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A search for resonant production of $t\bar{t}$ pairs in $4.8\
\rm{fb}^{-1}$ of integrated luminosity of $p\bar{p}$ collisions at
$\sqrt{s}=1.96\ \rm{TeV}$: We search for resonant production of tt pairs in 4.8 fb^{-1} integrated
luminosity of ppbar collision data at sqrt{s}=1.96 TeV in the lepton+jets decay
channel, where one top quark decays leptonically and the other hadronically. A
matrix element reconstruction technique is used; for each event a probability
density function (pdf) of the ttbar candidate invariant mass is sampled. These
pdfs are used to construct a likelihood function, whereby the cross section for
resonant ttbar production is estimated, given a hypothetical resonance mass and
width. The data indicate no evidence of resonant production of ttbar pairs. A
benchmark model of leptophobic Z \rightarrow ttbar is excluded with m_{Z'} <
900 GeV at 95% confidence level. | hep-ex |
Results from the first heavy ion run at the LHC: Early November 2010, the LHC collided for the first time heavy ions, Pb on
Pb, at a centre-of-mass energy of 2.76 TeV/nucleon. This date marked both the
end of almost 20 years of preparing for nuclear collisions at the LHC, as well
as the start of a new era in ultra-relativistic heavy ion physics at energies
exceeding previous machines by more than an order of magnitude. This
contribution summarizes some of the early results from all three experiments
participating in the LHC heavy ion program (ALICE, ATLAS, and CMS), which show
that the high density matter created at the LHC, while much hotter and larger,
still behaves like the very strongly interacting, almost perfect liquid
discovered at RHIC. Some surprising and even puzzling results are seen in
particle ratios, jet-quenching, and Quarkonia suppression observables. The
overall experimental conditions at the LHC, together with its set of powerful
and state-of-the-art detectors, should allow for precision measurements of
quark-gluon-plasma parameters like viscosity and opacity. | hep-ex |
Measurement of $CP$ asymmetries in $B^0 \rightarrow K^0_S K^0_S K^0_S$
decays at Belle II: We report a measurement of decay-time dependent charge-parity ($CP$)
asymmetries in $B^0 \rightarrow K^0_S K^0_S K^0_S$ decays. We use $387 \times
10^6 B\bar{B}$ pairs collected at the $\Upsilon(4S)$ resonance with the Belle
II detector at the SuperKEKB asymmetric-energy electron-positron collider. We
reconstruct 220 signal events and extract the $CP$-violating parameters $S$ and
$C$ from a fit to the distribution of the decay-time difference between the two
$B$ mesons. The resulting confidence region is consistent with previous
measurements in $B^0 \rightarrow K^0_S K^0_S K^0_S$ and $B^0 \rightarrow
(c\bar{c})K^0$ decays, and with predictions based on the standard model. | hep-ex |
A measurement of the WZ and ZZ production cross sections using leptonic
final states in 8.6 fb$^{-1}$ of $p\bar{p}$ collisions: We study the processes $p\bar{p} \rightarrow WZ \rightarrow
\ell\nu\ell^+\ell-$ and $p\bar{p} \rightarrow ZZ \rightarrow
\ell^+\ell^-\nu\bar{\nu}, where $\ell$ = $e$ or ${\mu}$. Using 8.6 fb$^{-1} of
integrated luminosity collected by the D0 experiment at the Fermilab Tevatron
collider, we measure the $WZ$ production cross section to be
4.50$^{+0.63}_{-0.66} pb which is consistent with, but slightly above a
prediction of the standard model. The ZZ cross section is measured to be 1.64
$\pm$ 0.46 pb, in agreement with a prediction of the standard model.
Combination with an earlier analysis of the $ZZ \rightarrow
\ell^+\ell^-\ell^+\ell^-$ channel yields a $ZZ$ cross section of
1.44$^{+0.35}_{-0.34}$ pb. | hep-ex |
Exclusively produced rho^0 asymmetries on the deuteron and future GPD
measurements at COMPASS: Generalized parton distributions (GPDs) provide a new and powerful framework
for a complete description of the nucleon structure. They can provide a
three-dimensional picture of how the quarks and gluons form a nucleon. GPDs can
be probed experimentally in hard exclusive meson production or deeply virtual
Compton scattering (DVCS). The COMPASS experiment at CERN is a unique place to
study these reactions. At COMPASS, a high energy polarized positive or negative
muon beam is scattered off a polarized or unpolarized fixed target. First
results for exclusive rho^0 meson production are shown. The transverse target
spin asymmetry for exclusively produced rho^0 on a transversely polarized
deuteron target has been measured. Prospects for future measurements of DVCS
and exclusive meson production at COMPASS will be shown. The experiment will
use the existing COMPASS spectrometer with a new target, a new recoil detector
and extended calorimetry. Simulations for different models and a test of the
recoil detector have been performed. | hep-ex |
Tracking Performance of the HERA-B Outer Tracker PC Chambers: The paper was withdrawn by the authors since it has not been reviewed and
approved by an official body within the collaboration. | hep-ex |
A realistic coalescence model for deuteron production: A microscopic understanding of (anti)deuteron production in hadron-hadron
collisions is the subject of many experimental and theoretical efforts in
nuclear physics. This topic is also very relevant for astrophysics, since the
rare production of antinuclei in our Universe could be a doorway to discover
new physics. In this work, we describe a new coalescence afterburner for event
generators based on the Wigner function formalism and we apply it to the
(anti)deuteron case, taking into account a realistic particle emitting source.
The model performance is validated using the EPOS and PYTHIA event generators
applied to proton-proton collisions at the centre-of-mass energy $\sqrt{s}=$ 13
TeV, triggered for high multiplicity events, and the experimental data measured
by ALICE in the same collision system. The model relies on the direct
measurement of the particle emitting source carried out by means of
nucleon-nucleon femtoscopic correlations in the same collision system and
energy. The resulting model is used to predict deuteron differential spectra
assuming different deuteron wavefunctions within the Wigner function formalism.
The predicted deuteron spectra show a clear sensitivity to the choice of the
deuteron wavefunction. The Argonne $v_{18}$ wavefunction provides the best
description of the experimental data. This model can now be used to study the
production of (anti)deuterons over a wide range of collision energies and be
extended to heavier nuclei. | hep-ex |
Heavy Flavors in High Energy ep Collisions: Most recent measurements of open charm and beauty production in high energy
ep collisions at HERA are reviewed. The measurements explored the different
aspects of quantum chromodynamics involved in the process of heavy flavor
production. The results are compared with perturbative theoretical calculations
at next-to-leading order. | hep-ex |
A potential sterile neutrino search utilizing spectral distortion in a
two-reactor/one-detector configuration: There is an observed deficit of about 6\% in the expected rate of
anti-neutrino interactions when averaging over many different reactor
experiments. While the significance of the deficit is low (98.6 \% CL), there
is speculation that a non-interacting "sterile" neutrino could be the cause. In
this paper we explore the possibility of a two-reactor/one-detector experiment
at intermediate distances (100-500 meters) to look for a sterile neutrino in
the mass range implied by this deficit. A method for probing $\Delta m^2$ phase
space is developed using interference patterns between two oscillated spectra
at different baselines. This method is used to investigate the potential
sensitivity of the Double Chooz experiment, which has a single Near Detector at
distances of 351 m and 465 m from two reactors of identical design. We conclude
that Double Chooz could investigate sterile neutrino in the $\Delta m^{2}$
range of 0.002 to 0.5 eV$^2$ over 5 years of near detector running. | hep-ex |
Higgs Discovery before LHC?: The proposed Run IIb of the Tevatron Collider will provide 15 fb-1 worth of
ppbar data at c.o.m energy of 2 TeV per experiment by year 2007. We review the
plans of the Tevatron accelerator complex upgrade and the plans for the
upgrades of the experiments to match this challenge. Perspectives for the
discovery of an Higgs particle are reviewed and the concrete possibility of a 5
sigmas discovery for a low mass Higgs are discussed. | hep-ex |
Measurement of the pi^0 -> e^+e^-gamma Dalitz decay at the Mainz
Microtron: The Dalitz decay pi^0 -> e^+e^-gamma has been measured in the gamma p -> pi^0
p reaction with the A2 tagged-photon facility at the Mainz Microtron, MAMI. The
value obtained for the slope parameter of the pi^0 electromagnetic transition
form factor, a_pi = 0.030+/-0.010_tot, is in agreement with existing
measurements of this decay and with recent theoretical calculations. The
uncertainty obtained in the value of a_pi is lower than in previous results
based on the pi^0 -> e^+e^-gamma decay. | hep-ex |
Physics reach of a low threshold scintillating argon bubble chamber in
coherent elastic neutrino-nucleus scattering reactor experiments: The physics reach of a low threshold (100 eV) scintillating argon bubble
chamber sensitive to Coherent Elastic neutrino-Nucleus Scattering (CE$\nu$NS)
from reactor neutrinos is studied. The sensitivity to the weak mixing angle,
neutrino magnetic moment, and a light $Z'$ gauge boson mediator are analyzed. A
Monte Carlo simulation of the backgrounds is performed to assess their
contribution to the signal. The analysis shows that world-leading sensitivities
are achieved with a one-year exposure for a 10 kg chamber at 3 m from a 1
MW$_{th}$ research reactor or a 100 kg chamber at 30 m from a 2000 MW$_{th}$
power reactor. Such a detector has the potential to become the leading
technology to study CE$\nu$NS using nuclear reactors. | hep-ex |
Probing gluon spin-momentum correlations in transversely polarized
protons through midrapidity isolated direct photons in $p^\uparrow+p$
collisions at $\sqrt{s}=200$ GeV: Studying spin-momentum correlations in hadronic collisions offers a glimpse
into a three-dimensional picture of proton structure. The transverse
single-spin asymmetry for midrapidity isolated direct photons in $p^\uparrow+p$
collisions at $\sqrt{s}=200$ GeV is measured with the PHENIX detector at the
Relativistic Heavy Ion Collider (RHIC). Because direct photons in particular
are produced from the hard scattering and do not interact via the strong force,
this measurement is a clean probe of initial-state spin-momentum correlations
inside the proton and is in particular sensitive to gluon interference effects
within the proton. This is the first time direct photons have been used as a
probe of spin-momentum correlations at RHIC. The uncertainties on the results
are a fifty-fold improvement with respect to those of the one prior measurement
for the same observable, from the Fermilab E704 experiment. These results
constrain gluon spin-momentum correlations in transversely polarized protons. | hep-ex |
Recent results on the helicity structure of the nucleon from HERMES: The HERMES experiment has measured double spin asymmetries of inclusive and
semi-inclusive cross sections for the production of charged hadrons in
deep-inelastic scattering of polarised positrons on polarised hydrogen and
deuterium targets, in the kinematic range 0.023 < x < 0.6, and 1 GeV^2 < Q^2 <
15 GeV^2. For the data taken on the deuterium target, a RICH detector provides
the complete identification of charged pions and kaons. From the inclusive
measurements on deuterium, the polarised structure function g_1^d has been
extracted with high precision. Together with the semi-inclusive measurements,
quark polarisations are extracted separately for the u, ubar, d, dbar, and (s +
sbar) flavours in a LO QCD analysis. Furthermore, a possible breaking of
flavour symmetry in the polarised light sea, (Delta ubar - Delta dbar), was
measured for the first time and found to be consistent with zero within the
experimental precision. | hep-ex |
A Data-Driven Method of Background Prediction at NOvA: NOvA is a long-baseline neutrino oscillation experiment that will use the
NuMI beam originating at Fermilab. NOvA enables the study of two oscillation
channels: $\nu_{\mu}$ disappearance and $\nu_{e}$ appearance. It consists of
two functionally identical detectors, the near detector (ND) at Fermilab and
the far detector (FD) near International Falls in Northern Minnesota. The ND
will be used to study the neutrino beam spectrum and composition before
oscillation, and measure background rate to the $\nu_e$ appearance search. In
this paper, I describe a data-driven technique to estimate the neutral current
(NC) component of the ND spectrum. Using the $\nu_{\mu}$ CC interactions where
the reconstructed muon is removed from the event, we produce a well understood
sample of hadronic showers that resemble NC interactions. | hep-ex |
Energy dependence of the charged multiplicity in deep inelastic
scattering at HERA: The charged multiplicity distributions and the mean charged multiplicity have
been investigated in inclusive neutral current deep inelastic $ep$ scattering
with the ZEUS detector at HERA, using an integrated luminosity of 38.6
pb$^{-1}$. The measurements were performed in the current region of the Breit
frame, as well as in the current fragmentation region of the hadronic
centre-of-mass frame. The KNO-scaling properties of the data were investigated
and the energy dependence was studied using different energy scales. The data
are compared to results obtained in $\epem$ collisions and to previous DIS
measurements as well as to leading-logarithm parton-shower Monte Carlo
predictions. | hep-ex |
Dalitz Plot Analysis of D_s+ -> pi+ pi- pi+: A Dalitz plot analysis of approximately 13,000 Ds+ decays to pi+pi-pi+ has
been performed. The analysis uses a 384 fb-1 data sample recorded by the BaBar
detector at the PEP-II asymmetric-energy e+e- storage ring running at center of
mass energies near 10.6 GeV. Amplitudes and phases of the intermediate
resonances which contribute to this final state are measured. A high precision
measurement of the ratio of branching fractions is performed: BR(Ds+ ->
pi+pi-pi+)/BR(Ds+ -> K+ K- pi+)=0.199 +/- 0.004 +/- 0.009. Using a
model-independent partial wave analysis, the amplitude and phase of the S-wave
have been measured. | hep-ex |
Measurement of ${C\!P}$ violation parameters and polarisation fractions
in ${B_s^0\to J/ψ\overline{K}^{*0}}$ decays: The first measurement of ${C\!P}$ asymmetries in the decay ${B_s^0\to J/\psi
\overline{K}^{*}(892)^{0}}$ and an updated measurement of its branching
fraction and polarisation fractions are presented. The results are obtained
using data corresponding to an integrated luminosity of $3.0\,fb^{-1}$ of
proton-proton collisions recorded with the LHCb detector at centre-of-mass
energies of $7$ and $8\,\mathrm{TeV}$. Together with constraints from ${B^0\to
J/\psi \rho^0}$, the results are used to constrain additional contributions due
to penguin diagrams in the ${C\!P}$-violating phase ${{\phi}_{s}}$, measured
through ${B_s^0}$ decays to charmonium. | hep-ex |
Search for the Standard Model Higgs Boson in the Lepton + Missing
Transverse Energy + Jets Final State in ATLAS: A search for the Standard Model Higgs boson has been performed in the H
\rightarrow WW \rightarrow l{\nu}jj channel in 1.04 fb-1 of pp collisions at
\surds = 7 TeV collected with the ATLAS detector at the Large Hadron Collider.
No significant excess of events is observed over the expected background and
limits on the Higgs boson production cross section are derived for a Higgs
boson mass in the range 240 GeV < mH < 600 GeV. The best sensitivity is reached
for mH = 400 GeV, where the 95% confidence level upper bound on the
cross-section for Higgs boson production times the branching ratio for H
\rightarrow W W is 3.1 pb, or 2.7 times the Standard Model prediction. | hep-ex |
First Measurement of the Double Spin Asymmetry in $\vec{e}\vec{p}\to e'
π^+ n$ in the Resonance Region: The double spin asymmetry in the $\vec{e}\vec{p}\to e' \pi^+ n$ reaction has
been measured for the first time in the resonance region for four-momentum
transfer $Q^2=0.35-1.5$ GeV$^2$. Data were taken at Jefferson Lab with the CLAS
detector using a 2.6 GeV polarized electron beam incident on a polarized solid
NH$_3$ target. Comparison with predictions of phenomenological models shows
strong sensitivity to resonance contributions. Helicity-1/2 transitions are
found to be dominant in the second and third resonance regions. The measured
asymmetry is consistent with a faster rise with $Q^2$ of the helicity asymmetry
$A_1$ for the $F_{15}(1680)$ resonance than expected from the analysis of the
unpolarized data. | hep-ex |
Measurement of the p\bar{p}\to WZ + X cross section at \sqrt{s}=1.96 TeV
and limits on WWZ trilinear gauge couplings: We present measurements of the process $p\bar{p} \to WZ+X \to \ell^{\prime}
\nu_{\ell^{\prime}} \ell \bar{\ell}$ at $\sqrt{s}=1.96$ TeV, where $\ell$ and
$\ell^{\prime}$ are electrons or muons. Using 1 fb$^{-1}$ of data from the D0
experiment, we observe 13 candidates with an expected background of $4.5\pm0.6$
events and measure a cross section $\sigma(WZ)=2.7^{+1.7}_{-1.3}$ pb. From the
number of observed events and the $Z$ boson transverse momentum distribution,
we limit the trilinear $WWZ$ gauge couplings to $-0.17 \le \lambda_Z \le 0.21$
$(\Delta \kappa_Z = 0)$ at the 95% C.L. for a form factor scale $\Lambda=2$
TeV. Further, assuming that $\Delta g^Z_1 = \Delta\kappa_Z$, we find $-0.12 \le
\Delta\kappa_Z \le 0.29$ $(\lambda_Z=0)$ at the 95% C.L. These are the most
restrictive limits on the $WWZ$ couplings available to date. | hep-ex |
Transverse-longitudinal HBT correlations in proton-antiproton collisions
at root(s) = 630 GeV: Correlations of like-sign pion pairs emerging from proton-antiproton
collisions are analysed in the two-dimensional (q_L,q_T) decomposition of the
three-momentum difference q. While the data cannot be adequately represented by
gaussian, exponential, power-law or Edgeworth parametrisations, more elaborate
ones such as Levy and an exponential with a cross term do better. A two-scale
model using a hard cut to separate small and large scales may indicate a core
that is more prolate than the halo. Consideration not only of the interference
peak at small (q_L,q_T), but also of the shape of the correlation distribution
at intermediate momentum differences is crucial to understanding the data. | hep-ex |
Study of tau-neutrino production at the CERN SPS: The DsTau project proposes to study tau-neutrino production in high-energy
proton interactions. The outcome of this experiment are prerequisite for
measuring the $\nu_\tau$ charged-current cross section that has never been well
measured. Precisely measuring the cross section would enable testing of lepton
universality in $\nu_\tau$ scattering and it also has practical implications
for neutrino oscillation experiments and high-energy astrophysical $\nu_\tau$
observations. $D_s$ mesons, the source of tau neutrinos, following high-energy
proton interactions will be studied by a novel approach to detect the
double-kink topology of the decays $D_s \rightarrow \tau\nu_\tau$ and
$\tau\rightarrow\nu_\tau X$. Directly measuring $D_s\rightarrow \tau$ decays
will provide an inclusive measurement of the $D_s$ production rate and decay
branching ratio to $\tau$. The momentum reconstruction of $D_s$ will be
performed by combining topological variables. This project aims to detect 1,000
$D_s \rightarrow \tau$ decays in $2.3 \times 10^8$ proton interactions in
tungsten target to study the differential production cross section of $D_s$
mesons. To achieve this, state-of-the-art emulsion detectors with a
nanometric-precision readout will be used. The data generated by this project
will enable the $\nu_\tau$ cross section from DONUT to be re-evaluated, and
this should significantly reduce the total systematic uncertainty. Furthermore,
these results will provide essential data for future $\nu_\tau$ experiments
such as the $\nu_\tau$ program in the SHiP project at CERN. In addition, the
analysis of $2.3 \times 10^8$ proton interactions, combined with the expected
high yield of $10^5$ charmed decays as by-products, will enable the extraction
of additional physical quantities. | hep-ex |
Search for Charmonium States Decaying to J/psi gamma gamma Using
Initial-State Radiation Events: We study the processes e+e- -> (J/psi gamma gamma) gamma and e+e- -> (J/psi
pi- pi+) gamma where the hard photon radiated from an initial e+e- collision
with center-of-mass (CM) energy near 10.58 GeV is detected. In the final state
J/psi gamma gamma we consider J/psi pi0, J/psi eta, chi_{c1} gamma, and
chi_{c2} gamma candidates. The invariant mass of the hadronic final state
defines the effective e+e- CM energy in each event, so these data can be
compared with direct e+e- measurements. We report 90% CL upper limits for the
integrated cross section times branching fractions of the J/psi gamma gamma
channels in the Y(4260) mass region. | hep-ex |
Hadronization mechanisms (via heavy-flavour hadrons): Experiment: The formation of hadrons is a fundamental process in nature that can be
investigated at particle colliders. Given their large mass, heavy quarks (charm
and beauty) are produced only in initial hard-scatterings, prior to
hadronisation, which determines instead the relative abundances and the
kinematics of the various heavy-flavour hadron species. As several recent
findings demonstrate, with \ee collisions as a "vacuum-like" reference at one
extreme, and central AA as a dense, extended-size system characterised by flow
and local equilibrium at the opposite extreme, different collision systems
offer a lever arm that can be exploited to probe with a range of heavy-flavour
hadron species the onset of various hadronisation processes. In these
proceedings, a selection of the experimental results related to heavy-flavour
hadronisation shown for the first time at the Hard Probes 2023 conference is
presented together with some of the most important ones of the last years. The
focus is on open-heavy flavour measurements. The comparison with model
predictions and connections among the results in \ee, proton--proton,
proton--nucleus, nucleus--nucleus collisions are discussed. | hep-ex |
Measurement of $ D^{*\pm}$ production in deep inelastic scattering at
HERA: The production of $D^{*\pm}$ mesons in deep inelastic $ep$ scattering has
been measured for exchanged photon virtualities $ 5<Q^2<1000 \gev^2 $, using an
integrated luminosity of 363 pb$^{-1}$ with the ZEUS detector at HERA.
Differential cross sections have been measured and compared to
next-to-leading-order QCD calculations. The cross-sections are used to extract
the charm contribution to the proton structure functions, expressed in terms of
the reduced charm cross section, $\sigma_{\rm red}^{c\bar{c}}$. Theoretical
calculations based on fits to inclusive HERA data are compared to the results. | hep-ex |
Why a NESSiE-like experiment at SBL is needed?: The NESSiE experiment is designed to perform an accurate measurement of
muon-neutrino disappearance at small L/E, in order to severely constrain models
with more than three-standard neutrinos, or even determine for the first time
the presence of a new kind of neutrino oscillation. NESSiE is a Short-Baseline
experiment with magnetic spectrometers at two different sites on the
FNAL-Booster neutrino beam. The experiment would allow to definitively solve
the existing tension of the muon-neutrino disappearance result with the
appearance and disappearance "anomalies" at eV mass scale, by spanning one more
order of magnitude in the mixing angle between standard and sterile neutrinos.
We demonstrate that this project constitutes the most robust and fast way to
unambigously study the neutrino physics at that scales. | hep-ex |
Updated measurement of decay-time-dependent CP asymmetries in $D^0 \to
K^+K^-$ and $D^0 \to π^+π^-$ decays: A search for decay-time-dependent charge-parity ($CP$) asymmetry in $D^0 \to
K^+K^-$ and $D^0 \to \pi^+\pi^-$ decays is performed at the LHCb experiment
using proton-proton collision data recorded at a center-of-mass energy of
13TeV, and corresponding to an integrated luminosity of 5.4fb$^{-1}$. The $D^0$
mesons are required to originate from semileptonic decays of $b$ hadrons, such
that the charge of the muon identifies the flavor of the neutral $D$ meson at
production. The asymmetries in the effective decay widths of $D^0$ and
$\overline{D}^0$ mesons are determined to be $A_{\Gamma}(K^+K^-) = ( -4.3 \pm
3.6 \pm 0.5 )\times 10^{-4}$ and $A_{\Gamma}(\pi^+\pi^-) = ( 2.2 \pm 7.0 \pm
0.8)\times 10^{-4}$, where the uncertainties are statistical and systematic,
respectively. The results are consistent with $CP$ symmetry and, when combined
with previous LHCb results, yield $A_{\Gamma}(K^+K^-) = ( -4.4 \pm 2.3 \pm 0.6
)\times 10^{-4}$ and $A_{\Gamma}(\pi^+\pi^-) = ( 2.5 \pm 4.3 \pm 0.7)\times
10^{-4}$. | hep-ex |
Imaging the nucleus with high-energy photons: In the 1930's, nuclear physicists developed the first realistic atomic
models, showing that nuclei were made up of protons and neutrons. In the
1960's, Deep Inelastic Scattering experiments showed that protons and neutrons
had internal structure: quarks and gluons (collectively, partons), and later
experiments showed that the parton momentum distributions are different in
heavy nuclei, compared to those in free nucleons. This difference is not
surprising; partons are sensitive to their environment, and two gluons from
different nucleons may fuse together, for example.
Understanding how quarks and gluons behave in the nuclear environment is a
significant focus of modern nuclear physics. Recent measurements have provided
us with an improved understanding of how quark and gluon densities are altered
in heavy nuclei. We have also begun to make multi-dimensional pictures of the
nucleus, exploring how these alterations are distributed within heavy nuclei.
We naturally expect these modifications to be largest in the core of a nucleus,
and smaller near its periphery; this can change the effective shape of the
nucleus. We have also started to explore the transverse momentum distribution
of the partons in the nuclei, and, using incoherent photoproduction as a probe,
study event-by-event fluctuations in nucleon and nuclei parton densities.
This article will explore recent progress in measurements of nuclear
structure at high energy, with some emphasis on these multi-dimensional
pictures. We will also discuss how a future electron-ion collider (EIC) with
high luminosity and center-of-mass energy will make exquisitely detailed images
of partons in a nucleus. | hep-ex |
The Character of Z-pole Data Constraints on Standard Model Parameters: Despite the impressive precision of the Z-pole measurements made at LEP and
SLC, the allowed region for the principle Standard Model parameters responsible
for radiative corrections (the mass of the Higgs, the mass of the top and
alpha(Mz)) is still large enough to encompass significant non-linearities. The
nature of the experimental constraints therefore depends in an interesting way
on the "accidental" relationships among the various measurements. In
particular, the fact that the Z-pole measurements favor values of the Higgs
mass excluded by direct searches leads us to examine the effects of external
Higgsstrahlung, a process ignored by the usual precision electroweak
calculations. | hep-ex |
B \to X_s \ell^+ \ell^- at Belle: Evidence for the inclusive $B \to X_s \ell^+ \ell^-$ decay has been presented
based on 41.8 fb-1 data sample collected at the Y(4S) resonance with the Belle
detector at the KEKB asymmetric e+e- collider. A preliminary result for the
branching fraction is B($B \to X_s \ell^+ \ell^-$) = (7.1 +- 1.6 (stat.) + 1.4
- 1.2(syst.)) \times 10^-6. | hep-ex |
Performance of the ATLAS Transition Radiation Tracker in Run 1 of the
LHC: tracker properties: The tracking performance parameters of the ATLAS Transition Radiation Tracker
(TRT) as part of the ATLAS inner detector are described in this paper for
different data-taking conditions in proton-proton, proton-lead and lead-lead
collisions at the Large Hadron Collider (LHC). The performance is studied using
data collected during the first period of LHC operation (Run 1) and is compared
with Monte Carlo simulations. The performance of the TRT, operating with two
different gas mixtures (xenon-based and argon-based) and its dependence on the
TRT occupancy is presented. These studies show that the tracking performance of
the TRT is similar for the two gas mixtures and that a significant contribution
to the particle momentum resolution is made by the TRT up to high particle
densities. | hep-ex |
First Measurement of the Absolute Branching Fraction of $Λ\to p
μ^- \barν_μ$: The absolute branching fraction of $\Lambda \to p \mu^- \bar{\nu}_{\mu}$ is
reported for the first time based on an $e^+e^-$ annihilation sample of ten
billion $J/\psi$ events collected with the BESIII detector at $\sqrt{s}=3.097$
GeV. The branching fraction is determined to be ${\mathcal B}(\Lambda \to
p\mu^- \bar{\nu}_{\mu}) = [1.48\pm0.21(\rm stat) \pm 0.08(\rm syst)]\times
10^{-4}$, which is a significant improvement in precision over the previous
indirect measurements. Combining this result with the world average of
${\mathcal B}(\Lambda \to p e^- \bar{\nu}_{e})$, we obtain the ratio,
$\frac{\Gamma(\Lambda \to p \mu^- \bar{\nu}_{\mu})}{\Gamma(\Lambda \to p e^-
\bar{\nu}_{e})}$, to be $0.178 \pm 0.028$, which agrees with the standard model
prediction assuming lepton flavor universality. The asymmetry of the branching
fractions of $\Lambda \to p \mu^- \bar{\nu}_{\mu}$ and $\bar{\Lambda} \to
\bar{p} \mu^+ \nu_{\mu}$ is also determined, and no evidence for $CP$ violation
is found. | hep-ex |
Measurement of Electron Neutrino Charged-Current Inclusive Cross Section
in 1-3 GeV energy region with the NOvA Near Detector: We present a measurement of the electron neutrino charged-current inclusive
cross section per nucleon with a data sample corresponding to 2.6E20
protons-on-target collected by NOvA near detector at Fermilab. | hep-ex |
Observation of the $Λ_\text{b}^0$ $\to$ J/$ψΞ^-$K$^+$ decay: Using proton-proton collision data corresponding to an integrated luminosity
of 140 fb$^{-1}$ collected by the CMS experiment at $\sqrt{s}$ = 13 TeV, the
$\Lambda_\text{b}^0$ $\to$ J/$\psi\Xi^-$K$^+$ decay is observed for the first
time, with a statistical significance exceeding 5 standard deviations. The
relative branching fraction, with respect to the $\Lambda_\text{b}^0$ $\to$
$\psi$(2S)$\Lambda$ decay, is measured to be $\mathcal{B}$($\Lambda_\text{b}^0$
$\to$ J/$\psi\Xi^-$K$^+$)/$\mathcal{B}$( $\Lambda_\text{b}^0$ $\to$
$\psi$(2S)$\Lambda$) = [3.38 $\pm$ 1.02 $\pm$ 0.61 $\pm$ 0.03]%, where the
first uncertainty is statistical, the second is systematic, and the third is
related to the uncertainties in $\mathcal{B}$($\psi$(2S) $\to$
J/$\psi\pi^+\pi^-$) and $\mathcal{B}$($\Xi^-$ $\to$ $\Lambda\pi^-$). | hep-ex |
Measurement of $b$ hadron masses in exclusive $J/ψ$ decays with the
CDF detector: We measure the masses of $b$ hadrons in exclusively reconstructed final
states containing a $J/\psi\to\mu^-\mu^+$ decay using $\rm 220 pb^{-1}$ of data
collected by the CDF II experiment. We find: m(B^+) = 5279.10 \pm
0.41_{(stat.)} \pm 0.36_{(sys.)} MeVcc, m(B^0) = 5279.63 \pm 0.53_{(stat.)} \pm
0.33_{(sys.)} MeVcc, m(B^0_s) = 5366.01 \pm 0.73_{(stat.)} \pm 0.33_{(sys.)}
MeVcc, m(\Lambda^0_b) = 5619.7 \pm 1.2_{(stat.)} \pm 1.2_{(sys.)} MeVcc. m(B^+)
- m(B^0) = -0.53 \pm 0.67_{(stat.)} \pm 0.14_{(sys.)} MeVcc, m(B^0_s) - m(B^0)
= 86.38 \pm 0.90_{(stat.)} \pm 0.06_{(sys.)} MeVcc m(\Lambda^0_b) - m(B^0) =
339.2 \pm 1.4_{(stat.)} \pm 0.1_{(sys.)} MeVcc. The measurements of the
$B^0_s$, $\Lambda^0_b$ mass, $m(B^0_s)-m(B^0)$ and $m(\Lambda^0_b)-m(B^0)$ mass
difference are of better precision than the current world averages. | hep-ex |
Measurement of Branching Fraction and CP Asymmetry in B-> eta h Decays: We report measurements of $B$ to pseudoscalar-pseudoscalar decays with at
least one eta meson in the final state using 140 fb^{-1} of data collected by
the Belle detector at KEKB e^+ e^- collider. We observe the decays of B^+-> eta
pi^+ and B^+-> eta K^+; the measured branching fractions are Br(B^+-> eta pi^+)
= (4.8^{+0.8}_{-0.7}(stat) +- 0.3 (sys)) * 10^-6 and Br(B^+-> eta K^+) = (2.1
+- 0.6 (stat) +- 0.2 (sys)) * 10^-6. Their corresponding CP violating
asymmetries are measured to be 0.07 +- 0.15 +- 0.03 for eta pi^+- and -0.49 +-
0.31 +- 0.07 for eta K^+-. No significant signals are found for neutral B meson
decays. We report the following upper limits on branching fractions at the 90%
confidence level: Br(B^0 -> eta K^0) < 2.0 * 10^-6, Br(B^0-> eta pi^0) < 2.5 *
10^-6 and Br(B^0 -> eta eta) < 2.0 * 10^-6. | hep-ex |
Working with Arrays of Inexpensive EIDE Disk Drives: In today's marketplace, the cost per Terabyte of disks with EIDE interfaces
is about a third that of disks with SCSI. Hence, three times as many particle
physics events could be put online with EIDE. The modern EIDE interface
includes many of the performance features that appeared earlier in SCSI. EIDE
bus speeds approach 33 Megabytes/s and need only be shared between two disks
rather than seven disks. The internal I/O rate of very fast (and expensive)
SCSI disks is only 50 per cent greater than EIDE disks. Hence, two EIDE disks
whose combined cost is much less than one very fast SCSI disk can actually give
more data throughput due to the advantage of multiple spindles and head
actuators. We explore the use of 12 and 16 Gigabyte EIDE disks with motherboard
and PCI bus card interfaces on a number of operating systems and CPUs. These
include Red Hat Linux and Windows 95/98 on a Pentium, MacOS and Apple's
Rhapsody/NeXT/UNIX on a PowerPC, and Sun Solaris on a UltraSparc 10
workstation. | hep-ex |
A measurement of CP-violation parameters in B0B0bar mixing using
partially reconstructed D*- l+ nu_l events at BaBar: CP violation in B0B0bar mixing is characterized by the value of the parameter
|q/p| being different from 1, and the Standard Model predicts this difference
to be smaller than 10^{-3}. We present a measurement of this parameter using a
partial reconstruction of one of the B mesons in the semileptonic channel D*-
l+ nu_l, where only the hard lepton and the soft pion from the D*- --> D0bar
pi- decay are reconstructed. The flavor of the other B is determined by means
of lepton tagging. The determination of |q/p| is then performed with a fit to
the proper time difference of the two B decays. We use a luminosity of 200.8
fb^-1, collected at the Y(4S) resonance by the BaBar detector at the PEP-II
asymmetrical-energy e+e- collider, in the period 1999-2004. We obtain the
preliminary result:
|q/p| - 1 = (6.5 +/- 3.4(stat.) +/- 2.0(syst.)) x 10^{-3} | hep-ex |
Measurement of the Ionization Yield of Neutron-Induced Proton Recoils in
Tetramethylsilane: We report on a low energy measurement of the ionization yield in a
Tetramethylsilane Time Projection Chamber (TPC) using 2.8 MeV neutrons from a
deuterium-deuterium neutron generator. The proton recoil charge yield is
measured at four different electric fields, finding a dependence that is well
described by the Thomas-Imel model. By comparing the proton recoil yield to
that obtained from $\gamma$-ray calibrations, a quenching factor is obtained
for each electric field. These results demonstrate the feasibility of using
room temperature organic ionisation detectors to detect MeV-scale neutrons in
the proton-recoil channel. | hep-ex |
Measurement of the UT angle phi_2: We give a status report on measurements of the angle phi_2 (alpha) of the CKM
unitarity triangle (UT) and the so-called Kpi puzzle. Results presented are
mostly from the two B-factory experiments, Belle and BaBar. | hep-ex |
Model Independent Searches for New Physics at the Fermilab Tevatron
Collider: The standard model is a successful but limited theory. There is significant
theoretical motivation to believe that new physics may appear at the energy
scale of a few TeV, the lower end of which is currently probed by the Fermilab
Tevatron Collider. The methods used to search for physics beyond the standard
model in a model independent way and the results of these searches based on 1.0
fb-1 of data collected with the D0 detector and 2.0 fb^-1 at the CDF detector
are presented. | hep-ex |
Is there new physics in the 1999 ALEPH data ?: The first results on searches performed by ALEPH on the 1999 data sample are
presented here. They are based on an integrated luminosity of about 54 pb$^-1$
collected at the two centre-of-mass energies of 192 and 196 GeV. Preliminary
results on searches for supersymmetric particles and for the neutral Higgs
bosons are shown. | hep-ex |
Prospects for discovering new gauge bosons, extra dimensions and contact
interaction at the LHC: This talk is a review of possible discoveries of exotic not Standard Model
Physics in the early stage of LHC (first two years), with the ATLAS and CMS
experiments. LHC will be the first experiment ever to explore the TeV region
and new exotic particles could be discovered at early stages of the LHC running
if their masses are not too large. This talk is focused on three main search
topics: new vector bosons, contact interaction and extra dimensions. | hep-ex |
Top Quark Modelling and Tuning at CMS: Recent measurements dedicated to improving the understanding of modelling top
quark pair (${\text{t}\overline{\text{t}}}$) production at the LHC are
summarised. These measurements, performed with proton-proton collision data
collected by the CMS detector at $\sqrt{s}=$ 13 TeV, probe the underlying event
in ${\text{t}\overline{\text{t}}}$ events, and use the abundance of jets in
${\text{t}\overline{\text{t}}}$ events to study the substructure of jets. A new
set of tunes for PYTHIA 8, and their performance with
${\text{t}\overline{\text{t}}}$ data, are also discussed. | hep-ex |
Virtual Photon Structure at HERA: Measurements of the structure of the virtual photon in the transition region
between quasi-real photons and those far from mass-shell have been made with
the ZEUS detector at HERA, using an integrated luminosity of 38pb-1. Dijet
final states are identified, and differential cross sections are presented in
terms of xgo, an estimator of the fraction of the photon energy which takes
part in the QCD subprocess. Comparison is made to theoretical predictions. | hep-ex |
A New Generation of Neutrino Cross Section Experiments: Challenges and
Opportunities: Our knowledge of neutrino cross sections at the GeV scale, instrumental to
test CP symmetry violation in the leptonic sector, has grown substantially in
the last two decades. Still, their precision and understanding are far from the
standard needed in contemporary neutrino physics. Nowadays, the knowledge of
the neutrino cross-section at $O(10\%)$ causes the main systematic uncertainty
in oscillation experiments and jeopardizes their physics reach. In this paper,
we envision the opportunities for a new generation of cross section experiments
to be run in parallel with DUNE and HyperKamiokande. We identify the most
prominent physics goals by looking at the theory and experimental limitations
of the previous generation of experiments. We highlight the priorities in the
theoretical understanding of GeV cross-sections and the experimental challenges
of this new generation of facilities. | hep-ex |
Proton Structure: Recent inclusive neutral current and charged current DIS data from
HERA are discussed in context of pQCD and parton density functions. | hep-ex |
Charged Current Quasi-Elastic Interactions at MiniBooNE Confront Cross
Section Monte Carlos: 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 signal with 1E21 protons on target. While working towards the
oscillation result, MiniBooNE will accumulate more than 1E6 neutrino
interactions in the 0 to 2 GeV range which will greatly increase the world's
knowledge of neutrino cross sections in this energy regime. Preliminary results
on the MiniBooNE muon neutrino charged current quasi-elastic analysis are
presented and compared to the NUANCE, NEUT, and NEUGEN cross section Monte
Carlos. | hep-ex |
Updated measurement of decay-time-dependent CP asymmetries in $D^0 \to
K^+K^-$ and $D^0 \to π^+π^-$ decays: A search for decay-time-dependent charge-parity ($CP$) asymmetry in $D^0 \to
K^+K^-$ and $D^0 \to \pi^+\pi^-$ decays is performed at the LHCb experiment
using proton-proton collision data recorded at a center-of-mass energy of
13TeV, and corresponding to an integrated luminosity of 5.4fb$^{-1}$. The $D^0$
mesons are required to originate from semileptonic decays of $b$ hadrons, such
that the charge of the muon identifies the flavor of the neutral $D$ meson at
production. The asymmetries in the effective decay widths of $D^0$ and
$\overline{D}^0$ mesons are determined to be $A_{\Gamma}(K^+K^-) = ( -4.3 \pm
3.6 \pm 0.5 )\times 10^{-4}$ and $A_{\Gamma}(\pi^+\pi^-) = ( 2.2 \pm 7.0 \pm
0.8)\times 10^{-4}$, where the uncertainties are statistical and systematic,
respectively. The results are consistent with $CP$ symmetry and, when combined
with previous LHCb results, yield $A_{\Gamma}(K^+K^-) = ( -4.4 \pm 2.3 \pm 0.6
)\times 10^{-4}$ and $A_{\Gamma}(\pi^+\pi^-) = ( 2.5 \pm 4.3 \pm 0.7)\times
10^{-4}$. | hep-ex |
Observation of B->etarho+ and search for B0 Decays to eta'eta, etapi0,
eta'pi0, and omegapi0: We present measurements of branching fractions for five B-meson decays to
two-body charmless final states. The data, collected with the BABAR detector at
the Stanford Linear Accelerator Center, represent 459 million BBbar pairs. The
results for branching fractions are, in units of 10^{-6} (upper limits at 90%
C.L.): BR(B+ -> etarho+) = 9.9 +/- 1.2 +/- 0.8, BR(B0 -> eta'eta) = 0.5 +/- 0.4
+/- 0.1 (<1.2), BR(B0 -> etapi0) = 0.9 +/- 0.4 +/- 0.1 (<1.5), BR(B0 ->
eta'pi0) = 0.9 +/- 0.4 +/- 0.1 (<1.5), and BR(B0 -> omegapi0) = 0.07 +/- 0.26
+/- 0.02 (<0.5). The first error quoted is statistical and the second
systematic. For the etarho+ mode, we measure the charge asymmetry Ach(B+ ->
etarho+) = 0.13 +/- 0.11 +/- 0.02. | hep-ex |
Capabilities of an Underwater Detector as a Neutrino Telescope and for
the Neutrino Oscillation Search: We report on the results of a Monte Carlo simulation study of a km^3 scale
deep underwater Cherenkov detector aimed at detecting neutrinos of
astrophysical origin. This analysis has been undertaken as part of the NEMO R&D
project to develop such an experiment close to the Southern Italian coasts. We
have studied the reconstruction capabilities of various arrays of phototubes in
order to determine the detector geometries which optimize performance and cost.
We have also investigated the possibility of designing a detector with
characteristics suited to an experiment on atmospheric neutrino oscillations. | hep-ex |
End-to-end particle and event identification at the Large Hadron
Collider with CMS Open Data: From particle identification to the discovery of the Higgs boson, deep
learning algorithms have become an increasingly important tool for data
analysis at the Large Hadron Collider (LHC). We present an innovative
end-to-end deep learning approach for jet identification at the Compact Muon
Solenoid (CMS) experiment at the LHC. The method combines deep neural networks
with low-level detector information, such as calorimeter energy deposits and
tracking information, to build a discriminator to identify different particle
species. Using two physics examples as references: electron vs. photon
discrimination and quark vs. gluon discrimination, we demonstrate the
performance of the end-to-end approach on simulated events with full detector
geometry as available in the CMS Open Data. We also offer insights into the
importance of the information extracted from various sub-detectors and describe
how end-to-end techniques can be extended to event-level classification using
information from the whole CMS detector. | hep-ex |
Jet properties and correlations in multi-jet topologies in CMS: We present measurements of multi-jet event properties, performed using
proton-proton collisions data recorded by the CMS experiment. The jet charge
and jet mass distributions are considered in addition to a measurement of the
azimuthal angular correlations in 2- and 3-jet events. The measurements are
compared to predictions including higher orders matched to parton shower and
hadronization, together with predictions from semi-analytical calculations
beyond next-to-leading logarithmic accuracy. | hep-ex |
Search for direct chargino production in anomaly-mediated supersymmetry
breaking models based on a disappearing-track signature in pp collisions at
sqrt(s)=7 TeV with the ATLAS detector: A search for direct chargino production in anomaly-mediated supersymmetry
breaking scenarios is performed in pp collisions at sqrt(s) = 7 TeV using 4.7
fb^-1 of data collected with the ATLAS experiment at the LHC. In these models,
the lightest chargino is predicted to have a lifetime long enough to be
detected in the tracking detectors of collider experiments. This analysis
explores such models by searching for chargino decays that result in tracks
with few associated hits in the outer region of the tracking system. The
transverse-momentum spectrum of candidate tracks is found to be consistent with
the expectation from the Standard Model background processes and constraints on
chargino properties are obtained. | hep-ex |
First Results from the TOTEM Experiment: The first physics results from the TOTEM experiment are here reported,
concerning the measurements of the total, differential elastic, elastic and
inelastic pp cross-section at the LHC energy of $\sqrt{s}$ = 7 TeV, obtained
using the luminosity measurement from CMS. A preliminary measurement of the
forward charged particle $\eta$ distribution is also shown. | hep-ex |
Searches for Heavy Neutrinos at the CERN SPS: Searches for heavy neutrinos can be successfully performed by fixed target
experiments at the CERN SPS. New results obtained by the NA62 and NA48/2 kaon
experiments are summarized in this paper. The physics potential of future
projects exploiting SPS protons with beam dump facilities to enlarge the
sensitivity to heavy neutrinos above the kaon mass limit are also outlined. | hep-ex |
Minimum Bias Measurements with ALICE at the LHC: ALICE (A Large Ion Collider Experiment) is one of the seven experiments at
the the Large Hadron Collider (LHC) at CERN, Geneva, Switzerland. ALICE is
especially designed for heavy-ion collisions but it also operates a rich
proton-proton (pp) program. ALICE has collected pp collision data at
$\sqrt{s}=$ 0.9, 2.36, 2.76, and 7 TeV and lead-lead (Pb--Pb) collision data at
$\sqrt{s_{\mathrm{NN}}}=$2.76 TeV. Here, we report minimum bias measurements
obtained until the end of 2010: the results include measurements of
charged-particle pseudorapidity, multiplicity and transverse momentum
distributions. Also, the two-pion Bose-Einstein correlation and the measurement
of antiproton-to-proton ratio will be discussed. Furthermore, results on the
production of identified particles including strange particles will be shown as
well as first results from the first Pb--Pb run at the LHC. | hep-ex |
Bose-Einstein Correlations and the Tau-Model: Bose-Einstein correlations of pairs of identical charged pions produced in
hadronic Z decays are analyzed in terms of various parametrizations. A good
description is achieved using a L\'evy stable distribution in conjunction with
a model where a particle's momentum is highly correlated with its space-time
point of production, the tau model. However, a small but significant elongation
of the particle emission region is observed in the Longitudinal Center of Mass
frame, which is not accommodated in the tau model. This is investigated using
an ad hoc modification of the tau model. | hep-ex |
Search for Anomalous Production of Diphoton Events with Missing
Transverse Energy at CDF and Limits on Gauge-Mediated Supersymmetry-Breaking
Models: We present the results of a search for anomalous production of diphoton
events with large missing transverse energy using the Collider Detector at
Fermilab. In 202 $\invpb$ of $\ppbar$ collisions at $\sqrt{s}=1.96$ TeV we
observe no candidate events, with an expected standard model background of
$0.27\pm0.07({\rm stat})\pm0.10({\rm syst})$ events. The results exclude a
lightest chargino of mass less than 167 GeV/$c^2$, and lightest neutralino of
mass less than 93 GeV/$c^2$ at 95% C.L. in a gauge--mediated supersymmetry--
breaking model with a light gravitino. | hep-ex |
Heavy-flavour and quarkonia in heavy-ion collisions: The comparison of heavy-flavour hadron production in proton-proton, proton-Pb
and Pb-Pb collisions at the LHC offers the opportunity to investigate the
properties of the high-density colour-deconfined state of strongly-interacting
matter (Quark Gluon Plasma, QGP) that is expected to be formed in high-energy
collisions of heavy nuclei. A review of the main quarkonium and open
heavy-flavour results obtained by the ALICE, ATLAS and CMS experiments is
presented. | hep-ex |
Status and prospects for the LHCb upgrade: High-precision measurements performed by the LHCb collaboration have opened a
new era in charm physics. Several crucial measurements, particularly in
spectroscopy, rare decays and CP violation, can benefit from the increased
statistical power of an upgraded LHCb detector. The upgrade of LHCb detector,
its software infrastructure, and the impact on charm physics are discussed in
detail. | hep-ex |
A novel current mode operating beam counter based on not preamplified
HPDs: A novel system to monitor the intensity and the stability of a bunched beam
of $\simeq 1.2\times 10^{7}$ antiprotons ($\bar{p}$s) with a length of $\simeq$
250 ns (FWHM) and to measure its trapping efficiency in a Penning trap is
described. This system operates parasitically detecting the pions from the
annihilation of part of the beam in a degrader. Six plastic scintillators have
been coupled from one side to six proximity focused HPDs without preamplifiers
and operating in current mode. This device works in the stray field of the
ATHENA magnet with no loss of efficiency; the gain can be varied from zero to a
few thousands with a precision better than 0.1% and the dynamic range is larger
than 8 orders of magnitude. Linearity and stability have been measured up to
charge responses of 100 nC, corresponding to the beam completely dumped. The
beam counter has been calibrated in two different and independent ways giving
consistent results. | hep-ex |
Search for New Physics Using High Mass Tau Pairs from 1.96-TeV
Proton-Antiproton Collisions: We present the results of a search for anomalous resonant production of tau
lepton pairs with large invariant mass, the first such search using the CDF II
Detector in Run II of the Tevatron $p\bar{p}$ collider. Such anomalous
production could arise from various new physics processes. In a data sample
corresponding to 195 pb$^{-1}$ of integrated luminosity we predict 2.8$\pm$0.5
events from Standard Model background processes and observe 4. We use this
result to set limits on the production of heavy scalar and vector particles
decaying to tau lepton pairs. | hep-ex |
Top quark properties measurement with the $D0$ detector: One of the main goals of the Tevatron RunII is to look for any hints for new
physics. At D0, the range of searches for new physics signals is large and one
of the places we look for hints for new physics is by measuring the top quark
properties. A few of these measurements are discussed in this paper. | hep-ex |
Observation of di-structures in $e^+e^-\rightarrow{J}/ψ{\rm X}$ at
center-of-mass energies around 3.773 GeV: We report a measurement of the observed cross sections of the inclusive
$J/\psi$ production in $e^+e^-\rightarrow {J}/\psi{\rm X}$ based on 3.21
fb$^{-1}$ of data accumulated at energies from 3.645 to 3.891 GeV with the
BESIII detector operated at the BEPCII collider. The energy-dependent lineshape
obtained from the measured cross sections cannot be well described by two
Breit-Wigner (BW) amplitudes of the expected decays $\psi(3686)\rightarrow
{J}/\psi{\rm X}$ and $\psi(3770)\rightarrow {J}/\psi{\rm X}$. Instead it can be
better described with three BW amplitudes of the decays $\psi(3686)\rightarrow
{J}/\psi{\rm X}$, $R(3760)\rightarrow {J}/\psi{\rm X}$ and $R(3790)\rightarrow
{J}/\psi{\rm X}$ with two distinct structures referred to as $R(3760)$ and
$R(3790)$. Under this assumption, we extracted their masses, total widths, and
the product of the leptonic width and decay branching fractions to be
$M_{R(3760)}= {3761.7\pm 2.2 \pm 1.2}$ MeV/$c^2$, $\Gamma^{\rm tot}_{R(3760)}=
{6.7\pm 11.1 \pm 1.1}$ MeV, $\Gamma^{ee}_{R(3760)}\mathcal B[R(3760)\rightarrow
{J}/\psi {\rm X}]=(4.0\pm 4.3\pm 1.2)$ eV, $M_{R(3790)} = {3784.7\pm 5.7 \pm
1.6}$ MeV/$c^2$, $\Gamma^{\rm tot}_{R(3790)} = {31.6 \pm 11.9 \pm 3.2}$ MeV,
$\Gamma^{ee}_{R(3790)}\mathcal B[R(3790)\rightarrow {J}/\psi {\rm X}]=(18.1\pm
10.3\pm 4.7)$ eV, where the first uncertainties are statistical and second
systematic. | hep-ex |
Study of particle production from quark and gluon jets in proton-proton
collisions: We investigate whether and how different fragmentation properties of quarks
and gluons affect identified particle spectra. We present a systematic study of
$\pi$, $K$ and $p$ production in minimum bias (inelastic, non-diffractive),
two- and three-jet events at RHIC, Tevatron and LHC energies. Through the study
of two- and three-jet events and various jet-production channels we can
directly access the fragmentation properties of quark and gluon jets. We
present MC estimate for the contribution of quark and gluon jets to individual
particle species spectra, that can be compared to experimental results and test
our current knowledge of the physics behind particle production inside jets. | hep-ex |
Machine learning approach for the search of resonances with topological
features at the Large Hadron Collider: The observation of resonances is unequivocal evidence of new physics beyond
the Standard Model at the Large Hadron Collider (LHC). So far, inclusive and
model dependent searches have not provided evidence of new resonances,
indicating that these could be driven by subtle topologies. Here, we use
machine learning techniques based on weak supervision to perform searches. Weak
supervision based on mixed samples can be used to search for resonances with
little or no prior knowledge on the production mechanism. Also, it offers the
advantage that sidebands or control regions can be used to effectively model
backgrounds with minimal reliance on simulations. However, weak supervision
alone is found to be highly inefficient in identifying corners of the
multi-dimensional space of interest. Instead, we propose an approach to search
for new resonances that involves a classification procedure that is signature
and topology based. A combination of weak supervision with Deep Neural Network
algorithms are applied following this classification. The performance of this
strategy is evaluated on the production of SM Higgs boson decaying to a pair of
photons inclusively and in exclusive regions of phase space tailored for
specific production modes at the LHC. After verifying the ability of the
methodology to extract different SM Higgs boson signal mechanisms, a search for
new phenomena in high-mass final states is setup for the LHC. | hep-ex |
Bilinear R Parity Violation at the ILC - Neutrino Physics at Colliders: Supersymmetry (SUSY) with bilinearly broken R parity (bRPV) offers an
attractive possibility to explain the origin of neutrino masses and mixings. In
such scenarios, the study of neutralino decays at colliders gives access to
neutrino sector parameters. The ILC offers a very clean environment to study
the neutralino properties as well as its subsequent decays, which typically
involve a $W$ or $Z$ boson and a lepton. This study is based on ILC beam
parameters according to the Technical Design Report for a center of mass energy
of $500\,\mathrm{GeV}$. A full detector simulation of the International Large
Detector (ILD) was performed for all Standard Model backgrounds and for
$\widetilde{\chi}_1^0$-pair production within a simplified model. The bRPV
parameters are fixed according to current neutrino data. In this scenario, the
$\widetilde{\chi}_1^0$ mass can be reconstructed with an uncertainty of $\delta
m = (40(\text{stat.}) + 50(\text{syst.}))\,\mathrm{MeV}$ for an integrated
luminosity of $500\,\mathrm{fb}^{-1}$ from direct $\widetilde{\chi}_1^0$-pair
production, thus, to a large extent independently of the rest of the SUSY
spectrum. The achievable precision on the atmospheric neutrino mixing angle
$\sin^2 \theta_{23}$ from measuring the neutralino branching fractions
$\mathrm{BR}(\widetilde{\chi}_1^0 \rightarrow W \mu)$ and
$\mathrm{BR}(\widetilde{\chi}_1^0 \rightarrow W \tau)$ at the ILC is better
than current uncertainties from neutrino experiments. Thus, the ILC could have
the opportunity to unveil the mechanism of neutrino mass generation. | hep-ex |
Search for exotics at $BABAR$: One of the most intriguing puzzles in hadron spectroscopy are the numerous
charmonium-like states observed in the last decade, including charged states
that are manifestly exotic. The $BABAR$ experiment has extensively studied
those in B meson decays, initial state radiation processes and two photon
reactions. The study of the process $B \rightarrow J/\psi \phi K$, with a
search for the resonant states X(4140) and X(4270) in their decays to $J/\psi
\phi$, will be highlighted. The recent results of the Dalitz analysis of
$\eta_c$ to 3 pseudoscalar mesons, via 2-photon interactions, will be presented
in this report | hep-ex |
A Theory of Pattern Recognition for the Discrimination between Muon and
Electron in the Super-Kamiokande: The standard Super-Kamiokande analysis uses an estimator for particle
identification by which it discriminates electrons (electron nutrinos) from
muons (muon nutrinos). Use of this estimator has led to the claim of a
significant deficiency of muons (muon nutrinos), suggesting the existence of
neutrino oscillations. We investigate three areas of concern for the
Super-Kamiokande estimator: the separation of the spatial part from the angular
part in the probability functions, the neglect of fluctuations in the Cherenkov
light in different physical processes due to the charged particles concerned,
and the point-like approximation for the emission of Cherenkov light. We show
that the first two factors are important for the consideration of stochastic
processes in the generation of the Cherenkov light, and that the point-like
assumption oversimplifies the estimation of the Cherenkov light quantities. We
develop a new discrimination procedure for separating electron neutrinos from
muon neutrinos, based on detailed simulations carried out with GEANT~3.21 and
with newly derived mean angular distribution functions for the charged
particles concerned (muons and electrons/positrons), as well as the
corresponding functions for the relative fluctuations. These angular
distribution functions are constructed introducing a ``moving point''
approximation. The application of our procedure between the discrimination
between electron and muon to the analysis of the experimental data in SK will
be made in a subsequent paper. | hep-ex |
Search for a dark matter candidate produced in association with a single
top quark in $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV: We report a new search for dark matter in a data sample of an integrated
luminosity of 7.7 fb$^{-1}$ of Tevatron $p\bar{p}$ collisions at $\sqrt{s} =
1.96$ TeV, collected by the CDF II detector. We search for production of a dark
matter candidate, $D$, in association with a single top quark. We consider the
hadronic decay mode of the top quark exclusively, yielding a final state of
three jets with missing transverse energy. The data are consistent with the
standard model; we thus set 95% confidence level upper limits on the cross
section of the process $p\bar{p}\rightarrow t+D$ as a function of the mass of
the dark-matter candidate. The limits are approximately 0.5 pb for a
dark-matter particle with mass in the range of 0-150 GeV/$c^{2}$. | hep-ex |
Detection of phi --> eta' photon, phi --> eta photon in pi+ pi- three
photons final state with KLOE at DAFNE: KLOE has collected about 30 pb^-1 in year 2000 at the DAFNE collider, which
yields the largest population of phi meson radiative decays studied so far. We
present the result obtained for phi-->eta photon and phi -->eta' photon: the
ratio of these two BR's has been measured to be (5.3 +- 0.5 +- 0.3) times
10^-3, leading to a very accurate determination of the mixing angle in the
flavor basis (40 +1.7 -1.5 degrees) and to the most accurate determination of
BR(phi -->eta' photon) to date: (6.8 +- 0.6 +-0.5) times 10^-5. | hep-ex |
Open Heavy Flavor Production in p+p, d+Au and Au+Au Collisions at
$\sqrt(s)= 200$ GeV: PHENIX results for open charm production from semi-lepton decay in p+p, d+Au
and Au+Au collisions in a wide rapidity ranges at $\sqrt(s)= 200$ GeV are
presented. Keywords: Relativistic Heavy-ion Collision, Open Charm production,
Nuclear Medium Effect PACS: 25.75.-q, 25.75 Dw, 13.20.Gd | hep-ex |
D0 status and first results from Run 2: In order to fully exploit the physics potential of the Tevatron Run 2, the D0
detector has been upgraded. Having nearly completed the commissioning phase,
the D0 detector is starting to produce its first physics results. An overview
of the status of the main subdetectors involved in the upgrade is given,
followed by some examples of preliminary physics results already emerging. | hep-ex |
Latest Constraints from Jet Measurements on Parton Distribution
Functions and on the Strong Coupling Constant: Recent measurements of jet cross sections at HERA, the Tevatron and the LHC
that provide constraints on parton distribution functions and allow for
determinations of the strong coupling constant are presented. | hep-ex |
Exploration of the Muon $g-2$ and Light Dark Matter explanations in NA64
with the CERN SPS high energy muon beam: We report on a search for a new $Z'$ ($L_\mu-L_\tau$) vector boson performed
at the NA64 experiment employing a high energy muon beam and a missing
energy-momentum technique. Muons from the M2 beamline at the CERN Super Proton
Synchrotron with a momentum of 160 GeV/c are directed to an active target. A
signal event is a single scattered muon with momentum $<$ 80 GeV/c in the final
state, accompanied by missing energy, i.e. no detectable activity in the
downstream calorimeters. For a total statistic of $(1.98\pm0.02)\times10^{10}$
muons on target, no event is observed in the expected signal region. This
allows us to set new limits on part of the remaining $(m_{Z'},\ g_{Z'})$
parameter space which could provide an explanation for the muon $(g-2)_\mu$
anomaly. Additionally, our study excludes part of the parameter space suggested
by the thermal Dark Matter relic abundance. Our results pave the way to explore
Dark Sectors and light Dark Matter with muon beams in a unique and
complementary way to other experiments. | hep-ex |
Evidence for hc Production from psi-prime at CLEO: Using the ~ 6 pb-1 of e+e- annihilation data taken at psi-prime(3686) with
CLEO III and CLEO-c detectors with estimated ~ 3.0 million psi-prime events, we
have searched for the h_c(1^1P_1) state of charmonium in the reaction
psi-prime(3686) -> pi^{0} hc -> (gamma gamma) (gamma eta_c). The preliminary
results are reported. | hep-ex |
Measurement of differential $t$-channel single top-quark production
cross-sections with ATLAS: Absolute and normalised differential cross-sections of single top quarks
produced in the $t$-channel are presented. 20.2 fb$^{-1}$ of proton-proton
collision data at a centre-of-mass energy of 8 TeV collected by the ATLAS
experiment at the LHC are used. Differential cross-sections as a function of
the transverse momentum and the absolute value of the rapidity of the top
quarks and the top antiquarks are measured at both parton level and particle
level. The transverse momentum and rapidity differential cross-sections of the
scattered light-quark jets are extracted at particle level. The measured
cross-sections are compared to various Monte Carlo predictions as well as to
available fixed-order QCD calculations. All results agree with the Standard
Model predictions. | hep-ex |
Searches for extra dimensions, gauge mediated SUSY and exotics at LEP: The results of searches for several type of physics beyond the Standard Model
using data from the four LEP experiments are presented. In the absence of any
excess signal events seen in the data limits are placed on the existence of
extra-dimensions, gauge mediated supersymmetry and some exotic states. | hep-ex |
Overview of Deeply Virtual Compton Scattering at HERMES: Deeply Virtual Compton Scattering represents the best experimental channel
through which to understand Generalised Parton Distributions. The HERMES
experiment measured the most diverse set of DVCS results of any experiment;
this talk discusses the most recent sets of DVCS results released by HERMES and
the unique experimental conditions found at HERMES that facilitated the
measurements. We also examine the various ways in which the HERMES experimental
measurements are being used to constrain GPDs and how future experiments can
learn from the HERMES program. | hep-ex |
Measurement of electroweak-induced production of W gamma with two jets
in pp collisions at sqrt(s) = 8 TeV and constraints on anomalous quartic
gauge couplings: A measurement of electroweak-induced production of W gamma and two jets is
performed, where the W boson decays leptonically. The data used in the analysis
correspond to an integrated luminosity of 19.7 inverse femtobarns collected by
the CMS experiment in sqrt(s) = 8 TeV proton-proton collisions produced at the
LHC. Candidate events are selected with exactly one muon or electron, missing
transverse momentum, one photon, and two jets with large rapidity separation.
An excess over the hypothesis of the standard model without electroweak
production of W gamma with two jets is observed with a significance of 2.7
standard deviations. The cross section measured in the fiducial region is 10.8
+/- 4.1 (stat) +/- 3.4 (syst) +/- 0.3 (lumi) fb, which is consistent with the
standard model electroweak predictions. The total cross section for W gamma
production in association with 2 jets in the same fiducial region is measured
to be 23.2 +/- 4.3 (stat) +/- 1.7 (syst) +/- 0.6 (lumi) fb, which is consistent
with the standard model prediction from the combination of electroweak- and
quantum chromodynamics-induced processes. No deviations are observed from the
standard model predictions and experimental limits on anomalous quartic gauge
couplings f[M, 0-7] / Lambda^4, f[T, 0-2] / Lambda^4, and f[T, 5-7] / Lambda^4
are set at 95% confidence level. | hep-ex |
Studies of heavy flavour production and the hadronic final state in high
energy ep collisions: An extract of recent results from the H1 and ZEUS Collaborations is shown.
Various properties of quantum chromo dynamics are investigated by studying the
details of the hadronic final state of high energy electron proton collisions
at HERA. The presented results include analyses of jet cross sections and
single particle production such as $\gamma$ and $D$. Part of the measurements
deal with final states involving identified heavy quarks (charm and beauty). | hep-ex |
Recent Results in Semileptonic B Decays With BaBar: In this note, recent results of studies of semileptonic B meson decays from
\babar are discussed and preliminary results given. In particular, a recent
measurement of $\mathcal{B}(B \to D^{(*)}\tau \nu)$ and the ratio
$\mathcal{B}(B \to D^{(*)}\tau \nu)/\mathcal{B}(B \to D^{(*)}\ell \nu)$ is
presented. For the $D^*$ mode, a branching fraction of
$1.79\pm0.13\stat\pm0.17\syst$ is found, with a ratio of
$0.325\pm0.023\stat\pm0.027\syst$. For the $D$ mode, the results are
$1.04\pm0.12\stat\pm0.14\syst$ and $0.456\pm0.053\stat\pm0.056\syst$,
respectively. In addition, a study of $B_s$ production and semileptonic decays
using data collected in a center-of-mass energy region above the \Y4S resonance
is discussed. The semileptonic branching fraction $\mathcal{B}(B_s \to \ell \nu
X)$ is measured to be $9.9{}^{+2.6}_{-2.1}\stat{}^{+1.3}_{-2.0}\syst$. | hep-ex |
Measurement of the Top Quark Mass with the Collider Detector at Fermilab: We present a new measurement of the top quark mass in $t\bar t$ events in
which both $W$ bosons from top quarks decay into lepton ($e \nu,\mu \nu$).
We use events collected by the CDF experiment from $p\bar p$ collisions at
\sqrt s=1.8 TeV at the Tevatron collider. We measure a top quark mass of 167.4
\pm 10.3(stat) \pm 4.8(syst) GeV/c^2 from a sample of eight events. We combine
this result with previous CDF measurements in other decay channels to obtain a
mass value of 176.0 \pm 6.5 GeV/c^2. | hep-ex |
Precision Determination of V_ub at an e+ e- B Factory: Current methods of determining V_ub are dominated by theoretical
uncertainties. We present Monte Carlo simulations of three promising methods of
determining V_ub with small theoretical and experimental errors. We find that
with data samples of order 1,000 fb-1 the B factories will attain combined
experimental errors of a few % on V_ub, much smaller than the theoretical
errors associated with new inclusive methods. Lattice QCD offers the promise of
rate calculations of exclusive semileptonic decays with errors of a few %. A
data sample of order 10,000 fb-1, beyond the capabilities of the current B
factories, may be required to achieve an experimental error on the exclusive
rate comparable to the theoretical error. | hep-ex |
The Need for an R&D and Upgrade Program for CMS Software and Computing: Over the next ten years, the physics reach of the Large Hadron Collider (LHC)
at the European Organization for Nuclear Research (CERN) will be greatly
extended through increases in the instantaneous luminosity of the accelerator
and large increases in the amount of collected data. Due to changes in the way
Moore's Law computing performance gains have been realized in the past decade,
an aggressive program of R&D is needed to ensure that the computing capability
of CMS will be up to the task of collecting and analyzing this data. | hep-ex |
Measurement of Ratios of $ν_μ$ Charged-Current Cross Sections on
C, Fe, and Pb to CH at Neutrino Energies 2-20 GeV: We present measurements of $\nu_{\mu}$ charged-current cross section ratios
on carbon, iron, and lead relative to a scintillator (CH) using the
fine-grained MINERvA detector exposed to the NuMI neutrino beam at Fermilab.
The measurements utilize events of energies $2<E_{\nu}<20~GeV$, with $\left<
E_{\nu}\right>=8~GeV$, which have a reconstructed $\mu^{-}$ scattering angle
less than $17^\circ$ to extract ratios of inclusive total cross sections as a
function of neutrino energy $E_{\nu}$ and flux-integrated differential cross
sections with respect to the Bjorken scaling variable $x$. These results
provide the first high-statistics direct measurements of nuclear effects in
neutrino scattering using different targets in the same neutrino beam. Measured
cross section ratios exhibit a relative depletion at low $x$ and enhancement at
large $x$. Both become more pronounced as the nucleon number of the target
nucleus increases. The data are not reproduced by GENIE, a conventional
neutrino-nucleus scattering simulation, or by the alternative models for the
nuclear dependence of inelastic scattering that are considered. | hep-ex |
Recent Top Properties Measurements at CDF: We present the most recent CDF results in the measurements of the decay and
production vertex of the top-quark. New results on forward-backward asymmetry
in top-antitop events are presented. Also, recent measurements of the branching
fractions of top-quark are discussed. Finally, measurements in single top
events, where top-quark is produced through electroweak processes, are
presented. Despite the much larger number of top events collected at the LHC,
due to the symmetric initial state and the better signal-to-background ratio in
specific channels, some results will be lasting heritage of the Tevatron. | hep-ex |
Study of the tau- --> 3h-2h+nu Decay: The branching fraction of the tau- --> 3h- 2h+ nu decay (h= pi, kaon) is
measured with the BaBar detector to be (8.56 +/- 0.05 +/- 0.42)E-04 where the
first error is statistical and the second systematic. The observed structure of
this decay is significantly different from the phase space prediction, with the
rho resonance playing a strong role. The decay tau- --> f1 pi nu with the f1
meson decaying to four charged pions, is observed and the branching fraction is
measured to be (3.9 +/- 0.7 +/- 0.5)E-04. | hep-ex |
New precise determination of the τlepton mass at KEDR detector: The status of the experiment on the precise $\tau$ lepton mass measurement
running at the VEPP-4M collider with the KEDR detector is reported. The mass
value is evaluated from the $\tau^+\tau^-$ cross section behaviour around the
production threshold. The preliminary result based on 6.7 pb$^{-1}$ of data is
$m_{\tau}=1776.80^{+0.25}_{-0.23} \pm 0.15$ MeV. Using 0.8 pb$^{-1}$ of data
collected at the $\psi'$ peak the preliminary result is also obtained:
$\Gamma_{ee}B_{\tau\tau}(\psi') = 7.2 \pm 2.1$ eV. | hep-ex |
Measuring the tau polarization at ILC: Measurement of the tau lepton polarization in \eett\ is an important
electro-weak measurement at ILC and other future electron-positron colliders.
In this paper we discuss several methods to extract polarimeter information for
\eett\ events at the nominal centre-of-mass energy, and develop a new method,
based on charged particle impact parameter measurement, which can accurately
reconstruct tau momenta even in events with significant Initial State
Radiation.
In future work we will extend the study to estimate the precision with which
the tau polarization can be measured at ILC-250, both for high-mass tau pairs
and for those which radiatively return to the $Z^0$ peak. This will complement
our past study which showed that the tau polarization can be measured to better
than 1\% at the ILC-500. | hep-ex |
Single Spin Asymmetry of Charged Hadron Production by 40 GeV/c Polarized
Protons: The single spin asymmetry for charge hadron production off nuclei (C, Cu) has
been measured using 40 GeV/c polarized proton beam.
The measurements were carried out using FODS-2 experimental setup at
IHEP. The data are presented in the central region and the forward region
with respect to the incident protons. | hep-ex |
First Search for the $K_L \to π^0 γ$ Decay: We report the first search for the $K_L \to \pi^0 \gamma$ decay, which is
forbidden by Lorentz invariance, using the data from 2016 to 2018 at the J-PARC
KOTO experiment. With a single event sensitivity of $(7.1\pm 0.3_{\rm stat.}
\pm 1.6_{\rm syst.})\times 10^{-8}$, no candidate event was observed in the
signal region. The upper limit on the branching fraction was set to be
$1.7\times 10^{-7}$ at the 90\% confidence level. | hep-ex |
Preliminary Measurement of the Differential Cross Section from
Neutrino-Nucleon Deeply Inelastic Scattering at Nutev: Preliminary results for the neutrino-nucleon differential cross section from
the NuTeV experiment are presented. The extraction of the differential cross
section from NuTeV is discussed and the structure functions $F_2$ and $\Delta
xF_3$ are presented. Comparisons are made with CCFR results. | hep-ex |
C$^3$: A "Cool" Route to the Higgs Boson and Beyond: We present a proposal for a cold copper distributed coupling accelerator that
can provide a rapid route to precision Higgs physics with a compact 8 km
footprint. This proposal is based on recent advances that increase the
efficiency and operating gradient of a normal conducting accelerator. This
technology also provides an $e^{+}e^{-}$ collider path to physics at multi-TeV
energies. In this article, we describe our vision for this technology and the
near-term R&D program needed to pursue it. | hep-ex |
Study of the structure of e+e- -> b bbar g events and improved limits on
the anomalous chromomagnetic coupling of the b-quark: The structure of e+e- -> bbg events was studied using Z0 decays recorded in
the SLD experiment at SLAC. Three-jet final states were selected and the
CCD-based vertex detector was used to identify two of the jets as b or bbar.
Distributions of the gluon energy and polar angle were measured over the full
kinematic range, and compared with perturbative QCD predictions. The energy
distribution is potentially sensitive to an anomalous b chromomagnetic moment
kappa. We measured kappa to be consistent with zero and set limits on its
value, -0.11 < kappa < 0.08 at 95% c.l. (preliminary). | hep-ex |
Jet Charge with the ATLAS Detector using $\sqrt{s}=8$ TeV $pp$ Collision
Data: The momentum-weighted sum of the charges of tracks associated to a jet
provides an experimental handle on the electric charge of fundamental
strongly-interacting particles. An overview of a study of this jet charge
observable for jets produced in dijet and semileptonic $t\bar{t}$ events using
$5.8$ $\mathrm{fb}^{-1}$ of data with the ATLAS detector at $\sqrt{s}=8$ TeV is
described here. In addition to providing a constraint on hadronization models,
jet charge has many possible applications in measurements and searches. The
modelling of jet charge and its performance as a charge-tagger are studied in
order to establish this observable as a tool for future physics analyses. | hep-ex |
Measurement of the forward-backward asymmetry in $Z/γ^{\ast}
\rightarrow μ^{+}μ^{-}$ decays and determination of the effective weak
mixing angle: The forward-backward charge asymmetry for the process $q\bar{q} \rightarrow
Z/\gamma^{\ast} \rightarrow \mu^{+}\mu^{-}$ is measured as a function of the
invariant mass of the dimuon system. Measurements are performed using proton
proton collision data collected with the LHCb detector at $\sqrt{s} = 7$ and
8\tev, corresponding to integrated luminosities of $1$fb$^{-1}$ and
$2$fb$^{-1}$ respectively. Within the Standard Model the results constrain the
effective electroweak mixing angle to be $$sin^{2}\theta_{W}^{eff} = 0.23142
\pm 0.00073 \pm 0.00052 \pm 0.00056 $$ where the first uncertainty is
statistical, the second systematic and the third theoretical. This result is in
agreement with the current world average, and is one of the most precise
determinations at hadron colliders to date. | hep-ex |
Measurement of D^0 and D^+ meson masses with the KEDR Detector: The masses of the neutral and charged D-mesons have been measured with the
KEDR detector at the VEPP-4M electron-positron collider:
M(D^0) = 1865.30 +- 0.33 +- 0.23 MeV,
M(D^+) = 1869.53 +- 0.49 +- 0.20 MeV. | hep-ex |
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