arXiv subjects

Efrain J. Ferrer

Publications and source records attributed to Efrain J. Ferrer.

48 records · Page 3Linked to original sources

arXiv2005

Colour superconductivity in a strong magnetic field

We explore the effects of an applied strong external magnetic field in a three flavour massless colour superconductor. The long-range component of the B field that penetrates the superconductor enhances some quark condensates, leading to a different condensation pattern. The external field also reduces the flavour symmetries in the system, and thus it changes drastically the corresponding low energy physics. Our considerations are relevant for the study of highly magnetized compact stars.

hep-ph↗

arXiv2005

Magnetic Color Flavor Locking Phase in High Density QCD

We investigate the effects of an external magnetic field in the gap structure of a color superconductor with three massless quark flavors. Using an effective theory with four-fermion interactions, inspired by one-gluon exchange, we show that the long-range component $\widetilde{B}$ of the external magnetic field that penetrates the color-flavor locked (CFL) phase modifies its gap structure, producing a new phase of lower symmetry. A main outcome of our study is that the $\widetilde{B}$ field tends to strengthen the gaps formed by $\widetilde{Q}$-charged and $\widetilde{Q}$-neutral quarks that coupled among themselves through tree-level vertices. These gaps are enhanced by the field-dependent density of states of the $\widetilde{Q}$-charged quarks on the Fermi surface. Our considerations are relevant for the study of highly magnetized compact stars.

hep-ph↗

arXiv2004

Photons and Fermions in Spacetime with a Compactified Spatial Dimension

The effects of a nonsimply connected spacetime with the topology of $S^{1}\times R^{3}$ in the vacua of QED and gauged-NJL theories are investigated. It is shown that the polarization effects of twisted and untwisted fermions in QED are equivalent, once the corresponding stable vacuum solution of each fermion class is taken into account. The photon propagation in QED is found to be anisotropic and characterized by several massive photon modes and a superluminal transverse mode. At small compactification radius the masses of the massive modes increase as the inverse of the radius, while the massless photon mode has a superluminal velocity that increases logarithmically with that distance. At low energies the photon masses lead to an effective confinement of the gauge fields into a $(2+1)-$dimensional manifold transverse to the compactified direction. In the gauged-NJL model, it is shown that for both twisted and untwisted fermions, the smaller the compactification radius, the larger the critical four-fermion coupling needed to generate a fermion-antifermion chiral symmetry breaking condensate.

hep-ph↗

arXiv2004

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 $M_{W}^{2}\gg B\gg m_{e}^{2}$. 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 $G_{F}$, 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.

hep-ph↗

arXiv2003

Anisotropic Node Removal in d-wave Superconductors under Magnetic Field

A phenomenological model that considers different secondary $id_{xy}$ gap amplitudes and quasiparticle effective charges for each nodal direction, is proposed to explain the observed anisotropic node removal by a magnetic field in high-$T_{c}$ cuprates. Two independent parity-breaking condensates $<\bar{Ψ_{i}}\bigwedgeΨ_{i}>$ develop, implying the induction of a magnetic moment per each nodal direction. The model outcomes are in agreement with the experimentally found relation $Δ_{i}\sim\sqrt{B}$. The secondary gap vanishes through a second-order phase transition at a critical temperature whose value for underdoped nodal-oriented YBCO is estimated to be $\sim 6K$ for a field of 15 T.

cond-mat.supr-con↗

arXiv2003

Neutrinos under Strong Magnetic Fields

In this talk we review the results on neutrino propagation under external magnetic fields. We concentrate on the effects of strong magnetic fields $M_{W}^{2}\gg B\gg m_{e}^{2}$ in neutral media. It is shown that the neutrino energy density get a magnetic contribution in the strong-field, one-loop approximation, which is linear in the Fermi coupling constant as in the charged medium. It is analyzed how this correction produces a significant oscillation resonance between electron-neutrinos and the other two active flavors, as well as with sterile neutrinos. The found resonant level-crossing condition is highly anisotropic. Possible cosmological applications are discussed. Effects due to primordial hypermagnetic fields on neutrinos propagating in the symmetric phase of the electroweak model are also presented. At sufficiently strong hypermagnetic fields, $B\geq T^{2}$, the neutrino energy is found to be similar to that of a massless charged particle with one-degree of freedom.

hep-ph↗

arXiv1998

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.

hep-ph↗

arXiv1998

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 ($T\gg ω_{c}$). 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 ($T\gg ω_{c}$)-phase acquires a periodic spatial arrangement.

hep-th↗

arXiv1998

Yukawa Interactions and Dynamical Generation of Mass in an External Magnetic Field

In this work we study the dynamical generation of a fermion mass induced by a constant and uniform external magnetic field in an Abelian gauge model with a Yukawa term. We show that the Yukawa coupling not only enhances the dynamical generation of the mass, but it substantially decreases the magnetic field required for the mass to be generated at temperatures comparable to the electroweak critical temperature. These results indicate that if large enough primordial magnetic fields were present during the early universe evolution, the field-induced generation of fermion masses, which in turn corresponds to the generation of fermion bound states, may play an important role in the electroweak phase transition.

hep-th↗

arXiv1998

Phase Transition in Anyon Superconductivity at Finite Temperature

The magnetic response of the charged anyon fluid at temperatures larger than the fermion energy gap is investigated in the self-consistent field approximation. In this temperature region a new phase, characterized by an inhomogeneous magnetic penetration, is found. The inhomogeneity is linked to the existence of an imaginary magnetic mass which increases with the temperature. The system stability in the new phase is proved by investigating the electromagnetic field rest-energy spectrum.

hep-th↗

arXiv1998

Ward-Takahashi Identity with External Field in Ladder QED

We derive the Ward-Takahashi identity obeyed by the fermion-antifermion-gauge boson vertex in ladder QED in the presence of a constant magnetic field. The general structure in momentum space of the fermion mass operator with external electromagnetic field is discussed. Using it we find the solutions of the ladder WT identity with magnetic field. The consistency of our results with the solutions of the corresponding Schwinger-Dyson equation ensures the gauge invariance of the magnetic field induced chiral symmetry breaking recently found in ladder QED.

hep-th↗

arXiv1996

High-Temperature Anyon Superconductivity

The screening of an applied magnetic field in the charged anyon fluid at finite density and temperature is investigated. For densities typical of high-temperature superconducting materials we find that the anyon fluid exhibits a superconducting behavior at any temperature. The total Meissner screening is characterized by two penetration lengths corresponding to two short-range eigenmodes of propagation within the anyon fluid.

hep-th↗