Nuclear Theory·nucl-th
16 papers—9 primary·7 cross-listed
This an English translation of a review of finite-density lattice QCD. The original version in Japanese appeared in Soryushiron Kenkyu Vol 31 (2020) No. 1.
A discrete formulation of the real-time path integral as the expectation value of a functional of paths with respect to a complex probability on a sample space of discrete valued paths is explored. The formulation in terms of complex probabilities is motivated by a recent reinterpretation of the real-time path integral as the expectation value of a potential functional with respect to a complex probability distribution on cylinder sets of paths. The discrete formulation in this work is based on a discrete version of Weyl algebra that can be applied to any observable with a finite number of outcomes. The origin of the complex probability in this work is the completeness relation. In the discrete formulation the complex probability exactly factors into products of conditional probabilities and exact unitarity is maintained at each level of approximation. The approximation of infinite dimensional quantum systems by discrete systems is discussed. Applications to scattering theory and quantum field theory are illustrated.
L.X. Gutiérrez-Guerrero🇲🇽 · A. Alfaro🇲🇽 · A. Raya🇲🇽
In this article, the mass spectra of mesons with one or two heavy quarks and their diquarks partners are estimated within a non-relativistic framework by solving Schrödinger equation with an effective potential inspired by a symmetry preserving Poincaré covariant vector-vector contact interaction model of quantum chromodynamics. Matrix Numerov method is implemented for this purpose. In our survey of mesons with heavy quarks, we fix the model parameter to the masses of ground-states and then extend our calculations for radial excitations and diquarks. The potential model used in this work gives results which are in good agreement with experimental data and other theoretical calculations.
Zhengyu Chen🇨🇳 · Zeyan Wang🇨🇳 · Carsten Greiner🇩🇪 · Zhe Xu🇨🇳
We predict a new effect due to the presence of the global vorticity in non-central relativistic heavy-ion collisions, namely a splitting of the elliptic flow parameter at non-zero rapidity. The size of the splitting is proposed as a new observable that can be used to constrain the initial vortical configuration of the produced QCD matter in experiments. The new findings are demonstrated by numerical calculations employing the parton cascade model, Boltzmann Approach of MultiParton Scatterings (BAMPS), for non-central Au + Au collisions at .
N. Sadooghi🇮🇷 · S. M. A. Tabatabaee🇮🇷 · F. Taghinavaz🇮🇷
We study the properties of a hot and magnetized quark matter in a rotating cylinder in the presence of a constant magnetic field. To do this, we solve the corresponding Dirac equation using the Ritus eigenfunction method. This leads to the energy dispersion relation, Ritus eigenfunctions, and the quantization relation for magnetized fermions. To avoid causality-violating effects, we impose a certain global boundary condition, and study its effect, in particular, on the energy eigenmodes and the quantization relations of fermions. Using the fermion propagator arising from this method, we then solve the gap equation at zero and nonzero temperatures. At zero temperature, the dynamical mass does not depend on the angular frequency, as expected. We thus study its dependence on the distance relative to the axis of rotation and the magnetic field , and explore the corresponding finite size effect for various couplings . We then consider the finite temperature case. The dependence of on the temperature , magnetic field , angular frequency , and distance for various is studied. We show that decreases, in general, with and . This is the ''inverse magneto-rotational catalysis (IMRC)'' or the ''rotational magnetic inhibition'', previously discussed in the literature. To explore the evidence of this effect in the phase diagrams of our model, we examine the phase portraits of the critical temperature as well as the critical angular frequency with respect to , and as well as , and , respectively. We show that and decrease, in particular, with . This is interpreted as clear evidence for IMRC.
Jia Jie Li (Southwest U., Chongqing)🇨🇳 · Armen Sedrakian (FIAS, Frankfurt)🇩🇪 · Mark Alford (Washington U., St. Louis)🇺🇸
We explore the implications of the recent radius determination of PSR J0740+6620 by the NICER experiment combined with the neutron skin measurement by the PREX-II experiment and the associated inference of the slope of symmetry energy, for the structure of hybrid stars with a strong first-order phase transition from nucleonic to quark matter. We combine a covariant density-functional nucleonic equation of state (EOS) with a constant-speed-of-sound EOS for quark matter. We show that the radius and tidal deformability ranges obtained from GW170817 can be reconciled with the implication of the PREX-II experiment if there is a phase transition to quark matter in the low-mass compact star. In the high-mass segment, the EoS needs to be stiff to comply with the large-radius inference for PSR J0740+6620 and J0030+0451 with masses and . We show that twin stars are not excluded, but the mass and radius ranges (with ) are restricted to narrow domains and ~km. We also show that the existence of twin configurations is compatible with the light companion in the GW190814 event being a hybrid star in the case of values of the sound-speed square and .
Tianbo Liu🇨🇳 · W. Melnitchouk🇺🇸 · Jian-Wei Qiu🇺🇸 · N. Sato🇺🇸
We present the details of a new factorized approach to semi-inclusive deep-inelastic scattering which treats QED and QCD radiation on equal footing, and provides a systematically improvable approximation to the extraction of transverse momentum dependent parton distributions. We demonstrate how the QED contributions can be well approximated by collinear factorization, and illustrate the application of the factorized approach to QED radiation in inclusive scattering. For semi-inclusive processes, we show how radiation effects prevent a well-defined "photon-nucleon" frame, forcing one to use a two-step process to account for the radiation. We illustrate the utility of the new method by explicit application to the spin-dependent Sivers and Collins asymmetries.
first authorsco-authorsvia INSPIRE