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High Energy Physics - Experiment

New submissions

[ total of 17 entries: 1-17 ]
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New submissions for Fri, 23 Aug 19

[1]  arXiv:1908.08215 [pdf, other]
Title: Search for electroweak production of charginos and sleptons decaying into final states with two leptons and missing transverse momentum in $\sqrt{s}=13$ TeV $pp$ collisions using the ATLAS detector
Comments: 30 pages plus author list + cover pages (47 pages total), 8 figures, 9 tables, submitted to EPJ C, All figures including auxiliary figures are available at this https URL
Subjects: High Energy Physics - Experiment (hep-ex)

A search for the electroweak production of charginos and sleptons decaying into final states with two electrons or muons is presented. The analysis is based on 139 fb$^{-1}$ of proton-proton collisions recorded by the ATLAS detector at the Large Hadron Collider at $\sqrt{s}=13$ TeV. Three $R$-parity-conserving scenarios where the lightest neutralino is the lightest supersymmetric particle are considered: the production of chargino pairs with decays via either $W$ bosons or sleptons, and the direct production of slepton pairs. The analysis is optimised for the first of these scenarios, but the results are also interpreted in the others. No significant deviations from the Standard Model expectations are observed and limits at 95 % confidence level are set on the masses of relevant supersymmetric particles in each of the scenarios. For a massless lightest neutralino, masses up to 420 GeV are excluded for the production of the lightest-chargino pairs assuming $W$-boson-mediated decays and up to 1 TeV for slepton-mediated decays, whereas for slepton-pair production, masses up to 700 GeV are excluded assuming three generations of mass-degenerate sleptons.

[2]  arXiv:1908.08461 [pdf, other]
Title: Search for flavour-changing neutral currents in processes with one top quark and a photon using 81 fb$^{-1}$ of $pp$ collisions at $\sqrt{s} = 13$ TeV with the ATLAS experiment
Comments: 34 pages in total, author list starting page 18, 2 figures, 1 table, submitted to Phys. Lett. B. All figures including auxiliary figures are available at this http URL
Subjects: High Energy Physics - Experiment (hep-ex)

A search for flavour-changing neutral current (FCNC) events via the coupling of a top quark, a photon, and an up or charm quark is presented using 81 fb$^{-1}$ of proton-proton collision data taken at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. Events with a photon, an electron or muon, a $b$-tagged jet, and missing transverse momentum are selected. A neural network based on kinematic variables differentiates between events from signal and background processes. The data are consistent with the background-only hypothesis, and limits are set on the strength of the $tq\gamma$ coupling in an effective field theory. These are also interpreted as 95% CL upper limits on the cross section for FCNC $t\gamma$ production via a left-handed (right-handed) $tu\gamma$ coupling of 36 fb (78 fb) and on the branching ratio for $t\rightarrow \gamma u$ of $2.8\times 10^{-5}$ ($6.1\times 10^{-5}$). In addition, they are interpreted as 95% CL upper limits on the cross section for FCNC $t\gamma$ production via a left-handed (right-handed) $tc\gamma$ coupling of 40 fb (33 fb) and on the branching ratio for $t\rightarrow \gamma c$ of $22\times 10^{-5}$ ($18\times 10^{-5}$).

[3]  arXiv:1908.08500 [pdf, other]
Title: Search for supersymmetry using Higgs boson to diphoton decays at $\sqrt{s}$ = 13 TeV
Comments: Submitted to JHEP. All figures and tables can be found at this http URL (CMS Public Pages)
Subjects: High Energy Physics - Experiment (hep-ex)

A search for supersymmetry (SUSY) is presented where at least one Higgs boson is produced and decays to two photons in the decay chains of pair-produced SUSY particles. Two complementary analysis strategies are pursued: one focused on strong SUSY production and the other focused on electroweak SUSY production. The presence of charged leptons, additional Higgs boson candidates, and various kinematic variables are used to categorize events into search regions that are sensitive to different SUSY scenarios. The results are based on data from proton-proton collisions at the Large Hadron Collider at a center-of-mass energy of 13 TeV collected by the CMS experiment, corresponding to an integrated luminosity of 77.5 fb$^{-1}$. No statistically significant excess of events is observed relative to the standard model expectations. We exclude bottom squark pair production for bottom squark masses below 530 GeV and a lightest SUSY particle mass of 1 GeV; wino-like chargino-neutralino production for chargino and neutralino masses below 235 GeV with a gravitino mass of 1 GeV; and higgsino-like chargino-neutralino production in the case where the neutralino decays exclusively to a Higgs boson and a gravitino for neutralino masses below 290 GeV.

Cross-lists for Fri, 23 Aug 19

[4]  arXiv:1908.08166 (cross-list from nucl-ex) [pdf, other]
Title: Nuclear Isotope Production by Ordinary Muon Capture Reaction
Comments: 21 pages, 5 figures
Subjects: Nuclear Experiment (nucl-ex); High Energy Physics - Experiment (hep-ex); Instrumentation and Detectors (physics.ins-det)

Muon capture isotope production (MuCIP) using negative ordinary muon capture reactions (OMC) is used to efficiently produce various kinds of nuclear isotopes for both fundamental and applied science studies. The large capture probability of muon into a nucleus, together with the high intensity muon beam, make it possible to produce nuclear isotopes in the order of 10^{9-10} per second depending on the muon beam intensity. Radioactive isotopes (RIs) produced by MuCIP are complementary to those produced by photon and neutron capture reactions and are used for various science and technology applications. MuCIP on ^{Nat}Mo by using the RCNP MuSIC \muon beam is presented to demonstrate the feasibility of MuCIP. Nuclear isotopes produced by MuCIP are evaluated by using a pre-equilibrium (PEQ) and equilibrium (EQ) proton neutron emission model. Radioactive $^{99}$Mo isotopes and the metastable ^{99m}Tc isotopes, which are used extensively in medical science, are produced by MuCIP on ^{Nat}Mo and ^{100}Mo.

[5]  arXiv:1908.08212 (cross-list from physics.acc-ph) [pdf, other]
Title: Operation of ILC250 at the Z-pole
Subjects: Accelerator Physics (physics.acc-ph); High Energy Physics - Experiment (hep-ex)

ILC (International Linear Collider) has been under consideration as the next global project of particle physics. It's Technical Design Report, published in 2013, described the accelerator for the center-of-mass energy above 200GeV. Operation of ILC at lower center-of-mass energy has not been studies intensively. This report discusses about the ILC for the center-of-mass energy 91.2GeV and presents a possible parameter set.

[6]  arXiv:1908.08302 (cross-list from nucl-th) [pdf, other]
Title: First-forbidden transitions in the reactor anomaly
Subjects: Nuclear Theory (nucl-th); High Energy Physics - Experiment (hep-ex); Nuclear Experiment (nucl-ex)

We describe here microscopic calculations performed on the dominant forbidden transitions in reactor antineutrino spectra above 4 MeV using the nuclear shell model. By taking into account Coulomb corrections in the most complete way, we calculate the shape factor with the highest fidelity and show strong deviations from allowed approximations and previously published results. Despite small differences in the ab initio electron cumulative spectra, large differences on the order of several percents are found in the antineutrino spectra. Based on the behaviour of the numerically calculated shape factors we propose a parametrization of forbidden spectra. Using Monte Carlo techniques we derive an estimated spectral correction and uncertainty due to forbidden transitions. We establish the dominance and importance of forbidden transitions in both the reactor anomaly and spectral shoulder analysis. Based on these results, we conclude that a correct treatment of forbidden transitions is indispensable in both the normalization anomaly and spectral shoulder.

[7]  arXiv:1908.08353 (cross-list from hep-ph) [pdf, other]
Title: CIMBA: fast Monte Carlo generation using cubic interpolation
Authors: Philip Ilten
Comments: 16 pages, 6 figures
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)

Monte Carlo generation of high energy particle collisions is a critical tool for both theoretical and experimental particle physics, connecting perturbative calculations to phenomenological models, and theory predictions to full detector simulation. The generation of minimum bias events can be particularly computationally expensive, where non-perturbative effects play an important role and specific processes and fiducial regions can no longer be well defined. In particular scenarios, particle guns can be used to quickly sample kinematics for single particles produced in minimum bias events. CIMBA (Cubic Interpolation for Minimum Bias Approximation) provides a comprehensive package to smoothly sample predefined kinematic grids, from any general purpose Monte Carlo generator, for all particles produced in minimum bias events. These grids are provided for a number of beam configurations including those of the Large Hadron Collider.

[8]  arXiv:1908.08355 (cross-list from hep-ph) [pdf, other]
Title: Towards the meV limit of the effective neutrino mass in neutrinoless double-beta decays
Comments: 16 pages, 6 figures
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)

In this paper, we emphasize why it is important for future neutrinoless double-beta ($0\nu\beta\beta$) decay experiments to reach the sensitivity to the effective neutrino mass $|m^{}_{\beta\beta}| \approx 1~{\rm meV}$. Assuming such a sensitivity and the precisions on neutrino oscillation parameters after the JUNO experiment, we fully explore the constrained regions of the lightest neutrino mass $m^{}_1$ and two Majorana-type CP-violating phases $\{\rho, \sigma\}$. The implications for the neutrino mass spectrum, the effective neutrino mass $m^{}_\beta$ in beta decays and the sum of three neutrino masses $\Sigma \equiv m^{}_1 + m^{}_2 + m^{}_3$ relevant for cosmological observations are also discussed.

[9]  arXiv:1908.08490 (cross-list from nucl-ex) [pdf, other]
Title: Constraining the Sea Quark Distributions Through W$^\pm$ Cross Section Ratio Measurements at STAR
Authors: M. Posik (for the STAR Collaboration)
Comments: Submitted to DIS 2019 Proceedings. 6 pgs. 5 fig
Subjects: Nuclear Experiment (nucl-ex); High Energy Physics - Experiment (hep-ex)

Over the past several years, parton distribution functions (PDFs) have become more precise. However there are still kinematic regions where more data are needed to help constrain global PDF extractions, such as the ratio of the sea quark distributions $\bar{d}$/$\bar{u}$ near the valence region. Furthermore, current measurements appear to suggest different high-$x$ behaviors of this ratio. The $W$ cross section ratio ($W^+$/$W^-$) is sensitive to the unpolarized quark distributions at large $Q^2$ set by the $W$ mass. Such a measurement can be used to help constrain the $\bar{d}$/$\bar{u}$ ratio. The STAR experiment at RHIC is well equipped to measure the leptonic decays of $W$ bosons, in the mid-pseudorapdity range $\left(|\eta| \leq 1 \right)$, produced in proton-proton collisions at $\sqrt{s}$ = 500/510 GeV. At these kinematics STAR is sensitive to quark distributions near $x$ of 0.16. STAR can also measure $W^+$/$W^-$ in a more forward region ranging from 1.0 $< \eta <$1.5, which extends the sea quark sensitivity to higher $x$. RHIC runs from 2011 through 2013 have collected about 350 pb$^{-1}$ of integrated luminosity, and an additional 350 pb$^{-1}$ from the 2017 run. These proceedings will present preliminary results of the 2011-2013 $W^+$/$W^-$ cross section ratio measurements. Additionally, the $W/Z$ cross section ratio, differential and total $W$ and $Z$ cross sections are presented.

[10]  arXiv:1908.08519 (cross-list from physics.data-an) [pdf, other]
Title: Unfolding as Quantum Annealing
Comments: 8 pages, 5 figures, the source code is available at this https URL
Subjects: Data Analysis, Statistics and Probability (physics.data-an); High Energy Physics - Experiment (hep-ex); Quantum Physics (quant-ph)

High-energy physics is replete with hard computational problems and it is one of the areas where quantum computing could be used to speed up calculations. We present an implementation of likelihood-based regularized unfolding on a quantum computer. The inverse problem is recast in terms of quadratic unconstrained binary optimization (QUBO), which has the same form of the Ising hamiltonian and hence it is solvable on a programmable quantum annealer. We tested the method using a model that captures the essence of the problem, and compared the results with a baseline method commonly used in precision measurements at the Large Hadron Collider (LHC) at CERN. The unfolded distribution is in very good agreement with the original one. We also show how the method can be extended to include the effect of nuisance parameters representing sources of systematic uncertainties affecting the measurement.

Replacements for Fri, 23 Aug 19

[11]  arXiv:1812.11931 (replaced) [pdf, ps, other]
Title: Probing the seesaw mechanism at the 250 GeV ILC
Comments: 8 pages, 4 figures, the version published in Phys. Lett. B (typos in Table III & IV have been corrected after the publication)
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)
[12]  arXiv:1903.05931 (replaced) [pdf, ps, other]
Title: Semileptonic decays of the scalar tetraquark $Z_{bc;\overline{u} \overline{d}}^{0}$
Comments: 10 Pages and 3 Figures
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); High Energy Physics - Lattice (hep-lat)
[13]  arXiv:1906.00489 (replaced) [pdf, other]
Title: Measurements of two-particle correlations in $e^+e^-$ collisions at 91 GeV with ALEPH archived data
Comments: Submitted to Phys. Rev. Lett
Subjects: High Energy Physics - Experiment (hep-ex)
[14]  arXiv:1906.02677 (replaced) [pdf, other]
Title: A First Look on 3D Effects in Open Axion Haloscopes
Comments: 41 pages, 20 figures; typos corrected, references updated
Journal-ref: JCAP08(2019)026
Subjects: Instrumentation and Detectors (physics.ins-det); High Energy Physics - Experiment (hep-ex); High Energy Physics - Phenomenology (hep-ph)
[15]  arXiv:1907.03647 (replaced) [pdf, other]
Title: Phonon and light read out of a Li$_2$MoO$_4$ crystal with multiplexed kinetic inductance detectors
Comments: 7 pages, 9 figures
Subjects: Instrumentation and Detectors (physics.ins-det); High Energy Physics - Experiment (hep-ex); Nuclear Experiment (nucl-ex)
[16]  arXiv:1907.11193 (replaced) [pdf, other]
Title: Searches for Connections Between Dark Matter and Neutrinos with the IceCube High-Energy Starting Event Sample
Authors: Carlos A. Argüelles, Hrvoje Dujmovic (for the IceCube Collaboration)
Comments: Presented at the 36th International Cosmic Ray Conference (ICRC 2019). See arXiv:1907.11699 for all IceCube contributions, 6 pages, 2 figures
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)
[17]  arXiv:1908.07602 (replaced) [pdf, other]
Title: Quest for new physics using astrophysical neutrino flavor in IceCube
Authors: Carlos A. Argüelles, Kareem Farrag, Teppei Katori, Shivesh Mandalia (for the IceCube Collaboration)
Comments: Presented at the 36th International Cosmic Ray Conference (ICRC 2019). See arXiv:1907.11699 for all IceCube contributions. 8 Pages, 2 Figures
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Experiment (hep-ex); High Energy Physics - Phenomenology (hep-ph)
[ total of 17 entries: 1-17 ]
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