Nuclear Theory·nucl-th

Tuesday·February 8, 2022

9 papers—4 primary·5 cross-listed

01
Kaon meson condensate in neutron star matter including hyperons
Fu Ma🇨🇳 · Wenjun Guo🇨🇳 · Chen Wu🇨🇳
The recent measurement of the mass of neutron stars (PSR J1614 - 2230, PSR J0348 + 0432, MSP J0740 + 6620) restricts the lower limit $\sim 2 M_{⊙}$ of the maximum mass of such compact stars, making it possible for dense matter to exist in massive stars. The relativistic mean field theory with parameter sets FSUGold including Kaon condensation is used to describe the properties of neutron stars in $β$ equilibrium. Through careful choice of the parameter of the $σ$ -cut $c_{σ}$ , we are able to produce a maximum mass neutron star with Kaon condensation heavier than $2 M_{⊙}$ , and we find that the parameter $Λ_{ν}$ of the $ρ - ω$ interaction term in this model has a significant effect on $K^{-}$ condensation. In the case of using $σ$ -cut scheme, $K^{-}$ condensation occurs only when the $ρ - ω$ interaction $Λ_{ν}$ is switched off.
nucl-thPRC(2022)·35 citations
02
Dynamics of rotation in chiral nuclei
Z. X. Ren🇨🇳 · P. W. Zhao🇨🇳 · J. Meng🇨🇳
The dynamics of chiral nuclei is investigated for the first time with the time-dependent and tilted axis cranking covariant density functional theories on a three-dimensional space lattice in a microscopic and self-consistent way. The experimental energies of the two pairs of the chiral doublet bands in $^{135}$ Nd are well reproduced without any adjustable parameters beyond the well-defined density functional. A novel mechanism, i.e., chiral precession, is revealed from the microscopic dynamics of the total angular momentum in the body-fixed frame, whose harmonicity is associated with a transition from the planar into aplanar rotations with the increasing spin. This provides a fully microscopic and dynamical view to understand the chiral excitations in nuclei.
nucl-thnucl-exPRC(2022)·33 citations
03
Quantum Computing for Heavy Quarkonium Spectroscopy
Daniel Gallimore🇺🇸 · Jinfeng Liao🇺🇸
We report a first demonstration for the application of quantum computing to heavy quarkonium spectroscopy study. Based on a Cornell-potential model for the heavy quark and antiquark system, we show how this Hamiltonian problem can be formulated and solved with the VQE approach on the IBM cloud quantum computing platform. Errors due to a global depolarizing noise channel are corrected with a zero-noise extrapolation method, resulting in good agreement with the expected value. We also extend the calculation to excited states on a noiseless quantum simulator by orthogonalization with respect to the ground state.
nucl-thPRD(2023)·11 citations
04
Mini-jet quenching in a concurrent jet+hydro evolution and the non-equilibrium quark-gluon plasma
Daniel Pablos🇮🇹 · Mayank Singh🇺🇸 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦
Mini-jets, created by perturbative hard QCD collisions at moderate energies, can represent a significant portion of the total multiplicity of a heavy-ion collision event. Since their transverse momenta are initially larger than the typical saturation scale describing the bulk of the equilibrating QGP, their typical stopping distances are larger than the usual hydrodynamization time, so they do not in general hydrodynamize at the same pace than the bulk of the collision. Therefore, in general mini-jets cannot be described solely by a unique pre-equilibrium stage that bridges the initial, over-occupied glasma state, with the hydrodynamical evolution. In this work we make use of a new concurrent mini-jet+hydrodynamic framework in which the properties of the hydrodynamically evolving QGP are modified due to the injection of energy and momentum from the mini-jets. We study the system for different choices of the minimum transverse momentum associated to mini-jet production. In order to achieve a realistic description of charged particle multiplicity, the amount of entropy associated to the low- $x$ initial state needs to be reduced. Moreover, the fact that the injected momentum from the randomly oriented mini-jets is not correlated with the spatial gradients of the system reduces overall flow, and the value of the QGP transport coefficients needs to be reduced accordingly. They are an important new source of fluctuations, resulting in a spikier, notably modified hydrodynamical evolution. We discuss the impact of the mini-jets on a number of observables, such as $p_{T}$ spectra and $p_{T}$ -differential flow $v_{n}$ for a wide range of centrality classes. In contrast to elliptic, triangular or quadrangular flow, we find that directed flow, $v_{1}$ , has the strongest potential to discriminate between different mini-jet production rates.
nucl-thPRC(2022)·25 citations
05
Entanglement entropy and flow in two dimensional QCD: parton and string duality
Yizhuang Liu🇵🇱 · Maciej A. Nowak🇵🇱 · Ismail Zahed🇺🇸
We discuss quantum entanglement between fast and slow degrees of freedom, in a two dimensional (2D) large $N_{c}$ gauge theory with Dirac quarks, quantized on the light front. Using the 't Hooft wave functions, we construct the reduced density matrix for an interval in the momentum fraction $x$ -space, and calculate its von Neumann entropy in terms of structure functions, that are measured by DIS on mesons (hadrons in general). We found that the entropy is bounded by an area law with logarithmic divergences, proportional to the rapidity of the meson. The evolution of the entanglement entropy with rapidity, is fixed by the cumulative singlet PDF, and bounded from above by a Kolmogorov-Sinai entropy of 1. At low- $x$ , the entanglement exhibits an asymptotic expansion, similar to the forward meson-meson scattering amplitude in the Regge limit. The evolution of the entanglement entropy in parton- $x$ per unit rapidity, measures the meson singlet PDF. The re-summed entanglement entropy along the single meson Regge trajectory, is string-like. We suggest that its extension to multi-meson states, models DIS scattering on a large 2D $^{'}$ nucleus $^{'}$ . The result, is a large rate of change of the entanglement entropy with rapidity, that matches the current Bekenstein-Bremermann bound for maximum quantum information flow. This mechanism may be at the origin of the large entropy deposition and rapid thermalization, reported in current heavy ion colliders, and may extend to future electron-ion colliders.
↳ hep-phhep-thnucl-exnucl-thPRD(2022)·23 citations
06
Heavy quarks at finite temperature
Johannes Heinrich Weber🇩🇪
New incarnations of heavy-ion collision experiments are turning our attention to hard processes and a more fine-grained resolution of the QGP. In this endeavor quarkonia or open heavy flavors turn out to be versatile probes, which are usually described through models based on perturbative QCD, AdS, and effective field theories. The lattice provides nonperturbative input and constraints to such models.\newline In-medium bottomonia, the complex static quark-antiquark potential, and the heavy-quark momentum diffusion coefficient are key quantities where lattice gauge theory has recently achieved significant progress with impact for heavy-ion phenomenology. We review these lattice results, relate them to phenomenological applications, and close with an outlook.
↳ hep-lathep-phnucl-exnucl-thPoS(2022)·1 citation
07
Lorentz transformation in Maxwell equations for slowly moving media
Xin-Li Sheng🇨🇳 · Yang Li🇨🇳 · Shi Pu🇨🇳 · Qun Wang🇨🇳
We use the method of field decomposition, a technique widely used in relativistic magnetohydrodynamics, to study the small velocity approximation (SVA) of the Lorentz transformation in Maxwell equations for slowly moving media. The "deformed" Maxwell equations derived under the SVA in the lab frame can be put into the conventional form of Maxwell equations in the medium's comoving frame. Our results show that the Lorentz transformation in the SVA up to $O (v / c)$ ( $v$ is the speed of the medium and $c$ is the speed of light in vacuum) is essential to derive these equations: the time and charge density must also change when transforming to a different frame even in the SVA, not just the position and current density as in the Galilean transformation. This marks the essential difference of the Lorentz transformation from the Galilean one. We show that the integral forms of Faraday and Ampere equations for slowly moving surfaces are consistent with Maxwell equations. We also present Faraday equation the covariant integral form in which the electromotive force can be defined as a Lorentz scalar independent of the observer's frame. No evidences exist to support an extension or modification of Maxwell equations.
↳ physics.class-phcond-mat.mes-hallcond-mat.mtrl-scihep-ph+1Symmetry(2022)·2 citations
08
Scrutinizing $π π$ scattering in light of recent lattice phase shifts
Xiu-Li Gao🇨🇳 · Zhi-Hui Guo🇨🇳 · Zhiguang Xiao🇨🇳 · Zhi-Yong Zhou🇨🇳
In this paper, the $I J = 00, 11, 20$ partial wave $π π$ scattering phase shifts determined by the lattice QCD approach are analyzed by using a novel dispersive solution of the S-matrix, i.e. the PKU representation, in which the unitarity and analyticity of scattering amplitudes are automatically satisfied and the phase shifts are conveniently decomposed into the contributions of the cuts and various poles, including bound states, virtual states and resonances. The contribution of the left-hand cut is estimated by the $S U (2)$ chiral perturbation theory to $O (p^{4})$ . The Balanchandran-Nuyts-Roskies relations are considered as constraints to meet the requirements of the crossing symmetry. It is found that the $I J = 00$ $π π$ scattering phase shifts obtained at $m_{π} = 391$ MeV by Hadron Spectrum Collaboration (HSC) reveal the presence of both a bound state pole and a virtual state pole below the $π π$ threshold rather than only one bound state pole for the $σ$ . To reproduce the lattice phase shifts at $m_{π} = 391$ MeV, a virtual-state pole in the $I J = 20$ channel is found to be necessary in order to balance the left-hand cut effects from the chiral amplitudes. Similar discussions are also carried out for the lattice results with $m_{π} = 236$ MeV from HSC. The observed behaviors of the pole positions with respect to the variation of the pion masses can provide deep insights into our understanding of the dynamical origin of $σ$ resonance.
↳ hep-phhep-latnucl-thPRD(2022)·13 citations
09
Polarized Antimatter in the Proton from Global QCD Analysis
C. Cocuzza🇺🇸 · W. Melnitchouk🇺🇸 · A. Metz🇺🇸 · N. Sato🇺🇸
We present the first simultaneous global QCD analysis of spin-dependent parton distribution functions alongside their spin-averaged counterparts and pion, kaon, and unidentified hadron fragmentation functions. This analysis includes all data relevant for constraining the polarized light quark sea asymmetry $Δ u ˉ - Δ d ˉ$ , in particular the latest polarized $W$ -lepton production data from the STAR collaboration at RHIC and semi-inclusive deep inelastic scattering data from COMPASS, allowing the most robust extraction available with minimal theoretical assumptions. We also extract a self-consistent set of antiquark polarization ratios $Δ u ˉ / u ˉ$ and $Δ d ˉ / d ˉ$ and determine the signs of the truncated contributions to the proton spin from the light antiquarks.
↳ hep-phhep-exnucl-thPRD(2022)·67 citations

Affiliations

first authorsco-authorsvia INSPIRE