Nuclear Theory·nucl-th

Tuesday·June 11, 2019

9 papers—4 primary·5 cross-listed

05
[Submitted on 8 Jun 2019] (cross-list from nucl-ex)
Charge-dependent pair correlations relative to a third particle in $p$ +Au and $d$ +Au collisions at RHIC
STAR collaboration
Quark interactions with topological gluon configurations can induce chirality imbalance and local parity violation in quantum chromodynamics. This can lead to electric charge separation along the strong magnetic field in relativistic heavy-ion collisions -- the chiral magnetic effect (CME). We report measurements by the STAR collaboration of a CME-sensitive observable in $p$ +Au and $d$ +Au collisions at 200 GeV, where the CME is not expected, using charge-dependent pair correlations relative to a third particle. We observe strong charge-dependent correlations similar to those measured in heavy-ion collisions. This bears important implications for the interpretation of the heavy-ion data.
Comments:
8 pages, 4 figures
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1906.03373 [pdf]
PLB(2019)·56 citations
06
[Submitted on 10 Jun 2019] (cross-list from hep-ph)
Neutron production induced by $α$ -decay with Geant4
E. Mendoza🇪🇸 · D. Cano-Ott🇪🇸 · P. Romojaro🇪🇸 · V. Alcayne🇪🇸 · P. García Abia🇪🇸 · V. Pesudo🇪🇸 · L. Romero🇪🇸 · R. Santorelli🇪🇸
Neutron production induced by ( $α$ ,n) reactions is important in various scenarios. One of the most relevant ones is related to underground dark matter experiments, where the neutrons produced by the $α$ -decay from radioactive contaminants in the detector materials can generate an irreducible background, limiting the sensitivity of the experiment. A precise estimate of the background due to these neutrons is crucial for the experiments currently taking data and for the design of the next generation detectors. In this work, we prove that Geant4 can be used to calculate neutron yields and energy spectra induced by $α$ -decay. These neutrons are produced according to the information compiled in data libraries originally written in the ENDF-6 format. In this article we also review the different databases available, showing the differences and similarities among them. Finally, we compare several Geant4 neutron production yields and spectra with experimental data and other codes.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1906.03903 [pdf]
Nucl.Instrum.Meth.A(2020)·34 citations
07
[Submitted on 6 Jun 2019] (cross-list from hep-ph)
Quarkonium Phenomenology from a Generalised Gauss Law
David Lafferty🇩🇪 · Alexander Rothkopf🇳🇴
We present an improved analytic parametrisation of the complex in-medium heavy quark potential derived rigorously from the generalised Gauss law. To this end we combine in a self-consistent manner a non-perturbative vacuum potential with a weak-coupling description of the QCD medium. The resulting Gauss-law parametrisation is able to reproduce full lattice QCD data by using only a single temperature dependent parameter, the Debye mass $m_{D}$ . Using this parametrisation we model the in-medium potential at finite baryo-chemical potential, which allows us to estimate the $Ψ^{'}$ / $J /Ψ$ ratio in heavy-ion collisions at different beam energies.
Comments:
10 pages, 4 figures. arXiv admin note: text overlap with arXiv:1906.00035
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1906.04014 [pdf]
Universe(2019)·1 citation
08
[Submitted on 7 Jun 2019] (cross-list from hep-ph)
A Baseline Study of the Event-shape and Multiplicity Dependence of Chemical Freeze-out Parameters in Proton-Proton Collisions at $s$ = 13 TeV Using PYTHIA8
Rutuparna Rath🇮🇳 · Arvind Khuntia🇵🇱 · Sushanta Tripathy🇮🇳 · Raghunath Sahoo🇮🇳
The event-shape and multiplicity dependence of the chemical freeze-out temperature ( $T_{ch}$ ), freeze-out radius ( $R$ ), and strangeness saturation factor ( $γ_{s}$ ) are obtained by studying the particle yields from the PYTHIA8 Monte Carlo event generator in proton-proton (pp) collisions at the centre-of-mass $s$ = 13 TeV. Spherocity is one of the transverse event-shape techniques to distinguish jetty and isotropic events in high-energy collisions and helps in looking into various observables in a more differential manner. In this study, spherocity~classes are divided into three categories, namely (i) spherocity integrated, (ii) isotropic, and~(iii) jetty. The~chemical freeze-out parameters are extracted using a statistical thermal model as a function of the spherocity class and charged particle multiplicity in the canonical, strangeness canonical, and grand canonical ensembles. A clear observation of the multiplicity and spherocity class dependence of $T_{ch}$ , $R$ , and $γ_{s}$ is observed. A final state multiplicity, $N_{ch} \geq$ 30 in the forward multiplicity acceptance of the ALICE detector appears to be a thermodynamic limit, where the freeze-out parameters become almost independent of the ensembles. This~study plays an important role in understanding the particle production mechanism in high-multiplicity pp collisions at the Large Hadron Collider (LHC) energies in view of a finite hadronic phase lifetime in small systems.
Comments:
Same as the published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1906.04047 [pdf]
Physics(2020)·7 citations
09
[Submitted on 10 Jun 2019] (cross-list from astro-ph.HE)
Treating quarks within neutron stars
Sophia Han🇺🇸 · M. A. A. Mamun🇺🇸 · S. Lalit🇺🇸 · C. Constantinou🇺🇸 · M. Prakash🇺🇸
Neutron star interiors provide the opportunity to probe properties of cold dense matter in the QCD phase diagram. Utilizing models of dense matter in accord with nuclear systematics at nuclear densities, we investigate the compatibility of deconfined quark cores with current observational constraints on the maximum mass and tidal deformability of neutron stars. We explore various methods of implementing the hadron-to-quark phase transition, specifically, first-order transitions with sharp (Maxwell construction) and soft (Gibbs construction) interfaces, and smooth crossover transitions. We find that within the models we apply, hadronic matter has to be stiff for a first-order phase transition and soft for a crossover transition. In both scenarios and for the equations of state we employed, quarks appear at the center of pre-merger neutron stars in the mass range $\approx 1.0 - 1.6 M_{⊙}$ , with a squared speed of sound $c_{QM}^{2} ≳ 0.4$ characteristic of strong repulsive interactions required to support the recently discovered neutron star masses $\geq 2 M_{⊙}$ . We also identify equations of state and phase transition scenarios that are consistent with the bounds placed on tidal deformations of neutron stars in the recent binary merger event GW170817. We emphasize that distinguishing hybrid stars with quark cores from normal hadronic stars is very difficult from the knowledge of masses and radii alone, unless drastic sharp transitions induce distinctive disconnected hybrid branches in the mass-radius relation.
Comments:
24 pages, 8 figures, 7 tables; accepted for publication in PRD
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
1906.04095 [pdf]
PRD(2019)·104 citations

Affiliations

first authorsco-authorsvia INSPIRE

Charge-dependent pair correlations relative to a third particle in p+Au and d+Au collisions at RHIC

Neutron production induced by α-decay with Geant4

Quarkonium Phenomenology from a Generalised Gauss Law

A Baseline Study of the Event-shape and Multiplicity Dependence of Chemical Freeze-out Parameters in Proton-Proton Collisions at s​ = 13 TeV Using PYTHIA8

Treating quarks within neutron stars

Affiliations

Charge-dependent pair correlations relative to a third particle in $p$ +Au and $d$ +Au collisions at RHIC

Neutron production induced by $α$ -decay with Geant4

A Baseline Study of the Event-shape and Multiplicity Dependence of Chemical Freeze-out Parameters in Proton-Proton Collisions at $s$ = 13 TeV Using PYTHIA8