Nuclear Theory·nucl-th

Wednesday·July 18, 2018

24 papers—12 primary·12 cross-listed

01
[Submitted on 16 Jul 2018]
Fluid dynamics of out of equilibrium boost invariant plasmas
Jean-Paul Blaizot🇫🇷 · Li Yan🇨🇦
We establish a set of equations for moments of the distribution function. In the relaxation time approximations, these moments obey a coupled set of equations that can be truncated order-by-order. Solving the equations of moments, we are able to identify an attractor solution that controls a transition from a free streaming fixed point to a hydrodynamic fixed point. In particular, this attractor solution provides a renormalization of the effective value of the shear viscosity to entropy density ratio, $η / s$ , taking into account off-equilibrium effects.
Comments:
2 figures and 4 pages; Proceedings of the 27th international conference on ultra-relativistic nucleus-nucleus collisions (Quark Matter 2018)
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1807.06104 [pdf]
NPA(2019)·1 citation
02
[Submitted on 17 Jul 2018]
Collective effects in nuclear collisions: theory overview
Jorge Noronha (Sao Paulo U.)🇧🇷
In these proceedings I review recent developments concerning the hydrodynamic description of the quark-gluon plasma (QGP). I report on the progress towards more realistic simulations and discuss new features about the QGP transport coefficients of the hot (and baryon dense) medium formed in heavy ion collisions. A brief discussion is included on the applicability of hydrodynamics and its extension to the far-from-equilibrium regime.
Comments:
7 pages, 3 figures, invited plenary talk at the 27th International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2018), Venice, Italy, 13-19 May 2018
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1807.06191 [pdf]
NPA(2019)·7 citations
03
[Submitted on 17 Jul 2018]
Z+jet productions in heavy-ion collisions
Shan-Liang Zhang🇨🇳 · Tan Luo🇨🇳 · Xin-Nian Wang🇨🇳 · Ben-Wei Zhang🇨🇳
We report a systematic study of Z+jet correlation in Pb+Pb collisions at the LHC by combining the next-leading-order matrix elements calculations with matched parton shower in Sherpa for the initial Z+jet production, and Linear Boltzmann transport Model for jet propagation in the expanding quark-gluon-plasma. Our numerical results can well explain CMS measurements on Z+jet correlation in Pb+Pb collisions: the shift of $p_{T}$ imbalance $x_{j Z} = p_{T}^{j e t} / p_{T}^{Z}$ and their mean values, the suppression of the average number of jet partners per Z boson $R_{j Z}$ , as well as the modification of azimuthal angle correlations $Δ ϕ_{j Z}$ . We also demonstrate that high-order corrections play a significant role in the understanding of Z+jet correlations at high energies.
Comments:
4 pages, 4 figures, talk at Quark Matter 2018 conference
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1807.06197 [pdf]
NPA(2019)·3 citations
04
[Submitted on 17 Jul 2018]
Quarkonium production in heavy ion collisions: coupled Boltzmann transport equations
Xiaojun Yao🇺🇸 · Weiyao Ke🇺🇸 · Yingru Xu🇺🇸 · Steffen Bass🇺🇸 · Berndt Müller🇺🇸
We develop a set of coupled Boltzmann equations to describe the dynamical evolution of heavy quarks and quarkonia inside the quark-gluon plasma. The quarkonium dissociation and recombination terms are calculated from pNRQCD. Their interplay drives the system to a detailed balance. The heavy quark energy loss term is necessary for the system to reach kinematic thermalization. By coupling the transport equations with initial particles' momenta generated by PYTHIA and hydrodynamic medium evolutions, we can describe the $R_{AA}$ of $Υ$ family at both RHIC and LHC energies. The transverse momentum azimuthal anisotropy of $Υ$ (1S) in $2.76$ TeV peripheral Pb-Pb collisions is also studied.
Comments:
4 pages, 3 figures, conference proceeding of Quark Matter 2018
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1807.06199 [pdf]
NPA(2019)·22 citations
05
[Submitted on 17 Jul 2018]
Rapidity decorrelation from hydrodynamic fluctuations
Azumi Sakai🇯🇵 · Koichi Murase🇯🇵 · Tetsufumi Hirano🇯🇵
We discuss rapidity decorrelation caused by hydrodynamic fluctuations in high-energy nuclear collisions at the LHC energy. We employ an integrated dynamical model which is a combination of the Monte Carlo version of Glauber model with extension to longitudinal direction for initial conditions, full three-dimensional relativistic fluctuating hydrodynamics for the space-time evolution of created matter in the intermediate stage and a hadronic cascade model in the late stage. We switch on and off the hydrodynamic fluctuations in the hydrodynamic stage to understand the effects of hydrodynamic fluctuations on factorisation ratios $r_{n} (η_{p}^{a}, η_{p}^{b})$ . To understand the rapidity gap dependence of the factorisation ratio comprehensively, we analyse Legendre coefficients $A_{2}^{k}$ and $B_{2}^{k}$ .
Comments:
4 pages, 3 figures, XXVIIth International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2018)
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1807.06254 [pdf]
NPA(2019)·9 citations
06
[Submitted on 17 Jul 2018]
Hydrodynamic response in simulations within a multiphase transport model
De-Xian Wei🇨🇳 · Xu-Guang Huang🇨🇳 · Li Yan🇨🇦
We carry out simulations using a multiphase transport (AMPT) model to describe the observed flow signatures in $s_{N N} = 2.76$ TeV Pb-Pb collisions. Especially, we calculate the flow fluctuations of $v_{2}$ in terms of cumulant ratios and the standardized skewness. Based on event-by-event AMPT simulations, we study the linear and cubic response relation between $v_{2}$ and $ε_{2}$ . We found that the observed response relation is compatible to what has been noticed in hydrodynamic modelings, with similar dependence on shear viscosity. Besides, this response relation is not sensitive to nonflow effects.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1807.06299 [pdf]
PRC(2018)·18 citations
07
[Submitted on 17 Jul 2018]
Nonlinear coupling of flow harmonics in heavy-ion collisions
Giuliano Giacalone🇫🇷
Anisotropic flow coefficients beyond triangular flow receive important contributions from lower-order harmonics through nonlinear coupling. We present a theoretical framework which allows one to quantify the contribution induced by such nonlinear couplings to any flow harmonic of any order. We show the effectiveness of this formalism through an application to hexagonal flow, $V_{6}$ . We study, in particular, the coupling of $V_{6}$ to triangular flow, $V_{3}$ , in Pb+Pb collisions at $s = 2.76$ TeV, using both Large Hadron Collider data and event-by-event hydrodynamic calculations.
Comments:
4 pages; 2 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1807.06382 [pdf]
NPA(2019)·1 citation
08
[Submitted on 17 Jul 2018]
Nature of isoscalar dipole resonances in heavy nuclei
V.I. Abrosimov🇺🇦 · O.I. Davidovskaya🇺🇦
Isoscalar dipole nuclear response reveals the low- and high-energy resonances. The nature of isoscalar dipole resonances in heavy spherical nuclei is studied by using the translation-invariant kinetic model of small oscillations of finite Fermi systems. Calculations of the velocity field at the centroid energy show a pure vortex character of the low-energy isoscalar dipole resonance in spherical nuclei and confirm the anisotropic compression character of the high-energy one. The evolution of the velocity field in dependence on the excitation energy of the nucleus within the resonance width is studied. It is found that the low-energy isoscalar dipole resonance retains a vortex character while with increasing energy this collective excitation also involves compression. The high-energy resonance keeps the compression character with a change in the excitation energy within the resonance width but the compression-expansion region of the velocity field related to this resonance shifts inside the nucleus.
Comments:
9 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.06407 [pdf]
Ukr.J.Phys.(2018)·2 citations
09
[Submitted on 14 Jul 2018]
Neutron star matter with strange interactions in a relativistic quark model
H. S. Sahoo🇮🇳 · R. N. Mishra🇮🇳 · D. K. Mohanty🇮🇳 · P. K. Panda🇮🇳 · N. Barik🇺🇸
The effect of strange interactions in neutron star matter and the role of the strange meson-hyperon couplings are studied in a relativistic quark model where the confining interaction for quarks inside a baryon is represented by a phenomenological average potential in an equally mixed scalar-vector harmonic form. The hadron-hadron interaction in nuclear matter is then realized by introducing additional quark couplings to $σ$ , $ω$ , $ρ$ , $σ^{*}$ and $ϕ$ mesons through mean-field approximations. The meson-baryon couplings are fixed through the SU(6) spin-flavor symmetry and the SU(3) flavor symmetry to determine the hadronic equation of state (EoS). We find that the SU(3) coupling set gives the potential depth between $Λ$ s around $- 5$ MeV and favours a stiffer EoS.The radius for the canonical neutron star lies within a range of $12.7$ to $13.1$ km.
Comments:
9 pages, 6 figures. arXiv admin note: substantial text overlap with arXiv:1609.02708, arXiv:1702.02310
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.06453 [pdf]
PRC(2018)·37 citations
10
[Submitted on 17 Jul 2018]
Statistical Properties of 56-57Fe with Multi-Shell Degrees of Freedom
Bassam Shehadeh🇸🇦 · James P. Vary🇺🇸
We investigate the statistical properties of 56-57Fe within a model capable of treating all the nucleons as active in an infinite model space including pairing effects. Working within the canonical ensemble, our model is built on single-particle states, thus it includes shell and subshell closures. We include spin correlation parameters to account for nucleon spin multiplicities. Pairing and shell effects are important in the low-temperature region where the quantum effects dominate. The validity of the model is extended to higher temperatures, approaching the classical regime, by including continuum states. We present results for excitation energy, heat capacity and level density of 56-57Fe. The resulting favorable comparisons with experimental data and with other approaches, where applicable, indicate that the methods we develop are useful for statistical properties of medium to heavy nuclei.
Comments:
26 pages and 10 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.06520 [pdf]
0 citations
11
[Submitted on 17 Jul 2018]
Measuring the Rate of Isotropization of Quark-Gluon Plasma Using Rapidity Correlations
George Moschelli🇺🇸 · Sean Gavin🇺🇸
We propose that rapidity dependent momentum correlations can be used to extract the shear relaxation time $τ_{π}$ of the medium formed in high energy nuclear collisions. The stress-energy tensor in an equilibrium quark-gluon plasma is isotropic, but in nuclear collisions it is likely very far from this state. The relaxation time $τ_{π}$ characterizes the rate of isotropization and is a transport coefficient as fundamental as the shear viscosity. We show that fluctuations emerging from the initial anisotropy survive to freeze-out, in excess of thermal fluctuations, influencing rapidity correlation patterns. We show that these correlations can be used to extract $τ_{π}$ . We describe a method for calculating the rapidity dependence of two-particle momentum correlations with a second order, causal, diffusion equation that includes Langevin noise as a source of thermal fluctuations. The causality requirement introduces the relaxation time and we link the shape of the rapidity correlation pattern to its presence. Here we examine how different equations of state and temperature dependent transport coefficients in the presence of realistic hydrodynamic flow influence the estimate of $τ_{π}$ . In comparison to RHIC data, we find that the ratio $τ_{π} / ν \approx 5 - 6$ where $ν = η / s T$ is the kinematic viscosity.
Comments:
Proceedings of The 27th International Conference on Ultrarelativistic Nucleus-Nucleus Collisions, Venezia, Italy 13-19 May 2018
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.06532 [pdf]
NPA(2019)·4 citations
12
[Submitted on 17 Jul 2018]
Jet modification with medium recoil in quark-gluon plasma
Chanwook Park🇨🇦 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦
Jet energy transported to quark-gluon plasma during jet-medium interaction excites the QGP medium and creates energetic thermal partons -- recoil particles or recoils. Modification of the jet structure in heavy ion collisions is studied using \textsc{martini}, in which recoil simulation is enabled. In large systems such as central Pb-Pb collisions, the recoil effect is expected to be critical due to strong jet-medium interaction. We show the results of the jet mass function and jet shape function are improved when the recoil particles are included in the reconstructed jets. We conclude that the energy carried by the recoil particles are regarded as a part of reconstructed jets and are necessary in studying jet modification in heavy ion collisions.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1807.06550 [pdf]
NPA(2019)·52 citations
13
[Submitted on 1 Jul 2018] (cross-list from hep-lat)
Lattice QCD Method To Study Hadron Mass Is Not Correct
Gouranga C Nayak🇺🇸
Since the numerical path integration in the lattice QCD involves quark and gluon fields (not hadron fields) the lattice QCD cannot calculate any hadronic observable. Because of this reason the hadronic properties are extracted in the lattice QCD method by inserting complete set of hadron states $\sum_{n} ∣ n >< n ∣ = 1$ in between the partonic operators by assuming $H_{QCD} ∣ n >= E_{n} ∣ n >$ where $E_{n}$ is the energy of the hadron. However, in this paper we find $H_{QCD} ∣ n > \neq = E_{n} ∣ n >$ because the QCD hamiltonian $H_{QC D}$ is unphysical but the $E_{n}$ and $∣ n >$ of the hadron are physical. We show that this is consistent with $E_{QCD} (t) =< n ∣ H_{QC D} ∣ n > \neq = E_{n}$ due to non-zero energy flux $E_{flux} (t)$ in QCD because of confinement involving non-perturbative QCD. Hence we find that the lattice QCD method to study hadron mass is not correct.
Comments:
11 pages latex
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1807.04127 [pdf]
2 citations
14
[Submitted on 16 Jul 2018] (cross-list from hep-ph)
Multiparticle correlations and collectivity in small systems from the initial state
Kevin Dusling🇺🇸 · Mark Mace🇺🇸 · Vladimir V. Skokov🇺🇸 · Prithwish Tribedy🇺🇸 · Raju Venugopalan🇺🇸
We report on recent progress in understanding multiparticle correlations in small systems from the initial state. First, we consider a proof-of-principle parton model, which we use to demonstrate that many of the multiparticle correlations observed in light-heavy ion collisions, often ascribed to hydrodynamic collectivity, can be qualitatively reproduced in an initial state model. Then, we study the two-particle harmonics $v_{2}$ and $v_{3}$ for p/d/ $^{3}$ He+Au collisions at RHIC using the dilute-dense Color Glass Condensate Effective Field Theory framework. We show that this provides a viable alternative explanation to hydrodynamics, and elaborate on how such modeling can be improved.
Comments:
4 pages, 2 figures. Proceedings for Quark Matter 2018 based on talk by M. Mace. v2: Minor edits, identical to published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1807.06032 [pdf]
NPA(2019)·0 citations
15
[Submitted on 17 Jul 2018] (cross-list from hep-ph)
Charge and spin asymmetries in elastic lepton-nucleon scattering
Oleksandr Koshchii🇺🇸 · Andrei Afanasev🇺🇸
Elastic lepton scattering off of a nucleon has proved to be an efficient tool to study the structure of the hadron. Modern cross section and asymmetry measurements at Jefferson Lab require effects beyond the leading order Born approximation to be taken into account. Availability of unpolarized beams of both electrons and positrons in respective experiments would enable to reduce systematic uncertainties due to higher-order charge-odd contributions. In addition, information on an unpolarized electron-to-positron cross section ratio could serve as a test for theoretical models that provide predictions for charge-dependent radiative corrections to elastic lepton-nucleon scattering. Availability of polarized beams of leptons would allow for even more comprehensive study of higher-order effects as some of them are dominant in polarized lepton-nucleon scattering asymmetries. We present a brief overview of effects due to the lepton's charge and target's polarization on elastic lepton-nucleon scattering measurements.
Comments:
5 pages, 5 figures. Contribution to the Proceedings of International Workshop on Physics with Positrons at Jefferson Lab, JPOS17
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1807.06163 [pdf]
AIP Conf.Proc.(2018)·2 citations
16
[Submitted on 17 Jul 2018] (cross-list from hep-ph)
Universal quark to gluon ratio in medium-induced parton cascade
Yacine Mehtar-Tani🇺🇸 · Soeren Schlichting🇺🇸
We investigate the radiative break-up of a highly energetic quark or gluon in a high-temperature QCD plasma. Within an inertial range of momenta $T ≪ ω ≪ E$ , where $E$ denotes the energy of the original hard parton (jet) and $T$ the temperature of of the medium, we find that, as a result of the turbulent nature of the underlying parton cascade, the quark to gluon ratio of the soft fragments tends to a universal constant value that is independent of the initial conditions. We discuss implications of this result to jet quenching physics and the problem of thermalization of the quark-gluon plasma in heavy ion collisions.
Comments:
22 pages; 5 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1807.06181 [pdf]
JHEP(2018)·46 citations
17
[Submitted on 17 Jul 2018] (cross-list from hep-ph)
Global Dyson-Schwinger-Bethe-Salpeter Approach to Mesons with Open Flavour
Thomas Hilger🇦🇹 · María Gómez-Rocha🇮🇹 · Andreas Krassnigg🇦🇹 · Wolfgang Lucha🇦🇹
Exploiting an interplay of the Bethe-Salpeter equation enabling us to regard mesons as bound states of quark and antiquark and the Dyson-Schwinger equation controlling the dressed quark propagator, we amend existing studies of quarkonia by a comprehensive description of open-flavour mesons composed of all conceivable combinations of quark flavour. Employing throughout a fixed set of model parameters, we predict some basic characteristics of these mesons, i.e., their masses, leptonic decay constants and corresponding in-hadron condensates entering in a generalized formulation of the Gell-Mann-Oakes-Renner relation.
Comments:
5 pages, 6 figures, contributed to "QCD@Work 2018 - International Workshop on Quantum Chromodynamics: Theory and Experiment" (25 - 28 June 2018, Matera, Italy)
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1807.06245 [pdf]
EPJ Web Conf.(2018)·2 citations
18
[Submitted on 17 Jul 2018] (cross-list from hep-ph)
Signature of gluon saturation in forward di-hadron correlations at the Large Hadron Collider
Giuliano Giacalone🇫🇷 · Cyrille Marquet🇫🇷
We argue that gluon saturation effects may be visible in Large Hadron Collider (LHC) data. We look at the centrality dependence of the away-side peak of two-particle correlations measured in p-Pb collisions, using both ALICE data at midrapidity, and LHCb data at forward rapidity. Once the collective flow-like signal measured at the near-side peak is removed from the correlation function, the centrality dependence of the away-side peak turns out to be much stronger in the forward region than at midrapidity. We argue that this is a very specific prediction of the saturation framework, and we compare LHCb data to a state-of-the-art calculation within the Color Glass Condensate theory.
Comments:
4 pages; 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1807.06388 [pdf]
NPA(2019)·8 citations
19
[Submitted on 16 Jul 2018] (cross-list from hep-lat)
Lattice-based QCD equation of state at finite baryon density: Cluster Expansion Model
V. Vovchenko🇩🇪 · J. Steinheimer🇩🇪 · O. Philipsen🇩🇪 · A. Pasztor🇩🇪 · Z. Fodor🇩🇪 · S.D. Katz🇭🇺 · H. Stoecker🇩🇪
The QCD equation of state at finite baryon density is studied in the framework of a Cluster Expansion Model (CEM), which is based on the fugacity expansion of the net baryon density. The CEM uses the two leading Fourier coefficients, obtained from lattice simulations at imaginary $μ_{B}$ , as the only model input and permits a closed analytic form. Excellent description of the available lattice data at both $μ_{B} = 0$ and at imaginary $μ_{B}$ is obtained. We also demonstrate how the Fourier coefficients can be reconstructed from baryon number susceptibilities.
Comments:
4 pages, 3 figures. Contribution to the Quark Matter 2018 conference proceedings
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1807.06472 [pdf]
NPA(2019)·21 citations
20
[Submitted on 17 Jul 2018] (cross-list from hep-ph)
Effect of the magnetized medium on the decay of neutral scalar bosons
Aritra Bandyopadhyay🇧🇷 · Ricardo L. S. Farias🇧🇷 · Rudnei O. Ramos🇧🇷
The decay of a heavy neutral scalar particle into fermions and into charged scalars are analyzed when in the presence of an external magnetic field and finite temperature. Working in the one-loop approximation for the study of these decay channels, it is shown that the magnetic field leads in general to a suppression of the decay width whenever the kinematic constrain depends explicitly on the magnetic field. Our results are also compared with common approximations found in the literature, e.g., when the magnitude of the external magnetic field is smaller than the decaying product particle masses, i.e., in the weak field approximation, and in the opposite case, i.e., in the strong field approximation. Possible applications of our results are discussed.
Comments:
17 pages, 4 figures; Replaced with updated version matching the published one
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1807.06515 [pdf]
PRD(2018)·9 citations
21
[Submitted on 17 Jul 2018] (cross-list from hep-ph)
Charged Kaon multiplicities of Semi-inclusive DIS off the deuteron target
Chung-Wen Kao🇹🇼 · Dong-Jing Yang🇹🇼 · Wen-Chen Chang🇹🇼
We investigate the results of the charged kaon multiplicities off the deuteron target from HERMES and COMPASS experiments. The discrepancy of the two data sets cannot be explained by different $Q^{2}$ values. Furthermore we examine the empirical parametrization of the fragmentation functions, DSS2017, and find that the agreement between the theoretical predictions and the HERMES data is less satisfactory as claimed.
Comments:
Contributed talk at the XXVI International Workshop on Deep Inelastic Scattering and Related Subjects at Kobe university, Kobe, Japan from April 16 to April 20, 2018
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1807.06524 [pdf]
2 citations
22
[Submitted on 17 Jul 2018] (cross-list from hep-lat)
Unpolarized isovector quark distribution function from Lattice QCD: A systematic analysis of renormalization and matching
Yu-Sheng Liu🇨🇳 · Jiunn-Wei Chen🇹🇼 · Yi-Kai Huo🇨🇳 · Luchang Jin🇺🇸 · Maximilian Schlemmer🇩🇪 · Andreas Schäfer🇩🇪 · Peng Sun🇨🇳 · Wei Wang🇨🇳 · Yi-Bo Yang🇺🇸 · Jian-Hui Zhang🇩🇪 · Qi-An Zhang🇨🇳 · Kuan Zhang🇨🇳 · Yong Zhao🇺🇸
We present a detailed Lattice QCD study of the unpolarized isovector quark Parton Distribution Function (PDF) using large-momentum effective theory framework. We choose a quasi-PDF defined by a spatial correlator which is free from mixing with other operators of the same dimension. In the lattice simulation, we use a Gaussian-momentum-smeared source at $M_{π} = 356$ MeV and $P_{z} \in {1.8, 2.3}$ GeV. To control the systematics associated with the excited states, we explore {five different source-sink separations}. The nonperturbative renormalization is conducted in a regularization-independent momentum subtraction scheme, and the matching between the renormalized quasi-PDF and $MS ˉ$ PDF is calculated based on perturbative QCD up to one-loop order. Systematic errors due to renormalization and perturbative matching are also analyzed in detail. Our results for lightcone PDF are in reasonable agreement with the latest phenomenological analysis.
Comments:
17 pages, 10 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1807.06566 [pdf]
PRD(2020)·119 citations
23
[Submitted on 17 Jul 2018] (cross-list from astro-ph.HE)
In-medium enhancement of the modified Urca neutrino reaction rates
P.S. Shternin🇷🇺 · M. Baldo🇮🇹 · P. Haensel🇵🇱
We calculate modified Urca neutrino emission rates in the dense nuclear matter in neutron star cores. We find that these rates are strongly enhanced in the beta-stable matter in regions of the core close to the direct Urca process threshold. This enhancement can be tracked to the use of the in-medium nucleon spectrum in the virtual nucleon propagator. We describe the in-medium nucleon scattering in the non-relativistic Bruckner-Hartree-Fock framework taking into account two-body as well as the effective three-body forces, although the proposed enhancement does not rely on a particular way of the nucleon interaction treatment. Finally we suggest a simple approximate expression for the emissivity of the n-branch of the modified Urca process that can be used in the neutron stars cooling simulations with any nucleon equation of state of dense matter.
Comments:
8 pages, 3 figures; accepted for publication in PLB. In v.2 misprint in eq.(9) corrected and discussion of cooling curves expanded
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1807.06569 [pdf]
PLB(2018)·40 citations
24
[Submitted on 17 Jul 2018] (cross-list from nucl-ex)
Constraining neutron-star equation of state using heavy-ion collisions
C.Y. Tsang🇺🇸 · M.B. Tsang🇺🇸 · P. Danielewicz🇺🇸 · W.G. Lynch🇺🇸 · F.J. Fattoyev🇺🇸
The LIGO-Virgo collaboration ground-breaking detection of the binary neutron-star merger event, GW170817, has intensified efforts towards the understanding of the equation of state (EoS) of nuclear matter. In this letter, we compare directly the density-pressure constraint on the EoS obtained from a recent analysis of the neutron-star merger event to density-pressure constraints obtained from nuclear physics experiments. To relate constraints from nuclear physics to the radii and the tidal deformabilities of neutron stars, we use a large collection of Skyrme density functionals that describe properties of nuclei to calculate properties of 1.4 solar maass neutron stars. We find that restricting this set of Skyrme equations of state to density functionals that describe nuclear masses, isobaric analog states, and low energy nuclear reactions does not sufficiently restrict the predicted neutron-star radii and the tidal deformabilities. Including pressure constraints on the EoS around twice saturation density, obtained from high energy nucleus-nucleus collisions, does constrain predicted radii and tidal deformabilities to be consistent with the results obtained from the analysis of GW170817. We discuss how new measurements of nucleus-nucleus collisions can improve these constraints on the EoS to be more restrictive than the current constraints from the GW170817 merger event.
Comments:
11 pages, 3 figures
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1807.06571 [pdf]
38 citations

Affiliations

first authorsco-authorsvia INSPIRE