Efrain J. Ferrer

MAGNETIC FIELD INDUCED GAP AND KINK BEHAVIOR OF THERMAL CONDUCTIVITY

The thermal conductivity of a quasiparticle (QP) system described by a relativistic four-fermion interaction model in the presence of an external magnetic field is calculated. It is shown that, for narrow widths of quasiparticles, the thermal conductivity, as a function of the applied magnetic field, exhibits a kink behavior at a critical field Bc ~ T2. The kink is due to the opening of a gap in the QP spectrum at a critical magnetic field Bc and to the enhancement of the transitions between the zeroth and first Landau levels. Possible applications of the results are discussed.

Yukawa coupling contribution to magnetic field induced dynamical mass

By solving the gap equation in the quenched, ladder approximation for an Abelian gauge model with Yukawa interaction in the presence of a constant magnetic field, we show that the Yukawa interactions enhance the dynamical generation of fermion mass. The theory is then studied at finite temperature, where we prove that the critical magnetic field, required for the mass generation to be important at temperatures comparable to the electroweak critical temperature, can be substantially decreased due to the Yukawa coupling.

High-Temperature Anyon Superconductivity

The screening of an applied magnetic field in a charged anyon fluid at finite density (μ≠0) and temperature (T≠0) is investigated. Using the semi-infinite sample boundary conditions we find, at densities typical of high-temperature superconducting materials, that the anyon fluid exhibits a superconducting behavior. The total Meissner screening is characterized by two penetration lengths, corresponding to two short-range eigenmodes of propagation within the anyon fluid.

NEUTRINO PROPAGATION AND OSCILLATIONS IN A STRONG MAGNETIC FIELD

We review the results on neutrino propagation in neutral and charged media under strong magnetic fields . It is shown that the neutrino energy density gets a magnetic contribution in both charged and neutral media, which is linear in the magnetic field, of first order in GF, and independent of the charge density. This new term enters as a correction to the neutrino kinetic energy and produces an anisotropic contribution to the neutrino index of refraction. As a consequence, in a neutral medium a highly anisotropic resonant level-crossing condition takes place for the oscillation between electron-neutrinos and the other neutrino species. Possible cosmological applications are presented.

Boundary effects in (2+1)-dimensional Maxwell-Chern-Simons theory

The effects of the samples boundaries in the magnetic response of the charged anyon fluid at finite temperature are investigated. For the case of an infinite-strip sample it is shown that the Meissner effect takes place at temperatures lower than the fermion energy gap ωc. The temperature dependence of the corresponding effective penetration depth is determined. At temperatures much larger than the scale ωc, a different phase is found, in which the external magnetic field penetrates the fluid.

Final Report for Project. Quark matter under extreme conditions

The results obtained in the two years of the grant have served to shine new light on several important questions about the phases of quantum chromodynamics (QCD) under extreme conditions that include quark matter at high density, as well quark-gluon plasma at high temperatures, both in the presence of strong magnetic fields. The interest in including an external magnetic field on these studies is motivated by the generation of large magnetic fields in off-central heavy-ion collisions and by their common presence in astrophysical compact objects, the two scenarios where the physics of quark matter becomes relevant. The tasks carried out in this DOE project led us, among other things, to discover the first connection between the physics of very dense quark matter and novel materials as for instance topological insulators and Weyl semimetals; they allowed us to find a physical explanation for and a solution to a standing puzzle in the apparent effect of a magnetic field on the critical temperature of the QCD chiral transition; and they led us to establish by the first time that the core of the observed two-solar-mass neutron stars could be made up of quark matter in certain inhomogeneous chiral phases in a magneticmorexa0» field and that this was consistent with current astrophysical observations. A major goal established by the Nuclear Science Advisory committee in its most recent report “Reaching for the Horizon” has been “to truly understand how nuclei and strongly interacting matter in all its forms behave and can predict their behavior in new settings.” The results found in this DOE project have all contributed to address this goal, and thus they are important for advancing fundamental knowledge in the area of nuclear physics and for enhancing our understanding of the role of strong magnetic fields in the two settings where they are most relevant, neutron stars and heavy-ion collisions.«xa0less

Inhomogeneous Magnetic Response in Anyon Fluid at High Temperature

The charged anyon fluid in the presence of an externally applied constant and homogeneous magnetic field is investigated at temperatures larger than the energy gap (T ≫ ωc). It is shown that the applied magnetic field inhomogeneously penetrates the sample with a spatial periodicity depending on a wavelength that decreases with temperature. The distribution of charges in the (T ≫ ωc)-phase acquires a periodic spatial arrangement.

Field Interaction Effects of a Charged String in a Magnetic Background

Exactly solvable models are models of strings in non-trivial background fields constructed under the requirement of the conformal invariance of the theory. Although these models are obtained by using an expansion in powers of the derivatives of the fields, their solutions are exact in the sense that they contain all orders in α′. In this way they provide nonperturbative information about the system and one expects they might be a good guide to discover the hidden symmetries of the theory.

Magnetic Response of the Many-Particle Chern-Simons Gauge Theory in (2+1) Dimensions

An investigation of the magnetic response of the many-particle (µ ≠ 0) anyon fluid in the low density limit (n e < Nm 2) is presented. We start from the criterion that in a many-particle system the self-consistent zero temperature formulation is obtained as the T → 0 limit of the thermal theory. Contrary to what occurs in anyon QFT (T = 0); in the T → 0 limit of the many-particle theory, superconductivity arises only in the case that an electric field, transverse to the supercurrent in the plane of the two dimensional fluid, is considered. We interpret this transverse electric field as a simulation of the vortex effects in charged anyon fluids. This boundary Hall potential in the effective linear theory can be seen as a simple way to model vortex effects in anyon superconductivity. In this way our simplified model serves to reveal that, even at zero temperature (T → 0) , superconductivity in a charged anyon fluid can take place only in the presence of vortices.

REGGE TRAJECTORIES AND CRITICAL FIELDS OF THE CHARGED STRING IN A MAGNETIC BACKGROUND

The Regge trajectories of a charged string in a magnetic background are derived by using a decomposition of the rest energy in terms of the Casimir operators of the theory. The first Regge trajectory is given by a family of infinitely many parallel straight lines, one for each spin projection along the magnetic field. Using the trajectories linking rest energy and spin, a critical magnetic field is found, for each spin value, at which the correspondent spin state with the highest spin projection becomes massless.