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                High Energy Physics - Experiment

                New submissions

                [ total of 20 entries: 1-20 ]
                [ showing up to 2000 entries per page: fewer | more ]

                New submissions for Mon, 25 May 20

                [1]  arXiv:2005.11211 [pdf, ps, other]
                Title: Measurement of the absolute branching fraction of the inclusive decay $Λ_c^+ \to K_S^0X$
                Comments: 8 pages, 3 figures
                Subjects: High Energy Physics - Experiment (hep-ex)

                We report the first measurement of the absolute branching fraction of the inclusive decay $\Lambda_c^+ \to K_S^0X$. The analysis is performed using an $e^+e^-$ collision data sample corresponding to an integrated luminosity of 567 pb$^{-1}$ taken at $\sqrt{s}$ = 4.6 GeV with the BESIII detector. Using eleven Cabibbo-favored $\Lambda_c^+$ decay modes and the double-tag technique, this absolute branching fraction is measured to be $\mathcal{B}(\Lambda_c^+ \to K_S^0X)=(10.1\pm0.6\pm0.4)\%$, where the first uncertainty is statistical and the second systematic. The relative deviation between the branching fractions for the inclusive decay and the observed exclusive decays is $(19.8\pm7.9)\%$, which indicates that there may be some unobserved decay modes with a neutron or excited baryons in the final state.

                [2]  arXiv:2005.11226 [pdf, other]
                Title: A $b$-baryon sonata
                Subjects: High Energy Physics - Experiment (hep-ex); High Energy Physics - Phenomenology (hep-ph)

                LHCb is one of the four experiments at the Large Hadron Collider (CERN), dedicated to the study of b-hadrons. Throughout my research, I studied in particular b-baryons which are abundantly produced at the LHCb. My habilitation summarises the studies of fundamental properties of these particles within the Standard Model. In particular, I discuss both lifetime and mass measurements. This work is followed by a search of New Physics using a Lepton universality test. Finally, I discuss my contribution to the upgrade detectors of the LHCb experiment in particular those related to the calorimeter and the scintillator fibre tracker.

                Cross-lists for Mon, 25 May 20

                [3]  arXiv:2005.10832 (cross-list from hep-ph) [pdf, other]
                Title: Exploring $J/ψ$ production mechanism at the future Electron-Ion Collider
                Comments: 6 pages, 6 figures
                Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)

                We propose to use transverse momentum $p_T$ distribution of $J/\psi$ production at the future Electron Ion Collider (EIC) to explore the production mechanism of heavy quarkonia in high energy collisions. We apply QCD and QED collinear factorization to the production of a $c\bar{c}$ pair at high $p_T$, and non-relativistic QCD factorization to the hadronization of the pair to a $J/\psi$. We evaluate $J/\psi$ $p_T$-distribution at both leading and next-to-leading order in strong coupling, and show that production rates for various color-spin channels of a $c\bar{c}$ pair in electron-hadron collisions are very different from that in hadron-hadron collisions, which provides a strong discriminative power to determine various transition rates for the pair to become a $J/\psi$. We predict that the $J/\psi$ produced in electron-hadron collisions is likely unpolarized, and the production is an ideal probe for gluon distribution of colliding hadron (or nucleus). We find that the $J/\psi$ production is dominated by the color-octet channel, providing an excellent probe to explore the gluon medium in large nuclei at the EIC.

                [4]  arXiv:2005.10907 (cross-list from physics.ins-det) [pdf, ps, other]
                Title: Reactor neutrino applications and coherent elastic neutrino nucleus scattering
                Comments: 5 pages, 3 figures
                Subjects: Instrumentation and Detectors (physics.ins-det); High Energy Physics - Experiment (hep-ex); High Energy Physics - Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Physics and Society (physics.soc-ph)

                Potential applications of neutrino detection to nuclear security have been discussed since the 1970s. Recent years have seen great progress in detector technologies based on inverse beta decay, with the demonstration of ton-scale surface-level detectors capable of high quality neutrino spectrum measurements. At the same time coherent elastic neutrino nucleus scattering has been experimentally confirmed in 2017 with neutrinos from stopped pion decay and there is a number of experiments aimed at seeing this reaction with reactor neutrinos. The large cross section and threshold-less nature of this reaction make it plausible to consider it for applications to nuclear security and here, we present a first direct comparison of the two reaction modes.

                [5]  arXiv:2005.11086 (cross-list from hep-ph) [pdf, other]
                Title: Probing triple Higgs coupling with machine learning at the LHC
                Comments: 20 pages, 6 figures
                Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)

                Measuring the triple Higgs coupling is a crucial task in the LHC and future collider experiments. We apply the Message Passing Neural Network (MPNN) to the study of non-resonant Higgs pair production process $pp \to hh$ in the final state with $2b + 2\ell + E_{\rm T}^{\rm miss}$ at the LHC. Although the MPNN can improve the signal significance, it is still challenging to observe such a process at the LHC. We find that a $2\sigma$ upper bound (including a 10\% systematic uncertainty) on the production cross section of the Higgs pair is 3.7 times the predicted SM cross section at the LHC with the luminosity of 3000 fb$^{-1}$, which will limit the triple Higgs coupling to the range of $[-3,11.5]$.

                [6]  arXiv:2005.11120 (cross-list from nucl-ex) [pdf, other]
                Title: Production of light-flavor hadrons in pp collisions at $\sqrt{s}$ = 7 and $\sqrt{s}$ = 13 TeV
                Comments: 52 pages, 18 figures, 8 tables, authors from page 47, submitted to EPJC, figures at this http URL
                Subjects: Nuclear Experiment (nucl-ex); High Energy Physics - Experiment (hep-ex)

                The production of $\pi^{\pm}$, $\rm{K}^{\pm}$, $\rm{K}^{0}_{S}$, $\rm{K}*(892)^{0}$, $\rm{p}$, $\phi(1020)$, $\Lambda$, $\Xi^{-}$, $\Omega^{-}$, and their antiparticles was measured in inelastic proton-proton (pp) collisions at a center-of-mass energy of $\sqrt{s}$ = 13 TeV at midrapidity ($|y|<0.5$) as a function of transverse momentum ($p_{\rm{T}}$) using the ALICE detector at the CERN LHC. Furthermore, the single-particle $p_{\rm{T}}$ distributions of $\rm{K}^{0}_{S}$, $\Lambda$, and $\overline{\Lambda}$ in inelastic pp collisions at $\sqrt{s}$ = 7 TeV are reported here for the first time. The $p_{\rm{T}}$ distributions are studied at midrapidity within the transverse momentum range $0\leq p_{\rm{T}}\leq20$ GeV/$c$, depending on the particle species. The $p_{\rm{T}}$ spectra, integrated yields, and particle yield ratios are discussed as a function of collision energy and compared with measurements at lower $\sqrt{s}$ and with results from various general-purpose QCD-inspired Monte Carlo models. A hardening of the spectra at high $p_{\rm{T}}$ with increasing collision energy is observed, which is similar for all particle species under study. The transverse mass and $x_{\rm{T}}\equiv2p_{\rm{T}}/\sqrt{s}$ scaling properties of hadron production are also studied. As the collision energy increases from $\sqrt{s}$ = 7 to 13 TeV, the yields of non- and single-strange hadrons normalized to the pion yields remain approximately constant as a function of $\sqrt{s}$, while ratios for multi-strange hadrons indicate enhancements. The $p_{\rm{T}}$-differential cross sections of $\pi^{\pm}$, $\rm{K}^{\pm}$ and $\rm{p}$ ($\overline{\rm{p}}$) are compared with next-to-leading order perturbative QCD calculations, which are found to overestimate the cross sections for $\pi^{\pm}$ and $\rm{p}$ ($\overline{\rm{p}}$) at high $p_{\rm{T}}$.

                [7]  arXiv:2005.11122 (cross-list from nucl-ex) [pdf, other]
                Title: Measurement of the low-energy antideuteron inelastic cross section
                Comments: 19 pages, 4 captioned figures, authors from page 14, submitted to PRL, figures at this http URL
                Subjects: Nuclear Experiment (nucl-ex); High Energy Physics - Experiment (hep-ex)

                In this Letter, we report the first measurement of the antideuteron inelastic cross section at low particle momenta, covering a range of $0.3 \leq p < 4$ GeV/$c$. The measurement is carried out using p-Pb collisions at a center-of-mass energy per nucleon-nucleon pair of $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV, recorded with the ALICE detector at the CERN LHC and utilizing the detector material as an absorber for antideuterons and antiprotons. The extracted raw primary antiparticle-to-particle ratios are compared to the results from detailed ALICE simulations based on the GEANT4 toolkit for the propagation of antiparticles through the detector material. The analysis of the raw primary (anti)proton spectra serves as a benchmark for this study, since their hadronic interaction cross sections are well constrained experimentally. The first measurement of the antideuteron inelastic cross section averaged over the ALICE detector material with atomic mass numbers $\langle A \rangle$ = 19.6 and 29.7 is obtained. The measured inelastic cross section points to a possible excess with respect to the Glauber model parameterization in the lowest momentum interval of $0.3 \leq p < 0.47$ GeV/$c$ up to a factor 2.1. This result is relevant for the understanding of antimatter propagation and the contributions to antinuclei production from cosmic ray interactions within the interstellar medium. In addition, the momentum range covered by this measurement is of particular importance to evaluate signal predictions for indirect dark-matter searches.

                [8]  arXiv:2005.11123 (cross-list from nucl-ex) [pdf, other]
                Title: Multiplicity dependence of J/$ψ$ production at midrapidity in pp collisions at $\sqrt{s}$ = 13 TeV
                Comments: 22 pages, 7 captioned figures, 2 tables, authors from page 17, submitted to PLB, figures at this http URL
                Subjects: Nuclear Experiment (nucl-ex); High Energy Physics - Experiment (hep-ex)

                Measurements of the inclusive J/$\psi$ yield as a function of charged-particle pseudorapidity density $\rm{d}N_\rm{ch}/\rm{d}\eta$ in pp collisions at $\sqrt{s}$ = 13 TeV with ALICE at the LHC are reported. The J/$\psi$ meson yield is measured at midrapidity ($|y|<0.9$) in the dielectron channel, for events selected based on the charged-particle multiplicity at midrapidity ($|\eta|<1$) and at forward rapidity ($-3.7<\eta<-1.7$ and $2.8<\eta<5.1$); both observables are normalized to their corresponding averages in minimum bias events. The increase of the normalized J/$\psi$ yield with normalized $\rm{d}N/\rm{d}\eta$ is significantly stronger than linear and dependent on the transverse momentum. The data are compared to theoretical predictions, which describe the observed trends well, albeit not always quantitatively.

                [9]  arXiv:2005.11124 (cross-list from nucl-ex) [pdf, other]
                Title: $Λ\rm{K}$ femtoscopy in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 2.76 TeV
                Comments: 32 pages, 10 captioned figures, 4 tables, authors from page 27, submitted to PRC, figures at this http URL
                Subjects: Nuclear Experiment (nucl-ex); High Energy Physics - Experiment (hep-ex)

                The first measurements of the scattering parameters of $\Lambda$K pairs in all three charge combinations ($\Lambda$K$^{+}$, $\Lambda$K$^{-}$, and $\Lambda\mathrm{K^{0}_{S}}$) are presented. The results are achieved through a femtoscopic analysis of $\Lambda$K correlations in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV recorded by ALICE at the LHC. The femtoscopic correlations result from strong final-state interactions, and are fit with a parametrization allowing for both the characterization of the pair emission source and the measurement of the scattering parameters for the particle pairs. Extensive studies with the THERMINATOR 2 event generator provide a good description of the non-femtoscopic background, which results mainly from collective effects, with unprecedented precision. Furthermore, together with HIJING simulations, this model is used to account for contributions from residual correlations induced by feed-down from particle decays. The extracted scattering parameters indicate that the strong force is repulsive in the $\Lambda\rm{K}^{+}$ interaction and attractive in the $\Lambda\rm{K}^{-}$ and $\Lambda\rm{K}^{0}_{S}$ interactions. The results suggest an effect arising either from different quark-antiquark interactions between the pairs ($\rm s\overline{s}$ in $\Lambda$K$^{+}$ and $\rm u\overline{u}$ in $\Lambda$K$^{-}$) or from different net strangeness for each system (S = 0 for $\Lambda$K$^{+}$, and S = $-2$ for $\Lambda$K$^{-}$). Finally, the $\Lambda$K systems exhibit source radii larger than expected from extrapolation from identical particle femtoscopic studies. This effect is interpreted as resulting from the separation in space-time of the single-particle $\Lambda$ and K source distributions.

                [10]  arXiv:2005.11126 (cross-list from nucl-ex) [pdf, other]
                Title: Z-boson production in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=8.16$ TeV and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV
                Comments: 22 pages, 5 captioned figures, 2 tables, authors from page 17, submitted to JHEP, figures at this http URL
                Subjects: Nuclear Experiment (nucl-ex); High Energy Physics - Experiment (hep-ex)

                Measurement of Z-boson production in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=8.16$ TeV and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV is reported. It is performed in the dimuon decay channel, through the detection of muons with pseudorapidity $-4 < \eta_{\mu} < -2.5$ and transverse momentum $p_{\rm T}^{\mu} > 20$ GeV/$c$ in the laboratory frame. The invariant yield and nuclear modification factor are measured for opposite-sign dimuons with invariant mass $60 < m^{\mu\mu} < 120$ GeV$c^2$ and rapidity $2.5 < y_{cms}^{\mu\mu} < 4$. They are presented as a function of rapidity and, for the Pb-Pb collisions, of centrality as well. The results are compared with theoretical calculations, both with and without nuclear modifications to the Parton Distribution Functions (PDFs). In p-Pb collisions the center-of-mass frame is boosted with respect to the laboratory frame, and the measurements cover the backward ($-4.46< y_{cms}^{\mu\mu}<-2.96$) and forward ($2.03< y_{cms}^{\mu\mu}<3.53$) rapidity regions. For the p-Pb collisions, the results are consistent within experimental and theoretical uncertainties with calculations that include both free-nucleon and nuclear-modified PDFs. For the Pb-Pb collisions, a $3.4\sigma$ deviation is seen in the integrated yield between the data and calculations based on the free-nucleon PDFs, while good agreement is found once nuclear modifications are considered.

                [11]  arXiv:2005.11128 (cross-list from nucl-ex) [pdf, other]
                Title: First measurement of quarkonium polarization in nuclear collisions at the LHC
                Comments: 20 pages, 3 captioned figures, 3 tables, authors from page 15, submitted to PLB, figures at this http URL
                Subjects: Nuclear Experiment (nucl-ex); High Energy Physics - Experiment (hep-ex)

                The polarization of inclusive J/$\psi$ and $\Upsilon(1{\rm S})$ produced in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}=5.02$ TeV at the LHC is measured with the ALICE detector. The study is carried out by reconstructing the quarkonium through its decay to muon pairs in the rapidity region $2.5<y<4$ and measuring the polar and azimuthal angular distributions of the muons. The polarization parameters $\lambda_{\theta}$, $\lambda_{\phi}$ and $\lambda_{\theta\phi}$ are measured in the helicity and Collins-Soper reference frames, in the transverse momentum interval $2<p_{\rm T}<10$ GeV/$c$ and $p_{\rm T}<15$ GeV/$c$ for the J/$\psi$ and $\Upsilon(1{\rm S})$, respectively. The polarization parameters for the J/$\psi$ are found to be compatible with zero, with a maximum deviation at low $p_{\rm T}$ of about $2\sigma$, for both reference frames and over the whole $p_{\rm T}$ range. The values are compared with the corresponding results obtained for pp collisions at $\sqrt{s}=7$ and 8 TeV in a similar kinematic region by the ALICE and LHCb experiments. Although with much larger uncertainties, the polarization parameters for $\Upsilon(1{\rm S})$ production in Pb-Pb collisions are also consistent with zero.

                [12]  arXiv:2005.11130 (cross-list from nucl-ex) [pdf, other]
                Title: Elliptic flow of electrons from beauty-hadron decays in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV
                Comments: 19 pages, 2 captioned figures, authors from page 14, submitted to PRL, figures at this http URL
                Subjects: Nuclear Experiment (nucl-ex); High Energy Physics - Experiment (hep-ex)

                The elliptic flow of electrons from beauty hadron decays at midrapidity ($|y|$ $<$ 0.8) is measured in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV with the ALICE detector at the LHC. The azimuthal distribution of the particles produced in the collisions can be parameterized with a Fourier expansion, in which the second harmonic coefficient represents the elliptic flow, $v_{\rm 2}$. The $v_{\rm 2}$ coefficient is measured for the first time in transverse momentum ($p_{\rm{T}}$) range 1.3-6 GeV/$c$ in the centrality class 30-50%. The measurement of electrons from beauty-hadron decays exploits their larger mean proper decay length $c\tau \approx$ 500 $\mu$m compared to that of charm hadrons and most of the other background sources. The $v_{\rm 2}$ of electrons from beauty hadron decays at midrapidity is found to be positive with a significance of 3.75$\sigma$. The results provide insights on the degree of thermalization of beauty quarks in the medium. A model assuming full thermalization of beauty quarks is strongly disfavoured by the measurement at high $p_{\rm{T}}$, but is in agreement with the results at low $p_{\rm{T}}$. Transport models including substantial interactions of beauty quarks with an expanding strongly-interacting medium describe the measurement.

                [13]  arXiv:2005.11131 (cross-list from nucl-ex) [pdf, other]
                Title: Transverse-momentum and event-shape dependence of D-meson flow harmonics in Pb-Pb collisions at $\sqrt{s_{NN}} = 5.02$ TeV
                Comments: 27 pages, 6 captioned figures, 1 table, authors from page 22, submitted to PLB, figures at this http URL
                Subjects: Nuclear Experiment (nucl-ex); High Energy Physics - Experiment (hep-ex)

                The elliptic and triangular flow coefficients $v_2$ and $v_3$ of prompt $D^{0}$, $D^{+}$, and $D^{*+}$ mesons were measured at midrapidity ($|y|<0.8$) in Pb-Pb collisions at the centre-of-mass energy per nucleon pair of $\sqrt{s_{NN}} = 5.02$ TeV with the ALICE detector at the LHC. The D mesons were reconstructed via their hadronic decays in the transverse momentum interval $1< p_{\rm T}<36$ GeV/$c$ in central (0-10%) and semi-central (30-50%) collisions. Compared to pions, protons, and J/$\psi$ mesons, the average D-meson $v_{n}$ harmonics are found to follow a mass ordering for $p_{\rm T}<3$ GeV/$c$, and to be similar to those of charged pions for higher $p_{\rm T}$. The coupling of the charm quark to the light quarks in the underlying medium is further investigated with the application of the event-shape engineering (ESE) technique to the D-meson $v_2$ and $p_{\rm T}$-differential yields. The D-meson $v_2$ is correlated with average bulk elliptic flow in both central and semi-central collisions. Within the current precision, the ratios of per-event D-meson yields in the ESE-selected and unbiased samples are found to be compatible with unity. All the measurements are found to be reasonably well described by theoretical calculations including the effects of charm-quark transport and the recombination of charm quarks with light quarks in a hydrodynamically expanding medium.

                [14]  arXiv:2005.11310 (cross-list from hep-ph) [pdf, other]
                Title: On the connection between quark propagation and hadronization
                Comments: 36 pages
                Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); Nuclear Theory (nucl-th)

                We investigate the properties and structure of the recently discussed "fully inclusive jet correlator", namely, the gauge-invariant field correlator characterizing the final state hadrons produced by a free quark as this propagates in the vacuum. Working at the operator level, we connect this object to the single-hadron fragmentation correlator of a quark, and exploit a novel gauge invariant spectral decomposition technique to derive a complete set of momentum sum rules for quark fragmentation functions up to twist-3 level; known results are recovered, and new sum rules proposed. We then show how one can explicitly connect quark hadronization and dynamical quark mass generation by studying the inclusive jet's gauge-invariant mass term. This mass is, on the one hand, theoretically related to the integrated chiral-odd spectral function of the quark, and, on the other hand, is experimentally accessible through the $E$ and $\tilde{E}$ twist-3 fragmentation function sum rules. Thus, measurements of these fragmentation functions in deep inelastic processes provide one with an experimental gateway into the dynamical generation of mass in Quantum Chromodynamics.

                Replacements for Mon, 25 May 20

                [15]  arXiv:1902.07246 (replaced) [pdf, other]
                Title: Scanning Strategies at the Top Threshold at ILC
                Authors: Frank Simon
                Comments: Talk presented at the International Workshop on Future Linear Colliders (LCWS2018), Arlington, Texas, 22-26 October 2018. C18-10-22, v2: clarified plots, slightly expanded results table
                Subjects: High Energy Physics - Experiment (hep-ex); High Energy Physics - Phenomenology (hep-ph)
                [16]  arXiv:1911.03800 (replaced) [pdf, other]
                Title: Measurement of the jet mass distribution and top quark mass in hadronic decays of boosted top quarks in pp collisions at $\sqrt{s} =$ 13 TeV
                Comments: Replaced with the published version. Added the journal reference and the DOI. All the figures and tables, including additional supplementary figures and tables, can be found at this http URL (CMS Public Pages)
                Journal-ref: Phys. Rev. Lett. 124 (2020) 202001
                Subjects: High Energy Physics - Experiment (hep-ex)
                [17]  arXiv:1912.05733 (replaced) [pdf, other]
                Title: New Directions for Axion Searches via Scattering at Reactor Neutrino Experiments
                Comments: 6 pages, 3 figures, Accepted for publication in Physical Review Letters. Figures have been updated since version 1
                Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)
                [18]  arXiv:2003.05688 (replaced) [pdf, other]
                Title: $D^{(\ast)}N$ interaction and the structure of $Σ_c(2800)$ and $Λ_c(2940)$ in chiral effective field theory
                Comments: 11 pages, 4 figures and 4 tables
                Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); Nuclear Theory (nucl-th)
                [19]  arXiv:2003.07135 (replaced) [pdf, other]
                Title: Role of the low-lying nucleon resonances in the $p\bar{p} \to ψη$ reaction
                Comments: 8 pages, 9 figures and 3 tables. Accepted by Phys. Rev. D
                Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); Nuclear Theory (nucl-th)
                [20]  arXiv:2005.01443 (replaced) [pdf, other]
                Title: Commissioning of the new ALICE Inner Tracking System
                Authors: James Philip Iddon (for the ALICE collaboration)
                Comments: 8 pages, 8 figures, proceedings of INSTR20, Novosibirsk, 24th-28th February 2020
                Subjects: Instrumentation and Detectors (physics.ins-det); High Energy Physics - Experiment (hep-ex)
                [ total of 20 entries: 1-20 ]
                [ showing up to 2000 entries per page: fewer | more ]
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