arXiv subjects

Manuel Torres

Publications and source records attributed to Manuel Torres.

28 records · Page 2Linked to original sources

arXiv2002

Neutrino damping rate at finite temperature and density

A first principle derivation is given of the neutrino damping rate in real-time thermal field theory. Starting from the discontinuity of the neutrino self energy at the two loop level, the damping rate can be expressed as integrals over space phase of amplitudes squared, weighted with statistical factors that account for the possibility of particle absorption or emission from the medium. Specific results for a background composed of neutrinos, leptons, protons and neutrons are given. Additionally, for the real part of the dispersion relation we discuss the relation between the results obtained from the thermal field theory, and those obtained by the thermal average of the forward scattering amplitude.

hep-th↗

arXiv2000

Bloch electrons in electric and magnetic fields

We investigate Bloch electrons in two dimensions subject to constant electric and magnetic fields. The model that results from our pursuit is governed by a finite difference equation with a quasienergy spectrum that interpolates between a butterfly-like structure and a Stark ladder structure. These findings ensued from the use of electric and magnetic translation operators.

cond-mat.mes-hall↗

arXiv1999

Right handed neutrino production in dense and hot plasmas

For Dirac neutrinos with magnetic moment, we compute the production rate for right-handed neutrinos in a hot and dense QED plasma containing an initial population of left-handed neutrinos thermally distributed. The most important mechanisms for $ν_L$ depolarization, or production of right-handed neutrinos, are the $ν_L \to ν_R$ chirality flip and the plasmon decay to $\barν_L + ν_R$. The rates for these processes are computed in terms of a resummed photon propagator which consistently incorporates the background effects to leading order. Applying the results to the cases of supernovae core collapse and the primordial nucleosynthesis in the early universe, we obtain upper limits on the neutrino magnetic moment.

hep-ph↗

arXiv1999

Bound on the neutrino magnetic moment from chirality flip in supernovae

For neutrinos with a magnetic moment, we show that the collisions in a hot and dense plasma act as an efficient mechanism for the conversion of $ν_L$ into $ν_R$. The production rate for right-handed neutrinos is computed in terms of a resummed photon propagator which consistently incorporates the background effects. Assuming that the entire energy in a supernova collapse is not carried away by the $ν_R$, our results can be used to place an upper limit on the neutrino magnetic moment $μ_ν< (0.1-0.4)\times 10^{-11}μ_B$

hep-ph↗

arXiv1997

Domain walls in a Chern-Simons theory

We study an Abelian Maxwell-Chern-Simons model in $2 +1 $ dimensions which includes a magnetic moment interaction. We show that this model possesses domain wall as well as vortex solutions.

hep-th↗

arXiv1997

Vortices and domain walls in a Chern-Simons theory with magnetic moment interaction

We study the structure and properties of vortices in a recently proposed Abelian Maxwell-Chern-Simons model in $2 +1 $ dimensions. The model which is described by gauge field interacting with a complex scalar field, includes two parity and time violating terms: the Chern-Simons and the anomalous magnetic terms. Self-dual relativistic vortices are discussed in detail. We also find one dimensional soliton solutions of the domain wall type. The vortices are correctly described by the domain wall solutions in the large flux limit.

hep-th↗

arXiv1997

QED symmetries in real-time thermal field theory

We study the discrete and gauge symmetries of Quantum Electrodynamics at finite temperature within the real-time formalism. The gauge invariance of the complete generating functional leads to the finite temperature Ward identities. These Ward identities relate the eight vertex functions to the elements of the self-energy matrix. Combining the relations obtained from the $Z_2$ and the gauge symmetries of the theory we find that only one out of eight longitudinal vertex functions is independent. As a consequence of the Ward identities it is shown that some elements of the vertex function are singular when the photon momentum goes to zero.

hep-th↗

arXiv1995

SELF-DUAL NON-ABELIAN VORTICES IN A $\PHI^2$ CHERN-SIMONS THEORY

We study a non-Abelian Chern-Simons gauge theory in $ 2+ 1$ dimensions with the inclusion of an anomalous magnetic interaction. For a particular relation between the Chern-Simons (CS) mass and the anomalous magnetic coupling the equations for the gauge fields reduce from second- to first order differential equations of the pure CS type. We derive the Bogomol'nyi-type or self-dual equations for a $\bphi^2$ scalar potential, when the scalar and topological masses are equal. The corresponding vortex solutions carry magnetic flux that is not quantized due to the non-toplogical nature of the solitons. However, as a consequence of the quantization of the CS term, both the electric charge and angular momentum are quantized.

hep-th↗

arXiv1995

SEMILOCAL NONTOPOLOGICAL SOLITONS IN A CHERN-SIMONS THEORY.

We show the existence of self-dual semilocal nontopological vortices in a $Φ^2$ Chern-Simons (C-S) theory. The model of scalar and gauge fields with a $SU(2)_{global} \times U(1)_{local}$ symmetry includes both the C-S term and an anomalous magnetic contribution. It is demonstrated here, that the vortices are stable or unstable according to whether the vector topological mass $κ$ is less than or greater than the mass $m$ of the scalar field. At the boundary, $κ= m$, there is a two-parameter family of solutions all saturating the self-dual limit. The vortex solutions continuously interpolates between a ring shaped structure and a flux tube configuration.

hep-th↗

arXiv1995

Parity Symmetry Restoration in Qed3 at High Temperature and Finite Density

We investigate the properties of quantum electrodynamics $(QED_3)$ in two spatial dimensions at finite temperature and density. The static as well as the dynamical properties of the planar plasma are calculated using the real time formalism of quantum field theory. It is shown, that due to the presence of the parity breaking Chern-Simons term, the propagating modes of the photon consists of two longielliptic waves with different values for the masses. However, it is shown that both in the high temperature and high density limit the parity symmetry is restored; in this limit the propagating modes reduce to the longitudinal and transverse ones, both with the same mass.

hep-ph↗