Nuclear Theory·nucl-th

Thursday·July 9, 2020

12 papers—5 primary·7 cross-listed

01
[Submitted on 7 Jul 2020]
GW190814: Impact of a 2.6 solar mass neutron star on nucleonic equations of state
F.J. Fattoyev · C.J. Horowitz · J. Piekarewicz · Brendan Reed
Is the secondary component of GW190814 the lightest black hole or the heaviest neutron star ever discovered in a double compact-object system [R. Abbott et al., ApJ Lett., 896, L44 (2020)]? This is the central question animating this letter. Covariant density functional theory provides a unique framework to investigate both the properties of finite nuclei and neutron stars, while enforcing causality at all densities. By tuning existing energy density functionals we were able to: (a) account for a 2.6 Msun neutron star, (b) satisfy the original constraint on the tidal deformability of a 1.4 Msun neutron star, and (c) reproduce ground-state properties of finite nuclei. Yet, for the class of models explored in this work, we find that the stiffening of the equation of state required to support super-massive neutron stars is inconsistent with either constraints obtained from energetic heavy-ion collisions or from the low deformability of medium-mass stars. Thus, we speculate that the maximum neutron star mass can not be significantly higher than the existing observational limit and that the 2.6 Msun compact object is likely to be the lightest black hole ever discovered.
Comments:
6 pages and 3 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)
arXiv:
2007.03799 [pdf]
PRC(2020)·236 citations
02
[Submitted on 8 Jul 2020]
Particle polarization, spin tensor and the Wigner distribution in relativistic systems
Leonardo Tinti🇩🇪 · Wojciech Florkowski🇵🇱
Particle spin polarization is known to be linked both to rotation (angular momentum) and magnetization of a many particle system. However, in the most common formulation of relativistic kinetic theory, the spin degrees of freedom appear only as degeneracy factors multiplying phase-space distributions. Thus, it is important to develop theoretical tools that allow to make predictions regarding the spin polarization of particles, which can be directly confronted with experimental data. Herein, we discuss a link between the relativistic spin tensor and particle spin polarization, and elucidate the connections between the Wigner function and average polarization. Our results may be useful for theoretical interpretation of heavy-ion data on spin polarization of the produced hadrons.
Comments:
30 pages, no figures, book chapter submitted to "Strongly Interacting Matter Under Rotation", edited by F. Becattini, J. Liao and M. Lisa
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
arXiv:
2007.04029 [pdf]
17 citations
03
[Submitted on 7 Jul 2020]
A unified view of the first-excited $2^{+}$ and $3^{-}$ states of Cd, Sn and Te isotopes
Bhoomika Maheshwari
Symmetries are known to play an important role in the low lying level structure of Sn isotopes, mostly in terms of the seniority and generalized seniority schemes. In this paper, we revisit the multi-j generalized seniority approach for the first excited $2^{+}$ and $3^{-}$ states in the Cd ( $Z = 48$ ), Sn ( $Z = 50$ ) and Te ( $Z = 52$ ) isotopes, where the Cd and Te isotopes represent two-proton hole and two-proton particle nuclei, thus involving both kind of particles (protons and neutrons) in contrast to Sn isotopes. Interestingly, the approach based on neutron valence space alone is able to explain the B(E2) and B(E3) trends respectively for the $2^{+}$ and $3^{-}$ states in all the three Cd, Sn and Te isotopes. The new results on the inverted parabolic behavior of B(E3) values in Cd and Te isotopes are understood in a manner identical to that of Sn isotopes by using the generalized seniority scheme. No shell quenching is supported by these calculations; hence, the neutron magic numbers, $N = 50$ and $N = 82$ , remain robust in these isotopic chains. It is quite surprising that the generalized seniority continues to be reasonably successful away from the semi-magic region, thus providing a unifying view of the $2^{+}$ and $3^{-}$ states.
Comments:
Accepted in European Physical Journal Special Topics on role of symmetries in nuclear physics. arXiv admin note: substantial text overlap with arXiv:1908.05028
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2007.04105 [pdf]
Eur.Phys.J.ST(2020)·5 citations
04
[Submitted on 8 Jul 2020]
Unitary ambiguity of NN contact interactions and the 3N force
L. Girlanda🇮🇹 · A. Kievsky🇮🇹 · L. E. Marcucci🇮🇹 · M. Viviani🇮🇹
We identify a redundancy between two- and three-nucleon contact interactions at the fourth and fifth order of the chiral expansion respectively. In particular we show that tensor-type and spin-orbit three-nucleon contact interactions effectively account for that part of the two-nucleon interaction which depends on the total center-of-mass momentum and is unconstrained by relativity. This might give the chiral effective field theory enough flexibility to successfully address $A = 3$ scattering observables already at N3LO.
Comments:
9 pages, discussion extended to OPE 3NF
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2007.04161 [pdf]
PRC(2020)·21 citations
05
[Submitted on 8 Jul 2020]
Pion interferometry at 200 GeV using anisotropic hydrodynamics
Mubarak Alqahtani🇸🇦 · Michael Strickland🇺🇸
In this paper, we continue our phenomenological studies of heavy-ion collisions using 3+1d anisotropic hydrodynamics (aHydro). In previous works, we compared quasiparticle aHydro (aHydroQP) with ALICE 2.76 TeV Pb-Pb and RHIC 200 GeV Au-Au collision results. At both energies, the agreement was quite good between aHydroQP and the experimental data for many observables. In this work, we present comparisons of the Hanbury Brown--Twiss (HBT) radii and their ratios determined using pi+ pi+ pairs produced in 200 GeV Au-Au collisions. We first present comparisons with STAR results for the HBT radii and their ratios. We then present comparisons with PHENIX results for the HBT radii and their ratios. In both cases, we find reasonable agreement between aHydroQP predictions and available experimental results for the ratios of HBT radii. At the level of the radii themselves, in some cases quantitative differences on the order of 10-20% remain, which deserve further study.
Comments:
12 pages, 4 multipanel figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2007.04209 [pdf]
PRC(2020)·15 citations
06
[Submitted on 3 Jul 2020] (cross-list from hep-lat)
Lattice QCD evaluation of the Compton amplitude employing the Feynman-Hellmann theorem
K. U. Can🇦🇺 · A. Hannaford-Gunn🇦🇺 · R. Horsley🇬🇧 · Y. Nakamura🇯🇵 · H. Perlt🇩🇪 · P. E. L. Rakow🇬🇧 · G. Schierholz🇩🇪 · K. Y. Somfleth🇦🇺 · H. Stüben🇩🇪 · R. D. Young🇦🇺 · J. M. Zanotti🇦🇺
The forward Compton amplitude describes the process of virtual photon scattering from a hadron and provides an essential ingredient for the understanding of hadron structure. As a physical amplitude, the Compton tensor naturally includes all target mass corrections and higher twist effects at a fixed virtuality, $Q^{2}$ . By making use of the second-order Feynman-Hellmann theorem, the nucleon Compton tensor is calculated in lattice QCD at an unphysical quark mass across a range of photon momenta $3 ≲ Q^{2} ≲ 7$ GeV $^{2}$ . This allows for the $Q^{2}$ dependence of the low moments of the nucleon structure functions to be studied in a lattice calculation for the first time. The results demonstrate that a systematic investigation of power corrections and the approach to parton asymptotics is now within reach.
Comments:
18 pages, 8 figures. Title has been changed due to the Editor's request. Version to appear in PRD
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2007.01523 [pdf]
PRD(2020)·57 citations
07
[Submitted on 7 Jul 2020] (cross-list from hep-lat)
Spectral functions and dynamic critical behavior of relativistic $Z_{2}$ theories
Dominik Schweitzer🇩🇪 · Sören Schlichting🇩🇪 · Lorenz von Smekal🇩🇪
We investigate the dynamic critical behaviour of a relativistic scalar field theory with $Z_{2}$ symmetry by calculating spectral functions of the order parameter at zero and non-vanishing momenta from first-principles classical-statistical lattice simulations in real-time. We find that at temperatures above the critical point $(T > T_{c})$ , the spectral functions are well described by relativistic quasi-particle peaks. Close to the transition temperature $(T \sim T_{c})$ , we observe strong infrared contributions building up. In the ordered phase at low temperatures $(T < T_{c})$ , in addition to the quasi-particle peak, we observe a soft mode with a dispersion relation indicative of collective excitations. Investigating the spectral functions close to $T_{c}$ , we demonstrate that the behavior in the vicinity of the critical point is controlled by dynamic scaling functions and the dynamic critical exponent $z$ , which we determine from our simulations. By considering the equations of motion for a closed system and a system coupled to a heat bath, we extract the dynamic critical behavior for two different dynamic universality classes (Models A & C) in two and three spatial dimensions.
Comments:
34 pages, 19 figures
Subjects:
High Energy Physics — Lattice (hep-lat); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2007.03374 [pdf]
NPB(2020)·35 citations
08
[Submitted on 7 Jul 2020] (cross-list from astro-ph.IM)
Correlated Energy Uncertainties in Reaction Rate Calculations
Richard Longland🇺🇸 · Nicolas de Séréville🇫🇷
Context. Monte Carlo methods can be used to evaluate the uncertainty of a reaction rate that arises from many uncertain nuclear inputs. However, until now no attempt has been made to find the effect of correlated energy uncertainties in input resonance parameters. Aims. To investigate the impact of correlated energy uncertainties on reaction rates. Methods. Using a combination of numerical and Monte Carlo variation of resonance energies, the effect of correlations are investigated. Five reactions are considered: two fictional, illustrative cases and three reactions whose rates are of current interest. Results. The effect of correlations in resonance energies depends on the specific reaction cross section and temperatures considered. When several resonances contribute equally to a reaction rate, and are located either side of the Gamow peak, correlations between their energies dilute their effect on reaction rate uncertainties. If they are both located above or below the maximum of the Gamow peak, however, correlations between their resonance energies can increase the reaction rate uncertainties. This effect can be hard to predict for complex reactions with wide and narrow resonances contributing to the reaction rate.
Comments:
9 pages, 9 figures, accepted to Astronomy and Astrophysics
Subjects:
Instrumentation and Methods for Astrophysics (astro-ph.IM); Nuclear Theory (nucl-th)
arXiv:
2007.03802 [pdf]
Astron.Astrophys.(2020)·2 citations
09
[Submitted on 8 Jul 2020] (cross-list from hep-ph)
Cumulants of multiple conserved charges and global conservation laws
Volodymyr Vovchenko🇺🇸 · Roman V. Poberezhnyuk🇺🇦 · Volker Koch🇺🇸
We analyze the behavior of cumulants of conserved charges in a subvolume of a thermal system with exact global conservation laws by extending a recently developed subensemble acceptance method (SAM) [V. Vovchenko et al., arXiv:2003.13905] to multiple conserved charges. Explicit expressions for all diagonal and off-diagonal cumulants up to sixth order that relate them to the grand canonical susceptibilities are obtained. The derivation is presented for an arbitrary equation of state with an arbitrary number of different conserved charges. The global conservation effects cancel out in any ratio of two second order cumulants, in any ratio of two third order cumulants, as well as in a ratio of strongly intensive measures $Σ$ and $Δ$ involving any two conserved charges, making all these quantities particularly suitable for theory-to-experiment comparisons in heavy-ion collisions. We also show that the same cancellation occurs in correlators of a conserved charge, like the electric charge, with any non-conserved quantity such as net proton or net kaon number. The main results of the SAM are illustrated in the framework of the hadron resonance gas model. We also elucidate how net-proton and net- $Λ$ fluctuations are affected by conservation of electric charge and strangeness in addition to baryon number.
Comments:
39 pages, 5 figures, to be published in JHEP
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2007.03850 [pdf]
JHEP(2020)·53 citations
10
[Submitted on 8 Jul 2020] (cross-list from hep-ph)
Fireball tomography from bottomonia elliptic flow in relativistic heavy-ion collisions
Partha Pratim Bhaduri🇮🇳 · Mubarak Alqahtani🇸🇦 · Nicolas Borghini🇩🇪 · Amaresh Jaiswal🇮🇳 · Michael Strickland🇺🇸
We calculate the elliptic flow of bottomonia produced in Pb $+$ Pb collisions at $s_{NN} = 5.02$ TeV. We consider temperature-dependent decay widths for the anisotropic escape of various bottomonium states and observe that the transverse momentum dependence of bottomonia elliptic flow provides a tomographic information about the QGP fireball at different stages of its evolution. For the space-time evolution of the fireball, we employ simulation results from the 3+1D quasiparticle anisotropic hydrodynamic model. We find that our results for transverse momentum dependence of bottomonia elliptic flow are in reasonable agreement with experimental results from the ALICE and CMS collaborations.
Comments:
8 pages, 5 figures, ancillary files with data of the figures are included in the source
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2007.03939 [pdf]
EPJC(2021)·21 citations
11
[Submitted on 8 Jul 2020] (cross-list from hep-lat)
Properties of the QCD thermal transition with $N_{f} = 2 + 1$ flavours of Wilson quark
G. Aarts🇬🇧 · C. Allton🇬🇧 · J. Glesaaen🇬🇧 · S. Hands🇬🇧 · B. Jäger🇩🇰 · S. Kim🇰🇷 · M. P. Lombardo🇮🇹 · A. A. Nikolaev🇬🇧 · S. M. Ryan🇮🇪 · J.-I. Skullerud🇮🇪 · L.-K. Wu🇨🇳
We study properties of the thermal transition in QCD, using anisotropic, fixed-scale lattice simulations with $N_{f} = 2 + 1$ flavours of Wilson fermion. Observables are compared for two values of the pion mass, focusing on chiral properties. Results are presented for the Polyakov loop, various susceptibilities, the chiral condensate and its susceptibility, and the onset of parity doubling in the light and strange baryonic sector.
Comments:
12 pages, 11 figures, 5 tables
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2007.04188 [pdf]
PRD(2022)·55 citations
12
[Submitted on 8 Jul 2020] (cross-list from hep-ph)
Deciphering QCD dynamics in small collision systems using event shape and final state multiplicity at the Large Hadron Collider
Suman Deb🇮🇳 · Sushanta Tripathy🇮🇳 · Golam Sarwar🇮🇳 · Raghunath Sahoo🇮🇳 · Jan-e Alam🇮🇳
The high-multiplicity pp collisions at the Large Hadron Collider energies with various heavy-ion-like signatures have warranted a deeper understanding of the underlying physics and particle production mechanisms. It is a common practice to use experimental data on the hadronic transverse momentum ( $p_{T}$ ) spectra to extract thermodynamical properties of the system formed in heavy ion and high multiplicity pp collisions. The non-availability of event topology dependent experimental data for pp collisions at $s$ = 13 TeV on the spectra of non-strange and strange hadrons constrains us to use the PYTHIA8 simulated numbers to extract temperature-like parameters to study the event shape and multiplicity dependence of specific heat capacity, conformal symmetry breaking measure (CSBM) and speed of sound. The observables show a clear dependence on event multiplicity and event topology. Thermodynamics of the system is largely governed by the light particles because of their relatively larger abundances. In this regards, a threshold in the particle production, $N_{ch} ≃$ (10-20) in the final state multiplicity emerges out from the present study, confirming some of the earlier findings in this direction. As for heavier hadrons with relatively small abundances, a similar threshold is observed for $⟨ N_{ch} ⟩ ≃$ 40 hinting towards formation of a thermal bath where all the heavier hadrons are in equilibrium.
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:
2007.04194 [pdf]
EPJA(2020)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE