Nuclear Theory·nucl-th

Monday·January 18, 2021

10 papers—7 primary·3 cross-listed

01
[Submitted on 14 Jan 2021]
Remarks on nuclear matter: how an $ω_{0}$ condensate can spike the speed of sound, and a model of $Z (3)$ baryons
Robert D. Pisarski🇺🇸
I make two comments about nuclear matter. First, I consider the effects of a coupling between the $O (4)$ chiral field, $ϕ$ , and the $ω_{μ}$ meson, $\sim + ω_{μ}^{2} ϕ^{2}$ ; for any net baryon density, a condensate for $ω_{0}$ is unavoidably generated. I assume that with increasing density, a decrease of the chiral condensate and the effective $ω_{0}$ mass gives a stiff equation of state (EoS). In order to match that onto a soft EoS for quarkyonic matter, I consider an $O (N)$ field at large $N$ , where at nonzero temperature quantum fluctuations disorder any putative pion "condensate" into a quantum pion liquid (Q $π$ L) (arXiv:2005.10259). In this paper I show that the Q $π$ L persists at zero temperature. If valid qualitatively at $N = 4$ , the $ω_{0}$ mass goes up sharply and suppresses the $ω_{0}$ condensate. This could generate a spike in the speed of sound at high density, which is of relevance to neutron stars. Second, I propose a toy model of a $Z (3)$ gauge theory with three flavors of fermions, where $Z (3)$ vortices confine fermions into baryons. In $1 + 1$ dimensions this model can be studied numerically with present techniques, using either classical or quantum computers.
Comments:
Slightly expanded from published version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2101.05813 [pdf]
PRD(2021)·49 citations
02
[Submitted on 15 Jan 2021]
The chiral phase transition and equation of state in the chiral imbalance
Qing-Wu Wang🇨🇳 · Chao shi🇨🇳 · Hong-Shi Zong🇨🇳
The chiral phase transition and equation of state are studied within a new self-consistent mean-field approximation of the two-flavor Nambu $-$ Jona-Lasinio model. In this newly developed model, modifications to the chemical potential $μ$ and chiral chemical potential $μ_{5}$ is naturally included by adding vector and axial-vector channels from Fierz-transformed Lagrangian to the standard Lagrangian. In proper-time scheme, the chiral phase transition is a crossover in the $T - μ$ plane. But when $μ_{5}$ is increased, our study shows that there may exist first order phase transition. Furthermore, the chiral imbalance will soften the equation of state of quark matter. The mass-radius relations and tidal deformability of quark stars are calculated. As $μ_{5}$ increases, the maximum mass and radius decrease. The vector channel and axial-vector channel have opposite influence on the equation of state. However, when EOS is constrained by astronomical observations, the shape of the mass-radius curve can be used to determine whether there is chiral imbalance in the dense object, and thus indirectly proving the CP violation in the dense matter. Our study shows a different influence of the chiral imbalance on the chiral phase transition in contrary to tree-momentum-cutoff scheme.
Comments:
7pages and 7 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2101.05932 [pdf]
CPC(2021)·3 citations
03
[Submitted on 15 Jan 2021]
The effect of the quantization of the centrifugal stretching on the analysis of rotational spectra of even-even deformed nuclei in rare earth and actinide regions
Abdurahim A. Okhunov · Mohd Kh. M. Abu El Sheikh
Deviation from the I(I+1) rule in the even-even isotopes 62Sm, 64Gd, 66Dy, 68Er, 70Y b, 72Hf, 74W and 76Os nuclei have been studied with a new approach based on the idea that the rotational nucleus being stretched out along the symmetry axis, where such stretching is treated according to quantum mechanics. This approach led to a new formula that describes the dependence of the moment of inertia on the angular momentum, and such formula works well for all even-even nuclei in the actinide and rare-earth region in the range 2.9<R<3.3. The calculations were carried out with the stretched model where the stretching of the nucleus with the rotation is quantized. The obtained results with a new derived formula which gives a reasonable agreement with the experimental date for all I up to 16.
Comments:
11 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2101.05980 [pdf]
0 citations
04
[Submitted on 15 Jan 2021]
Statistical and dynamical bimodality in multifragmentation reactions
S. Mallik🇮🇳 · G. Chaudhuri🇮🇳 · F. Gulminelli🇫🇷 · S. Das Gupta🇨🇦
The bimodal behavior of the order parameter is studied in the framework of Boltzmann-Uehling-Uhlenbeck (BUU) transport model. In order to do that, simplified yet accurate method of BUU model is used which allow calculation of fluctuations in systems much larger than what was considered feasible in a well-known and already existing model. It is observed that depending on the projectile energy and centrality of the reaction, both entrance channel and exit channel effects can be at the origin of the experimentally observed bimodal behavior. Both dynamical and statistical bimodality mechanisms are associated in the theoretical model to different time scales of the reaction, and to different energy regimes.
Comments:
arXiv admin note: substantial text overlap with arXiv:1802.05047
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2101.06036 [pdf]
1 citation
05
[Submitted on 15 Jan 2021]
Production of super-heavy nuclei in cold fusion reactions
V. Yu. Denisov🇺🇦 · I. Yu. Sedykh🇷🇺
The model for the cold-fusion reactions related to the synthesis of super-heavy nuclei in collisions of heavy projectile-nuclei with $^{208}$ Pb target nucleus is discussed. In the framework of this model the production of the compound nucleus by two paths through, the di-nuclear system and the fusion way, are taken into account simultaneously. The formation of the compound nucleus in the framework of the di-nuclear system is related to the transfer of nucleons from the light nucleus to the heavy one. The fusion way is linked to the sequential evolution of the nuclear shape from the system of contacting nuclei to the compound nucleus. It is shown that the compound nucleus is mainly formed by the fusion way in the cold-fusion reactions. The landscape of the potential energy related to the fusion path is discussed in detail. This landscape for very heavy nucleus-nucleus systems has the intermediate state, which is linked to the formation of both the compound nucleus and the quasi-fission fragments. The decay of the intermediate state is taken into account in the calculation of the compound nucleus production cross sections and the quasi-fission cross sections. The values of the cold-fusion cross sections obtained in the model are well agreed with the experimental data.
Comments:
23 pages, 10 figures, 5 tables. To be published in Chinese Physics C
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2101.06037 [pdf]
CPC(2021)·11 citations
06
[Submitted on 15 Jan 2021]
New signatures of phase transition from Statistical Models of Nuclear multifragmentation
G. Chaudhuri🇮🇳 · S. Mallik🇮🇳 · P. Das🇮🇳 · S. Das Gupta🇨🇦
The study of liquid-gas phase transition in heavy ion collisions has generated a lot of interest amongst the nuclear physicists in the recent years. In heavy ion collisions, there is no direct way of measuring the state variables like entropy, pressure, energy and hence unambiguous characterization of phase transition becomes difficult. This work proposes new signatures of phase transition that can be extracted from the observables which are easily accessible in experiments. It is observed that the temperature dependence of the first order derivative of the order parameters in nuclear liquid gas phase transition exhibit similar behavior as that of the variation of specific heat at constant volume Cv which is an established signature of first order phase transition. This motivates us to propose these derivatives as confirmatory signals of liquid-gas phase transition. The measurement of these signals in easily feasible in most experiments as compared to the other signatures like specific heat, caloric curve or bimodality. Total multiplicity, size of largest cluster are some of the order parameters which have been studied. Statistical Models based on canonical ensemble and lattice gas model has been used for the study. This temperature where the peak appears is designated to be the transition temperature and the effect of certain parameters on this has also been examined. The multiplicity derivative signature proposed in this work has been further confirmed by other theoretical models as well as in experimental study.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2101.06062 [pdf]
0 citations
07
[Submitted on 15 Jan 2021]
Coulomb corrections to Fermi beta decay in nuclei
Naftali Auerbach · Minh-Loc Bui
We study the influence of the Coulomb force on the Fermi beta-decays in nuclei. This work is composed of two main parts. In the first part, we calculate the Coulomb corrections to super-allowed beta decay. We use the notion of the isovector monopole state and the self-consistent charge-exchange Random Phase Approximation to compute the correction. In the second part of this work, we examine the influence of the anti-analog state on isospin mixing in the isobaric analog state and the correction to the beta-decay Fermi transition.
Comments:
Some numerical mistakes were corrected. The present version matches the online version published in NPA
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2101.06199 [pdf]
NPA(2022)·9 citations
08
[Submitted on 15 Jan 2021] (cross-list from hep-lat)
Three-body interactions from the finite-volume QCD spectrum
Ruairí Brett🇺🇸 · Chris Culver🇬🇧 · Maxim Mai🇺🇸 · Andrei Alexandru🇺🇸 · Michael Döring🇺🇸 · Frank X. Lee🇺🇸
We perform a fit of the finite-volume QCD spectrum of three pions at maximal isospin to constrain the three-body force. We use the unitarity-based relativistic three-particle quantization condition, with the GWUQCD spectrum obtained at 315 MeV and 220 MeV pion mass in two-flavor QCD. For the heavier pion mass we find that the data is consistent with a constant contact term close to zero, whereas for the lighter mass we see a statistically significant energy dependence in tension with the prediction of leading order ChPT. Our results also suggest that with enough three-body energy levels, the two-body amplitude could be constrained.
Comments:
17 pages, 6 figures. Updated to match published version
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2101.06144 [pdf]
PRD(2021)·73 citations
09
[Submitted on 15 Jan 2021] (cross-list from physics.flu-dyn)
Two Dimensional Turbulence in a Massless Fluid with a Relativistic Lattice Boltzmann Model
Mark Watson🇺🇸
We investigate a relativistic adaptation of the Lattice Boltzmann Method that reproduces the equations of motion for a turbulent, two-dimensional, massless hydrodynamic system. The classical Lattice Boltzmann Method and its extension to relativistic fluid dynamics is described. The numeric formulation is evaluated using a zero-averaged stirring force introduced into the numerics to induce turbulence, and the flow characteristics produced are compared to properties of a classical turbulent hydrodynamic flow. The model can reasonably be expected to offer quantitative simulations of electron fluid flows in graphene or Kagome lattices.
Comments:
28 pages, 11 Figures, Comments Welcome
Subjects:
Fluid Dynamics (physics.flu-dyn); High Energy Astrophysical Phenomena (astro-ph.HE); Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th)
arXiv:
2101.06187 [pdf]
AIP Adv.(2021)·2 citations
10
[Submitted on 15 Jan 2021] (cross-list from hep-ph)
Electron-Ion Collider impact study on the tensor charge of the nucleon
Leonard Gamberg🇺🇸 · Zhong-Bo Kang🇺🇸 · Daniel Pitonyak🇺🇸 · Alexei Prokudin🇺🇸 · Nobuo Sato🇺🇸 · Ralf Seidl🇺🇸
In this letter we study the impact of the Electron-Ion Collider (EIC) on the phenomenological extraction of the tensor charge from a QCD global analysis of single transverse-spin asymmetries (SSAs). We generate EIC pseudo-data for the Collins effect in semi-inclusive deep-inelastic scattering for proton and $^{3} H e$ beams across multiple center-of-mass energies. We find a significant reduction in the uncertainties for the up, down, and isovector tensor charges that will make their extraction from EIC data on SSAs as precise as current lattice QCD calculations. We also analyze the constraints placed by future data from the proposed SoLID experiment at Jefferson Lab, discuss its important complementary role to the EIC, and present the combined impact from both facilities.
Comments:
12 pages, 6 figures, 1 table; minor changes; version to be published in PLB
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2101.06200 [pdf]
PLB(2021)·18 citations

Affiliations

first authorsco-authorsvia INSPIRE