2,167 research outputs found
Chiral asymmetry during the EWPT from CP-violating scattering off bubble walls
We compute a net electric current during a first order EWPT arising from the
asymmetric propagation of fermion chiral modes due to a CP-violating
interaction with the Higgs. The interaction is quantified in terms of a
CP-violating phase in the bubble wall that separate both false and true vacuum
phases. We comment on the possibility of this current to generate a seed
magnetic field and its implications for primordial magne- togenesis in the
early Universe.Comment: To appear in the proceedings of the XLVII of the International
Symposium of Multiparticle Dynamics, Tlaxcala, Mexico, September 10-15, 201
Prompt photon yield and coefficient from gluon fusion induced by magnetic field in heavy-ion collision
We compute the production of prompt photons and the harmonic
coefficient in relativistic heavy-ion collisions induced by gluon fusion in the
presence of an intense magnetic field, during the early stages of the reaction.
The calculations take into account several parameters which are relevant to the
description of the experimental transverse momentum distribution, and elliptic
flow for RHIC and LHC energies. The main imput is the strength of the magnetic
field which varies in magnitude from 1 to 3 times the pion mass squared, and
allows the gluon fusion that otherwise is forbidden in the absence of the
field. The high gluon occupation number and the value of the saturation scale
also play an important role in our calculation, as well as a flow velocity and
geometrical factors. Our results support the idea that the origin of at least
some of the photon excess observed in heavy-ion experiments may arise from
magnetic field induced processes, and gives a good description of the
experimental data.Comment: 6 pages, 2 figures, conference paper from ISMD 201
Isometries of Almost-Riemannian structures on nonnilpotent, solvable 3D Lie groups
In this paper we prove that automorphisms are the only isometries between
rank two Almost-Riemannian Structures on the class of nonnilpotent, solvable,
connected 3D Lie groups. As a consequence, a classification result for rank two
ARSs on the groups in question is obtained.Comment: arXiv admin note: substantial text overlap with arXiv:2201.0641
QCD phase diagram in a magnetized medium from the chiral symmetry perspective: The linear sigma model with quarks and the Nambu--Jona-Lasinio model effective descriptions
We review the main features of the QCD phase diagram description, at finite
temperature, baryon density and in the presence of a magnetic field, from the
point of view of effective models, whose main ingredient is chiral symmetry. We
concentrate our attention on two of these models: The linear sigma model with
quarks and the Nambu--Jona-Lasinio model. We show that a main ingredient to
understand the characteristics of the phase transitions is the inclusion of
plasma screening effects that capture the physics of collective, long-wave
modes, and thus describe a prime property of plasmas near transition lines,
namely, long distance correlations. Inclusion of plasma screening makes
possible to understand the inverse magnetic catalysis phenomenon even without
the need to consider magnetic field-dependent coupling constants. Screening is
also responsible for the emergence of a critical end point in the phase diagram
even for small magnetic field strengths. Although versatile, the NJL model is
also a more limited approach since, being a non-renormalizable model, a clear
separation between pure vacuum and medium effects is not always possible. The
model cannot describe inverse magnetic catalysis unless a magnetic field
dependent coupling is included. The location of the critical end point strongly
depends on the choice of the type of interaction and on the magnetic field
dependence of the corresponding coupling. Overall, both models provide sensible
tools to explore the properties of magnetized, strongly interacting matter.
However, a cross talk among them as well as a consistent physical approach to
determine the model parameters is much needed.Comment: 27 pages, 12 figures, Expanded discussion, version to appear in EPJ
A, contribution for the topical Issue "The QCD Phase Diagram in Strong
Magnetic Fields
QCD equation of state at finite isospin density from the linear sigma model with quarks: The cold case
We use the two-flavor linear sigma model with quarks to study the phase
structure of isospin asymmetric matter at zero temperature. The meson degrees
of freedom provide the mean field chiral- and isospin-condensates on top of
which we compute the effective potential accounting for constituent quark
fluctuations at one-loop order. Using the renormalizability of the model, we
absorb the ultraviolet divergences into suitable counter-terms that are added
respecting the original structure of the theory. These counter-terms are
determined from the stability conditions which require the effective potential
to have minima in the condensates directions at the classical values, as well
as the transition from the non-condensed to the condensed phase to be smooth as
a function of the isospin chemical potential. We use the model to study the
evolution of the condensates as well as the pressure, energy and isospin
densities and the sound velocity as functions of the isospin chemical
potential. The approach does a good average description up to isospin chemical
potentials values not too large as compared to the vacuum pion mass.Comment: 11 pages and 7 figures. Expanded discussion, references and graphs
added, conclusions unchange
Study of the effects of magnetic braking on the lithium abundances of the Sun and solar-type stars
The study of lithium (Li) surface abundance in the Sun and young stellar
globular clusters which are seemingly anomalous in present-day scenarios, as
well as the influence of rotation and magnetic braking (MB) on its depletion
during pre-main sequence (PMS) and main sequence (MS). In this work, the
effects of rotational mixing and of the rotational hydrostatic effects on Li
abundances are studied by simulating several grids of PMS and MS rotating and
non-rotating models. Those effects are combined with the additional impact of
the MB (with magnetic field intensities ranging between 3.0 and 5.0 G). The
data obtained from simulations are confronted by comparing different stellar
parameters. The results show that the surface Li abundance for the Sun like
models at the end of the PMS and throughout the MS decreases when rotational
effects are included, i.e. the Li depletion rate for rotating models is higher
than for non-rotating ones. This effect is attenuated when the MB produced by a
magnetic field is present. This physical phenomena impacts also the star
effective temperature () and its location in the HR diagram.
The impact of MB in Li depletion is sensitive to the magnetic field intensity:
the higher it is, the lower the Li destruction. A direct link between the
magnetic fields and the convective zone (CZ) size is observed: stronger
magnetic fields produce shallower CZ's. This result suggests that MB effect
must be taken into consideration during PMS if we aim to reproduce Li
abundances in young clusters
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