7 research outputs found
Unruh effect and information entropy approach
Total entropy generated by the Unruh effect is calculated within the
framework of information theory. In contrast to previous studies, here the
calculations are done for the finite time of existence of the non-inertial
reference frame. In this case only the finite number of particles is produced.
Dependence on mass of the emitted particles is taken into account. Analytic
expression for the entropy of radiated boson and fermion spectra is derived. We
study also its asymptotics corresponding to limiting cases of low and high
acceleration. The obtained results can be further generalized to other
intrinsic degrees of freedom of the emitted particles, such as spin and
electric charge.Comment: REVTEX, 8 pages, 5 figure
Shear viscosity in microscopic calculations of A+A collisions at energies of Nuclotron-based Ion Collider fAcility (NICA)
Time evolution of shear viscosity , entropy density , and their
ratio in the central area of central gold-gold collisions at NICA
energy range is studied within the UrQMD transport model. The extracted values
of energy density, net baryon density and net strangeness density are used as
input to (i) statistical model of ideal hadron gas to define temperature,
baryo-chemical potential and strangeness chemical potential, and to (ii) UrQMD
box with periodic boundary conditions to study the relaxation process of highly
excited matter. During the relaxation stage, the shear viscosity is determined
in the framework of Green-Kubo approach. The procedure is performed for each of
20 time slices, corresponding to conditions in the central area of the fireball
at times from 1~fm/ to 20~fm/. For all tested energies the ratio reaches minimum, at ~fm/. Then it increases up to the late stages of the system evolution.
This rise is accompanied by the drop of both, temperature and strangeness
chemical potential, and increase of baryo-chemical potential.Comment: LATEX, 9 pages, 10 figure
Hydrodynamical approach to chirality production during axion inflation
We study chirality production in the pseudoscalar inflation model of
magnetogenesis taking into account the Schwinger effect and particle collisions
in plasma in the relaxation time approximation. We consider the Schwinger
production of one Dirac fermion species by an Abelian gauge field in two cases:
(i) the fermion carries only the weak charge with respect to the U(1) group and
(ii) it is also charged with respect to another strongly coupled gauge group.
While the gradient-expansion formalism is employed for the description of the
evolution of gauge field, plasma is described by hydrodynamical approach which
allows us to determine the number, energy density, and chirality of produced
fermions. It is found that while chirality production is very efficient for
both, weakly and strongly interacting fermions, the resulting gauge field is
typically stronger in the case of strongly interacting fermions due to
suppression of the Schwinger conductivity by particle collisions.Comment: 16 pages, 6 figure
Magnetogenesis in non-local models during inflation
The generation of magnetic fields during inflation in an electromagnetic
model with a non-local form factor in Maxwell`s action is studied. The
equations of motion for the electromagnetic field are derived and solved. It is
found that the conformal symmetry breaking due to the non-local form factor
does not lead to the generation of magnetic fields during inflation in the
absence of interaction with the inflaton field. If such a coupling takes place,
then the presence of the form factor inhibits the generation of primordial
magnetic fields compared to the case where the non-local form factor is absent.Comment: 7 page
Unruh entropy of Schwarzschild black hole
The entropy produced by the Unruh radiation is estimated and compared to the
entropy of a Schwarzschild black hole. We simulate a spherical system of mass by set of Unruh horizons and estimate the total entropy of the outgoing
radiation. Dependence on mass and spin of the emitted particles is taken into
account. The obtained results can be easily extended to any other intrinsic
degrees of freedom of outgoing particles. The ratio of Unruh entropy to the
Schwarzschild black hole entropy is derived in exact analytical form. For large
black holes this ratio is highly sensitive to quantum numbers of emitted
quanta, e.g., spin , for which it varies from for to for .Comment: LATEX, 16 pages, 3 figure
Generation of an electromagnetic field nonminimally coupled to gravity during Higgs inflation
In the framework of Higgs inflation, we consider the electromagnetic field nonminimally coupled to gravity via the parity-preserving proportional to RF2 and parity-violating proportional to RF (F) over tilde terms. Using the perturbation theory to the leading order in these couplings, we study the generation of the electromagnetic field during the inflation stage. We derive the effective kinetic and axial coupling functions arising in the Einstein frame in the usual metric as well as Palatini formulations of gravity. For both formulations, we determine the power spectrum, energy density, and helicality of the generated electromagnetic fields for different values of the nonminimal coupling constants. Finally, we estimate the maximal present-day magnitude of the magnetic field as 10(-14)-10(-15) G with the correlation length of order 10 pc