Nuclear Theory·nucl-th

Wednesday·January 19, 2022

26 papers—10 primary·16 cross-listed

11
Chiral phase transition of a dense, magnetized and rotating quark matter
S. M. A. Tabatabaee Mehr🇮🇷 · F. Taghinavaz🇮🇷
We investigate the chiral symmetry restoration/breaking of a dense, magnetized and rotating quark matter within the Nambu Jona-Lasinio model including $N_{f} = 2$ and $N_{c} = 3$ numbers of flavors and colors, respectively. Imposing the spectral boundary conditions, as well as the positiveness of energy levels, lead to a correlation between the magnetic and rotation fields such that strongly magnetized plasma can not rotate anymore. We solve the gap equation at zero and finite temperature. At finite temperature and baryon chemical potential $μ_{B}$ , we sketch the phase diagrams $T_{c} (μ_{B})$ and $T_{c} (R Ω)$ in different cases. As a result, we always observe inverse-rotational catalysis mean to decrease $T_{c}$ by increasing $R Ω$ . But the magnetic field has a more complex structure in the phase diagram. For slowly rotating plasma, we find that $T_{c}$ decreases by increasing $e B$ , while in the fast rotating plasma we see that $T_{c}$ increases by increasing $e B$ . Also, we locate exactly the position of Critical End Point by solving the equations of first and second derivatives of effective action with respect to the order parameters, simultaneously.
↳ hep-phhep-thnucl-thAnnals Phys.(2023)·14 citations
12
The applicability of hydrodynamics in heavy ion collisions at $s_{NN}$ = 2.4-7.7 GeV
Gabriele Inghirami🇩🇪 · Hannah Elfner🇩🇪
To assess the degree of equilibration of the matter created in heavy-ion reactions at low to intermediate beam energies, a hadronic transport approach (SMASH) is employed. By using a coarse-graining method, we compute the energy momentum tensor of the system at fixed time steps and evaluate the degree of isotropy of the diagonal terms and the relative magnitude of the off-diagonal terms. This study focuses mostly on Au+Au collisions in the energy range $s_{NN}$ = 2.4-7.7 GeV, but central collisions of lighter ions like C+C, Ar+KCl and Ag+Ag are considered as well. We find that the conditions concerning local equilibration for a hydrodynamic description are reasonably satisfied in a large portion of the system for a significant amount of time (several fm/c) when considering the average evolution of many events, yet they are rarely fulfilled on an event by event basis. This is relevant for the application of hybrid approaches at low beam energies as they are or will be reached by the HADES experiment at GSI, the future CBM experiment at FAIR as well as the beam energy scan program at RHIC.
↳ hep-phnucl-thEPJC(2022)·29 citations
13
Replica Symmetry Breaking for the Integrable Two-Site Sachdev-Ye-Kitaev Model
Yiyang Jia🇮🇱 · Dario Rosa🇰🇷 · Jacobus J. M. Verbaarschot🇺🇸
We analyze a two-body nonhermitian two-site Sachdev-Ye-Kitaev model with the couplings of one site complex conjugated to the other site. This model, with no explicit coupling between the sites, shows an infinite number of phase transitions which is a consequence of the partition function factorizing into a product over Matsubara frequencies. We calculate the quenched free energy in two different ways, first in terms of the single-particle energies, and second by solving the Schwinger-Dyson equations. The first calculation can be done entirely in terms of a one-site model. The conjugate replica enters due to non-analyticities when Matsubara frequencies enter the spectral support of the coupling matrix. The second calculation is based on the replica trick of the two-site partition function. Both methods give the same result. The free-fermion partition function can be rephrased as a matrix model for the coupling matrix. Up to minor details, this model is the random matrix model that describes the chiral phase transition of QCD, and the order parameter of the two-body model corresponds to the chiral condensate of QCD. Comparing to the corresponding four-body model, we are able to determine which features of the free energy are due to chaotic nature of the four-body model. The high-temperature phase of both models is entropy dominated, and in both cases is determined by the spectral density. The four-body SYK model has a low-temperature phase whose free energy is almost temperature-independent, signaling an effective gap of the theory even though the actual spectrum does not exhibit a gap. However the low-temperature free energy of the two-body SYK model is not flat, in fact it oscillates to arbitrarily low temperature. This indicates a less desirable feature that the entropy of the two-body model is not always positive, which most likely is a consequence of the nonhermiticity.
↳ hep-thcond-mat.dis-nnnucl-thJ.Math.Phys.(2022)·8 citations
14
Light mesons with one dynamical gluon within basis light-front quantization
Jiangshan Lan🇨🇳 · Kaiyu Fu🇨🇳 · Chandan Mondal🇨🇳 · Xingbo Zhao🇨🇳 · James P. Vary🇺🇸
We investigate the structure of the light meson with one dynamical gluon from the light-front QCD Hamiltonian, determined for their constituent quark-antiquark and quark-antiquark-gluon Fock sectors, together with a three-dimensional confinement. After fitting the light meson mass spectroscopy, the light-front wave functions provide a good quality description of the pion electromagnetic form factor, and the valence quark distribution functions following QCD scale evolution.
↳ hep-phnucl-th3 citations
15
Charge-dependent directed flows in heavy-ion collisions by Boltzmann-Maxwell equations
Jun-Jie Zhang🇨🇳 · Xin-Li Sheng🇨🇳 · Shi Pu🇨🇳 · Jian-Nan Chen🇨🇳 · Guo-Liang Peng🇨🇳 · Jian-Guo Wang🇨🇳 · Qun Wang🇨🇳
We have calculated the directed flow $v_{1}$ and charge-dependent directed flow $Δ v_{1}$ for pions and protons in Au+Au collisions at $s_{N N} = 200$ GeV by solving the coupled Boltzmann-Maxwell equations self-consistently. Our numerical results show that $v_{1}$ for pions and protons are all negative in the positive mid rapidity region and have similar behavior and magnitude. In contrast we find a quite different behavior in $Δ v_{1}$ for pions and protons. The difference lies in that $Δ v_{1}$ for protons mainly comes from pressure gradients of the medium, while the dominant contribution to $Δ v_{1}$ for pions is from electromagnetic fields. Our results indicate that the effect of the electric field will slightly exceed that of the magnetic and lead to a small negative slope of $Δ v_{1}$ for pions
↳ hep-phnucl-thPRResearch(2022)·23 citations
16
The decay of $N^{*}$ (1895) to light hyperon resonances
K. P. Khemchandani🇧🇷 · A. Martínez Torres🇧🇷 · Sang-Ho Kim🇰🇷 · Seung-il Nam🇰🇷 · H. Nagahiro🇯🇵 · A. Hosaka🇯🇵
In this talk I review the findings of our recent works where we have studied the decay of $N^{*} (1895)$ and the implications of such properties on the photoproduction of light hyperons. I discuss that meson-baryon interactions play an essential role in describing the nature of $N^{*} (1895)$ and report the details of our investigation of its decays to different meson-baryon systems and to final states involving $Λ (1405)$ and a proposed $Σ (1400)$ . We find that the width of $N^{*} (1895)$ gets important contributions from the decay to light hyperon resonances. Such an information can be used to look for alternative processes to study $N^{*} (1895)$ in experimental data.
↳ hep-phnucl-thRev.Mex.Fis.Suppl.(2022)·3 citations
17
Electromagnetic spectral functions in hot and dense chirally imbalanced quark matter
Snigdha Ghosh🇮🇳 · Nilanjan Chaudhuri🇮🇳 · Sourav Sarkar🇮🇳 · Pradip Roy🇮🇳
The photon self-energy from chirally imbalanced quark matter is evaluated at finite temperature and density using the real time formulation of thermal field theory. The analytic structure is explored in detail exposing the cut structure which corresponds to a variety of physical scattering and decay processes in the medium and their thresholds. The mass of the quarks in the chiral symmetry broken phase are obtained from the gap equation of the Nambu--Jona-Lasinio model. It is found that, in presence of finite chiral chemical potential, the chiral condensate tends to get stronger at low temperature while the opposite is observed at high values of temperature. A continuous spectrum is obtained for the electromagnetic spectral function and this is purely a finite chiral chemical potential effect.
↳ hep-phnucl-thPRD(2022)·11 citations
18
Gravitational search for near Earth black holes or other compact dark objects
Tomoyo Namigata🇺🇸 · C. J. Horowitz🇺🇸 · R. Widmer-Schnidrig🇩🇪
Primordial black holes, with masses comparable to asteroids, are an attractive possibility for dark matter. In addition, other forms of dark matter could form compact dark objects (CDO). We search for small tidal accelerations from low mass black holes or CDOs orbiting near the Earth, and find none. Using about 10 years of data from the superconducting gravimeters in the Black Forest Observatory in South-Western Germany and at Djougou, Northern Benin in Western Africa we set an upper limit on the maximum mass of any dark object orbiting the Earth as a function of orbital radius. For semi-major axis less than two earth radii we exclude all black holes or CDOs with masses larger than 6.7x10^{13} kg. Lower mass primordial black holes may be strongly constrained by Hawking radiation. We conclude that near Earth black holes are extremely unlikely.
↳ gr-qcastro-ph.COastro-ph.EPastro-ph.HE+25 citations
19
Useful relations and sum rules for PDFs and multiparton distribution functions of spin-1 hadrons
S. Kumano🇯🇵 · Qin-Tao Song🇨🇳
There are two types of polarizations in spin-1 hadrons, and they are vector and tensor polarizations. The latter is a unique one since it does not exist in the spin-1/2 proton. The vector-polarized PDFs are the same for both the proton and spin-1 hadrons; therefore, we mainly investigate the unique PDFs in tensor-polarized hadrons. By using the operator product expansion, the twist-3 PDF $f_{L T}$ can be expressed by two terms in the same way with $g_{T}$ of the proton. The first term is determined by the twist-2 PDF $f_{1 LL}$ (or $b_{1}$ ) which was measured by an experiment, and the second term is expressed by twist-3 quark-gluon distributions. If we neglect the higher-twist effects, $f_{L T}$ is simply given by $f_{1 LL}$ , and this relation is similar to the Wandzura-Wilczek relation of $g_{T}$ . Furthermore, a new sum rule is also obtained for $f_{2 L T} = 2/3 f_{L T} - f_{1 LL}$ , which is analogous to the Burkhardt-Cottingham sum rule, in the tensor-polarized spin-1 hadrons. In future, these interesting relations could be studied at accelerator facilities, such as the Jefferson Laboratory, the Fermilab, the nuclotron-based ion collider facility in Russia, the proposed electron-ion colliders in US and China.
↳ hep-phhep-latnucl-thJPS Conf.Proc.(2022)·0 citations
20
Family of New Exact Solutions for Longitudinally Expanding Ideal Fluids
Shuzhe Shi🇨🇦 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦
We report on the discovery of new analytical solutions of the equations of relativistic ideal hydrodynamics. In this solution, the fluid expands in the longitudinal direction and contains a plateau structure that extends over a finite range in rapidity and can be either symmetric or asymmetric in that variable. We further calculate the corresponding pseudo-rapidity distribution of hadron yields, and find decent agreement with experimental measurements in high-energy Pb+Pb, Au+Au, p+Pb, and d+Au collisions.
↳ hep-phnucl-thPRC(2022)·13 citations
21
Taking Neutrino Pictures via Electrons
Guey-Lin Lin🇹🇼 · Thi Thuy Linh Nguyen🇹🇼 · Martin Spinrath🇹🇼 · Thi Dieu Hien Van🇹🇼 · Tse-Chun Wang🇹🇼
In this paper we discuss the prospects to take a picture of an extended neutrino source, i.e., resolving its angular neutrino luminosity distribution. This is challenging since neutrino directions cannot be directly measured but only estimated from the directions of charged particles they interact with in the detector material. This leads to an intrinsic blurring effect. We first discuss the problem in general terms and then apply our insights to solar neutrinos scattering elastically with electrons. Despite the aforementioned blurring we show how with high statistics and precision the original neutrino distributions could be reconstructed.
↳ hep-phastro-ph.HEastro-ph.SRhep-ex+1JCAP(2022)·2 citations
22
Sensitivity of Parity-violating Electron Scattering to a Dark Photon
A. W. Thomas🇦🇺 · X. G. Wang🇦🇺 · A. G. Williams🇦🇺
We explore the sensitivity of the parity-violating electron scattering (PVES) asymmetry in both elastic and deep-inelastic scattering to the properties of a dark photon. Given advances in experimental capabilities in recent years, there are interesting regions of parameter space where PVES offers the chance to discover new physics in the near future. There are also cases where the existence of a dark photon could significantly alter our understanding of the structure of atomic nuclei and neutron stars as well as parton distribution functions.
↳ hep-phhep-exnucl-thPRL(2022)·27 citations
23
Implicit correlations within phenomenological parametric models of the neutron star equation of state
Isaac Legred · Katerina Chatziioannou · Reed Essick · Philippe Landry
The rapid increase in the number and precision of astrophysical probes of neutron stars in recent years allows for the inference of their equation of state. Observations target different macroscopic properties of neutron stars which vary from star to star, such as mass and radius, but the equation of state allows for a common description of all neutron stars. To connect these observations and infer the properties of dense matter and neutron stars simultaneously, models for the equation of state are introduced. Parametric models rely on carefully engineered functional forms that reproduce a large array of realistic equations of state. Such models benefit from their simplicity but are limited because any finite-parameter model cannot accurately approximate all possible equations of state. Nonparametric models overcome this by increasing model freedom at the cost of increased complexity. In this study, we compare common parametric and nonparametric models, quantify the limitations of the former, and study the impact of modeling on our current understanding of high-density physics. We show that parametric models impose strongly model-dependent, and sometimes opaque, correlations between density scales. Such interdensity correlations result in tighter constraints that are unsupported by data and can lead to biased inference of the equation of state and of individual neutron star properties.
↳ astro-ph.HEgr-qcnucl-thPRD(2022)·52 citations
24
A stable and causal model of magnetohydrodynamics
Jay Armas🇳🇱 · Filippo Camilloni🇮🇹
We formulate the theory of first-order dissipative magnetohydrodynamics in an arbitrary hydrodynamic frame under the assumption of parity-invariance and discrete charge symmetry. We study the mode spectrum of Alfvén and magnetosonic waves as well as the spectrum of gapped excitations and derive constraints on the transport coefficients such that generic equilibrium states with constant magnetic fields are stable and causal under linearised perturbations. We solve these constraints for a specific equation of state and show that there exists a large family of hydrodynamic frames that renders the linear fluctuations stable and causal. This theory does not require introducing new dynamical degrees of freedom and therefore is a promising and simpler alternative to Müller-Israel-Stewart-type theories. Together with a detailed analysis of transport, entropy production and Kubo formulae, the theory presented here is well suited for studying dissipative effects in various contexts ranging from heavy-ion collisions to astrophysics.
↳ hep-thastro-ph.HEgr-qchep-ph+1JCAP(2022)·41 citations
25
Thermal Relaxation and Cooling of Quark Stars with a Strangelet Crust
Joas Zapata🇧🇷 · Rodrigo Negreiros🇧🇷 · Thiago Sales🇺🇸 · Prashanth Jaikumar🇧🇷
In this article, we explore the cooling of isolated quark stars. These objects are structured of a homogeneous quark matter core and crusted by matter. To do this, we adopt two kinds of crust: (i) a crust made of purely nuclear matter following the Baym-Pethick-Sutherland (BPS) equation of state (EoS) and (ii) a crust made of nuggets of strange quark matter (strangelets). Both models have the same quark matter core described by the MIT bag model EoS. Our main purpose is to quantify the effects of a strangelet crust on the cooling and relaxation times of these strange stars. We also perform a thorough study of the thermal relaxation of quark stars, in which we have found that objects with a strangelet crust have a significantly different thermal relaxation time. Our study also includes the possible effects of color superconductivity in the quark core.
↳ hep-phastro-ph.HEnucl-thAstron.Astrophys.(2022)·11 citations
26
Competition of chiral soliton lattice and Abrikosov vortex lattice in QCD with isospin chemical potential
Martin Spillum Grønli🇳🇴 · Tomáš Brauner🇳🇴
We investigate the thermodynamics of two-flavor quark matter in presence of nonzero isospin chemical potential and external magnetic field. It is known that at sufficiently high isospin chemical potential, charged pions undergo Bose-Einstein condensation (BEC). The condensate behaves as a superconductor, exhibiting Meissner effect in weak external magnetic fields. Stronger fields stress the superconducting state, turning it first into an Abrikosov lattice of vortices, and eventually destroying the condensate altogether. On the other hand, for sufficiently strong magnetic fields and low-to-moderate isospin chemical potential, the ground state of quantum chromodynamics (QCD) is expected to be a spatially modulated condensate of neutral pions, induced by the chiral anomaly: the chiral soliton lattice (CSL). We map the phase diagram of QCD as a function of isospin chemical potential and magnetic field in the part of the parameter space accessible to a low-energy effective field theory description of QCD. Our main result is an explicit account of the competition between the CSL and the Abrikosov vortex lattice. This is accomplished by adopting a fast numerical algorithm for finding the vortex lattice solution of the equation of motion and the corresponding Gibbs energy. We find that the Abrikosov vortex lattice phase persists in the phase diagram, separating the uniform charged pion BEC phase from the CSL phase. The precise layout of the phase diagram depends sensitively on the choice of the vacuum pion mass.
↳ hep-phnucl-thEPJC(2022)·23 citations

Affiliations

first authorsco-authorsvia INSPIRE