of the production of $WW$ or $WZ$ boson pairs,
with one $W$ boson decaying to $e\nu$ or $\mu\nu$ and one $W$ or $Z$ boson
decaying hadronically. The analysis uses 20.2 fb$^{-1}$ of $\sqrt{s}=8$ TeV
$pp$ collision data, collected by the ATLAS detector at the Large Hadron
Collider. Cross-sections for $WW/WZ$ production are measured in high-$p_{T}$
fiducial regions defined close to the experimental event selection. The
cross-section is measured for the case where the hadronically decaying boson is
reconstructed as two resolved jets, and the case where it is reconstructed as a
single jet. The transverse momentum distribution of the hadronically decaying
boson is used to search for new physics. Observations are consistent with the
Standard Model predictions, and $95\%$ confidence intervals are calculated for
parameters describing anomalous triple gauge-boson couplings. | hep-ex |
Zeus at HERA II: The ZEUS detector has been upgraded in a number of areas to prepare for the
physics opportunities of HERA II. These upgrades, and their physics rationale
and promise, are briefly outlined. The measurement of polarisation at HERA II,
and its importance for the HERA II physics programme, is also discussed. | hep-ex |
Measurement of Longitudinal Spin Asymmetries From $W\rightarrow e$ Boson
Decay in Polarized pp Collisions at $\sqrt{s}=500$ GeV at RHIC-PHENIX: We report the measurement of the parity violating single spin asymmetries for
inclusive high transverse momentum electrons and positrons in polarized $p+p$
collisions at a center of mass energy of $\sqrt{s}=500$ GeV with the PHENIX
detector at RHIC. These electrons are attributed to the decay of $W^\pm$ and
$Z^0$ bosons, and measured production cross section is consistent with the
expectations. The $W$ production is confirmed for the first time in $p+p$
collisions. Its spin asymmetry in the polarized $p+p$ collisions is a important
probe for the quark flavor decomposition of the proton spin. | hep-ex |
The Search and Study of Low-mass Scalar Mesons in the Reaction $np -->
npπ^+π^-$ at Pn=3.83 Gev/c: This work is devoted to search and study scalar $\sigma_0 0^+[0^++]$ - mesons
in the system of $\pi^+\pi^-$ from the reaction $np -> np\pi^+\pi^-$ at the
impulse of the quasimonochromatic neutrons c from the data obtained in an
exposure of the 1m H2 bubble chamber of LHE (JINR)The resonance with and has
been found out in effective mass distribution. Value of a statistical deviation
of this peculiarity from a background is more than four. Spin of the resonance
has been estimated, which, with high probability, is equal 0. The other quantum
numbers of the resonance have been estimated. | hep-ex |
A study of meson and baryon decays to strange final states with GlueX in
Hall D (A proposal to the 39th Jefferson Lab Program Advisory Committee): The primary motivation of the GlueX experiment is to search for and
ultimately study the pattern of gluonic excitations in the meson spectrum
produced in gamma p collisions. Recent lattice QCD calculations predict a rich
spectrum of hybrid mesons that have both exotic and non-exotic JPC,
corresponding to q q-bar (q=u, d, or s) states coupled with a gluonic field. A
thorough study of the hybrid spectrum, including the identification of the
isovector triplet, with charges 0 and +-1, and both isoscalar members, |s
s-bar> and |u u-bar> + |d d-bar>, for each predicted hybrid combination of JPC,
may only be achieved by conducting a systematic amplitude analysis of many
different hadronic final states. We propose the development of a kaon
identification system, supplementing the existing GlueX forward time-of-flight
detector, in order to cleanly select meson and baryon decay channels that
include kaons. Once this detector has been installed and commissioned, we plan
to collect a total of 200 days of physics analysis data at an average intensity
of 5 x 10^7 tagged photons on target per second. This data sample will provide
an order of magnitude statistical improvement over the initial GlueX data set
and, with the developed kaon identification system, a significant increase in
the potential for GlueX to make key experimental advances in our knowledge of
hybrid mesons and Cascade baryons. | hep-ex |
Search for the Standard Model Higgs boson in WH -> lnubb and H -> WW(*)
-> lnulnu channels at ATLAS: Results for the Standard Model Higgs boson search by the ATLAS experiment in
the WH -> lnubb and H -> WW(*) -> lnulnu channels are presented. The results
are based on 1.04 fb^-1 of data from pp collisions at sqrt(s) = 7 TeV produced
by the LHC in 2011. No evidence is found for the Standard Model Higgs boson in
either decay mode. The WH -> lnubb channel is not yet sensitive to the Standard
Model Higgs, while the H -> WW(*) -> lnulnu channel excludes the Standard Model
Higgs in the range of 158 < m_H < 186 GeV at the 95% confidence level. | hep-ex |
Inclusive Hadron Production and Dijets at HERA: This article summarizes a talk given at the International Symposium on
Multiparticle Dynamics 1999 in Providence/USA. It provides an overview on the
variety of measurements of the hadronic final state in jet production for
deep-inelastic scattering and photoproduction at HERA. | hep-ex |
Angular Intermittency and Analytical QCD Predictions: We present a comparison of local multiplicity fluctuations in angular
phase-space intervals with first-order QCD predictions. The data are based on
810k hadronic events at 91.2 GeV collected with the L3 detector at LEP during
1994. | hep-ex |
Significant Excess of ElectronLike Events in the MiniBooNE
Short-Baseline Neutrino Experiment: The MiniBooNE experiment at Fermilab reports results from an analysis of
$\nu_e$ appearance data from $12.84 \times 10^{20}$ protons on target in
neutrino mode, an increase of approximately a factor of two over previously
reported results. A $\nu_e$ charged-current quasielastic event excess of $381.2
\pm 85.2$ events ($4.5 \sigma$) is observed in the energy range
$200<E_\nu^{QE}<1250$~MeV. Combining these data with the $\bar \nu_e$
appearance data from $11.27 \times 10^{20}$ protons on target in antineutrino
mode, a total $\nu_e$ plus $\bar \nu_e$ charged-current quasielastic event
excess of $460.5 \pm 99.0$ events ($4.7 \sigma$) is observed. If interpreted in
a two-neutrino oscillation model, ${\nu}_{\mu} \rightarrow {\nu}_e$, the best
oscillation fit to the excess has a probability of $21.1\%$, while the
background-only fit has a $\chi^2$ probability of $6 \times 10^{-7}$ relative
to the best fit. The MiniBooNE data are consistent in energy and magnitude with
the excess of events reported by the Liquid Scintillator Neutrino Detector
(LSND), and the significance of the combined LSND and MiniBooNE excesses is
$6.0 \sigma$. A two-neutrino oscillation interpretation of the data would
require at least four neutrino types and indicate physics beyond the three
neutrino paradigm.Although the data are fit with a two-neutrino oscillation
model, other models may provide better fits to the data. | hep-ex |
New results on $ν_μ\to ν_τ$ appearance with the OPERA
experiment in the CNGS beam: The OPERA neutrino experiment is designed to perform the first observation of
neutrino oscillations in direct appearance mode in the $\nu_\mu \to \nu_\tau$
channel, via the detection of the $\tau$-leptons created in charged current
$\nu_\tau$ interactions. The detector, located in the underground Gran Sasso
Laboratory, consists of an emulsion/lead target with an average mass of about
1.2 kt, complemented by electronic detectors. It is exposed to the CERN
Neutrinos to Gran Sasso beam, with a baseline of 730 km and a mean energy of 17
GeV. The observation of the first $\nu_\tau$ candidate event and the analysis
of the 2008-2009 neutrino sample have been reported in previous publications.
This work describes substantial improvements in the analysis and in the
evaluation of the detection efficiencies and backgrounds using new simulation
tools. The analysis is extended to a sub-sample of 2010 and 2011 data,
resulting from an electronic detector-based pre-selection, in which an
additional $\nu_\tau$ candidate has been observed. The significance of the two
events in terms of a $\nu_\mu \to \nu_\tau$ oscillation signal is of 2.40
$\sigma$. | hep-ex |
Search for supersymmetry with Higgs boson to diphoton decays using the
razor variables at $\sqrt{s} = $ 13 TeV: An inclusive search for anomalous Higgs boson production in the diphoton
decay channel and in association with at least one jet is presented, using LHC
proton-proton collision data collected by the CMS experiment at a
center-of-mass energy of 13 TeV and corresponding to an integrated luminosity
of 35.9 fb$^{-1}$. The razor variables $M_\mathrm{R}$ and $\mathrm{R}^2$, as
well as the momentum and mass resolution of the diphoton system, are used to
categorize events into different search regions. The search result is
interpreted in the context of strong and electroweak production of
supersymmetric particles. We exclude bottom squark pair-production with masses
below 450 GeV for bottom squarks decaying to a bottom quark, a Higgs boson, and
the lightest supersymmetric particle (LSP) for LSP masses below 250 GeV. For
wino-like chargino-neutralino production, we exclude charginos with mass below
170 GeV for LSP masses below 25 GeV. In the GMSB scenario, we exclude charginos
with mass below 205 GeV for neutralinos decaying to a Higgs boson and a
goldstino LSP with 100% branching fraction. | hep-ex |
Pentaquarks - Facts and Mysteries or Sisyphus at Work: Recent evidence for pentaquark baryons is critically reviewed in the light of
new high statistics data. The search of the WA89 experiment for the
$\Xi^{--}(1860)$ is presented in detail and consequences of its
non-observations are discussed. | hep-ex |
Vertex Detection for a Charm Tag in e+e- -> W+W- at a High Energy
Electron-Positron Linear Collider: The study of the process $e^+e^- \to W^+W^-$ at Linear Collider energies
presents a good opportunity to investigate anomalous triple gauge boson
couplings and $W^+_LW^-_L$ rescattering. The helicity analysis of the $e^+e^-
\to W^+_LW^-_L$ decays will benefit if the charm quark containing jet can be
identified for events which contain one hadronic $W$ boson decay to a charm and
another quark. A JAVA implementation of the SLD collaboration's topological
vertex finding algorithm (ZVTOP) in the linear collider analysis framework has
been used to extract charm tag efficiencies and purities based on vertex
multiplicities. | hep-ex |
B-tagging in CMS: The identification of b jets is a crucial issue to study and characterize
various channels like top quark events and many new physics scenarios.
Different b-tagging techniques are defined in CMS which benefit from the long
life time, high mass and large momentum fraction of the b-hadron produced in
b-quark jet. Effcient algorithms have been developed based on the measure of
b-hadron secondary vertex or on tracks with a large impact parameter. Data
collected in pp collisions at 7TeV in 2011 are used to estimate both the
b-tagging effciency and the mistag rate from light flavor jets. | hep-ex |
DAMA/LIBRA results and perspectives: The DAMA/LIBRA experiment ($\sim$ 250 kg of highly radio-pure NaI(Tl)) is
running deep underground at the Gran Sasso National Laboratory (LNGS) of the
I.N.F.N. Here we briefly recall the results obtained in its first phase of
measurements (DAMA/LIBRA--phase1, total exposure: 1.04 ton $\times$ yr).
DAMA/LIBRA--phase1 and the former DAMA/NaI (cumulative exposure: $1.33$ ton
$\times$ yr) give evidence at 9.3 $\sigma$ C.L. for the presence of DM
particles in the galactic halo by exploiting the model-independent DM annual
modulation signature. No systematic or side reaction able to mimic the
exploited DM signature has been found or suggested by anyone over more than a
decade. At present DAMA/LIBRA--phase2 is running with increased sensitivity. | hep-ex |
Top FCNC searches at HL-LHC with the CMS experiment: The Large Hadron Collider is the world's largest and highest center-of-mass
energy particle accelerator. During the Phase I operation it is expected that
the LHC operated at a centre-of-mass energy of 13 TeV will deliver to the CMS
experiment total integrated luminosity of $\sim$300 fb$^{-1}$ till 2023. The
High Luminosity LHC upgrade is expected to run at a centre-of-mass energy of 14
TeV and will allow ATLAS and CMS to collect integrated luminosities of the
order of 300 fb$^{-1}$ per year, and up to 3000 fb$^{-1}$ during the HL-LHC
projected lifetime of ten years. The large expected integrated luminosity
enables the exploration of the multi-TeV scale by searches for particles with
high masses as well as by investigation of processes with very low cross
sections such as Flavor-Change Neutral Current interactions in top quark
sector. In this report we present a proposal for the top quark FCNC searches at
HL-LHC based on Monte-Carlo simulation of the upgraded CMS detector. | hep-ex |
Search for long-lived neutral particles in $pp$ collisions at $\sqrt{s}$
= 13 TeV that decay into displaced hadronic jets in the ATLAS calorimeter: This paper describes a search for pairs of neutral, long-lived particles
decaying in the ATLAS calorimeter. Long-lived particles occur in many
extensions to the Standard Model and may elude searches for new promptly
decaying particles. The analysis considers neutral, long-lived scalars with
masses between 5 GeV and 400 GeV, produced from decays of heavy bosons with
masses between 125 GeV and 1000 GeV, where the long-lived scalars decay into
Standard Model fermions. The analysis uses either 10.8 fb$^{-1}$ or 33.0
fb$^{-1}$ of data (depending on the trigger) recorded in 2016 at the LHC with
the ATLAS detector in proton-proton collisions at a centre-of-mass energy of 13
TeV. No significant excess is observed, and limits are reported on the
production cross section times branching ratio as a function of the proper
decay length of the long-lived particles. | hep-ex |
Results of the NEMO3 experiment: The purpose of the NEMO3 experiment is to detect neutrinoless double beta
decay in order to determine the nature of neutrino and its absolute mass. We
analysed the 389 effective days of data from the $\sim 7$ kg of $^{100}$Mo and
$\sim 1$ kg of $^{82}$Se and obtained the following limits on the half-life for
the \bb process: $T_{1/2}(\beta\beta0 \nu) > 4.6 \times 10^{23}$ years (Mo) and
$T_{1/2}(\beta \beta 0 \nu) > 1.0 \times 10^{23}$ years (Se). The corresponding
limits on the neutrino effective mass are $<m_{\nu}> <$ 0.7 - 2.8 eV (Mo) and
$<m_{\nu}> >$ 1.7 - 4.9 eV (Se) at 90% Confident Level. We also performed a
detailled analysis on the double beta decay of $^{100}$Mo into the excited
states $0^+_1$, $2^+_1$ of $^{100}$Ru. The results are: $T_{1/2}(\beta \beta 2
\nu \to 0^+_1) = 5.7^{+1.3}_{-0.9}(stat)\pm 0.7 (syst) \times 10^{20}$ years,
$T_{1/2}(\beta \beta 2 \nu \to 2^+_1) > 1.1 \times 10^{21}$ years,
$T_{1/2}(\beta \beta 0 \nu \to 0^+_1) > 8.9 \times 10^{22}$ years,
$T_{1/2}(\beta \beta 0 \nu \to 2^+_1) > 1.6 \times 10^{23}$ years. | hep-ex |
Search for the Decay tau- --> 3pi- 2pi+ 2pi0 nu_tau: A search for the decay of the tau lepton to five charged and two neutral
pions is performed using data collected by the BABAR detector at the PEP-II
asymmetric-energy e+e- collider. The analysis uses 232 fb-1 of data at
center-of-mass energies on or near the Y(4S) resonance. We observe 10 events
with an expected background of 6.5^{+2.0}_{-1.4} events. In the absence of a
signal, we set the limit on the branching ratio B(tau- --> 3pi- 2pi+ 2pi0
nu_tau) < 3.4x10^{-6} at the 90% confidence level. This is a significant
improvement over the previously established limit. In addition, we search for
the decay mode tau- --> 2omega pi- nu_tau. We observe 1 event with an expected
background of 0.4^{+1.0}_{-0.4} events and calculate the upper limit B(tau- -->
2omega pi- nu_tau) < 5.4x10^{-7} at the 90% confidence level. This is the first
upper limit for this mode. | hep-ex |
Differential cross sections of the charge-exchange reaction pi- p -->
pi0 n in the momentum range from 103 to 178 MeV/c: Measured values of the differential cross sections for pion-nucleon charge
exchange, pi- p --> pi0 n, are presented for pi- momenta of 103, 112, 120, 130,
139, 152, and 178 MeV/c. Complete angular distributions were obtained by using
the Crystal Ball detector at the Alternating Gradient Synchrotron at Brookhaven
National Laboratory. Statistical uncertainties of the differential cross
sections vary from 3% to 6% in the backward angle region, and from 6% to about
20% in the forward region with the exception of the two most forward angles.
The systematic uncertainties are estimated to be about 3% for all momenta. | hep-ex |
Total Cross Section of the Process e+e- -> pi+pi-pi+pi- in the
C.M.Energy Range 980-1380 MeV: The e+e- -> pi+pi-pi+pi- cross section has been measured using 5.8/pb of
integrated luminosity collected with the CMD-2 detector at the VEPP-2M
collider. Analysis of the data with a refined efficiency determination and use
of both three- and four-track events allowed doubling of a data sample and
reduction of systematic errors to 5-7%. | hep-ex |
Latest Results from the MiniBooNE Experiment and Updated Oscillation
Sensitivity: Neutrino oscillations have been established in solar and atmospheric
neutrinos, but a third signal from the LSND experiment is incompatible with
three Standard Model neutrinos. The MiniBooNE experiment can confirm or refute
the LSND oscillation signal with 1E21 protons on target. Preliminary results on
muon neutrino analyses and an updated oscillation sensitivity are presented. | hep-ex |
Multivariate Techniques for Identifying Diffractive Interactions at the
LHC: Close to one half of the LHC events are expected to be due to elastic or
inelastic diffractive scattering. Still, predictions based on extrapolations of
experimental data at lower energies differ by large factors in estimating the
relative rate of diffractive event categories at the LHC energies. By
identifying diffractive events, detailed studies on proton structure can be
carried out.
The combined forward physics objects: rapidity gaps, forward multiplicity and
transverse energy flows can be used to efficiently classify proton-proton
collisions. Data samples recorded by the forward detectors, with a simple
extension, will allow first estimates of the single diffractive (SD), double
diffractive (DD), central diffractive (CD), and non-diffractive (ND) cross
sections. The approach, which uses the measurement of inelastic activity in
forward and central detector systems, is complementary to the detection and
measurement of leading beam-like protons.
In this investigation, three different multivariate analysis approaches are
assessed in classifying forward physics processes at the LHC. It is shown that
with gene expression programming, neural networks and support vector machines,
diffraction can be efficiently identified within a large sample of simulated
proton-proton scattering events. The event characteristics are visualized by
using the self-organizing map algorithm. | hep-ex |
Search for CP violation in D+ -> phi pi+ and Ds+ -> Ks pi+ decays: A search for CP violation in D+ -> phi pi+ decays is performed using data
collected in 2011 by the LHCb experiment corresponding to an integrated
luminosity of 1.0 fb^{-1} at a centre of mass energy of 7 TeV. The CP-violating
asymmetry is measured to be (-0.04+/-0.14+/-0.14)% for candidates with K-K+
mass within 20 MeV/c^{2} of the phi meson mass. A search for a CP-violating
asymmetry that varies across the phi mass region of the D+ -> K-K+pi+ Dalitz
plot is also performed, and no evidence for CP violation is found. In addition,
the CP asymmetry in the Ds+ -> Ks pi+ decay is measured to be
(0.61+/-0.83+/-0.14)%. | hep-ex |
B Physics (Experiment): In past few years the flavor physics made important transition from the work
on confirmation the standard model of particle physics to the phase of search
for effects of a new physics beyond standard model. In this paper we review
current state of the physics of b-hadrons with emphasis on results with a
sensitivity to new physics. | hep-ex |
Forward Pion Production in p+p and d+Au Collisions at STAR: Measurements are reported of the production of high energy pi-zero mesons
from the STAR experiment in p+p and d+Au collisions at sqrt(s_NN)=200 GeV and
<eta>=4.00 (d beam direction). The inclusive yield agrees with perturbative QCD
calculations in p+p collisions, but is found to be reduced in d+Au collisions.
The azimuthal correlations of the forward pi-zero with charged hadrons at
midrapidity agree with PYTHIA in p+p collisions, but are suppressed in d+Au
collisions. The results are consistent with the conjecture that the gluon
density in nuclei is suppressed. | hep-ex |
Search for pair production of first-generation scalar leptoquarks at
$\sqrt{s} =$ 13 TeV: A search for the pair production of first-generation scalar leptoquarks is
performed using proton-proton collision data recorded at 13 TeV center-of-mass
energy with the CMS detector at the LHC. The data correspond to an integrated
luminosity of 35.9 fb$^{-1}$. The leptoquarks are assumed to decay to a quark,
and either an electron or a neutrino with branching fractions $\beta$ and
1$-\beta$, respectively. The search targets the decay final states comprising
two electrons, or one electron and large missing transverse momentum, along
with two quarks that are detected as hadronic jets. First-generation scalar
leptoquarks with masses below 1435 (1270) GeV are excluded for $\beta =$ 1.0
(0.5). These are the most stringent limits on the mass of first-generation
scalar leptoquarks to date. The data are also interpreted to set exclusion
limits in the context of an $R$-parity violating supersymmetric model,
predicting promptly decaying top squarks with a similar dielectron final state. | hep-ex |
Searches for Majorana Neutrinos and Direct Searches for Exotics at LHCb: These proceedings present the LHCb results on Majorana neutrino searches and
direct production of exotic particles using the data collected during Run I of
LHC. For the former, Majorana neutrinos are searched for both on-shell and
off-shell in $B$ and $D$ decays to final states with two same-sign muons. For
the latter, different types of new particles are studied profiting the unique
coverage of LHCb with respect to other detectors. | hep-ex |
Muon $g-2$: A review: The muon magnetic anomaly, $a_{\mu}=(g_{\mu}-2)/2$, plays a special role in
the history of the Standard Model (SM). Precise calculations and measurements
of this fundamental quantity provide a stringent test of the SM and a window to
the physics beyond. In light of the first result published by the Fermilab Muon
$g-2$ experiment, this article reviews the current status of the experimental
measurement and theoretical prediction of the muon anomalous magnetic moment.
It also provides an overview on resulting constraints of associated physics
beyond the SM (BSM), future muon $g-2$ experiments, and on the progress of
experiments that are closely connected to the physics of the muon $g-2$, such
as measurements that could provide complementary information about BSM physics
in the muon sector. | hep-ex |
First Measurement of Monoenergetic Muon Neutrino Charged Current
Interactions: We report the first measurement of monoenergetic muon neutrino charged
current interactions. MiniBooNE has isolated 236 MeV muon neutrino events
originating from charged kaon decay at rest ($K^+ \rightarrow \mu^+ \nu_\mu$)
at the NuMI beamline absorber. These signal $\nu_\mu$-carbon events are
distinguished from primarily pion decay in flight $\nu_\mu$ and
$\overline{\nu}_\mu$ backgrounds produced at the target station and decay pipe
using their arrival time and reconstructed muon energy. The significance of the
signal observation is at the 3.9$\sigma$ level. The muon kinetic energy,
neutrino-nucleus energy transfer ($\omega=E_\nu-E_\mu$), and total cross
section for these events is extracted. This result is the first known-energy,
weak-interaction-only probe of the nucleus to yield a measurement of $\omega$
using neutrinos, a quantity thus far only accessible through electron
scattering. | hep-ex |
Amplitude analysis of $D_s^{+} \rightarrow π^{+} π^{-} π^{+}$: Utilizing the data set corresponding to an integrated luminosity of $3.19$
fb$^{-1}$ collected by the BESIII detector at a center-of-mass energy of 4.178
GeV, we perform an amplitude analysis of the $D_s^+\to\pi^+\pi^-\pi^+$ decay.
The sample contains 13,797 candidates with a signal purity of $\sim$80%. The
amplitude and phase of the contributing $\pi\pi$ ${\cal S}$ wave are measured
based on a quasi-model-independent approach, along with the amplitudes and
phases of the ${\cal P}$ and ${\cal D}$ waves parametrized by Breit-Wigner
models. The fit fractions of different intermediate decay channels are also
reported. | hep-ex |
Reply to 'Corrections to the HARP-CDP Analysis of the LSND Neutrino
Oscillation Backgrounds': The alleged mistakes in recent papers that reanalyze the backgrounds to the
'LSND anomaly' do not exist. We maintain our conclusion that the significance
of the 'LSND anomaly' is not 3.8 sigma but not larger than 2.3 sigma. | hep-ex |
Top mass measurements: The top quark mass measurements are based either on a direct kinematic
reconstruction of the top quark decay products or on indirect measurements,
where an observable sensitive to the top quark mass, such as the production
cross section, is used to infer it. The ATLAS and CMS collaborations have
measured the top quark mass using various methods with increasing precision.
Recent measurements using 13 TeV pp collision data recorded at the LHC are
presented in this review. | hep-ex |
Top Quark Pair Production Cross-Section Measurements at DO: We present recent measurements of the top quark pair production cross-section
in the dilepton, lepton+jets and lepton+tau final states with the D0 detector
in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV. | hep-ex |
The E6 inspired isosinglet quark and the Higgs boson: We consider the experimental implications of the down type isosinglet quark,
$D$, predicted by the $E_{6}$, group to Higgs boson searches at the LHC. The
pair production of $D$ quarks at the LHC and their subsequent decays $D\to h d$
and $D\to W u$ has been analyzed. For a light Higgs boson of mass O(120 GeV),
an analysis based on fast simulation of the ATLAS detector response shows that,
the $b\bar{b}$ channel becomes as efficient as the $\gamma\gamma$ channel for
discovering the Higgs particle if $m_{D}<630$ GeV. | hep-ex |
Search for ZZ and Zγ^* production in p-barp collisions at sqrt(s) =
1.96 TeV and limits on anomalous ZZZ and ZZγ^* couplings: We present a study of four muon, four electron, and two muon two electron
events using 1 fb^(-1) of data collected with the D0 detector at the Fermilab
Tevatron p-barp Collider at sqrt(s) = 1.96 TeV. Requiring the lepton pair
masses to be greater than 30 GeV, we observe one event, consistent with the
expected background of 0.13 +- 0.03 events and with the predicted standard
model ZZ and Z\gamma^* production of 1.71 +-0.15 events. We set an upper limit
on the ZZ and Z\gamma^* cross section of 4.4 pb at the 95% C.L. We also derive
limits on anomalous neutral trilinear ZZZ and ZZ\gamma^* gauge couplings. The
one-parameter 95%$ C.L. coupling limits with a form factor scale Lambda = 1.2
TeV are -0.28 < f_(40)^Z < 0.28, -0.31 < f_(50)^Z < 0.29, -0.26 < f_(40)^\gamma
< 0.26, and -0.30 < f_(5 0)^\gamma < 0.28. | hep-ex |
The BABAR Detector: BABAR, the detector for the SLAC PEP-II asymmetric e+e- B Factory operating
at the upsilon 4S resonance, was designed to allow comprehensive studies of
CP-violation in B-meson decays. Charged particle tracks are measured in a
multi-layer silicon vertex tracker surrounded by a cylindrical wire drift
chamber. Electromagentic showers from electrons and photons are detected in an
array of CsI crystals located just inside the solenoidal coil of a
superconducting magnet. Muons and neutral hadrons are identified by arrays of
resistive plate chambers inserted into gaps in the steel flux return of the
magnet. Charged hadrons are identified by dE/dx measurements in the tracking
detectors and in a ring-imaging Cherenkov detector surrounding the drift
chamber. The trigger, data acquisition and data-monitoring systems, VME- and
network-based, are controlled by custom-designed online software. Details of
the layout and performance of the detector components and their associated
electronics and software are presented. | hep-ex |
Diffraction and Total Cross-Section at the Tevatron and the LHC: At the Tevatron, the total p_bar-p cross-section has been measured by CDF at
546 GeV and 1.8 TeV, and by E710/E811 at 1.8 TeV. The two results at 1.8 TeV
disagree by 2.6 standard deviations, introducing big uncertainties into
extrapolations to higher energies. At the LHC, the TOTEM collaboration is
preparing to resolve the ambiguity by measuring the total p-p cross-section
with a precision of about 1 %. Like at the Tevatron experiments, the
luminosity-independent method based on the Optical Theorem will be used. The
Tevatron experiments have also performed a vast range of studies about soft and
hard diffractive events, partly with antiproton tagging by Roman Pots, partly
with rapidity gap tagging. At the LHC, the combined CMS/TOTEM experiments will
carry out their diffractive programme with an unprecedented rapidity coverage
and Roman Pot spectrometers on both sides of the interaction point. The physics
menu comprises detailed studies of soft diffractive differential
cross-sections, diffractive structure functions, rapidity gap survival and
exclusive central production by Double Pomeron Exchange. | hep-ex |
Search for $C\!P$ violation in $Λ^0_b \to p K^-$ and $Λ^0_b
\to p π^-$ decays: A search for $C\!P$ violation in $\Lambda^0_b \to p K^-$ and $\Lambda^0_b \to
p \pi^-$ decays is presented using a sample of $pp$ collisions collected with
the LHCb detector and corresponding to an integrated luminosity of 3.0
fb$^{-1}$. The $C\!P$-violating asymmetries are measured to be
$A_{\mathrm{CP}}^{pK^-} = -0.020 \pm 0.013\pm 0.019$ and
$A_{\mathrm{CP}}^{p\pi^-} = -0.035 \pm 0.017 \pm 0.020 $, and their difference
$A_{\mathrm{CP}}^{pK^-}-A_{\mathrm{CP}}^{p\pi^-} = 0.014 \pm 0.022 \pm 0.010$,
where the first uncertainties are statistical and the second systematic. These
are the most precise measurements of such asymmetries to date. | hep-ex |
A stronger classical definition of Confidence Limits: A novel way of defining limits in classical statistics is proposed. This is a
natural extension of the original Neyman's method, and has the desirable
property that only information relevant to the problem is used in making
statistical inferences. The result is a strong restriction on the allowed
confidence bands, excluding in full generality pathologies as empty confidence
regions or unstable solutions. The method is completely general and directly
applicable to all problems of limits. | hep-ex |
Measurement of the Branching Fraction Br(Lambda_c+ -> p K- pi+): We present the first model-independent measurement of the absolute branching
fraction of the Lambda_c+ -> p K- pi+ decay using a data sample of 978 fb^-1
collected with the Belle detector at the KEKB asymmetric-energy e+e- collider.
The number of Lambda_c+ baryons is determined by reconstructing the recoiling
D(*)- anti-p pi+ system in events of the type e+e- -> D(*)- anti-p pi+
Lambda_c+. The branching fraction is measured to be Br(Lambda_c+ -> p K- pi+) =
(6.84 +- 0.24^{+0.21}_{-0.27})%, where the first and second uncertainties are
statistical and systematic, respectively. | hep-ex |
Search for Low Mass Higgs Boson at the Tevatron: We present the current status of searches for a low mass Standard Model Higgs
boson (M_H below ~ 135 GeV/c^2) using data collected from ppbar collisions at
the Fermilab Tevatron collider at \sqrt{s}= 1.96 TeV. A summary of the latest
results from the CDF and D0 collaborations is reported in this paper, focusing
in particular on ongoing efforts to increase overall search sensitivity through
improvements to the analysis methods. | hep-ex |
Experimental study of the e+e- -> pi0 gamma process in the energy region
sqrt(s)=0.60-0.97 GeV: Results of the study of the e+e-->pi0 gamma process with SND detector at
VEPP-2M collider in the c.m.s. energy range sqrt(s)=0.60-0.97 GeV are
presented. Using 36513 selected events corresponding to a total integrated
luminosity of 3.4 pb^-1 the e+e-->pi0 gamma cross section was measured. The
energy dependence of the cross section was analyzed in the framework of the
vector meson dominance model. The data are well described by a sum of
phi,omega,rho0->pi0 gamma decay contributions with measured decay
probabilities: Br(omega->pi0 gamma)=(9.34+-0.15+-0.31)% and Br(rho0->pi0
gamma)=(5.15+-1.16+-0.73)*10^-4 . The rho-omega relative interference phase is
phi(rho,omega}=(-10.2+-6.5+-2.5) degree. | hep-ex |
Amplitude Analysis and Branching Fraction Measurement of $D^0\rightarrow
K^-π^+π^0π^0$: Utilizing the dataset corresponding to an integrated luminosity of $2.93$
fb$^{-1}$ at $\sqrt{s}=3.773$ GeV collected by the BESIII detector, we report
the first amplitude analysis and branching fraction measurement of the
$D^0\rightarrow K^-\pi^+\pi^0\pi^0$ decay. We investigate the sub-structures
and determine the relative fractions and the phases among the different
intermediate processes. Our results are used to provide an accurate detection
efficiency and allow measurement of ${\cal B}(D^0\rightarrow
K^-\pi^+\pi^0\pi^0) \,=\, (8.86 \pm 0.13(\text{stat}) \pm
0.19(\text{syst}))\%$. | hep-ex |
Determination of electron-nucleus collision geometry with forward
neutrons: There are a large number of physics programs one can explore in
electron-nucleus collisions at a future electron-ion collider. Collision
geometry is very important in these studies, while the measurement for an
event-by-event geometric control is rarely discussed in the prior deep
inelastic scattering experiments off a nucleus. This paper seeks to provide
some detailed studies on the potential of tagging collision geometries through
forward neutron multiplicity measurements with a zero degree calorimeter. This
type of geometry handle, if achieved, can be extremely beneficial in
constraining nuclear effects for the electron-nucleus program at an
electron-ion collider. | hep-ex |
Measurements of charm lifetimes at Belle II: We report on absolute lifetime measurements of charmed hadrons using the data
collected by the Belle II experiment between 2019 and 2021. The measured
lifetimes of $D^0$, $D^+$, and $\Lambda_c^+$ are the most precise to date and
consistent with previous measurements. Our result indicates that $\Omega_c^0$
is not the shortest-living singly charmed baryon. | hep-ex |
Measurements of the top-quark mass using charged particle tracking: We present three measurements of the top-quark mass in the lepton plus jets
channel with approximately 1.9 fb-1 of integrated luminosity collected with the
CDF II detector using quantities with minimal dependence on the jet energy
scale. One measurement exploits the transverse decay length of b-tagged jets to
determine a top-quark mass of 166.9+9.5-8.5 (stat) +/- 2.9 (syst) GeV/c2, and
another the transverse momentum of electrons and muons from W-boson decays to
determine a top-quark mass of 173.5+8.8-8.9 (stat) +/- 3.8 (syst) GeV/c2. These
quantities are combined in a third, simultaneous mass measurement to determine
a top-quark mass of 170.7 +/- 6.3 (stat) +/- 2.6 (syst) GeV/c2. | hep-ex |
Search for new physics in dijet angular distributions using
proton-proton collisions at $\sqrt{s}=$ 13 TeV and constraints on dark matter
and other models: A search is presented for physics beyond the standard model, based on
measurements of dijet angular distributions in proton-proton collisions at
$\sqrt{s}=$ 13 TeV. The data collected with the CMS detector at the LHC
correspond to an integrated luminosity of 35.9 fb$^{-1}$. The observed
distributions are found to be in agreement with predictions from perturbative
quantum chromodynamics that include electroweak corrections. Constraints are
placed on models containing quark contact interactions, extra spatial
dimensions, quantum black holes, or dark matter using the detector-level
distributions. In a benchmark model where only left-handed quarks participate,
contact interactions are excluded at the 95% confidence level up to a scale of
12.8 or 17.5 TeV, for destructive or constructive interference, respectively.
The most stringent lower limits to date are set on the ultraviolet cutoff in
the Arkani-Hamed-Dimopoulos-Dvali model of extra dimensions. In the
Giudice-Rattazzi-Wells convention, the cutoff scale is excluded up to 10.1 TeV.
The production of quantum black holes is excluded for masses below 5.9 and 8.2
TeV, depending on the model. For the first time, lower limits between 2.0 and
4.6 TeV are set on the mass of a dark matter mediator for (axial-)vector
mediators, for the universal quark coupling $g_\mathrm{q}\geq$ 1. | hep-ex |
Measurement of the cross-section ratio
$σ(χ_{c2})/σ(χ_{c1})$ for prompt $χ_c$ production at
$\sqrt{s}=7$ TeV: The prompt production of the charmonium $\chi_{c1}$ and $\chi_{c2}$ mesons
has been studied in proton-proton collisions at the Large Hadron Collider at a
centre-of-mass energy of $\sqrt{s}=7$ TeV. The $\chi_c$ mesons are identified
through their decays $\chi_c\to J/\psi\,\gamma$ with $J/\psi \to \mu^+ \mu^-$
using 36 $\mathrm{pb^{-1}}$ of data collected by the LHCb detector in 2010. The
ratio of the prompt production cross-sections for the two $\chi_c$ spin states,
$\sigma(\chi_{c2})/\sigma(\chi_{c1})$, has been determined as a function of the
$J/\psi$ transverse momentum, $p_{\mathrm{T}}^{J/\psi}$, in the range from 2 to
15 GeV/$c$. The results are in agreement with the next-to-leading order
non-relativistic QCD model at high $p_{\mathrm{T}}^{J/\psi}$ and lie
consistently above the pure leading-order colour singlet prediction. | hep-ex |
A Measurement of the K0 Charge Radius and a CP Violating Asymmetry
Together with a Search for CP Violating E1 Direct Photon Emission in the Rare
Decay KL->pi+pi-e+e-: Using the complete KTeV data set of 5241 candidate KL->pi+pi-e+e- decays
(including an estimated background of 204+-14 events), we have measured the
coupling gCR=0.163+- 0.014(stat)+-0.023(syst) of the CP conserving charge
radius process and from it determined a K0 charge radius of
<r**2>(K0)=(-0.077+-0.007(stat)+-0.011(syst)) fm**2. We have also determined a
first experimental upper limit of 0.04 (90% CL) for the ratio |g_{E1}|/|g_{M1}|
of the coupling for the E1 direct photon emission process relative to the
coupling for M1 direct photon emission process. We also report the measurement
of its associated vector form factor |gM1`|(1+
(a_1/a_2)/(M(rho)**2-M(K)**2)+2M(K)E(gamma*)) where |gM1`|=(1.11+-
0.12(stat)+-0.08(syst) and a_1/a_2 = (-0.744+-0.027(stat)0.032(syst))
GeV**2/c**2. In addition, a measurement of the manifestly CP violating
asymmetry of magnitude (13.6+- 1.4+-(stat)+-1.5(syst))% in the CP and T odd
angle phi between the decay planes of the e+e- and pi+pi- pairs in the KL
center of mass system is reported. | hep-ex |
photon+jet event rate estimation for the gluon distribution
determination at the Tevatron Run II: Since a lot of theoretical predictions on the production of new particles
(Higgs, SUSY) at the Tevatron are based on model estimations of the proton
gluon density behavior at low $x$ and high values of a transfered momentum Q^2,
the study of a possibility of a measurement of the gluon density in this
kinematic region directly in Tevatron experiments is obviously of a big
interest [1].
Basing on the selection criteria proposed ealier in [1,2], the background
events suppression factors and corresponding signal events selection
efficiencies are determined here. The estimation of the number of photon+jet
events suitable for measurement of gluon distribution in different x and Q^2
intervals at Tevatron Run II is also done.
It is shown that with integrated luminosity L_{int}=3 fb^-1 it would be
possible to collect about one million of these events. This number would allow
to cover a new kinematical region, 10^-3 < x < 1.0 with 1.6*10^3 < Q^2 < 2*10^4
(GeV/c)^2, not studied in any previous experiment. This area includes the
values of Q^2 that are, on the average, by about one order of magnitude higher
than those reached at HERA now. The rates of g c-> photon + jet events are also
obtained. | hep-ex |
Studies of $X(3872)$ and $ψ(2S)$ production in $p\bar{p}$ collisions
at 1.96 TeV: We present various properties of the production of the $X(3872)$ and
$\psi(2S)$ states based on 10.4 fb$^{-1}$ collected by D0 experiment in
Tevatron $p \bar p$ collisions at $\sqrt{s}$ = 1.96 TeV. For both states, we
measure the nonprompt fraction $f_{NP}$ of the inclusive production rate due to
decays of $b$-flavored hadrons. We find the $f_{NP}$ values systematically
below those obtained at the LHC. The $f_{NP}$ fraction for $\psi(2S)$ increases
with transverse momentum whereas for the X(3872) it is constant within large
uncertainties, in agreement with the LHC results. The ratio of prompt to
nonprompt $\psi(2S)$ production, $(1 - f_{NP}) / f_{NP}$, decreases only
slightly going from the Tevatron to the LHC, but for the $X(3872)$ this ratio
decreases by a factor of about 3. We test the soft-pion signature of the
$X(3872)$ modeled as a weakly-bound charm-meson pair by studying the production
of the $X(3872)$ as a function of the kinetic energy of the $X(3872)$ and the
pion in the $X(3872)\pi$ center-of-mass frame. For a subsample consistent with
prompt production, the results are incompatible with a strong enhancement in
the production of the $X(3872)$ at small kinetic energy of the $X(3872)$ and
the $\pi$ in the $X(3872)\pi$ center-of-mass frame expected for the
$X$+soft-pion production mechanism. For events consistent with being due to
decays of $b$ hadrons, there is no significant evidence for the soft-pion
effect but its presence at the level expected for the binding energy of 0.17
MeV and the momentum scale $\Lambda=M(\pi)$ is not ruled out. | hep-ex |
Top-quark mass at hadron colliders: Top quarks can be produced abundantly at hadron colliders like the Tevatron
at Fermilab and the Large Hadron Collider at CERN, and a variety of
measurements of top-quark properties have been gathered in the recent years
from four experiments: CDF and D0 at the Tevatron and ATLAS and CMS at the
Large Hadron Collider. In this review the most recent results on the
measurement of the top-quark mass by the four different collaborations, with
various techniques and considering different topologies, are reported. | hep-ex |
Measurements of jet-related observables at the LHC: During the first years of the LHC operation a large amount of jet data was
recorded by the ATLAS and CMS experiments. In this review several measurements
of jet-related observables are presented, such as multi-jet rates and cross
sections, ratios of jet cross sections, jet shapes and event shape observables.
All results presented here are based on jet data collected at a center-of-mass
energy of 7 TeV. Data are compared to various Monte Carlo generators, as well
as to theoretical next-to-leading-order calculations allowing a test of
perturbative Quantum Chromodynamics in a previously unexplored energy region. | hep-ex |
Nucleon Electromagnetic Form Factors in the Timelike Region: The electromagnetic form factors of the proton and the neutron in the
timelike region are reviewed. In view of the forthcoming experimental projects
devoted to investigate these observables, we present the current status of the
field and we emphasize the relevant role, that accurate measurements, refined
phenomenological analyses, as well as microscopic models will play with the
goal of achieving deeper insights into the structure of the nucleon and its
inner dynamics. | hep-ex |
Recent structure function results from neutrino scattering at Fermilab: We report on the extraction of the structure functions F_2 and Delta xF_3 =
xF_3(nu)-xF_3(nubar) from CCFR nu_mu-Fe and nubar_mu-Fe different ial cross
sections. The extraction is performed in a physics model independent (PMI) way.
This first measurement of Delta xF_3, which is useful in testing models of
heavy charm production, is higher than current theoretical predictios. The
ratio of the F_2 (PMI) values measured in nu_mu and mu scattering is in
agreement (within 5%) with the NLO predictions using massive charm production
schemes, thus resolving the long-standing discrepancy between the two sets of
data. In addition, measurements of F_L (or, equivalently, R) and 2xF_1 are
reported in the kinematic region where anomalous nuclear effects in R are
observed at HERMES. | hep-ex |
Recent Results on Light-Meson Spectroscopy from COMPASS: The main goal of the spectroscopy program at COMPASS is to explore the
light-meson spectrum below about $2\,\text{GeV}/c^2$ in diffractive production.
Our flagship channel is the decay into three charged pions: $p + \pi^-\to
\pi^-\pi^-\pi^+ + p_\text{recoil}$, for which COMPASS has acquired the so far
world's largest dataset of roughly $50\,\text{M}$ exclusive events using an
$190\,\text{GeV}/c$ $\pi^-$ beam. Based on this dataset, we performed an
extensive partial-wave analysis. In order to extract the resonance parameters
of the $\pi_J$ and $a_J$ states that appear in the $\pi^-\pi^-\pi^+$ system, we
performed the so far largest resonance-model fit, using Breit-Wigner resonances
and non-resonant contributions.
This method in combination with the high statistical precision of our
measurement allows us to study ground and excited states. We have found an
evidence of the $a_1(1640)$ and $a_2(1700)$ in our data, which are the first
excitations of the $a_1(1260)$ and $a_2(1320)$, respectively. The relative
strength of the excited states with respect to the corresponding ground state
is larger in the $f_2(1270)\,\pi$ decay mode compared to the $\rho(770)\,\pi$
decay mode. We also study the spectrum of $\pi_2$ states in our data.
Therefore, we simultaneously describe four $J^{PC}=2^{-+}$ waves in the
resonance-model fit by using three $\pi_2$ resonances, the $\pi_2(1670)$, the
$\pi_2(1880)$, and the $\pi_2(2005)$. Within the limits of our model, we can
conclude that the $\pi_2(2005)$ is required to describe all four $2^{-+}$ waves
properly. | hep-ex |
Subsets and Splits
No saved queries yet
Save your SQL queries to embed, download, and access them later. Queries will appear here once saved.