Nuclear Theory·nucl-th

Thursday·October 29, 2020

10 papers—6 primary·4 cross-listed

07
Exploring axial $U (1)$ restoration in a modified 2+1 flavor Polyakov quark meson model
Suraj Kumar Rai🇮🇳 · Vivek Kumar Tiwari🇮🇳
We report on the $U_{A} (1)$ symmetry restoration resulting due to temperature dependence of the coefficient c(T) for the Kobayashi-Maskawa-'t Hooft determinant (KMT) term in a modified 2+1 flavor Polyakov loop quark meson model having fermionic vacuum correction term (PQMVT).Temperature dependence of KMT coupling c(T) drives the non-strange condensate melting to significantly smaller temperatures in comparison to the constant c case.Further due to c(T), $m_{η^{'}}$ decreases from its vacuum value by 220 MeV near T=176 MeV after the chiral transition ( $T_{c}^{χ} = 154.9$ MeV).This is similar to the $η^{'}$ in-medium mass drop of at least 200 MeV as reported by Csorgo and Vertesi in Ref (Phys Rev Lett 105:182301,2010; Phys Rev C 83:054903,2011), as an experimental signature of the effective restoration of $U_{A} (1)$ symmetry. The pseudoscalar mixing angle $θ_{p}$ achieves anti-ideal mixing in the influence of c(T). The $η$ meson becomes light quark system ( $η_{N S}$ ) at T=176 MeV and changes its identity with $η^{'}$ meson which becomes strange quark system ( $η_{S}$ ). The degenerated temperature variations of $σ$ , $π$ meson masses merges with the temperature variations of the masses of degenerated $a_{0}$ , $η$ mesons near 275 MeV. It means that for c(T) when $m_{σ} = 400$ MeV, the $U_{A} (1)$ restoration takes place at 1.75 $T_{c}^{χ}$ =275 MeV.
↳ hep-phnucl-thEur.Phys.J.Plus(2020)·17 citations
08
Thermodynamic properties of the trigonometric Rosen-Morse potential and applications to a quantum gas of mesons
Aram Bahroz Brzo🇮🇶 · David Alvarez-Castillo🇵🇱
In this study we work out thermodynamic functions for a quantum gas of mesons described as color-electric charge dipoles. They refer to a particular parametrization of the trigonometric Rosen-Morse potential which allows to be transformed to a perturbation of free quantum motion on the three-dimensional hyper-sphere, $S^{3}$ , a manifold that can host only charge-neutral systems, the charge dipoles being the configuration of the minimal number of constituents. To the amount charge neutrality manifests itself as an important aspect of the color confinement in the theory of strong interaction, the Quantum Chromodynamics, we expect our findings to be of interest to the evaluation of temperature phenomena in the physics of hadrons and in particular in a quantum gas of color charge dipoles as are the mesons. The results are illustrated for $f_{0}$ and $J / ψ$ mesons.
↳ hep-phastro-ph.HEnucl-thquant-phMod.Phys.Lett.A(2021)·5 citations
09
Correlated Dirac Eigenvalues and Axial Anomaly in Chiral Symmetric QCD
H.-T. Ding🇨🇳 · S.-T. Li🇨🇳 · Swagato Mukherjee🇺🇸 · A. Tomiya🇺🇸 · X.-D. Wang🇨🇳 · Y. Zhang🇨🇳
We introduce novel relations between the derivatives [ $\partial^{n} ρ (λ, m_{l}) / \partial m_{l}^{n}$ ] of the Dirac eigenvalue spectrum [ $ρ (λ, m_{l})$ ] with respect to the light sea quark mass ( $m_{l}$ ) and the $(n + 1)$ -point correlations among the eigenvalues ( $λ$ ) of the massless Dirac operator. Using these relations we present lattice QCD results for $\partial^{n} ρ (λ, m_{l}) / \partial m_{l}^{n}$ ( $n = 1, 2, 3$ ) for $m_{l}$ corresponding to pion masses $m_{π} = 160 - 55$ MeV, and at a temperature of about 1.6 times the chiral phase transition temperature. Calculations were carried out using (2+1) flavors of highly improved staggered quarks with the physical value of strange quark mass, three lattice spacings $a = 0.12, 0.08, 0.06$ fm, and lattices having aspect ratios $4 - 9$ . We find that $ρ (λ \to 0, m_{l})$ develops a peaked structure. This peaked structure arises due to non-Poisson correlations within the infrared part of the Dirac eigenvalue spectrum, becomes sharper as $a \to 0$ , and its amplitude is proportional to $m_{l}^{2}$ . We demonstrate that this $ρ (λ \to 0, m_{l})$ is responsible for the manifestations of axial anomaly in two-point correlation functions of light scalar and pseudoscalar mesons. After continuum and chiral extrapolations we find that axial anomaly remains manifested in two-point correlation functions of scalar and pseudoscalar mesons in the chiral limit.
↳ hep-lathep-phhep-thnucl-thPRL(2021)·96 citations
10
Manifestation of the Berry phase in the atomic nucleus $^{213}$ Pb
J.J. Valiente-Dobón · A. Gottardo · G. Benzoni · A. Gadea · S. Lunardi · A. Algora · G. de Angelis · D. Bazzacco · J. Benlliure · P. Boutachkov · A. Bracco · A.M. Bruce and 48 other authors
The neutron-rich $^{213}$ Pb isotope was produced in the fragmentation of a primary 1 GeV $A$ $^{238}$ U beam, separated in FRS in mass and atomic number, and then implanted for isomer decay $γ$ -ray spectroscopy with the RISING setup at GSI. A newly observed isomer and its measured decay properties indicate that states in $^{213}$ Pb are characterized by the seniority quantum number that counts the nucleons not in pairs coupled to angular momentum $J = 0$ . The conservation of seniority is a consequence of the Berry phase associated with particle-hole conjugation, which becomes gauge invariant and therefore observable in semi-magic nuclei where nucleons half-fill the valence shell. The $γ$ -ray spectroscopic observables in $^{213}$ Pb are thus found to be driven by two mechanisms, particle-hole conjugation and seniority conservation, which are intertwined through the Berry phase.
↳ nucl-exnucl-thPLB(2021)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE

Exploring axial U(1) restoration in a modified 2+1 flavor Polyakov quark meson model

Thermodynamic properties of the trigonometric Rosen-Morse potential and applications to a quantum gas of mesons

Correlated Dirac Eigenvalues and Axial Anomaly in Chiral Symmetric QCD

Manifestation of the Berry phase in the atomic nucleus 213Pb

Affiliations

Exploring axial $U (1)$ restoration in a modified 2+1 flavor Polyakov quark meson model

Manifestation of the Berry phase in the atomic nucleus $^{213}$ Pb