Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new user(In-)Significance of the Anomalous Magnetic Moment of Charged Fermions for the Equation of State of a Magnetized and Dense Medium
101
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We investigate the effects of the anomalous magnetic moment (AMM) in the equation of state (EoS) of a system of charged fermions at finite density in the presence of a magnetic field. In the region of strong magnetic fields (eB>m^2) the AMM is found from the one-loop fermion self-energy. In contrast to the weak-field AMM found by Schwinger, in the strong magnetic field region the AMM depends on the Landau level and decreases with it. The effects of the AMM in the EoS of a dense medium are investigated at strong and weak fields using the appropriate AMM expression for each case. In contrast with what has been reported in other works, we find that the AMM of charged fermions makes no significant contribution to the EoS at any field value.
rate research
Read More
We investigate the quantum corrections of the anomalous magnetic moment (AMM) for fermions in the presence of a strong magnetic field using the Rituss approach. At strong fields the particles get different AMMs depending on the LLs. This result is different from what is obtained with the Schwingers approximation at weak field where the AMM is independent of the LL. We analyze the significance of the AMM contribution to the Equation of State (EoS) of the magnetized system, in the weak and strong field approximations.
Effects of neutrino charge radius and magnetic moment, as well as the medium modifications of the weak and electromagnetic nucleon form factors of the constituents of matter on the neutrino electroweak interaction with dense nuclear matter, are estimated. A relativistic mean-field and quark-meson coupling models are adopted for the in-medium effective nucleon mass and nucleon form factors. We find that the neutrino scattering cross section increases in the cold nuclear medium when neutrino form factors and the in-medium modifications of the nucleon weak and electromagnetic form factors are simultaneously taken into account relative to that without neutrino form factors. The increase of the cross section results in the decrease of the neutrino mean free path, particularly at larger neutrino magnetic moment and charge radius. The quenching of the neutrino mean free path is estimated to be about 12-58% for the values of $mu_ u = 3 times 10^{-12} mu_B$ and $R_ u = 3.5 times 10^{-5}~textrm{MeV}^{-1}$, obtained from the constraints of the astrophysical observations, compared to that of $mu_ u =0$ and $R_ u =0$. The decrease of the neutrino mean free path is expected to decelerate the cooling of neutron stars. Each contribution of the neutrino form factors to the neutrino mean free path is discussed.
We discuss the Hard Dense Loop resummation at finite quark mass and evaluate the equation of state (EoS) of cold and dense QCD matter in $beta$ equilibrium. The resummation in the quark sector has an effect of lowering the baryon number density and the EoS turns out to have much smaller uncertainty than the perturbative QCD estimate. Our numerical results favor smooth matching between the EoS from the resummed QCD calculation at high density and the extrapolated EoS from the nuclear matter density region. We also point out that the speed of sound in our EoS slightly exceeds the conformal limit.
A previously derived three-dimensional effective lattice theory describing the thermodynamics of QCD with heavy quarks in the cold and dense region is extended through order $sim u^5kappa^8$ in the combined character and hopping expansion of the original four-dimensional Wilson action. The systematics of the effective theory is investigated to determine its range of validity in parameter space. We demonstrate the severe cut-off effects due to lattice saturation, which afflict any lattice results at finite baryon density independent of the sign problem or the quality of effective theories, and which have to be removed by continuum extrapolation. We then show how the effective theory can be solved analytically by means of a linked cluster expansion, which is completely unaffected by the sign problem, in quantitative agreement with numerical simulations. As an application, we compute the cold nuclear equation of state of heavy QCD. Our continuum extrapolated result is consistent with a polytropic equation of state for non-relativistic fermions.
We investigate the stability of the pion string in a thermal bath and a dense medium. We find that stability is dependent on the order of the chiral transition. String core stability within the experimentally allowed regime is found only if the chiral transition is second order, and even there the stable region is small, i.e., the temperature below which the core is unstable is close to the critical temperature of the phase transition. We also find that the presence of a dense medium, in addition to the thermal bath, enhances the experimentally accessible region with stable strings. We also argue that once the string core decays, the effective winding of the string persists at large distances from the string core. Our analysis is done both in the chiral limit, which is mainly what has been explored in the literature up to now, and for the physical $h e 0$ case, where a conceptual framework is set up for addressing this regime and some simple estimates are done.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
