Nuclear Theory·nucl-th

Wednesday·January 26, 2022

9 papers—4 primary·5 cross-listed

05
Color-flavor dependence of the Nambu-Jona-Lasinio model and QCD phase diagram
Aftab Ahmad🇵🇰 · Ali Murad🇵🇰
We study the dynamical chiral symmetry breaking/restoration for the various numbers of light quarks flavors $N_{f}$ and colors $N_{c}$ , using the Nambu-Jona-Lasinio (NJL) model of quarks, dressed with a color-flavor dependence of effective coupling. Initially, we set $N_{f} = 2$ , and varying the number of colors $N_{c}$ , we find that the dynamical chiral symmetry is broken when $N_{c}$ exceeds to its critical value $N_{c}^{c} \approx 2.2$ . Secondly, we take $N_{c} = 3$ , and varying $N_{f}$ , we observed that the dynamical chiral symmetry is restored when $N_{f}$ reaches to its critical value $N_{f}^{c} \approx 8$ . The strong interplay observed between $N_{c}$ and $N_{f}$ , i.e., $N_{c}$ anti-screens the strong interactions by strengthening the dynamical mass and quark-antiquark condensate, while $N_{f}$ screens the strong interaction by suppressing both the parameters. We further sketch the quantum chromodynamics (QCD) phase diagram at finite temperature $T$ and quark chemical potential $μ$ for various $N_{c}$ and $N_{f}$ . At finite $T$ and $μ$ , we observed that the critical number of colors $N_{c}^{c}$ enhances while the critical number of flavors $N_{f}^{c}$ suppresses as $T$ and $μ$ increases. Of course, the parameters $T$ and $μ$ produce the screening effect. Consequently, the critical temperature $T_{c}$ , $μ_{c}$ and co-ordinates of the critical endpoint $(T_{c}^{E}, μ_{c}^{E})$ in the QCD phase diagram enhances as $N_{c}$ increases while suppresses when $N_{f}$ increases. Our findings agree with the Lattice QCD and Schwinger-Dyson equations predictions.
↳ hep-phnucl-thCPC(2022)·7 citations
06
Production characteristics of light (anti-)nuclei from (anti-)nucleon coalescence in heavy ion collisions at energies employed at the RHIC beam energy scan
Xiang-Yu Zhao🇨🇳 · Yan-Ting Feng🇨🇳 · Feng-Lan Shao🇨🇳 · Rui-Qin Wang🇨🇳 · Jun Song🇨🇳
With the kinetic freeze-out nucleons and antinucleons obtained from the quark combination model, we study the production of light nuclei and antinuclei in the (anti-)nucleon coalescence mechanism in relativistic heavy ion collisions. We derive analytic formulas of the momentum distributions of different light nuclei and apply them to compute transverse momentum ( $p_{T}$ ) spectra of (anti-)deuterons ( $d$ , $d ˉ$ ) and (anti-)tritons ( $t$ , $t ˉ$ ) in Au-Au collisions at $s_{N N} =$ 7.7, 11.5, 19.6, 27, 39, 54.4 GeV. We find that the experimental data available for these $p_{T}$ spectra can be well reproduced. We further study the yields and yield ratios of different light (anti-)nuclei and naturally explain their interesting behaviors as a function of the collision energy. We especially point out that the multi-particle yield ratio $tp / d^{2}$ should be carefully corrected from hyperon weak decays for protons to probe the production characteristics of light nuclei. All of our results show that the coalescence mechanism for (anti-)nucleons plays a dominant role for the production of light nuclei and antinuclei at the RHIC beam energy scan energies.
↳ hep-phhep-exnucl-thPRC(2022)·11 citations
07
Investigating the predicted breathing-mode excitation of the Hoyle state
K. C. W. Li · F. D. Smit · P. Adsley · R. Neveling · P. Papka · E. Nikolskii · J. W. Brümmer · L. M. Donaldson · M. Freer · M. N. Harakeh · F. Nemulodi · L. Pellegri and 16 other authors
Knowledge of the low-lying monopole strength in $^{12} C$ $-$ the Hoyle state in particular $-$ is crucial for our understanding of both the astrophysically important $3 α$ reaction and of $α$ -particle clustering. Multiple theoretical models have predicted a breathing mode of the Hoyle State at $E_{x} \approx 9$ MeV, corresponding to a radial in-phase oscillation of the underlying $α$ clusters. The $^{12} C (α, α^{'})^{12} C$ and $^{14} C (p, t)^{12} C$ reactions were employed to populate states in $^{12}$ C in order to search for this predicted breathing mode. A self-consistent, simultaneous analysis of the inclusive spectra with R-matrix lineshapes, together with angular distributions of charged-particle decay, yielded clear evidence for excess monopole strength at $E_{x} \approx 9$ MeV which is highly collective. Reproduction of the experimentally observed inclusive yields using a fit, with consistent population ratios for the various broad states, required an additional source of monopole strength. The interpretation of this additional monopole resonance as the breathing-mode excitation of the Hoyle state would provide evidence supporting a $D_{3 h}$ symmetry for the Hoyle state itself. The excess monopole strength may complicate analysis of the properties of the Hoyle state, modifying the temperature dependence of the $3 α$ rate at $T_{9} ≳ 2$ and ultimately, the predicted nucleosynthesis in explosive stars.
↳ nucl-exnucl-thPLB(2022)·12 citations
08
Strong decays of multi-strangeness baryon resonances in the quark model
Ahmad Jafar Arifi🇰🇷 · Daiki Suenaga🇯🇵 · Atsushi Hosaka🇯🇵 · Yongseok Oh🇰🇷
Decay properties of multi-strangeness $Ξ$ and $Ω$ baryon resonances are investigated within the constituent quark model by including relativistic corrections. The strong decay widths of various $Ξ$ and $Ω$ resonances are computed and tested for internal quark configurations to pin down their spin-parity ( $J^{P}$ ) quantum numbers and internal structures. We found that the Roper-like resonances in the multi-strangeness sector have large decay widths bearing resemblances to their siblings in light and heavy baryon sectors. In addition, we obtained the decay ratio for the $Ω (2012)$ as $Γ (Ω \to Ξ K ˉ π) /Γ (Ω \to Ξ K ˉ) = 4.5%$ , which is consistent with the experimental data when $J^{P} = 3/ 2^{-}$ is assigned. This observation holds the possibility that the $Ω (2012)$ could naturally be explained as a three-quark state in the quark model. The decays of other low-lying $Ξ$ and $Ω$ resonances are systematically analyzed, which would be useful to unveil the structure of these resonances in future experiments.
↳ hep-phhep-exnucl-thPRD(2022)·38 citations
09
Kinetics of hydrodynamic pions in chiral perturbation theory
Juan M. Torres-Rincon🇪🇸 · Derek Teaney🇺🇸
We determine the kinetic coefficients of ultrasoft pions using chiral perturbation theory at finite temperature close to the chiral limit. This is used to compute the axial charge diffusion and damping coefficients in the hydrodynamic effective theory for these pion waves. We show that to provide a leading order answer for these coefficients one needs to explore the dynamics of hard, soft, and ultrasoft pion modes, which are represented microscopically by the appropriate kinetic and hydrodynamic descriptions..
↳ hep-phnucl-thPRD(2022)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE

Color-flavor dependence of the Nambu-Jona-Lasinio model and QCD phase diagram

Production characteristics of light (anti-)nuclei from (anti-)nucleon coalescence in heavy ion collisions at energies employed at the RHIC beam energy scan

Investigating the predicted breathing-mode excitation of the Hoyle state

Strong decays of multi-strangeness baryon resonances in the quark model

Kinetics of hydrodynamic pions in chiral perturbation theory

Affiliations