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Models of the hadron structure and Data of the TOTEM Collaboration: The region of the small and large momentum transfer is examined from a view
point of the contribution of the different parts of the scattering amplitude,
soft and hard pomeron, and odderon contribution. The new model taking into
account the different moments of the General Parton Distribution of the hadron
is presented. The comparison with the preliminary data of the TOTEM
Collaboration at an energy of 7 TeV is made. | hep-ex |
Transverse Spin Physics at HERMES: HERMES has measured azimuthal single-spin asymmetries of charged pions
produced in deep-inelastic scattering of positrons on a transversely polarised
hydrogen target. The presented azimuthal moments provide access to two yet
unknown quark distribution functions, the transversity distribution function
\delta q and the Sivers function f_{1T}^{perp}. | hep-ex |
Theta 13 Determination with Nuclear Reactors: Recently there has been a lot of interest around the world in the use of
nuclear reactors to measure theta 13, the last undetermined angle in the
3-neutrino mixing scenario. In this paper the motivations for theta 13
measurement using short baseline nuclear reactor experiments are discussed. The
features of such an experiment are described in the context of Double Chooz,
which is a new project planned to start data-taking in 2008, and to reach a
sensitivity of sinsq(2 theta 13) < 0.03. | hep-ex |
Measurement of the electroweak production of a Z boson and two jets in
proton-proton collisions at 7 and 8 TeV: A measurement of the electroweak production cross section of a Z boson and
two jets is performed using proton-proton collision data at centre-of-mass
energies of 7 and 8 TeV. The data is collected by the CMS experiment at the LHC
with an integrated luminosity of 5 and 19 fb$^{-1}$, respectively. A study on
the hadronic activity between the two tagging jets is also presented. | hep-ex |
Exclusive $ρ^0$ Meson Photoproduction with a Leading Neutron at HERA: A first measurement is presented of exclusive photoproduction of $\rho^0$
mesons associated with leading neutrons at HERA. The data were taken with the
H1 detector in the years $2006$ and $2007$ at a centre-of-mass energy of
$\sqrt{s}=319$ GeV and correspond to an integrated luminosity of $1.16$
pb$^{-1}$. The $\rho^0$ mesons with transverse momenta $p_T<1$ GeV are
reconstructed from their decays to charged pions, while leading neutrons
carrying a large fraction of the incoming proton momentum, $x_L>0.35$, are
detected in the Forward Neutron Calorimeter. The phase space of the measurement
is defined by the photon virtuality $Q^2 < 2$ GeV$^2$, the total energy of the
photon-proton system $20 < W_{\gamma p} < 100$ GeV and the polar angle of the
leading neutron $\theta_n < 0.75$ mrad. The cross section of the reaction
$\gamma p \to \rho^0 n \pi^+$ is measured as a function of several variables.
The data are interpreted in terms of a double peripheral process, involving
pion exchange at the proton vertex followed by elastic photoproduction of a
$\rho^0$ meson on the virtual pion. In the framework of one-pion-exchange
dominance the elastic cross section of photon-pion scattering, $\sigma^{\rm
el}(\gamma\pi^+ \to \rho^0\pi^+)$, is extracted. The value of this cross
section indicates significant absorptive corrections for the exclusive reaction
$\gamma p \to \rho^0n\pi^+$. | hep-ex |
Measurement of inclusive $π^0$ production in the Charged-Current
Interactions of Neutrinos in a 1.3-GeV wide band beam: In this paper we report on the measurement of the rate of inclusive $\pi^0$
production induced by charged-current neutrino interactions in a C$_8$H$_8$
target at a mean energy of 1.3 GeV in the K2K near detector. Out of a sample of
11,606 charged current neutrino interactions, we select 479 $\pi^0$ events with
two reconstructed photons. We find that the cross section for the inclusive
$\pi^0$ production relative to the charged-current quasi-elastic cross section
is
$$\frac{\sigma_{CC\pi^0}}{\sigma_{CCQE}}=0.426\pm0.032(stat.)\pm0.035(syst.)$$
The energy dependent cross section ratio is also measured. The results are
consistent with previous experiments for exclusive channels on different
targets. | hep-ex |
Search for dark photons using a multilayer dielectric haloscope equipped
with a single-photon avalanche diode: We report on the results of the search for dark photons with mass around
1.5$\,\rm eV/c^2$ using a multilayer dielectric haloscope equipped with an
affordable and commercially available photosensor. The multilayer stack, which
enables the conversion of dark photons (DP) to Standard Model photons, is made
of 23 bilayers of alternating SiO$_2$ and Si$_3$N$_4$ thin films with linearly
increasing thicknesses through the stack (a configuration known as a "chirped
stack"). The thicknesses have been chosen according to an optimisation
algorithm in order to maximise the DP-photon conversion in the energy region
where the photosensor sensitivity peaks. This prototype experiment, baptised
MuDHI (Multilayer Dielectric Haloscope Investigation) by the authors of this
paper, has been designed, developed and run at the Astroparticle Laboratory of
New York University Abu Dhabi, which marks the first time a dark matter
experiment has been operated in the Middle East. No significant signal excess
is observed, and the method of maximum log-likelihood is used to set exclusion
limits at $90\%$ confidence level on the kinetic mixing coupling constant
between dark photons and ordinary photons. | hep-ex |
Double parton interactions in photon + 3 jet and photon + b/c jet + 2
jet events in ppbar collisions at sqrt{s}=1.96 TeV: We determine the fraction of events with double parton (DP) scattering in a
single ppbar collision at sqrt{s}=1.96 TeV in samples of photon + 3 jet and
photon + b/c jet + 2 jet events collected with the D0 detector and
corresponding to an integrated luminosity of about 8.7 fb^{-1}. The DP
fractions and effective cross sections (sigma_eff) are measured for both event
samples using the same kinematic selections. The measured DP fractions range
from 0.21 to 0.17, with effective cross sections in the photon + 3 jet and
photon + b/c jet + 2 jet samples of sigma_eff^incl = 12.7 +- 0.2 (stat) +- 1.3
(syst) mb and sigma_eff^HF = 14.6 +- 0.6 (stat) +- 3.2 (syst) mb, respectively. | hep-ex |
Constraints on Neutrino Lifetime from the Sudbury Neutrino Observatory: The long baseline between the Earth and the Sun makes solar neutrinos an
excellent test beam for exploring possible neutrino decay. The signature of
such decay would be an energy-dependent distortion of the traditional survival
probability which can be fit for using well-developed and high precision
analysis methods. Here a model including neutrino decay is fit to all three
phases of $^8$B solar neutrino data taken by the Sudbury Neutrino Observatory.
This fit constrains the lifetime of neutrino mass state $\nu_2$ to be
${>8.08\times10^{-5}}$ s/eV at $90\%$ confidence. An analysis combining this
SNO result with those from other solar neutrino experiments results in a
combined limit for the lifetime of mass state $\nu_2$ of ${>1.04\times10^{-3}}$
s/eV at $99\%$ confidence. | hep-ex |
Time synchronization system of Baikal-GVD: The Baikal-GVD neutrino telescope currently consists of 8 clusters of 288
optical modules (photodetectors). One cluster comprises 8 strings, each of
which is subdivided into 3 sections of 12 optical modules. This paper presents
the methods of time synchronization between the different GVD components
(optical modules, sections, clusters) and estimations of time synchronization
accuracy. | hep-ex |
Search for Narrow Diphoton Resonances and for gamma-gamma+W/Z Signatures
in p\bar p Collisions at sqrt(s)=1.8 TeV: We present results of searches for diphoton resonances produced both
inclusively and also in association with a vector boson (W or Z) using 100
pb^{-1} of p\bar p collisions using the CDF detector. We set upper limits on
the product of cross section times branching ratio for both p\bar
p\to\gamma\gamma + X and p\bar p\to\gamma\gamma + W/Z. Comparing the inclusive
production to the expectations from heavy sgoldstinos we derive limits on the
supersymmetry-breaking scale sqrt{F} in the TeV range, depending on the
sgoldstino mass and the choice of other parameters. Also, using a NLO
prediction for the associated production of a Higgs boson with a W or Z boson,
we set an upper limit on the branching ratio for H\to\gamma\gamma. Finally, we
set a lower limit on the mass of a `bosophilic' Higgs boson (e.g. one which
couples only to \gamma, W, and Z$ bosons with standard model couplings) of 82
GeV/c^2 at 95% confidence level. | hep-ex |
Study of CP asymmetry in B0-B0bar mixing with inclusive dilepton events: We present a measurement of the asymmetry $A_{CP}$ between same-sign
inclusive dilepton samples $\ell^+ \ell^+$ and $\ell^- \ell^-$ ($\ell= e, \mu$)
from semileptonic B decays in Y(4S) --> BBbar events, using the complete data
set recorded by the BABAR experiment near the Y(4S) resonance, corresponding to
471 million BBbar pairs. The asymmetry A_{CP} allows comparison between the
mixing probabilities P(B0bar --> B0) and P(B0 --> B0bar), and therefore probes
CP and T violation. The result, $A_{CP} = (-3.9 \pm 3.5 (stat) \pm 1.9 (syst))
\times 10^{-3}$, is consistent with the Standard Model expectation. | hep-ex |
The CLEO-III RICH Detector and Beam Test Results: We are constructing a Ring Imaging Cherenkov detector (RICH) for the CLEO III
upgrade for precision charged hadron identification. The RICH uses plane and
sawtooth LiF crystals as radiators, MWPCs as photon detectors with TEA as the
photo-sensitive material, and low-noise Viking readout electronics. Results of
a beam test of the first two out of total 30 sectors are presented. | hep-ex |
Study of the photon remnant in resolved photoproduction at HERA: Photoproduction at HERA is studied in $ep$ collisions, with the ZEUS
detector, for $\gamma p$ centre-of-mass energies ranging from 130-270 GeV. A
sample of events with two high-$p_T$ jets ($p_T > 6$ GeV, $\eta <1.6$) and a
third cluster in the approximate direction of the electron beam is isolated
using a clustering algorithm. These events are mostly due to resolved
photoproduction. The third cluster is identified as the photon remnant. Its
properties, such as the transverse and longitudinal energy flows around the
axis of the cluster, are consistent with those commonly attributed to jets, and
in particular with those found for the two jets in these events. The mean value
of the photon remnant $p_T$ with respect to the beam axis is measured to be
$2.1 \pm 0.2$ GeV, which demonstrates substantial mean transverse momenta for
the photon remnant. | hep-ex |
Measurements of differential cross-sections in four-lepton events in 13
TeV proton-proton collisions with the ATLAS detector: Measurements of four-lepton differential and integrated fiducial
cross-sections in events with two same-flavour, opposite-charge electron or
muon pairs are presented. The data correspond to 139 fb$^{-1}$ of $\sqrt{s}=13$
TeV proton-proton collisions, collected by the ATLAS detector during Run 2 of
the Large Hadron Collider (2015-2018). The final state has contributions from a
number of interesting Standard Model processes that dominate in different
four-lepton invariant mass regions, including single $Z$ boson production,
Higgs boson production and on-shell $ZZ$ production, with a complex mix of
interference terms, and possible contributions from physics beyond the Standard
Model. The differential cross-sections include the four-lepton invariant mass
inclusively, in slices of other kinematic variables, and in different lepton
flavour categories. Also measured are dilepton invariant masses, transverse
momenta, and angular correlation variables, in four regions of four-lepton
invariant mass, each dominated by different processes. The measurements are
corrected for detector effects and are compared with state-of-the-art Standard
Model calculations, which are found to be consistent with the data. The
$Z\rightarrow 4\ell$ branching fraction is extracted, giving a value of
$\left(4.41 \pm 0.30\right) \times 10^{-6}$. Constraints on effective field
theory parameters and a model based on a spontaneously broken $B-L$ gauge
symmetry are also evaluated. Further reinterpretations can be performed with
the provided information. | hep-ex |
Measurement of the CKM angle $γ$ in the $B^0 \to DK^{*0}$ channel
using self-conjugate $D \to K_S^0 h^+ h^-$ decays: A model-independent study of CP violation in $B^0 \to DK^{*0}$ decays is
presented using data corresponding to an integrated luminosity of 9fb$^{-1}$
collected by the LHCb experiment at centre-of-mass energies of $\sqrt{s}=7, \,
8$ and $13$TeV. The CKM angle $\gamma$ is determined by examining the
distributions of signal decays in phase-space bins of the self-conjugate $D \to
K_S^0 h^+ h^-$ decays, where $h = \pi, K$.
Observables related to CP violation are measured and the angle $\gamma$ is
determined to be $\gamma=(49^{+ 22}_{-19})^\circ$. Measurements of the
amplitude ratio and strong-phase difference between the favoured and suppressed
$B^0$ decays are also presented. | hep-ex |
Measurement of the CP-Violating Asymmetry Amplitude sin2beta: We present results on time-dependent CP-violating asymmetries in neutral B
decays to several CP eigenstates. The measurements use a data sample of about
88 million Y(4S) --> B Bbar decays collected between 1999 and 2002 with the
BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We study
events in which one neutral B meson is fully reconstructed in a final state
containing a charmonium meson and the other B meson is determined to be either
a B0 or B0bar from its decay products. The amplitude of the CP-violating
asymmetry, which in the Standard Model is proportional to sin2beta, is derived
from the decay-time distributions in such events. We measure sin2beta = 0.741
+/- 0.067 (stat) +/- 0.034 (syst) and |lambda| = 0.948 +/- 0.051 (stat) +/-
0.030 (syst). The magnitude of lambda is consistent with unity, in agreement
with the Standard Model expectation of no direct CP violation in these modes. | hep-ex |
Measurement of Transverse Single-Spin Asymmetries for Di-Jet Production
in Proton-Proton Collisions at $\sqrt{s} = 200$ GeV: We report the first measurement of the opening angle distribution between
pairs of jets produced in high-energy collisions of transversely polarized
protons. The measurement probes (Sivers) correlations between the transverse
spin orientation of a proton and the transverse momentum directions of its
partons. With both beams polarized, the wide pseudorapidity ($-1 \leq \eta \leq
+2$) coverage for jets permits separation of Sivers functions for the valence
and sea regions. The resulting asymmetries are all consistent with zero and
considerably smaller than Sivers effects observed in semi-inclusive deep
inelastic scattering (SIDIS). We discuss theoretical attempts to reconcile the
new results with the sizable transverse spin effects seen in SIDIS and forward
hadron production in pp collisions. | hep-ex |
Genuine Correlations of Like-Sign Particles in Hadronic Z0 Decays: Correlations among hadrons with the same electric charge produced in Z0
decays are studied using the high statistics data collected from 1991 through
1995 with the OPAL detector at LEP. Normalized factorial cumulants up to fourth
order are used to measure genuine particle correlations as a function of the
size of phase space domains in rapidity, azimuthal angle and transverse
momentum. Both all-charge and like-sign particle combinations show strong
positive genuine correlations. One-dimensional cumulants initially increase
rapidly with decreasing size of the phase space cells but saturate quickly. In
contrast, cumulants in two- and three-dimensional domains continue to increase.
The strong rise of the cumulants for all-charge multiplets is increasingly
driven by that of like-sign multiplets. This points to the likely influence of
Bose-Einstein correlations. Some of the recently proposed algorithms to
simulate Bose-Einstein effects, implemented in the Monte Carlo model PYTHIA,
are found to reproduce reasonably well the measured second- and higher-order
correlations between particles with the same charge as well as those in
all-charge particle multiplets. | hep-ex |
Analysis of the decay $D^0\rightarrow K_{S}^{0} K^{+} K^{-}$: Using a data sample of $2.93~fb^{-1}$ of $e^+e^-$ collisions collected at
$\sqrt{s}=3.773 GeV$ in the BESIII experiment, we perform an analysis of the
decay $D^0\rightarrow K_{S}^{0} K^{+} K^{-}$. The Dalitz plot is analyzed using
$1856\pm 45$ flavor-tagged signal decays. We find that the Dalitz plot is well
described by a set of six resonances: $a_0(980)^0$, $a_0(980)^+$, $\phi(1020)$,
$a_2(1320)^+$, $a_2(1320)^-$ and $a_0(1450)^-$. Their magnitudes, phases and
fit fractions are determined as well as the coupling of $a_0(980)$ to
$K\bar{K}$, $g_{K\bar{K}}=3.77\pm 0.24\text{(stat.)}\pm0.35\text{(sys.)} GeV$.
The branching fraction of the decay $D^0\rightarrow K_{S}^{0} K^{+} K^{-}$ is
measured using $11660\pm 118$ untagged signal decays to be $(4.51\pm
0.05\text{(stat.)}\pm 0.16\text{(sys.)})10^{-3}$. Both measurements are limited
by their systematic uncertainties. | hep-ex |
alpha_S Evolution from 35 GeV to 202 GeV and Flavour Independence: Determinations of the strong coupling constant alpha_S at centre-of-mass
energies of 192 through 202 GeV at LEP are presented. The energy evolution of
alpha_S is in agreement with the prediction of QCD. The combined investigation
of
OPAL and JADE data in the energy range of 35 through 189 GeV yields
alpha_S(m_Z)=0.1187^{+0.0034}_{-0.0019}. The strenght of the strong coupling is
flavour independent if quark mass effects are taken into account. | hep-ex |
Measurement of D*+- Cross Sections and the Charm Contribution to the
Structure Function of the Proton in Deep Inelastic Scattering at HERA: We present measurements on D*+- production cross sections in deep inelastic
e+p scattering with 1<Q^2<600 GeV^2 and 0.02<y<0.7 in two restricted kinematic
regions in p_t(D*) and eta(D*). The decay channels D*+ -> D0 pi+ with
subsequent decay D0 -> K- pi+ or D0 -> K- pi+ pi+ pi- (+c.c) are used. The
cross sections are extrapolated to the full kinematic region to determine the
charm contribution to the proton structure function. | 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 |
B Physics at D0: The Fermilab Tevatron (p pbar), operating at sqrt(s)=1.96 TeV, is a rich
source of B hadrons. The large acceptance in terms of rapidity and transverse
momentum of the charged particle tracking system and the muon system make the
upgraded Run II D0 detector an excellent tool for B physics. In this article,
we report on selected physics results based on the first 250 pb^-1 of Run II
data. This includes results on the X(3872) state, semileptonic B decays, B
hadron lifetimes, flavour oscillations, and the rare decay B_s -> mu^+ mu^-. | hep-ex |
Search for new physics in dijet final states in ATLAS and CMS: Events containing a pair of high energy hadronic jet can provide clear
signatures in the search for new physics at high energy hadron colliders. The
ATLAS and CMS experiments collected the data from LHC collisions at $\sqrt{s}$=
13 TeV during 2015 and 2016, looking for evidence of new resonances or
deviations from the Standard Model predictions. Althoug no hint of new physics
was seen, strong limits have been set on the most interesting benchmark models,
improving LHC Run1 reach. | hep-ex |
Measurement of the gluon polarisation at COMPASS: COMPASS experiment measurements of the gluon polarisation in nucleon,
DeltaG/G are reviewed. Two different approaches based on tagging the Photon
Gluon Fusion process are described. They rely on the open charm meson or
high-p_T hadron pairs detection. | hep-ex |
Measurement of the transverse momentum distribution of Z/gamma* bosons
in proton-proton collisions at sqrt(s)=7 TeV with the ATLAS detector: A measurement of the Z/gamma* transverse momentum (p_T^Z)) distribution in
proton-proton collisions at sqrt(s)=7 TeV is presented using Z/gamma*->e+e- and
Z/gamma*->mu+mu- decays collected with the ATLAS detector in data sets with
integrated luminosities of 35 pb^-1 and 40 pb^-1, respectively. The normalized
differential cross sections are measured separately for electron and muon decay
channels as well as for their combination up to p_T^Z of 350 GeV for invariant
dilepton masses 66 GeV<m_ll<116 GeV. The measurement is compared to predictions
of perturbative QCD and various event generators. The prediction of resummed
QCD combined with fixed order perturbative QCD is found to be in good agreement
with the data. | hep-ex |
Report of the Frontier For Rare Processes and Precision Measurements: This is the Snowmass 2021 Rare and Precision Frontier Report. The Rare
Processes and Precision Measurements Frontier, referred to as the ``Rare and
Precision Frontier", or RPF, encompasses searches for extremely rare processes
or tiny deviations from the Standard Model (SM) that can be studied with
intense sources and high-precision detectors. Our community studies have
identified several unique research opportunities that may pin down the scales
associated with New Physics (NP) interactions and constrain the couplings of
possible new degrees of freedom. Searches for rare flavor transition processes
and precision measurements are indispensable probes of flavor and fundamental
symmetries, and provide insights into physics that manifests itself at higher
energy or through weaker interactions than those directly accessible at
high-energy colliders. | hep-ex |
Boosted top: new algorithms and perspectives: Studies of the boosted sector in top-quark physics have known a fast-growing
development with the arrival of high-energy data at LHC. This short review
summarizes the current status of the boosted top-tagging techniques in ATLAS
and CMS and presents an overview of some of the most noticeable developments. | hep-ex |
Neglected heavy leptons at the LHC: New heavy leptons with standard model gauge couplings have well determined
cross sections for pair production. A standard pattern of mass mixing implies
that the most likely decays are $\tau^\prime\to W \nu'$ and $ \nu'\to W \tau$.
Interestingly there have been no direct searches for heavy leptons with these
decays at the LHC. However comparison with several multi-lepton searches allow
us to set new limits on the heavy lepton masses. Three observed excesses in the
signal regions prevent us from setting stronger limits. | hep-ex |
Updated search for $B_c^+$ decays to two charm mesons: A data set corresponding to an integrated luminosity of $9 \text{fb}^{-1}$ of
proton-proton collisions collected by the LHCb experiment has been analysed to
search for $B_c^+ \to D^{(*)+}_{(s)} \overset{\scriptstyle (-)}{D}{}^{(*)0}$
decays. The decays are fully or partially reconstructed, where one or two
missing neutral pions or photons from the decay of an excited charm meson are
allowed. Upper limits for the branching fractions, normalised to $B^+$ decays
to final states with similar topologies, are obtained for fourteen $B_c^+$
decay modes. For the decay $B_c^+ \to D_s^+ {\overline{D}}^0$, an excess with a
significance of 3.4 standard deviations is found. | hep-ex |
Measurement of inclusive D*+- and associated dijet cross sections in
photoproduction at HERA: Inclusive photoproduction of D*+- mesons has been measured for photon-proton
centre-of-mass energies in the range 130 < W < 280 GeV and a photon virtuality
Q^2 < 1 GeV^2. The data sample used corresponds to an integrated luminosity of
37 pb^-1. Total and differential cross sections as functions of the D*
transverse momentum and pseudorapidity are presented in restricted kinematical
regions and the data are compared with next-to-leading order (NLO) perturbative
QCD calculations using the "massive charm" and "massless charm" schemes. The
measured cross sections are generally above the NLO calculations, in particular
in the forward (proton) direction. The large data sample also allows the study
of dijet production associated with charm. A significant resolved as well as a
direct photon component contribute to the cross section. Leading order QCD
Monte Carlo calculations indicate that the resolved contribution arises from a
significant charm component in the photon. A massive charm NLO parton level
calculation yields lower cross sections compared to the measured results in a
kinematic region where the resolved photon contribution is significant. | hep-ex |
Exploring Nuclear Effects in Neutrino-Nucleus Interactions Using
Measurements of Transverse Kinematic Imbalance from T2K and MINERvA: Predictions from widely-used neutrino-nucleus interaction event generators
are compared to measurements of transverse kinematic imbalances, made by both
the T2K and MINERvA experiments, to allow a joint characterisation of the
nuclear physics processes responsible for some of the largest uncertainties in
measurements of neutrino oscillations. The role of nucleon-nucleon
correlations, initial state nucleon Fermi motion and hadronic re-interactions
inside the nuclear medium are explored and areas requiring more theoretical
input are identified. | hep-ex |
The Relevance of Muon Deflections for Neutrino Telescopes: Large-scale neutrino telescopes have the primary objective to detect and
characterize neutrino sources in the universe. These experiments rely on the
detection of charged leptons produced in the interaction of neutrinos with
nuclei. Angular resolutions are estimated to be better than 1 degree, which is
achieved by the reconstruction of muons. This angular resolution is a measure
of the accuracy with which the direction of incoming neutrinos can be
determined. Since muons can traverse distances of several kilometers through
media, the original muon direction can differ from the muon direction inside
the detector due to deflections by stochastic interactions and multiple
scattering. In this contribution, a recently published study of muon
deflections based on the simulation tool PROPOSAL is presented. Muons with
various energies are propagated through different media over several distances.
Data-Monte-Carlo comparisons as well as comparisons to the simulation tools
MUSIC and Geant4 are performed. Finally, the impact of muon deflections on
large-scale neutrino telescopes is discussed. | hep-ex |
Forward-backward asymmetry of Drell-Yan lepton pairs in pp collisions at
sqrt(s) = 8 TeV: A measurement of the forward-backward asymmetry A[FB] of oppositely charged
lepton pairs (mu mu and e e) produced via Z/gamma* boson exchange in pp
collisions at sqrt(s) = 8 TeV is presented. The data sample corresponds to an
integrated luminosity of 19.7 inverse femtobarns collected with the CMS
detector at the LHC. The measurement of A[FB] is performed for dilepton masses
between 40 GeV and 2 TeV and for dilepton rapidity up to 5. The A[FB]
measurements as a function of dilepton mass and rapidity are compared with the
standard model predictions. | hep-ex |
IceCube as a discovery observatory for physics beyond the standard model: Construction of the cubic-kilometer neutrino detector IceCube at the South
Pole has been completed in December 2010. It forms a lattice of 5160
photomultiplier tubes monitoring a gigaton of the deep Antarctic ice for
particle induced photons. The telescope is primarily designed to detect
neutrinos with energies greater than 100 GeV from astrophysical sources. Beyond
this astrophysical motivation IceCube is also a discovery instrument for the
search for physics beyond the Standard Model. Owing to subfreezing ice
temperatures, the photomultiplier dark noise rates are particularly low which
opens up tantalizing possibilities for particle detection. This includes the
indirect detection of weakly interacting dark matter, direct detection of SUSY
particles, monopoles and extremely-high energy phenomena. | hep-ex |
Search for a heavy resonance decaying to a pair of vector bosons in the
lepton plus merged jet final state at 13 TeV: A search for a new heavy particle decaying to a pair of vector bosons (WW or
WZ) is presented using data from the CMS detector corresponding to an
integrated luminosity of 35.9/fb collected in proton-proton collisions at a
centre-of-mass energy of 13 TeV in 2016. One of the bosons is required to be a
W boson decaying to e{\nu} or {\mu}{\nu}, while the other boson is required to
be reconstructed as a single massive jet with substructure compatible with that
of a highly-energetic quark pair from a W or Z boson decay. The search is
performed in the resonance mass range between 1.0 and 4.5 TeV. The largest
deviation from the background-only hypothesis is observed for a mass near 1.4
TeV and corresponds to a local significance of 2.5 standard deviations. The
result is interpreted as an upper bound on the resonance production cross
section. Comparing the excluded cross section values and the expectations from
theoretical calculations in the bulk graviton and heavy vector triplet models,
spin-2 WW resonances with mass smaller than 1.07 TeV and spin-1 WZ resonances
lighter than 3.05 TeV, respectively, are excluded at 95% confidence level. | hep-ex |
Spin physics with light and heavy neutral mesons at Protvino: PROZA-M experiment results as well the proposal of a new spin program with
the use of a polarized proton beam are presented. Significant asymmetries were
observed in inclusive $\pi^0$ production. The new program proposes to study a
wealth of single- and double-spin observables in various reactions using
longitudinally and transversely polarized proton beams at U70. The main goal is
to define gluon contribution to nucleon spin by measuring double-spin asymmetry
in charmonium production. | hep-ex |
Search for Invisible Decays of the Upsilon(1S) Resonance: We present a measurement of the branching fraction of invisible Upsilon(1S)
decays, using 1.2 fb^{-1} of data collected at the Upsilon(2S) resonance with
the CLEO III detector at CESR. After subtracting expected backgrounds from
events that pass selection criteria for invisible Upsilon(1S) decay in
Upsilon(2S) -> pi+ pi- Upsilon(1S), we deduce a 90% C.L. upper limit of
B[Upsilon(1S) -> invisible] < 0.39%. | hep-ex |
A new search for the $K_{L} \to π^0 ν\overlineν$ and $K_{L} \to
π^{0} X^{0}$ decays: We searched for the $CP$-violating rare decay of neutral kaon, $K_{L} \to
\pi^0 \nu \overline{\nu}$, in data from the first 100 hours of physics running
in 2013 of the J-PARC KOTO experiment. One candidate event was observed while
$0.34\pm0.16$ background events were expected. We set an upper limit of
$5.1\times10^{-8}$ for the branching fraction at the 90\% confidence level
(C.L.). An upper limit of $3.7\times10^{-8}$ at the 90\% C.L. for the $K_{L}
\to \pi^{0} X^{0}$decay was also set for the first time, where $X^{0}$ is an
invisible particle with a mass of 135 MeV/$c^{2}$. | hep-ex |
A Compact Beam Stop for a Rare Kaon Decay Experiment: We describe the development and testing of a novel beam stop for use in a
rare kaon decay experiment at the Brookhaven AGS. The beam stop is located
inside a dipole spectrometer magnet in close proximity to straw drift chambers
and intercepts a high-intensity neutral hadron beam. The design process,
involving both Monte Carlo simulations and beam tests of alternative beam-stop
shielding arrangements, had the goal of minimizing the leakage of particles
from the beam stop and the resulting hit rates in detectors, while preserving
maximum acceptance for events of interest. The beam tests consisted of
measurements of rates in drift chambers, scintilation counter hodoscopes, a gas
threshold Cherenkov counter, and a lead glass array. Measurements were also
made with a set of specialized detectors which were sensitive to low-energy
neutrons, photons, and charged particles. Comparisons are made between these
measurements and a detailed Monte Carlo simulation. | hep-ex |
Results of direct dark matter detection with CDEX experiment at CJPL: The China Dark Matter Experiment (CDEX), located at the China Jinping
Underground Laboratory (CJPL) whose overburden is about 2400m rock, aims at
direct searches of light Weakly Interacting Massive Particles (WIMPs). A
single-element 994-gram p-type point contact (PPC) germanium detector (CDEX-1B)
runs inside a solid passive shielding system. To achieve lower background, a
prototype 10kg PPC germanium detector array (CDEX-10), consisting of three
detector strings with three germanium crystals each, is directly immersed in
the liquid nitrogen. With the energy threshold of 160eV, the limits on
WIMP-nucleus scattering are set by energy spectra and annual modulation
analysis, respectively. Incorporating Migdal effect, the data of CDEX-1B are
re-analyzed to search sub-GeV WIMPs. Finally, the future plan of CDEX
experiment in CJPL-II is introduced. | hep-ex |
Meeting Tight Frequency Requirement of Rounded Damped Detuned Structure: Following successful design and fabrication of damped detuned structures, the
R&D for the accelerating structures of the NLC/JLC linear collider project
proceeded to studies of Rounded Damped Detuned Structure with curved cross
section of the cavity shape for increased shunt impedance. The important
features of the structure are the accurately tuned accelerating mode frequency
and the distribution of the first dipole modes smooth and close to the design
distribution. These requirements were met based on the high-accuracy diamond
turning with its capability to realize the periphery tolerance of two microns.
The lowest dipole mode frequencies scattered by 0.6 MHz RMS. The error in the
accelerating mode frequency averaged over a structure was 0.1 MHz by applying a
feed-forward method. | hep-ex |
A Measurement of the tau->electron Branching Ratio: The branching ratio for the decay tau->e nue nutau has been measured using Z0
decay data collected by the OPAL experiment at LEP. In total 33073 tau->e nue
nutau candidates were identified from a sample of 186197 selected tau decays,
giving a branching ratio of 17.81 +- 0.09(stat) +_ 0.06(sys)%. This result is
combined with other measurements to test e-mu and mu-tau universality in
charged-current weak interactions. Additionally, the strong coupling constant
alpha_s has been extracted and evolved to the Z0 mass scale, giving alpha_s =
0.1204 +- 0.0011(exp) +- 0.0019(theory). | hep-ex |
Photoproduction of Dijets with High Transverse Momenta at HERA: Differential dijet cross sections are measured in photoproduction in the
region of photon virtualities Q^2 < 1 GeV^2 with the H1 detector at the HERA ep
collider using an integrated luminosity of 66.6 pb^{-1}. Jets are defined with
the inclusive k_T algorithm and a minimum transverse momentum of the leading
jet of 25 GeV is required. Dijet cross sections are measured in direct and
resolved photon enhanced regions separately. Longitudinal proton momentum
fractions up to 0.7 are reached. The data compare well with predictions from
Monte Carlo event generators based on leading order QCD and parton showers and
with next-to-leading order QCD calculations corrected for hadronisation
effects. | hep-ex |
Indirect CP violation results and HFAG averages: The current status of the search for indirect CP violation in the neutral D
meson system at the B-factories and at LHCb is reported. The indirect CP
asymmetry search is performed by the measurement of the proper-time asymmetry
($A_{\Gamma}$) in decays of $D^0-\bar{D^0}$ mesons to CP eigenstates, $K^-K^+$
and $\pi^- \pi^+$, and by $y_{CP}$, the ratio between the effective lifetime
measured in decay to a CP eigenstate and that to the mixed eigenstate $K \pi$.
All results are consistent with the no CP violation hypothesis. The latest
world averages for mixing and CP asymmetry in the charm sector evaluated by the
Heavy Flavour Averaging Group are presented. The no mixing hypothesis is
excluded at more than 12 standard deviations. The search for direct and
indirect CP violation in the charm sector is consistent with no CP violation at
2.0% confident level. | hep-ex |
Highlight: Forward Physics (LHCf + FASER): The LHC Run III will be a crucial run for the two LHC forward experiments:
LHCf and FASER. In particular, Run III will be the last run where the LHCf
detector can operate and, at the same time, the first run of the new FASER
project. The LHCf experiment is dedicated to precise measurements of forward
production, necessary to tune hadronic interaction models employed in
cosmic-ray physics. In Run III, the experiment will accomplish two fundamental
goals: operating in p-p collisions at $\sqrt{s} = $ 14 TeV, it will acquire a
ten times larger statistics respect to Run II, in order to have precise
measurements of $\pi^{0}$ production; operating in high energy p-O and O-O
collisions, it will measure forward production in a configuration that is very
similar to the first interaction of an Ultra High Energy Cosmic Ray with an
atmospheric nucleus. The FASER experiment is dedicated to the search of new
weakly-interacting light particles, thanks to a forward detector with proper
shielding from Standard Model background. In Run III, the experiment will
search for new particles with a good sensitivity, which can be strongly
improved by a following possible upgrade before HL-LHC. In addition, thanks to
the dedicated FASER$\nu$ detector, the experiment will measure neutrino
production at a collider for the first time. In this contribution, we discuss
the main results expected from the LHCf and FASER experiments in Run III,
highlighting their fundamental contribution in research fields that are not
accessible to the four large LHC experiments. | hep-ex |
Emerging Computing Technologies in High Energy Physics: While in the early 90s High Energy Physics (HEP) lead the computing industry
by establishing the HTTP protocol and the first web-servers, the long
time-scale for planning and building modern HEP experiments has resulted in a
generally slow adoption of emerging computing technologies which rapidly become
commonplace in business and other scientific fields. I will overview some of
the fundamental computing problems in HEP computing and then present the
current state and future potential of employing new computing technologies in
addressing these problems. | hep-ex |
Transition to the region of central collisions: The experimental results on the behaviour of the characteristics of secondary
particles depending on the disintegration degree of nuclei are used to
determine the region of central collisions. It was therefore possible that : -
the correlation between the prosesses of total disintegration of nuclei and the
central collisions of nuclei had been shown; - the existence of the regime
change points in the behaviour of the considered characteristics of secondary
particles depending on the disintegration degree of nuclei had been observed in
the other earlier experiments as well. The number of all protons in
12CC-interactions at the momentum of 4.2 A GeV/c obtained from the 2-m propane
bubble chamber exposed at the Dubna machine is considered as a disintegration
degree of nuclei. The experimental results demonstrate that there are cases
corresponding to the critical phenomena among the events with the central
collisions of nuclei. For 12CC-interaction the behaviour of the number of the
events, depending on Q also depends on the number of fragments and has a
two-steps form. This result could be explained by the existence of nuclear
clusters. The experimental results on the relation between the number of
events, the angular distributions of protons and full number of protons are
presented for 12CC-interactions at the momentum of 4.2 A GeV/c. The influence
of nuclear fragmentation process on the results is also considered. The
obtained results confirm the assumption that there exist the critical phenomena
among the central collisions and it is necessary to use a percolation approach
for the full description of the central collisions. | hep-ex |
Towards Designing and Exploiting Generative Networks for Neutrino
Physics Experiments using Liquid Argon Time Projection Chambers: In this paper, we show that a hybrid approach to generative modeling via
combining the decoder from an autoencoder together with an explicit generative
model for the latent space is a promising method for producing images of
particle trajectories in a liquid argon time projection chamber (LArTPC).
LArTPCs are a type of particle physics detector used by several current and
future experiments focused on studies of the neutrino. We implement a
Vector-Quantized Variational Autoencoder (VQ-VAE) and PixelCNN which produces
images with LArTPC-like features and introduce a method to evaluate the quality
of the images using a semantic segmentation that identifies important
physics-based features. | hep-ex |
Mini-review of rare charmonium decays at BESIII: Recently, LHCb experiment announced a 3.5$\sigma$ evidence for direct CP
violation in $D^0$ decay by looking at the difference between
$A_{CP}(D^0\rightarrow K^+K^-)$ and $A_{CP}(D^0\rightarrow \pi^+\pi^-)$. This
is the first evidence of CP violation in charm system, which may indicate new
physics beyond the Standard Model. Motivated by this measurement, we review
rare processes in charmonium decay, especially, the weak decay, $C$ or $P$
violated decay and lepton flavor violated decays. In case the new physics
appears in charm sector, these rare decays of charmonium states will provide
opportunity to search for significant contributions from physics beyond the
Standard Model. With huge $J/\psi$ and $\psi(2S)$ samples in BESIII experiment,
the rare decays may be feasible. | hep-ex |
Jet Results and Jet Reconstruction Techniques in p+p and their Prospects
in Pb+Pb Collisions in CMS: Copious production of very energetic jets is expected at the LHC due to the
large increase in collision energy. Jet reconstruction at these high center of
mass energies will provide crucial leverage to map out the QCD evolution of
parton energy loss and a unique insight into the nature of the hot QCD matter.
This article presents jet reconstruction techniques and the preliminary jet
results in p+p collisions at $\sqrt{s}=7$ TeV collected by the CMS experiment
at the LHC. Jet reconstruction prospects for the heavy ion collisions are also
discussed. | hep-ex |
Improved measurement of $ψ(2S)$ decays into $τ^{+}τ^{-}$: Using 14M $\psi (2S)$ events collected at BESII, the branching fraction of
$\psi (2S)\to \tau ^{+}\tau ^{-}$ is measured to be $Br_{\tau \tau}=(3.10\pm
0.21\pm 0.38)\times 10^{-3}$, where the first error is statistical and the
second is systematic. | hep-ex |
The CMS Experiment: Status and First Results: After nearly two decades of design, construction and commissioning, the CMS
detector was operated with colliding LHC proton beams for the first time in
November 2009. Collision data were recorded at centre-of-mass energies of 0.9
and 2.36 TeV, and analyzed with a fast turn-around time by the CMS
collaboration. In this talk I will present a selection of commissioning results
and striking first physics resonances observed. Then I will discuss the
analysis of the transverse momentum and rapidity distribution of charged
hadrons, which led to the first CMS physics publication. The excellent
performance of the CMS detector and agreement with predictions from simulation
are impressive for a collider detector at startup and show a great potential
for discovery physics in the upcoming LHC run. | hep-ex |
Measurement of the Branching Fractions for Inclusive $B^-$ and $\bar
B^0$ Decays to Flavor-tagged $D$, $D_s$ and $Λ_c$: We report on the inclusive branching fractions of $B^-$ and of ${\bar B}^0$
mesons decaying to ${D^0 X}$, ${{\bar D}^0 X}$, ${D^+ X}$, ${D^- X}$, ${D_s^+
X}$, ${D_s^- X}$, ${\Lambda_c^+ X}$, ${{\bar \Lambda}_c^- X}$, based on a
sample of 88.9 million $B \bar B$ events recorded with the $BABAR$ detector at
the $\Upsilon(4S)$ resonance. Events are selected by completely reconstructing
one $B$ and searching for a reconstructed charmed particle in the rest of the
event. We measure the number of charmed and of anti-charmed particles per $B$
decay and derive the total charm yield per $B^-$ decay, $n_c^- = 1.313 \pm
0.037 \pm 0.062 ^{+0.063}_{-0.042} $, and per ${\bar B}^0$ decay, $n_c^0 =
1.276 \pm 0.062 \pm 0.058 ^{+0.066}_{-0.046}$ where the first uncertainty is
statistical, the second is systematic, and the third reflects the charm
branching-fraction uncertainties. | hep-ex |
Measurement of the solar neutrino energy spectrum using
neutrino-electron scattering: A measurement of the energy spectrum of recoil electrons from solar neutrino
scattering in the Super--Kamiokande detector is presented. The results shown
here are obtained from 504 days of data taken between the 31st of May, 1996 and
the 25th of March, 1998. The shape of the measured spectrum is compared with
the expectation for solar B8 neutrinos. The comparison takes into account both
kinematic and detector related effects in the measurement process. The spectral
shape comparison between the observation and the expectation gives a chi-square
of 25.3 with 15 degrees of freedom, corresponding to a 4.6% confidence level. | hep-ex |
Search for single top quark production in ppbar collisions at
sqrt(s)=1.96 TeV: We present a search for electroweak production of single top quarks in the
s-channel and t-channel using neural networks for signal-background separation.
We have analyzed 230 pb$^{-1}$ of data collected with the D0 detector at the
Fermilab Tevatron Collider at a center-of-mass energy of 1.96 TeV and find no
evidence for a single top quark signal. The resulting 95% confidence level
upper limits on the single top quark production cross sections are 6.4 pb in
the s-channel and 5.0 pb in the t-channel. | hep-ex |
Measurement of spin correlation in ttbar production using dilepton final
states: We measure the correlation between the spin of the top quark and the spin of
the anti-top quark in (ttbar -> W+ W- b bbar -> l+ nu b l- nubar bbar) final
states produced in ppbar collisions at a center of mass energy sqrt(s)=1.96
TeV, where l is an electron or muon. The data correspond to an integrated
luminosity of 5.4 fb-1 and were collected with the D0 detector at the Fermilab
Tevatron collider. The correlation is extracted from the angles of the two
leptons in the t and tbar rest frames, yielding a correlation strength C=
0.10^{+0.45}_{-0.45}, in agreement with the NLO QCD prediction within two
standard deviations, but also in agreement with the no correlation hypothesis. | hep-ex |
Charmonia production in ALICE: Quarkonia states are expected to provide essential information on the
properties of the high-density strongly-interacting system formed in the early
stages of high-energy heavy-ion collisions. ALICE is the LHC experiment
dedicated to the study of nucleus-nucleus collisions and can study charmonia at
forward rapidity (2.5 < y < 4) via the mu+ mu- decay channel and at mid
rapidity (|y| < 0.9) via the e+ e- decay channel. In both cases charmonia are
measured down to zero transverse momentum. The inclusive J/psi production as a
function of transverse momentum and rapidity in pp collisions at sqrt{s} = 2.76
and 7 TeV are presented. For pp collisions at sqrt{s} = 7 TeV, the inclusive
J/psi production as a function of the charged particle multiplicity, the
inclusive J/psi polarization at forward rapidity and the J/psi prompt to
non-prompt fraction are discussed. Finally, the analysis of the inclusive J/psi
production in the Pb-Pb data collected fall 2011 at a center of mass energy of
sqrt{s_{NN}} = 2.76 TeV is presented. Results on the nuclear modification
factor are then shown as a function of centrality, transverse momentum and
rapidity and compared to model predictions. First results on inclusive J/psi
elliptic flow are given. | hep-ex |
Measurement of final-state correlations in neutrino muon-proton
mesonless production on hydrocarbon at $\langle E_ν\rangle=3$ GeV: Final-state kinematic imbalances are measured in mesonless production of
$\nu_\mu + A \to \mu^- + p + X$ in the MINERvA tracker. Initial- and
final-state nuclear effects are probed using the direction of the $\mu^-$-p
transverse momentum imbalance and the initial-state momentum of the struck
neutron. Differential cross sections are compared to predictions based on
current approaches to medium modeling. These models under-predict the cross
section at intermediate intranuclear momentum transfers that generally exceed
the Fermi momenta. As neutrino interaction models need to correctly incorporate
the effect of the nucleus in order to predict neutrino energy resolution in
oscillation experiments, this result points to a region of phase space where
additional cross section strength is needed in current models, and demonstrates
a new technique that would be suitable for use in fine grained liquid argon
detectors where the effect of the nucleus may be even larger. | hep-ex |
Jet charge identification in ee-Z-qq process at Z pole operation: Accurate jet charge identification is essential for precise electroweak and
flavor measurements at the high-energy frontier. We propose a novel method
called the Leading Particle Jet Charge method (LPJC) to determine the jet
charge based on information about the leading charged particle. Tested on Z -
bb and Z - cc samples at a center-of-mass energy of 91.2GeV, the LPJC achieves
an effective tagging power of 20%/9% for the c/b jet, respectively. Combined
with the Weighted Jet Charge method (WJC), we develop a Heavy Flavor Jet Charge
method (HFJC), which achieves an effective tagging power of 39%/20% for c/b
jet, respectively. This paper also discusses the dependencies between jet
charge identification performance and the fragmentation process of heavy flavor
jets, and critical detector performances. | hep-ex |
Spin-Parity Analysis of ppbar Mass Threshold Structure in J/psi and psi'
Radiative Decays: A partial wave analysis of the $p \bar{p}$ mass-threshold enhancement in the
reaction $J/\psi\rightarrow\gamma p\bar{p}$ is used to determine: its $J^{PC}$
quantum numbers to be $0^{-+}$; its peak mass to be below threshold at
$M=1832^{+19}_{-5} {\rm(stat.)}^{+18}_{-17} {\rm (syst.)}\pm19 {\rm (model)}
{\rm MeV}/c^2$; and its total width to be $\Gamma<76 {\rm MeV}/c^2$ at the 90%
C.L. The product branching ratio is measured to be $B(J/\psi\rightarrow\gamma
X(p\bar{p}))B(X(p\bar{p})\rightarrow p\bar{p})=(9.0^{+0.4}_{-1.1} {\rm
(stat.)}^{+1.5}_{-5.0} {\rm (syst.)}\pm2.3 {\rm (model)})\times10^{-5}$. A
similar analysis performed on $\psi^\prime\rightarrow\gamma p\bar{p}$ decays
shows, for the first time, the presence of a corresponding enhancement with a
production rate relative to that for $J/\psi$ decays of
$R=(5.08^{+0.71}_{-0.45} {\rm (stat.)}^{+0.67}_{-3.58} {\rm (syst.)}\pm0.12
{\rm (model)})%$. | hep-ex |
Precision Electroweak Measurements at FCC-ee: The prospects for electroweak precision measurements at the Future Circular
Collider with electron-positron beams (FCC-ee) are discussed. The Z mass and
width, as well as the value of the electroweak mixing angle, can be measured
with very high precision at the Z pole thanks to an instantaneous luminosity
five to six order of magnitudes larger than LEP. At centre-of-mass energies
around 160 GeV, corresponding to the WW production threshold, the W mass can be
determined very precisely with high-statistics cross section measurements at
several energy points. Similarly, a very precise determination of the top mass
can be provided by an energy scan at the $\mathrm{t \bar t}$ production
threshold, around 350 GeV. | hep-ex |
Search for lepton flavor violating $τ\to \ell V^0$ decays at Belle: We have searched for neutrinoless $\tau$ lepton decays into $\ell$ and $V^0$,
where $\ell$ stands for an electron or muon, and $V^0$ for a vector meson
($\phi$, $\omega$, $K^{*0}$ or $\bar{K}^{*0}$), using 543 fb$^{-1}$ of data
collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$
collider. No excess of signal events over the expected background is observed,
and we set upper limits on the branching fractions in the range $(0.7 - 1.8)
\times 10^{-7}$ at the 90% confidence level. These upper limits include the
first results for $\ell \omega$ as well as new limits that are $3.6 - 9.6$
times more restrictive than our previous results for $\ell \phi$, $\ell K^{*0}$
and $\ell \bar{K}^{*0}$. | hep-ex |
Vector Boson Fusion Higgs Production at the LHC - Mass Variables: There exist substantial backgrounds to the vector boson fusion production of
Higgs at the LHC. Mass variables are studied which may alleviate the need to
assume a spin zero WW resonance in order to achieve a sufficient signal to
noise ratio in the two jet plus two lepton and missing energy final state. | hep-ex |
Measurements of t t-bar spin correlations and top-quark polarization
using dilepton final states in pp collisions at sqrt(s) = 7 TeV: Spin correlations in the top quark-antiquark system and the polarization of
the top quark are measured using dilepton final states produced in pp
collisions at the LHC at sqrt(s) = 7 TeV. The data correspond to an integrated
luminosity of 5.0 inverse femtobarns collected with the CMS detector. The
measurements are performed using events with two oppositely charged leptons
(electrons or muons), a significant imbalance in transverse momentum, and two
or more jets, where at least one of the jets is identified as originating from
a b quark. The spin correlations and polarization are measured through
asymmetries in angular distributions of the two selected leptons, unfolded to
the parton level. All measurements are found to be in agreement with
predictions of the standard model. | hep-ex |
High-statistics measurement of neutral-pion pair production in
two-photon collisions: We present a high-statistics measurement of differential cross sections and
the total cross section for the process gamma gamma -> pi^0 pi^0 in the
kinematic range 0.6 GeV <= W <= 4.0 GeV and |cos theta*| <= 0.8, where W and
theta* are the energy and pion scattering angle, respectively, in the gamma
gamma center-of-mass system. Differential cross sections are fitted to obtain
information on S, D_0, D_2, G_0 and G_2 waves. The G waves are important above
W ~= 1.6 GeV. General behavior of partial waves is studied by fitting
differential cross sections in a simple parameterization where amplitudes
contain resonant contributions and smooth background. The D_2 wave is dominated
by the f_2(1270) meson whose parameters are consistent with the with the
current world averages. The D_0 wave contains a f_2(1270) component, whose
fraction is fitted. For the S wave, the f_0(980) parameters are found to be
consistent with the values determined from our recent pi^+ pi^- data. In
addition to the f_0(980), the S wave prefers to have another resonance-like
contribution whose parameters are obtained. | hep-ex |
Measurement of the $B^0$--$\bar B^0$ oscillation frequency $Δm_d$
with the decays $B^0 \to D^- π^+$ and $B^0 \to J/ ψK^{*0}$: The $B^0$--$\bar B^0$ oscillation frequency $\Delta m_d$ is measured by the
LHCb experiment using a dataset corresponding to an integrated luminosity of
$1.0\,$fb$^{-1}$ of proton-proton collisions at $\sqrt{s} = 7\,$TeV, and is
found to be $\Delta m_d = 0.5156 \pm 0.0051\,($stat.$) \pm
0.0033\,($syst.$)\,$ps$^{-1}$. The measurement is based on results from
analyses of the decays $B^0 \to D^- \pi^+$ ($D^- \to K^+ \pi^- \pi^-$) and $B^0
\to J/ \psi K^{*0}$ ($ J/ \psi \to \mu^+ \mu^-$, $K^{*0} \to K^+ \pi^-$) and
their charge conjugated modes. | hep-ex |
Measurements of Parity-Violation Parameters at SLD: We present direct measurements of the parity-violation parameters $A_b$,
$A_c$, and $A_s$ at the $Z^0$ resonance with the SLD detector. The measurements
are based on approximately 530k hadronic $Z^0$ events collected in 1993-98.
Obtained results are $A_b = 0.914\pm0.024$ (SLD combined: preliminary), $A_c =
0.635\pm0.027$ (SLD combined: preliminary), and $A_s = 0.895\pm0.066(stat.)\pm
0.062(sys.)$. | hep-ex |
Searches for Extra Spatial Dimensions with the CMS Detector at the LHC: The success of the first three years of operations of the LHC at
center-of-mass energies of 7 and 8 TeV radically changed the landscape of
searches for new physics beyond the standard model and our very way of thinking
about its possible origin and its hiding place. Among the paradigms of new
physics that have been probed quite extensively at the LHC, are various models
that predict the existence of extra spatial dimensions. In this review, the
current status of searches for extra dimensions with the CMS detector is
presented, along with prospects for future searches at the full energy of the
LHC, expected to be reached in the next few years. | hep-ex |
Search for the Rare Decays J/Psi --> Ds- e+ nu_e, J/Psi --> D- e+ nu_e,
and J/Psi --> D0bar e+ e-: We report on a search for the decays J/Psi --> Ds- e+ nu_e + c.c., J/Psi -->
D- e+ nu_e + c.c., and J/Psi --> D0bar e+ e- + c.c. in a sample of 5.8 * 10^7
J/Psi events collected with the BESII detector at the BEPC. No excess of signal
above background is observed, and 90% confidence level upper limits on the
branching fractions are set: B(J/Psi --> Ds- e+ nu_e + c.c.)<4.8*10^-5, B(J/Psi
--> D- e+ nu_e + c.c.)<1.2*10^-5, and B(J/Psi --> D0bar e+ e- + c.c.)<1.1*10^-5 | hep-ex |
Midrapidity antiproton-to-proton ratio in pp collisions at $\sqrt{s} =
0.9$ and $7$ TeV measured by the ALICE experiment: The ratio of the yields of antiprotons to protons in pp collisions has been
measured by the ALICE experiment at $\sqrt{s} = 0.9$ and $7$ TeV during the
initial running periods of the Large Hadron Collider(LHC). The measurement
covers the transverse momentum interval $0.45 < p_{\rm{t}} < 1.05$ GeV/$c$ and
rapidity $|y| < 0.5$. The ratio is measured to be $R_{|y| < 0.5} = 0.957 \pm
0.006 (stat.) \pm 0.014 (syst.)$ at $0.9$ TeV and $R_{|y| < 0.5} = 0.991 \pm
0.005 (stat.) \pm 0.014 (syst.)$ at $7$ TeV and it is independent of both
rapidity and transverse momentum. The results are consistent with the
conventional model of baryon-number transport and set stringent limits on any
additional contributions to baryon-number transfer over very large rapidity
intervals in pp collisions. | hep-ex |
Exclusive $π^+π^-$ Production at the LHC with Forward Proton Tagging: A process of Central Exclusive $\pi^+\pi^-$ production in proton-proton
collisions and its theoretical description is presented. A possibility of its
measurement, during the special low luminosity LHC runs, with the help of the
ATLAS central detector for measuring pions and the ALFA stations for tagging
the scattered protons is studied. A visible cross section is estimated to be 21
$\mu$b for $\sqrt{s}=7$ TeV, which gives over 2000 events for 100 $\mu$b$^{-1}$
of integrated luminosity. Differential distributions in pion pseudorapidities,
pion and proton transverse momenta as well as $\pi^+\pi^-$ invariant mass are
shown and discussed. | hep-ex |
Inclusive Jet Production in DIS at High Q^2 and Extraction of the Strong
Coupling: Inclusive jet production is studied in neutral current deep-inelastic
positron-proton scattering at large four momentum transfer squared Q^2>150
GeV^2 with the H1 detector at HERA. The measurements are found to be well
described by calculations at next-to-leading order in perturbative QCD.
The running of the strong coupling is demonstrated and the value of
alpha_s(M_Z) is determined. | hep-ex |
CP Violation in B Decays at the Tevatron: Between 1992 to 1996, the CDF and D0 detectors each collected data samples
exceeding 100 pb^{-1} of p\bar{p} collisions at sqrt{s}=1.8 TeV at the Fermilab
Tevatron. These data sets led to a large number of precision measurements of
the properties of B hadrons including lifetimes, masses, neutral B meson flavor
oscillations, and relative branching fractions, and to the discovery of the B_c
meson. Perhaps the most exciting result was the first look at the CP violation
parameter sin(2beta) using the world's largest sample of fully reconstructed
B^0/bar{B}^0 -> J/psi K^0_S decays. A summary of this result is presented here.
In the year 2000, the Tevatron will recommence p\bar{p} collisions with an over
order of magnitude expected increase in integrated luminosity (1 fb^{-1} per
year). The CDF and D0 detectors will have undergone substantial upgrades,
particularly in the tracking detectors and the triggers. With these
enhancements, the Tevatron B physics program will include precision
measurements of sin(2beta) and B^0_s flavor oscillations, as well as studies of
rare B decays that are sensitive to new physics. The studies of B^0_s mesons
will be particularly interesting as this physics will be unique to the Tevatron
during the first half of the next decade. | hep-ex |
Measurement of b-jet Shapes in Inclusive Jet Production in p pbar
Collisions at sqrt{s} = 1.96 TeV: We present a measurement of the shapes of b-jets using 300 pb-1 of data
obtained with the upgraded Collider Detector at Fermilab (CDF II) in p pbar
collisions at center of mass energy sqrt{s}=1.96 TeV. This measurement covers a
wide transverse momentum range, from 52 to 300 GeV/c. Samples of heavy-flavor
enhanced jets together with inclusive jets are used to extract the average
shapes of b-jets. The b-jets are expected to be broader than inclusive jets.
Moreover, b-jets containing a single b-quark are expected to be narrower than
those containing a b bbar pair from gluon splitting. The measured b-jet shapes
are found to be significantly broader than expected from the PYTHIA and HERWIG
Monte Carlo simulations. This effect may arise from an underestimation of the
fraction of b-jets originating from gluon splitting in these simulations. | hep-ex |
Identification of boosted Higgs bosons decaying into $b$-quark pairs
with the ATLAS detector at 13 TeV: This paper describes a study of techniques for identifying Higgs bosons at
high transverse momenta decaying into bottom-quark pairs, $H \rightarrow
b\bar{b}$, for proton-proton collision data collected by the ATLAS detector at
the Large Hadron Collider at a centre-of-mass energy $\sqrt{s}=13$ TeV. These
decays are reconstructed from calorimeter jets found with the anti-$k_{t}$ $R =
1.0$ jet algorithm. To tag Higgs bosons, a combination of requirements is used:
$b$-tagging of $R = 0.2$ track-jets matched to the large-$R$ calorimeter jet,
and requirements on the jet mass and other jet substructure variables. The
Higgs boson tagging efficiency and corresponding multijet and hadronic
top-quark background rejections are evaluated using Monte Carlo simulation.
Several benchmark tagging selections are defined for different signal
efficiency targets. The modelling of the relevant input distributions used to
tag Higgs bosons is studied in 36 fb$^{-1}$ of data collected in 2015 and 2016
using $g\to b\bar{b}$ and $Z(\rightarrow b\bar{b})\gamma$ event selections in
data. Both processes are found to be well modelled within the statistical and
systematic uncertainties. | hep-ex |
Search for Hidden Photon Dark Matter Using a Multi-Cathode Counter: A search for hidden-photon (HP) dark matter using a multi-cathode counter is
reported. The technique based on counting of single electrons emitted from
outer cathode of the proportional counter by hidden-photons was used. The
apparatus and the calibration of the counter by ultraviolet lamp are described.
It is shown that this technique attains a maximum sensitivity in the energy
range of Vacuum Ultraviolet. From the results of measurements we set an upper
limit on the photon-HP mixing parameter \chi. A further progress of using a
multi-cathode technique is discussed. | hep-ex |
Observation of $B^+ \to χ_{c0} K^+ $: We report the first observation of the decay $B^+ \to \chi_{c0} K^+$ using
21.3 fb$^{-1}$ of data collected by the Belle detector at the $\Upsilon$(4S)
resonance. The preliminary result for the branching fraction is
${\cal{B}}(B^+\to \chi_{c0}K^+)=(8.0^{+2.7}_{-2.4}\pm 1.0\pm 1.1)\times
10^{-4}$ where the first error is statistical, the second is systematic, and
the third comes from the uncertainty in the $\chi_{c0}\to\pi^+\pi^-$ branching
fraction. | hep-ex |
Measurement of the CP-violating phase φ_s^{J/ψφ} at D0: This paper is a report of an updated measurement of the CP-violating phase
and the decay width difference for the two mass eigenstates from flavor-tagged
decay Bs0 to J/psi phi}. The 68% confidence level intervals, including
systematic uncertainties, are phi_s=-0.55 ^{+0.38}_{-0.36}$ and \Delta \Gamma_s
= 0.163 ^{+0.065}_{-0.064}$ ps^{-1}. This measurement is in agreement with SM
expected value, the p-value for the Standard Model point is 29.8%. The data
sample corresponds to an integrated luminosity of 8.0 fb^{-1} accumulated with
the D0 detector at the Fermilab Tevatron collider. | hep-ex |
Inclusive production of $W$ in pp Collisions in a range of
center-of-mass energy from 7 to 100 TeV: The proton-proton collision energy at Large Hadron Collider (LHC) has been 7,
8 and 13 TeV recently with the goal of reaching to 14 TeV which is the maximum
capacity of the LHC. However, there is still more physics yet to be explored
and tested beyond the energy regime of the LHC to reach new discoveries.
Therefore, a new collider bigger than the LHC machine, which will be able to
collide protons at 100 TeV center-of-mass energy, is under consideration by the
high-energy physics community. To provide an insight to the transition from LHC
to 100 TeV collider, some properties of W processes are investigated in a range
of collision energy from 7 to 100 TeV using HERAPDF2.0, MMHT2014, NNPDF3.1 and
CT14 NNLO PDF models at NNLO QCD. The considered properties are the production
rates of W, the change of uncertainties (PDF, renormalization and factorization
scales, strong coupling constant, model and parameterization), and W boson
lepton charge asymmetry. | hep-ex |
Searches for the Supersymmetric Partner of the Bottom Quark: We have performed a search for the scalar bottom quark from gluino decays in
an R-parity conserving SUSY scenario with m(gluino) > m(sbottom), by
investigating a final state of large missing transverse energy, with three or
more jets, and some of them from the hadronization of b-quarks. A data sample
of 156pb-1 collected by the Collider Detector at Fermilab at a center-of-mass
energy of 1.96TeV was used. For the final selection, jets containing secondary
displaced vertices were required. This analysis has been performed 'blind', in
that the inspection of the signal region was only made after the standard model
prediction was fina lized. Comparing data with SUSY predictions, we can exclude
masses of the gluino and sbottom of up to 280 and 240GeV/c^2 respectively. | hep-ex |
Real and Virtual Photon Structure at HERA: The structure of real and virtual photons has been studied in ep collisions
at HERA using dijet production. Measurements of differential dijet cross
sections as function of the fraction of photon's momentum invested in the dijet
system are presented. The dependence of the cross sections on the virtuality of
the photon and mean transverse energy squared of the two leading jets has been
investigated. QCD calculations based on current parametrizations of the real
and virtual photon parton distribution functions have been compared to the
data. | hep-ex |
A Non-parametric Approach to Measuring the \kpi{} Amplitudes in
\dpkkpi{} Decay: Using a large sample of \dpkkpi{} decays collected by the FOCUS
photoproduction experiment at Fermilab, we present the first non-parametric
analysis of the \kpi{} amplitudes in \dpkkpi{} decay. The technique is similar
to the technique used for our non-parametric measurements of the \krzmndk{}
form factors. Although these results are in rough agreement with those of E687,
we observe a wider S-wave contribution for the \ksw{} contribution than the
standard, PDG \cite{pdg} Breit-Wigner parameterization. We have some weaker
evidence for the existence of a new, D-wave component at low values of the $K^-
\pi^+$ mass. | hep-ex |
Results from LHCf Experiment: The LHCf experiment has taken data in 2009 and 2010 p-p collisions at LHC at
$\sqrt{s} = 0.9$ TeV and $\sqrt{s} = 7$ TeV. The measurement of the forward
neutral particle spectra produced in proton-proton collisions at LHC up to an
energy of 14 TeV in the center of mass system are of fundamental importance to
calibrate the Monte Carlo models widely used in the high energy cosmic ray
(HECR) field, up to an equivalent laboratory energy of the order of $10^{17}$
eV. In this paper the first results on the inclusive photon spectrum measured
by LHCf is reported. Comparison of this spectrum with the model expectations
show significant discrepancies, mainly in the high energy region. In addition,
perspectives for future analyses as well as the program for the next data
taking period, in particular the possibility to take data in p-Pb collisions,
will be discussed. | hep-ex |
Tests of the Electroweak Symmetry Breaking Sector at the Tevatron: The phenomenology of the electroweak symmetry breaking sector is expected to
involve resonances decaying preferentially into heavy fermions. Three recent
CDF analyses are reviewed and used to constrain Higgs and Technicolor models. | hep-ex |
A search for a doubly-charged Higgs boson in pp collisions at sqrt(s) =
7 TeV: A search for a doubly-charged Higgs boson in pp collisions at sqrt(s) = 7 TeV
is presented. The data correspond to an integrated luminosity of 4.9 inverse
femtobarns, collected by the CMS experiment at the LHC. The search is performed
using events with three or more isolated charged leptons of any flavor, giving
sensitivity to the decays of pair-produced triplet components Phi[++]Phi[--],
and Phi[++]Phi[-] from associated production. No excess is observed compared to
the background prediction, and upper limits at the 95% confidence level are set
on the Phi[++] production cross section, under specific assumptions on its
branching fractions. Lower bounds on the Phi[++] mass are reported, providing
significantly more stringent constraints than previously published limits. | hep-ex |
High Energy Colliding Beams; What Is Their Future?: The success of the first few years of LHC operations at CERN, and the
expectation of more to come as the LHC performance improves, are already
leading to discussions of what should be next for both proton-proton and
electron-positron colliders. In this discussion I see too much theoretical
desperation caused by the so far unsuccessful hunt for what is beyond the
Standard Model, and too little of the necessary interaction of the accelerator,
experimenter, and theory communities necessary for a scientific and engineering
success. Here, I give my impressions of the problem, its possible solution, and
what is needed to have both a scientifically productive and financially viable
future. | hep-ex |
An Improved Determination of $α_{S}$ From Neutrino-Nucleon
Scattering: We present an improved determination of the proton structure functions
$F_{2}$ and $xF_{3}$ from the CCFR $\nu $-Fe deep inelastic scattering (DIS)
experiment. Comparisons to high-statistics charged-lepton scattering results
for $F_{2}$ from the NMC, E665, SLAC, and BCDMS experiments, after correcting
for quark-charge and heavy-target effects, indicate good agreement for $x>0.1$
but some discrepancy at lower x. The $Q^{2}$ evolution of the structure
functions yields the quantum chromodynamics (QCD) scale parameter
$\Lambda_{\bar{MS}}^{NLO,(4)}=337 \pm 28$(exp.) MeV. This corresponds to a
value of the strong coupling constant at the scale of mass of the Z-boson of
$\alpha _{S}(M_{Z}^{2})=0.119 \pm 0.002 (exp.) \pm 0.004 (theory)$ and is one
of the most precise measurements of this quantity. | hep-ex |
Measurement of the ttbar production cross section using dilepton events
in ppbar collisions: We present a measurement of the ttbar production cross section sigma(ttbar)
in ppbar collisions at sqrt{s} = 1.96 TeV using 5.4 fb-1 of integrated
luminosity collected with the D0 detector. We consider final states with at
least two jets and two leptons (ee, emu, mumu), and events with one jet for the
the emu final state as well. The measured cross section is sigma(ttbar)= 7.36
+0.90-0.79 (stat + syst) pb. This result combined with the cross section
measurement in the lepton + jets final state yields sigma(ttbar)=7.56
+0.63-0.56 (stat + syst) pb, which agrees with the standard model expectation.
The relative precision of 8% of this measurement is comparable to the latest
theoretical calculations. | hep-ex |
Observation of a new χ_b state at ATLAS and a new Ξ_b baryon at CMS: Two recent observations of new b hadrons in pp collisions at \sqrt{s} = 7 TeV
at the Large Hadron Collider (LHC) are presented. The ATLAS collaboration has
observed a new state in radiative transitions to \Upsilon(1S) and \Upsilon(2S)
and interprets this as the first observation of the \chi_b(3P) states. The CMS
collaboration has observed a new b baryon decaying to \Xi_b-\pi+ (plus charge
conjugates). This is interpreted as a neutral J^P = 3/2^+ \Xi_b* baryon. | hep-ex |
Charmed Hadrons from Fragmentation and B Decays: The fragmentation functions of $D^0$, $D^{\pm}$, $D_s^{\pm}$, $D^{*o}$,
$D^{*\pm}$ and $\Lambda_c^{\pm}$ at $\sqrt{s}$$\simeq$10.6 GeV are measured
with a data set of 102.7 fb$^{-1}$. Fragmentation model parametrizations
(Peterson, Kartvelishvili, Collins-Spiller, Lund, and Bowler models) are
compared to the data. The data at high $x$$\simeq$1 indicate a contribution of
non-perturbative QCD processes. | hep-ex |
Elliptic flow of charm and strange hadrons in high-multiplicity pPb
collisions at $\sqrt{s_{_\mathrm{NN}}} =$ 8.16 TeV: The elliptic azimuthal anisotropy coefficient ($v_2$) is measured for charm
(D$^0$) and strange (K$_\mathrm{S}^0$, $\Lambda$, $\Xi^-$, and $\Omega^-$)
hadrons, using a data sample of pPb collisions collected by the CMS experiment,
at a nucleon-nucleon center-of-mass energy $\sqrt{s_{_\mathrm{NN}}} =$ 8.16
TeV. A significant positive $v_2$ signal from long-range azimuthal correlations
is observed for all particle species in high-multiplicity pPb collisions. The
measurement represents the first observation of possible long-range
collectivity for open heavy flavor hadrons in small systems. The results
suggest that charm quarks have a smaller $v_2$ than the lighter quarks,
probably reflecting a weaker collective behavior. This effect is not seen in
the larger PbPb collision system at $\sqrt{s_{_\mathrm{NN}}} =$ 5.02 TeV, also
presented. | hep-ex |
Search for Extra Dimensions in the Diphoton Channel: We present a search for extra dimensions in the diphoton channel using the
CMS detector at the Large Hadron Collider. The search is focused on the
forthcoming 2009--2010 run at 10 TeV center$-$of$-$mass energy and $\sim 100$
pb$^{-1}$ of data. We discuss event selection and optimization, as well as
data-driven methods of estimating various backgrounds and efficiencies. The
dominant source of background after all the selection requirements is SM
diphoton production. We quote the sensitivity of the search both in terms of
limits on the parameters of large and warped extra dimensions in the case of no
excess observed, and in terms of signal discovery significance, if an excess is
seen in data. | hep-ex |
Study of hard double-parton scattering in four-jet events in $pp$
collisions at $\sqrt{s} = 7$ TeV with the ATLAS experiment: Inclusive four-jet events produced in proton-proton collisions at a
centre-of-mass energy of $\sqrt{s} = 7$ TeV are analysed for the presence of
hard double-parton scattering using data corresponding to an integrated
luminosity of 37.3 pb$^{-1}$, collected with the ATLAS detector at the LHC. The
contribution of hard double-parton scattering to the production of four-jet
events is extracted using an artificial neural network, assuming that hard
double-parton scattering can be approximated by an uncorrelated overlaying of
dijet events. For events containing at least four jets with transverse momentum
$p_{\mathrm{T}} \geq 20$ GeV and pseudorapidity $\eta \leq 4.4$, and at least
one having $p_{\mathrm{T}} \geq 42.5$ GeV, the contribution of hard
double-parton scattering is estimated to be $f_{\mathrm{DPS}} = 0.092
^{+0.005}_{-0.011} (\mathrm{stat.}) ^{+0.033}_{-0.037} (\mathrm{syst.})$. After
combining this measurement with those of the inclusive dijet and four-jet
cross-sections in the appropriate phase space regions, the effective overlap
area between the interacting protons, $\sigma_{\mathrm{eff}}$, was determined
to be $\sigma_{\mathrm{eff}} = 14.9 ^{+1.2}_{-1.0} (\mathrm{stat.})
^{+5.1}_{-3.8} (\mathrm{syst.})$ mb. This result is consistent within the
quoted uncertainties with previous measurements of $\sigma_{\mathrm{eff}}$,
performed at centre-of-mass energies between 63 GeV and 8 TeV using various
final states, and it corresponds to $21^{+7}_{-6}$% of the total inelastic
cross-section measured at $\sqrt{s} = 7$ TeV. The distributions of the
observables sensitive to the contribution of hard double-parton scattering,
corrected for detector effects, are also provided. | hep-ex |
Observation of a diffractive contribution to dijet production in
proton-proton collisions at $\sqrt{s} = 7$ TeV: The differential cross section measurement for dijet production at
proton-proton collisions at $\sqrt{s}=7$ TeV is presented as a function of an
approximation for the fractional momentum loss of the scattered proton
($\tilde{\xi}$), an useful observable to distinguish model predictions of
diffractive and nondiffractive components. The data was collected by the CMS
detector at low instantaneous luminosity runs at LHC, corresponding to an
integrated luminosity of $2.7 {\rm nb}^{-1}$. This is the first observation of
single diffractive dijets at LHC. | hep-ex |
The Physics of Deep-Inelastic Scattering at HERA: In this paper an introduction to the physics of deep-inelastic scattering is
given together with an account of some of the most recent results on the proton
structure obtained in electron-- and positron--proton collisions at the HERA
collider. | hep-ex |
Measurements of Neutrino Cross Sections Near 1 GeV: We summarise recent neutrino and antineutrino measurements near 1 GeV by the
K2K, MiniBooNE and SciBooNE collaborations. We focus on experimental methods
and note discrepancies between the most commonly used models for
neutrino-nucleus interactions and recent high statistics observations of
charged-current quasi-elastic scattering as well as charged and neutral current
pion production on carbon and oxygen. We discuss possible directions for future
measurements. | hep-ex |
Some Properties of the Very High Q^2 Events of HERA: The kinematic reconstruction of neutral current high Q^2 events at HERA is
discussed in detail using as an example the recently published events of the H1
and ZEUS collaborations at Q^2 > 15000 GeV^2 and M > 180 GeV, which are more
numerous than expected from Standard Model predictions. Taking into account the
complete information of these events, the mass reconstruction is improved and
the difference between the average mass of the samples of the two experiments
is reduced from 26+/-10 GeV to 17+/-7 GeV, but remains different enough to
render unlikely an interpretation of the excess observed by the two
collaborations as originating from the decay of a single narrow resonance. | hep-ex |
Measurement of the neutrino mixing angle $θ_{23}$ in NOvA: This Letter reports new results on muon neutrino disappearance from NOvA,
using a 14 kton detector equivalent exposure of $6.05\times10^{20}$
protons-on-target from the NuMI beam at the Fermi National Accelerator
Laboratory. The measurement probes the muon-tau symmetry hypothesis that
requires maximal mixing ($\theta_{23} = \pi/4$). Assuming the normal mass
hierarchy, we find $\Delta m^2 = (2.67 \pm 0.11)\times 10^{-3}$ eV$^2$ and
$\sin^2 \theta_{23}$ at the two statistically degenerate values
$0.404^{+0.030}_{-0.022}$ and $0.624^{+0.022}_{-0.030}$, both at the 68%
confidence level. Our data disfavor the maximal mixing scenario with 2.6
$\sigma$ significance. | hep-ex |
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