Nuclear Theory·nucl-th

Thursday·February 8, 2024

10 papers—4 primary·6 cross-listed

05
The fermion self-energy and damping rate in a hot magnetized plasma
Ritesh Ghosh🇺🇸 · Igor A. Shovkovy🇺🇸
We derive a general expression for the fermion self-energy in a hot magnetized plasma by using the Landau-level representation. In the one-loop approximation, the Dirac structure of the self-energy is characterized by five different functions that depend on the Landau-level index $n$ and the longitudinal momentum $p_{z}$ . We derive general expressions for all five functions and obtain closed-form expressions for their imaginary parts. The latter receive contributions from three types of on-shell processes, which are interpreted in terms of Landau-level transitions, accompanied by a single photon (gluon) emission or absorption. By making use of the imaginary parts of the self-energy functions, we also derive the Landau-level dependent fermion damping rates $Γ_{n} (p_{z})$ and study them numerically in a wide range of model parameters. We also demonstrate that the two-spin degeneracy of the Landau levels is lifted by the one-loop self-energy corrections. While the spin splitting of the damping rates is small, it may be important for some spin and chiral effects. We argue that the general method and the numerical results for the rates can have interesting applications in heavy-ion physics, astrophysics, and cosmology, where strongly magnetized QED or QCD plasmas are ubiquitous.
↳ hep-phhep-thnucl-thPRD(2024)·13 citations
06
Semiclassics for the QCD vacuum structure through $T^{2}$ -compactification with the baryon-'t Hooft flux
Yui Hayashi🇯🇵 · Yuya Tanizaki🇯🇵
We study QCD vacuum structure with the topological $θ$ angle using a recently proposed semiclassical approach on $R^{2} \times T^{2}$ with the 't Hooft and baryon magnetic fluxes. Under the assumption of adiabatic continuity in this setup, the confining vacuum can be described by the dilute gas of center vortices. With this semiclassical approach, we derive the 2d effective description at small $T^{2}$ and successfully explain the reasonable theta dependence of the QCD vacuum: In the one-flavor QCD at $θ = π$ , the $C P$ symmetry is spontaneously broken for quark mass above a critical value and restored for a subcritical mass, while the $C P$ symmetry is always spontaneously broken in the multi-flavor QCD at $θ = π$ . From our semiclassical description, we discuss implications to the $4$ d chiral Lagrangian and propose how the $η^{'}$ meson should be incorporated in consistent with known global structures: The periodicity of the $η^{'}$ should be extended from the naive one $2 π$ to $2 π N$ . Additionally, we revisit the phase diagram of $N_{f} = 1 + 1$ and $N_{f} = 1 + 1 + 1$ QCD on the up and down quark mass plane, confirming and refining the existence of the $C P$ -broken Dashen phase.
↳ hep-thhep-lathep-phnucl-thJHEP(2024)·32 citations
07
A domain wall and chiral edge currents in holographic chiral phase transitions
Shuta Ishigaki🇨🇳 · Masataka Matsumoto🇨🇳 · Ryosuke Yoshii🇯🇵
We investigate spatially inhomogeneous solutions in a top-down holographic model: the D3/D7 model which provides a holographic description of the chiral phase transition for a finite external magnetic field, chemical potential, and temperature. We numerically find a domain wall (or kink) solution in the three dimensional space, which incorporates between the chiral symmetry broken phase at the spatial infinity, under the homogeneous sources. Along with the inhomogeneity of the chiral condensate, the charge density is also spatially modulated. The modulated charge density and finite magnetic field lead to the chiral edge current close to the domain wall. We explore the dependences of those profiles on the chemical potential and temperature near the first and second order phase transition points. Our results indicate that the inhomogeneous solutions we found are in good agreement with those obtained by the Ginzburg--Landau theory in the vicinity of the transition points.
↳ hep-thcond-mat.str-elnucl-thJHEP(2024)·1 citation
08
Non-relativistic trace anomaly and equation of state in dense fermionic matter
Hiroyuki Tajima🇯🇵 · Kei Iida🇯🇵 · Haozhao Liang🇯🇵
We theoretically investigate a non-relativistic trace anomaly and its impact on the low-temperature equation of state in spatially one-dimensional three-component fermionic systems with a three-body interaction, which exhibit a non-trivial three-body crossover from a bound trimer gas to dense fermionic matter with increasing density. By applying the $G$ -matrix approach to the three-body interaction, we obtain the analytical expression for the ground-state equation of state relevant to the high-density degenerate regime and thereby address how the three-body contact or, equivalently, the trace anomaly emerges. The analytical results are compared with the recent quantum Monte Carlo data. Our study of the trace anomaly and the sound speed could have some relevance to the physics of hadron-quark crossover in compact stars.
↳ hep-phcond-mat.quant-gashep-thnucl-thPRC(2024)·6 citations
09
Once-in-a-lifetime encounter models for neutrino media: From coherent oscillations to flavor equilibration
Anson Kost (UNM)🇺🇸 · Lucas Johns (LANL)🇺🇸 · Huaiyu Duan (UNM)🇺🇸
Collective neutrino oscillations are typically studied using the lowest-order quantum kinetic equation, also known as the mean-field approximation. However, some recent quantum many-body simulations suggest that quantum entanglement among neutrinos may be important and may result in flavor equilibration of the neutrino gas. In this work, we develop new quantum models for neutrino gases in which any pair of neutrinos can interact at most once in their lifetimes. A key parameter of our models is $γ = μ Δ z$ , where $μ$ is the neutrino coupling strength, which is proportional to the neutrino density, and $Δ z$ is the duration over which a pair of neutrinos can interact each time. Our models reduce to the mean-field approach in the limit $γ \to 0$ and achieve flavor equilibration in time $t ≫ (γ μ)^{- 1}$ . These models demonstrate the emergence of coherent flavor oscillations from the particle perspective and may help elucidate the role of quantum entanglement in collective neutrino oscillations.
↳ hep-phastro-ph.HEnucl-thquant-phPRD(2024)·29 citations
10
Measuring Neutron Star Radius with second and third generation Gravitational Wave Detector Networks
Ananya Bandopadhyay🇺🇸 · Keisi Kacanja🇺🇸 · Rahul Somasundaram🇺🇸 · Alexander H. Nitz🇺🇸 · Duncan A. Brown🇺🇸
The next generation of ground-based interferometric gravitational wave detectors will observe mergers of black holes and neutron stars throughout cosmic time. A large number of the binary neutron star merger events will be observed with extreme high fidelity, and will provide stringent constraints on the equation of state of nuclear matter. In this paper, we investigate the systematic improvement in the measurability of the equation of state with increase in detector sensitivity by combining constraints obtained on the radius of a $1.4 M_{⊙}$ neutron star from a simulated source population. Since the measurability of the equation of state depends on its stiffness, we consider a range of realistic equations of state that span the current observational constraints. We show that a single 40km Cosmic Explorer detector can pin down the neutron star radius for a soft, medium and stiff equation of state to an accuracy of 10m within a decade, whereas the current generation of ground-based detectors like the Advanced LIGO-Virgo network would take $O (1 0^{5})$ years to do so for a soft equation of state.
↳ astro-ph.HEgr-qcnucl-thClass.Quant.Grav.(2024)·22 citations

Affiliations

first authorsco-authorsvia INSPIRE

The fermion self-energy and damping rate in a hot magnetized plasma

Semiclassics for the QCD vacuum structure through T2-compactification with the baryon-'t Hooft flux

A domain wall and chiral edge currents in holographic chiral phase transitions

Non-relativistic trace anomaly and equation of state in dense fermionic matter

Once-in-a-lifetime encounter models for neutrino media: From coherent oscillations to flavor equilibration

Measuring Neutron Star Radius with second and third generation Gravitational Wave Detector Networks

Affiliations

Semiclassics for the QCD vacuum structure through $T^{2}$ -compactification with the baryon-'t Hooft flux