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New submissions

[ total of 24 entries: 1-24 ]
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New submissions for Thu, 21 Jun 18

[1]  arXiv:1806.07617 [pdf, other]
Title: Measuring hydrodynamical expansion via the production of identified hadrons in Pb$-$Pb collisions with ALICE
Authors: Nicolò Jacazio (for the ALICE Collaboration)
Comments: 4 pages, 8 figures, Proceedings for the contribution presented at the conference 'Rencontres de Moriond QCD and High Energy Interactions'
Subjects: Nuclear Experiment (nucl-ex); High Energy Physics - Experiment (hep-ex)

During the LHC Run-2, ALICE has collected data from Pb$-$Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV. The centrality dependence of identified particle production, including elliptic ($v_{2}$) and higher harmonic flow coefficients ($v_{3},v_{4}$), has been measured. The high-precision measurement of transverse momentum ($p_{\rm T}$) differential elliptic flow of the $\phi$-meson (whose mass is close to that of the proton) allows for a unique testing of mass ordering at low $p_{\rm T}$ as well as baryon and meson grouping at intermediate $p_{\rm T}$. The $p_{\rm T}$-differential hadron spectra are presented and, together with flow coefficients, compared with state-of-the-art calculations from models based on relativistic hydrodynamics coupled with UrQMD. The added transport code is to describe rescattering in the hadronic phase, which has been successful in describing the $p_{\rm T}$-spectra of identified particles up to a few GeV/$c$. Moreover, results from the simultaneous Blast-Wave fit to the $p_{\rm T}$ distributions are compared across multiple collisions energies and system sizes in order to address the evolution of collective behaviour from small systems to large systems.

[2]  arXiv:1806.07854 [pdf, ps, other]
Title: Azimuthal correlations of the longitudinal structure of the mid-rapidity charged-particle multiplicity in Pb-Pb collisions at $\sqrt{s_{_\mathrm{NN}}} =$ 2.76 TeV with ALICE
Authors: Saehanseul Oh (for the ALICE Collaboration)
Comments: contribution to proceedings of the 34th Winter Workshop on Nuclear Dynamics (WWND 2018), Guadeloupe
Subjects: Nuclear Experiment (nucl-ex)

Studies of longitudinal correlations of the charged-particle multiplicity in heavy-ion collisions have provided insights into the asymmetry and fluctuations of the initial-state collision geometry. In addition to the expansion of the medium in the transverse direction, commonly quantified using Fourier coefficients ($v_{n}$), the initial geometry and resulting longitudinal expansion as a function of azimuthal angle enable us to better understand the full 3-dimensional picture of heavy-ion collisions. In these proceedings, azimuthal correlations of the longitudinal structure of charged-particle multiplicity are reported for Pb-Pb collisions at a nucleon-nucleon center-of-mass energy of 2.76 TeV. The azimuthal angle distribution is divided into regions of in-plane and out-of-plane with respect to the second-order event plane, and the coefficients of Legendre polynomials are estimated from a decomposition of the longitudinal structure of the charged-particle multiplicity at midrapidity ($|\eta| < 0.8$) on an event-by-event basis in each azimuthal region for different centralities. Correlations between the coefficients of various orders in different azimuthal regions are studied and exhibit collective features of longitudinal structure in the azimuthal direction. The results are compared with HIJING and AMPT simulations.

Cross-lists for Thu, 21 Jun 18

[3]  arXiv:1806.06332 (cross-list from nucl-th) [pdf, other]
Title: Transverse Momentum Balance and Angular Distribution of $b\bar{b}$ Dijets in Pb+Pb collisions
Comments: 6 pages, 5 figures
Subjects: Nuclear Theory (nucl-th); High Energy Physics - Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)

The productions of inclusive b-jet and $b\bar{b}$ dijets in Pb+Pb collisions have been investigated by considering the heavy quark and the light quark in-medium evolution simultaneously. The initial hard processes of inclusive b-jet and $b\bar{b}$ dijets productions are described by a next-to-leading order (NLO) plus parton shower Monte Carlo (MC) event generator SHERPA which can be well matched with the experimental data in p+p collisions. The framework combines the Langevin transport model to describe the evolution of bottom quark also its collisional energy loss and the higher-twist description to consider the radiative energy loss of both bottom and light quarks. We compare the theoretical simulation of inclusive jet and inclusive b-jet $R_{\rm AA}$ in Pb+Pb collisions at $\sqrt{S_{\rm NN}}=2.76$~TeV with the experimental data, and then present the theoretical simulation of the momentum balance of the $b\bar{b}$ dijet in Pb+Pb collisions at $5.02$~TeV with the recent CMS data for the first time. A similar trend as that in dijets has been observed in $b\bar{b}$ dijets, the production-distribution shifted to smaller $x_J$ due to the jet quenching effect. At last, the prediction of the normalized azimuthal angle distribution of the $b\bar{b}$ dijet in Pb+Pb collisions at $5.02$ TeV has been reported. The medium induced energy loss effect of the $b\bar{b}$ dijets will overall suppress its production, but the near side ($\Delta \phi \to 0$ region) suffers more energy loss than away side ($\Delta \phi \to \pi$ region), therefore lead to the suppression on the near side and the enhancement on the away side in the normalized azimuthal angle distribution.

[4]  arXiv:1806.06355 (cross-list from physics.ins-det) [pdf]
Title: A High Precision Signals Readout System for Micromegas Detector Based on the VMM
Comments: 3 pages
Subjects: Instrumentation and Detectors (physics.ins-det); Nuclear Experiment (nucl-ex)

Micromegas detector is a gas detector with parallel plate structure, and it consists of a conversion gap in which radiations liberate ionization electrons and a thin amplification gap. The signal of the micromegas detector consists of two parts: the electron peak and the ion tail. The electronic signal just keeps few nanoseconds, which is used for precise time measurement. The ion signal carries most of the signal energy, and it is used to reconstruct particle energy. The micromegas detector has the advantages of high counting rate, high gain, good time resolution and position resolution, excellent radiation-hardened performance, large sensitive area and readout convenience. This paper introduces a signals readout electronics system for micromegas detector based on VMM chips. The VMM is the front end ASIC to be used in the front end electronics readout system of both the micromegas and sTGC detectors of the New Small Wheels Upgrade project. The VMM is designed by Brookhaven National Laboratory, and each chip is composed of 64 linear front-end channels. Each channel integrates a low-noise charge amplifier (CA) with adaptive feedback, test capacitor, and adjustable polarity (to process either positive or negative charge). Based on those characteristics, the VMM is applicable for the signals readout system of multichannel detectors. The readout system consists of three parts: the front-end board, the data acquisition board, and the host computer with the control software.

[5]  arXiv:1806.06794 (cross-list from nucl-th) [pdf, other]
Title: A new and finite family of solutions of hydrodynamics. Part I: Fits to pseudorapidity distributions
Comments: Invited talk of T. Csorgo at the WPCF 2018 conference in Cracow, Poland, May 22-26, 2018. Submitted to Acta Physica Polonica B
Subjects: Nuclear Theory (nucl-th); High Energy Physics - Experiment (hep-ex); High Energy Physics - Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)

We highlight some of the interesting properties of a new and finite, exact family of solutions of 1 + 1 dimensional perfect fluid relativistic hydrodynamics. After reviewing the main properties of this family of solutions, we present the formulas that connect it to the measured rapidity and pseudo-rapidity densities and illustrate the results with fits to p+p collisions at 8 TeV and Pb+Pb collisions at $\sqrt{s_{NN}} = 5.02 $ TeV.

[6]  arXiv:1806.07043 (cross-list from physics.ins-det) [pdf, other]
Title: Production Rate Measurement of Tritium and Other Cosmogenic Isotopes in Germanium with CDMSlite
Comments: 14 pages, 10 figures, 5 tables
Subjects: Instrumentation and Detectors (physics.ins-det); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Physics - Experiment (hep-ex); Nuclear Experiment (nucl-ex)

Future direct searches for low-mass dark matter particles with germanium detectors, such as SuperCDMS SNOLAB, are expected to be limited by backgrounds from radioactive isotopes activated by cosmogenic radiation inside the germanium. There are limited experimental data available to constrain production rates and a large spread of theoretical predictions. We examine the calculation of expected production rates, and analyze data from the second run of the CDMS low ionization threshold experiment (CDMSlite) to estimate the rates for several isotopes. We model the measured CDMSlite spectrum and fit for contributions from tritium and other isotopes. Using the knowledge of the detector history, these results are converted to cosmogenic production rates at sea level. The production rates in atoms/(kg$\cdot$day) are 74$\pm$9 for $^3$H, 1.5$\pm$0.7 for $^{55}$Fe, 17$\pm$5 for $^{65}$Zn, and 30$\pm$18 for $^{68}$Ge.

[7]  arXiv:1806.07177 (cross-list from hep-ph) [pdf, ps, other]
Title: Jet quenching parameter in an expanding QCD plasma
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)

We study the phenomenon of transverse momentum broadening for a high-$p_T$ parton propagating through a weakly-coupled quark-gluon plasma undergoing boost-invariant longitudinal expansion. We propose a boost-invariant description for this phenomenon, in which the broadening refers to the angular variables $\eta$ (the pseudo-rapidity) and $\phi$ (the azimuthal angle). The jet quenching parameter $\hat{q}$ which enters this description depends upon the proper time alone. We furthermore consider radiative corrections to $\hat q$. As in the case of a static medium, we find potentially large corrections enhanced by a double logarithm. But unlike for the static medium, these corrections are now local in time: they depend upon the local (proper) time characterizing the expansion, and not upon the overall path length. We resum such corrections to all orders into a renormalized jet quenching parameter. The main effect of this resummation is to slow down the decrease of $\hat q$ with increasing proper time.

[8]  arXiv:1806.07311 (cross-list from hep-ph) [pdf, other]
Title: Inclusive jet production as a probe of polarized PDFs at a future EIC
Comments: 18 pages, 23 figures
Subjects: High Energy Physics - Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)

We present a detailed phenomenological study of polarized inclusive jet production in electron-proton collisions at a future Electron-Ion Collider (EIC). Our analysis is performed at next-to-leading order in perturbative QCD using the numerical code DISTRESS and includes all relevant partonic channels and resolved photon contributions. We elucidate the role of different kinematic regions in probing different aspects of proton and photon structure and study the impact of the EIC collision energy on the measurement of polarized parton distribution functions.

[9]  arXiv:1806.07763 (cross-list from hep-ex) [pdf, other]
Title: Nonperturbative factorization breaking and color entanglement effects in dihadron and direct photon-hadron angular correlations in $p$$+$$p$ and $p$$+$A collisions
Authors: Joseph D. Osborn
Comments: Thesis submitted to the University of Michigan in partial fulfillment of the requirements for the degree of Ph.D
Subjects: High Energy Physics - Experiment (hep-ex); Nuclear Experiment (nucl-ex)

New predictions regarding the role of color flow in high energy Quantum Chromodynamics (QCD) processes have emerged in the last decade. In particular, the role of color flow is now being explored through many different observables; one such observable is nearly back-to-back hadron correlations in proton-proton collisions which are predicted to be sensitive to states that are entangled via their QCD color charge. The PHENIX detector at the Relativistic Heavy Ion Collider is well suited to study potential effects from color flow. Angular correlations between nearly back-to-back hadrons or a direct photon-hadron are measured to study the prediction of color entanglement or factorization breaking. The correlations can be treated in a transverse-momentum-dependent framework where sensitivity to non-Abelian effects from color are predicted. These measurements are the first ever to search for experimental evidence of these entangled states and will help establish color flow in hadronic interactions as a new area of focus within QCD research. Results are presented for proton-proton collisions at center-of-mass energies of 200 and 510 GeV and proton-nucleus collisions at nucleon-nucleon center-of-mass energies of 200 GeV. World measurements of processes where factorization is predicted to hold are also compiled and analyzed to compare to the new experimental results presented here. The measured results do not indicate any obvious qualitative differences from observables where factorization is predicted to hold. This indicates that quantitative comparisons with phenomenological calculations will be necessary to identify the magnitude of effects from color entanglement. As QCD is the only non-Abelian quantum field theory known to exist in nature that admits bound states, it will be essential to continue exploring unique QCD phenomena due to color interactions in controlled ways in the coming years.

Replacements for Thu, 21 Jun 18

[10]  arXiv:1705.03578 (replaced) [pdf, other]
Title: A novel approach to the bias-variance problem in bump hunting
Authors: Mike Williams
Comments: 26 pages, 17 figures
Journal-ref: JINST 12, P09034 (2017)
Subjects: High Energy Physics - Experiment (hep-ex); Nuclear Experiment (nucl-ex); Data Analysis, Statistics and Probability (physics.data-an)
[11]  arXiv:1712.05700 (replaced) [pdf, ps, other]
Title: Simulation Study of Energy Resolution with Changing Pixel Size for Radon Monitor Based on \textit{Topmetal-${II}^-$} TPC
Comments: 6 pages, 5 figures
Subjects: Instrumentation and Detectors (physics.ins-det); Nuclear Experiment (nucl-ex)
[12]  arXiv:1712.07198 (replaced) [pdf, other]
Title: Study of Bose-Einstein correlations in pp, pPb, and PbPb collisions at $\sqrt{s_\mathrm{NN}} =$ 0.9-7 TeV
Comments: Replaced with the published version. Added the journal reference and the DOI. All the figures and tables can be found at this http URL (CMS Public Pages)
Journal-ref: Phys. Rev. C 97, 064912 (2018)
Subjects: High Energy Physics - Experiment (hep-ex); Nuclear Experiment (nucl-ex)
[13]  arXiv:1803.05777 (replaced) [pdf, other]
Title: Practical considerations for measuring global spin alignment of vector mesons in relativistic heavy ion collisions
Comments: 6 pages. Updated two sections. Submitted to PRC
Subjects: Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
[14]  arXiv:1803.10951 (replaced) [pdf, ps, other]
[15]  arXiv:1804.01887 (replaced) [pdf, ps, other]
[16]  arXiv:1804.06558 (replaced) [pdf, ps, other]
Title: Disappearance of nuclear deformation in hypernuclei: a perspective from a beyond-mean-field study
Comments: 6 pages, 5 figures. The version to appear in Phys. Rev. C
Subjects: Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
[17]  arXiv:1806.01152 (replaced) [pdf, other]
Title: Search for Variations of Po-213 Half-Life
Comments: 6 pages, 9 figures; to be published in PEPAN
Subjects: Nuclear Experiment (nucl-ex)
[18]  arXiv:1806.01303 (replaced) [pdf, other]
Title: Estimation of the freeze-out parameters reachable in the AFTER@LHC project
Comments: 6 pages, 4 figures
Subjects: Nuclear Theory (nucl-th); High Energy Physics - Experiment (hep-ex); High Energy Physics - Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
[19]  arXiv:1611.09359 (replaced) [pdf, ps, other]
Title: The branching ratio $ω\to π^+π^-$ revisited
Comments: 11+2 pages, 7+1 figures; v3: erratum appended that rectifies erroneous treatment of the BaBar data
Journal-ref: Eur. Phys. J. C77 (2017) 98
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
[20]  arXiv:1712.07009 (replaced) [pdf, other]
[21]  arXiv:1805.02865 (replaced) [pdf, other]
Title: Description of neutron-rich odd-mass krypton isotopes within the interacting boson-fermion model based on the Gogny energy density functional
Comments: 9 pages, 11 figures, 2 tables
Journal-ref: Physical Review C 97, 064313 (2018)
Subjects: Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
[22]  arXiv:1712.08959 (replaced) [pdf, other]
Title: Measurement of prompt and nonprompt charmonium suppression in PbPb collisions at 5.02 TeV
Comments: Replaced with the published version. Added the journal reference and the DOI. All the figures and tables can be found at this http URL (CMS Public Pages)
Journal-ref: Eur. Phys. J. C 78 (2018) 509
Subjects: Nuclear Experiment (nucl-ex); High Energy Physics - Experiment (hep-ex)
[23]  arXiv:1802.09011 (replaced) [pdf, ps, other]
Title: $η'$ Production in Nucleus-Nucleus collisions as a probe of chiral dynamics
Authors: Giorgio Torrieri
Comments: Version accepted for publication, physical review C
Subjects: Nuclear Theory (nucl-th); High Energy Physics - Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
[24]  arXiv:1806.07043 (replaced) [pdf, other]
Title: Production Rate Measurement of Tritium and Other Cosmogenic Isotopes in Germanium with CDMSlite
Comments: 14 pages, 10 figures, 5 tables
Subjects: Instrumentation and Detectors (physics.ins-det); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Physics - Experiment (hep-ex); Nuclear Experiment (nucl-ex)
[ total of 24 entries: 1-24 ]
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