高能物理-实验学术速递[1.10]
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hep-ex高能物理-实验，共计14篇
【1】 Vertex finding in neutrino-nucleus interaction: A Model Architecture Comparison
标题：中微子-原子核相互作用中的顶点发现：一种模型结构比较
链接：https://arxiv.org/abs/2201.02523
摘要：We compare different neural network architectures for Machine Learning (ML)
algorithms designed to identify the neutrino interaction vertex position in the
MINERvA detector. The architectures developed and optimized by hand are
compared with the architectures developed in an automated way using the package
"Multi-node Evolutionary Neural Networks for Deep Learning" (MENNDL), developed
at Oak Ridge National Laboratory (ORNL). The two architectures resulted in a
similar performance which suggests that the systematics associated with the
optimized network architecture are small. Furthermore, we find that while the
domain expert hand-tuned network was the best performer, the differences were
negligible and the auto-generated networks performed well. There is always a
trade-off between human, and computer resources for network optimization and
this work suggests that automated optimization, assuming resources are
available, provides a compelling way to save significant expert time.
【2】 Inclusive & differential cross-section measurements of top-quark pair production with ATLAS and CMS
标题：用ATLAS和CMS测量顶夸克对产生的包含式和差动式截面
链接：https://arxiv.org/abs/2201.02492
备注：7 pages, 6 figures, Talk at the 14th International Workshop on Top Quark Physics (videoconference), 13-17 September 2021
摘要：Latest results on inclusive top-quark pair production cross-sections are
presented using collision data collected by ATLAS and CMS experiments at the
LHC. Inclusive and differential measurements of top-quark pair production
cross-sections from ATLAS and CMS are presented in the resolved and boosted
kinematic regions. The cross-sections are measured as a function of various
kinematic observables of the top quarks, the jets and leptons of the event
final state.
【3】 Search for long-lived charginos based on a disappearing-track signature using 136 fb$^{-1}$ of $pp$ collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector
链接：https://arxiv.org/abs/2201.02472
备注：Comments: 51 pages in total, author list starting page 35, 9 figures, 8 tables, submitted to EPJC. All figures including auxiliary figures are available at this https URL
摘要：A search for long-lived charginos produced either directly or in the cascade
decay of heavy prompt gluino states is presented. The search is based on
proton-proton collision data collected at a centre-of-mass energy of $\sqrt{s}$
= 13 TeV between 2015 and 2018 with the ATLAS detector at the LHC,
corresponding to an integrated luminosity of 136 fb$^{-1}$. Long-lived
charginos are characterised by a distinct signature of a short and then
disappearing track, and are reconstructed using at least four measurements in
the ATLAS pixel detector, with no subsequent measurements in the
silicon-microstrip tracking volume nor any associated energy deposits in the
calorimeter. The final state is complemented by a large missing
transverse-momentum requirement for triggering purposes and at least one
high-transverse-momentum jet. No excess above the expected backgrounds is
observed. Exclusion limits are set at 95% confidence level on the masses of the
chargino and gluino for different chargino lifetimes. Chargino masses up to 660
(210) GeV are excluded in scenarios where the chargino is a pure wino
(higgsino). For charginos produced during the cascade decay of a heavy gluino,
gluinos with masses below 2.1 TeV are excluded for a chargino mass of 300 GeV
and a lifetime of 0.2 ns.
【4】 An Experiment for Electron-Hadron Scattering at the LHC
标题：大型强子对撞机上的电子-强子散射实验
链接：https://arxiv.org/abs/2201.02436
备注：27 pages, 24 figures, 6 tables; to appear in Eur. Phys. J. C
摘要：Novel considerations are presented on the physics, apparatus and accelerator
designs for a future, luminous, energy frontier electron-hadron ($eh$)
scattering experiment at the LHC in the thirties for which key physics topics
and their relation to the hadron-hadron HL-LHC physics programme are discussed.
Demands are derived set by these physics topics on the design of the LHeC
detector, a corresponding update of which is described. Optimisations on the
accelerator design, especially the interaction region (IR), are presented.
Initial accelerator considerations indicate that a common IR is possible to be
built which alternately could serve $eh$ and $hh$ collisions while other
experiments would stay on $hh$ in either condition. A forward-backward
symmetrised option of the LHeC detector is sketched which would permit
extending the LHeC physics programme to also include aspects of hadron-hadron
physics. The vision of a joint $eh$ and $hh$ physics experiment is shown to
open new prospects for solving fundamental problems of high energy heavy-ion
physics including the partonic structure of nuclei and the emergence of
hydrodynamics in quantum field theory while the genuine TeV scale DIS physics
is of unprecedented rank.
【5】 Search for single production of a vector-like T quark decaying to a top quark and a Z boson in the final state with jets and missing transverse momentum at $\sqrt{s}$ = 13 TeV
链接：https://arxiv.org/abs/2201.02227
备注：Submitted to the Journal of High Energy Physics. All figures and tables can be found at this http URL (CMS Public Pages)
摘要：A search is presented for single production of a vector-like T quark with
charge 2/3 $e$, in the decay channel featuring a top quark and a Z boson, with
the top quark decaying hadronically and the Z boson decaying to neutrinos. The
search uses data collected by the CMS experiment in proton-proton collisions at
a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of
137 fb$^{-1}$ recorded at the CERN LHC in 2016-2018. The search is sensitive to
a T quark mass between 0.6 and 1.8 TeV with decay widths ranging from
negligibly small up to 30% of the T quark mass. Reconstruction strategies for
the top quark are based on the degree of Lorentz boosting of its final state.
At 95% confidence level, the upper limit on the product of the cross section
and branching fraction for a T quark of small decay width varies between 15 and
602 fb, depending on its mass. For a T quark with decay widths between 10 and
30% of its mass, this upper limit ranges between 16 and 836 fb. For most of the
studied range, the results provide the best limits to date. This is the first
search for single T quark production based on the full Run 2 data set of the
LHC.
【6】 Dark sectors in neutron-shining-through-a-wall and nuclear absorption signals
标题：中子穿壁照射信号中的暗区和核吸收信号
链接：https://arxiv.org/abs/2201.02603
备注：12 pages, 2 figures
摘要：We propose new searches for $n^\prime$, a dark baryon that can mix with the
Standard Model neutron. We show that IsoDAR, a proposal to place an intense
cyclotron near a large-volume neutrino detector deep underground, can look for
$n\to n^\prime \to n$ transitions with much lower backgrounds than surface
experiments. This neutron-shining-through-a-wall search would be possible
without any modifications to the experiment and would provide the strongest
laboratory constraints on the $n$-$n^\prime$ mixing for a wide range of mass
splittings. We also consider dark neutrons as dark matter and show that their
nuclear absorption at deep-underground detectors such as SNO and Borexino
places some of the strongest limits in parameter space. Finally, we describe
other $n^\prime$ signatures, such as neutrons shining through walls at
spallation sources, reactors, and the disappearance of ultracold neutrons.
【7】 Fieldable Muon Momentum Measurement using Coupled Pressurized Gaseous Cherenkov Detectors
标题：用耦合加压气态切伦科夫探测器测量可场µ子动量
链接：https://arxiv.org/abs/2201.02591
备注：Transactions of American Nuclear Society Winter meeting, 125 (1), 400-403, 2021
摘要：Cosmic ray muons present a large part of the radiation background and
depending on the application of interest muons can be seen as background noise,
e.g., radiation mapping, radiation protection, dosimetry, or as a useful
interrogation probe such as cosmic ray muon tomography. It is worth noting
recent developments on muon scattering tomography which has emerged as a
prospective noninvasive monitoring method for many applications including spent
nuclear fuel cask monitoring and geotomography. However, it is still very
challenging to measure muon momentum in the field, despite the apparent
benefits, without resorting to large and expensive calorimeters, ring imagers,
or time of flight detectors. Recent efforts at CNL and INFN have developed
large prototypes based on multiple Coulomb scattering coupled with the muon
momentum reconstruction algorithms. While these efforts show promise, no
portable detectors exist that can measure muon momentum in the field. In this
work, we present a new concept for measuring muon momentum using coupled
pressurized gaseous Cherenkov radiators. By carefully selecting the gas
pressure at each radiator we can optimize the muon momentum threshold for which
a muon signal will be detected. This way, a muon passing through the radiators
will only trigger those radiators with momentum threshold less than the actual
muon momentum. By measuring the presence of Cherenkov signals in each radiator,
our system can then estimate the muon momentum. The primary benefit of such a
concept is that it can be compact and portable enough so that it can be
deployed in the field separately or in combination with existing tomography
systems.
【8】 On the definition of local spatial densities in hadrons
标题：关于强子局域空间密度的定义
链接：https://arxiv.org/abs/2201.02565
备注：5 pages, 1 figure
摘要：We show that the matrix element of a local operator between hadronic states
gives rise to an unambiguous definition of the associated spatial density. As
an explicit example, we consider the charge density of a spinless particle in
the rest and moving frames and clarify its relationship to the electric form
factor. Our results suggest that the interpretation of the spatial densities of
local operators and their moments such as the mean square charge radius needs
to be revised.
【9】 Revisiting the gluino mass limits in the pMSSM in the light of the latest LHC data and Dark Matter constraints
标题：根据最新的LHC数据和暗物质约束重新讨论pMSSM中的胶子质量极限
链接：https://arxiv.org/abs/2201.02531
备注：37 pages LaTex, comments are welcome
摘要：The purpose of this paper is to examine the model dependence of the stringent
constraints on the gluino mass obtained from the Large Hadron Collider (LHC)
experiments by analyzing the Run II data using specific simplified models based
on several ad hoc sparticle spectra which cannot be realized even in the fairly
generic pMSSM models. We first revisit the bounds on the gluino mass placed by
the ATLAS collaboration using the $1l + jets + \met$ data. We show that the
exclusion region in the $M_{\widetilde{g}}-M_{\widetilde{\chi}^0_1}$ plane in
the pMSSM scenario sensitively depends on the mass hierarchy between the left
and right squarks and composition of the lighter electroweakinos and, to a
lesser extent, other parameters. Most importantly, for higgsino type lighter
electroweakinos (except for the LSP), the bound on the gluino mass from this
channel practically disappears. However, if such models are confronted by the
ATLAS $jets + \met$ data, fairly strong limits are regained. Thus in the pMSSM
an analysis involving a small number of channels may provide more reliable mass
limits. We have also performed detailed analyses on neutralino dark matter
(DM)constraints in the models we have studied and have found that for a
significant range of LSP masses, the relic density constraints from the
WMAP/PLANCK data are satisfied and LSP-gluino coannihilation plays an important
role in relic density production. We have also checked the simultaneous
compatibility of the models studied here with the direct DM detection, the
IceCube data, and the LHC constraints.
【10】 Commissioning of a hybrid readout TPC test set-up and gas gain simulations
标题：混合读出TPC测试装置的调试和气体增益模拟
链接：https://arxiv.org/abs/2201.02464
备注：Proceedings of TIPP 2021, submitted to: Journal of Physics: Conference Series
摘要：A hybrid readout Time Projection Chamber (TPC) has a simultaneous optical-
and charge readout. The optical readout provides 2D images of particle tracks
in the active volume, whilst the charge readout provides additional information
on the particle position perpendicular to the image plane. A hybrid readout TPC
working at high pressure is an attractive device for physics cases where an
excellent space point resolution and a high target density is required as e.g.
measuring a neutrino beam at the source of a long baseline neutrino oscillation
experiment. In this paper we present two different lines of work towards the
goal of developing hybrid TPC technology: a) Commissioning of a set-up with gas
electron multipliers employing optical and charge readout. b) An analytical
parametrisation of the gas gain for a multi wire proportional chamber based on
garfield++ simulations, which - when validated with measurements - allows to
skip these simulations in the future altogether.
【11】 $m_b(m_Z)$ revisited with Zedometry
标题：$m_b(M_Z)$再论容量计量学
链接：https://arxiv.org/abs/2201.02417
备注：9 pages, 1 figure
摘要：Precision measurements of $Z^0$ boson properties could enable a determination
of the mass of the b quark at the scale of the $Z^0$ boson mass $m_b(m_Z)$. The
dependence of Standard Model predictions on the b quark mass using the program
Gfitter is studied. The precision of the currently available measurements by
the LEP experiments and SLD, together with measurements from the LHC
experiments of the mass of the top quark and the Higgs boson, is not sufficient
for a relevant measurement. The predicted precision of $Z^0$ boson resonance
measurements at future $e^+e^-$ colliders will allow a competitive
determination of $m_b(m_Z)$.
【12】 The mass spectrum and wave functions of the $B_c$ system
标题：$B_c$系统的质量谱和波函数
链接：https://arxiv.org/abs/2201.02318
备注：22 pages, 1 table
摘要：The spectrum and relativistic wave functions of $B_c$ system are investigated
via solving the complete Salpeter equation. Emphasis is placed on the study of
the partial wave content of each $J^P$ state, our study shows that there are 3
categories of $J^P$ states. The first category contains $0^-$ and $0^+$ states,
which are ${}^1S_0$ dominant state with a small amount of $P$ wave and
${}^3P_0$ dominant state with a small amount of $D$ wave, respectively. The
second category includes $1^-$, $2^+$ and $3^-$, etc, natural parity states;
take the $1^-$ state as an example, whose solution is further divided into two
cases, one is ${}^3S_1$ dominant state with small amount of $P$ and $D$ waves,
the other is ${}^3D_1$ dominant state but contains large amount of $S$ and $P$
wave components. The third category includes $1^+$, $2^-$ and $3^+$, etc,
unnatural parity states; take the $1^+$ state as an example, its solutions
appear in pairs, each pair is two ${}^1P_1-{}^3P_1$ mixing states, and the
corresponding mixing angle is calculated using the relativistic wave function.
【13】 Solving Combinatorial Problems at Particle Colliders Using Machine Learning
标题：用机器学习解决粒子对撞机中的组合问题
链接：https://arxiv.org/abs/2201.02205
备注：6 pages, 5 figures, submitted to PRL
摘要：High-multiplicity signatures at particle colliders can arise in Standard
Model processes and beyond. With such signatures, difficulties often arise from
the large dimensionality of the kinematic space. For final states containing a
single type of particle signature, this results in a combinatorial problem that
hides underlying kinematic information. We explore using a neural network that
includes a Lorentz Layer to extract high-dimensional correlations. We use the
case of squark decays in $R$-Parity-violating Supersymmetry as a benchmark,
comparing the performance to that of classical methods.
【14】 How well do we know the gluon polarization in the proton?
标题：我们对质子中的胶子极化有多了解？
链接：https://arxiv.org/abs/2201.02075
备注：36 pages, 11 figures
摘要：We perform the first simultaneous global QCD analysis of spin-averaged and
spin-dependent parton distribution functions (PDFs), including single jet
production data from unpolarized and polarized hadron collisions. We critically
assess the impact of SU(3) flavor symmetry and PDF positivity assumptions on
the quark and gluon helicity PDFs, and find strong bias from these,
particularly on the gluon polarization. The simultaneous analysis allows for
the first time extraction of individual helicity-aligned and antialigned PDFs
with a consistent treatment of uncertainties.
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