11,463 research outputs found
Using zeros of the canonical partition function map to detect signatures of a Berezinskii-Kosterlitz-Thouless transition
Using the two dimensional model as a test case, we show that
analysis of the Fisher zeros of the canonical partition function can provide
signatures of a transition in the Berezinskii-Kosterlitz-Thouless ()
universality class. Studying the internal border of zeros in the complex
temperature plane, we found a scenario in complete agreement with theoretical
expectations which allow one to uniquely classify a phase transition as in the
class of universality. We obtain in excellent accordance with
previous results. A careful analysis of the behavior of the zeros for both
regions and in the
thermodynamic limit show that goes to zero in the former
case and is finite in the last one
Periodic Gravitational Waves From Small Cosmic String Loops
We consider a population of small, high-velocity cosmic string loops. We
assume the typical length of these loops is determined by the gravitational
radiation scale and use the results of \cite{Polchinski:2007rg} which pointed
out their highly relativistic nature. A study of the gravitational wave
emission from such a population is carried out. The large Lorentz boost
involved causes the lowest harmonics of the loops to fall within the frequency
band of the LIGO detector. Due to this feature the gravitational waves emitted
by such loops can be detected in a periodic search rather than in burst or
stochastic analysis.
It is shown that, for interesting values of the string tension
(10^{-10}\lsim G\mu\lsim 10^{-8}) the detector can observe loops at
reasonably high redshifts and that detection is, in principle, possible. We
compute the number of expected observations produced by such a process. For a
10 hour search we find that this number is of order . This is a
consequence of the low effective number density of the loops traveling along
the line of sight. However, small probabilities of reconnection and longer
observation times can improve the result.Comment: 1+15 pages, 7 figure
Electromagnetic Fields of Slowly Rotating Magnetized Gravastars
We study the dipolar magnetic field configuration and present solutions of
Maxwell equations in the internal background spacetime of a a slowly rotating
gravastar. The shell of gravastar where magnetic field penetrated is modeled as
sphere consisting of perfect highly magnetized fluid with infinite
conductivity. Dipolar magnetic field of the gravastar is produced by a circular
current loop symmetrically placed at radius at the equatorial plane.Comment: 5 pages, 2 figures, accepted for publication to Mod. Phys. Lett.
Gravitational collapse of Type II fluid in higher dimensional space-times
We find the general solution of the Einstein equation for spherically
symmetric collapse of Type II fluid (null strange quark fluid) in higher
dimensions. It turns out that the nakedness and curvature strength of the shell
focusing singularities carry over to higher dimensions. However, there is
shrinkage of the initial data space for a naked singularity of the Vaidya
collapse due to the presence of strange quark matter.Comment: RevTex4 style, 4 pages; Accepted in Phys. Rev.
Connecting the Unstable Region of the Entropy to the Pattern of the Fisher's Zeros Map
Phase transitions are one of the most interesting natural phenomena. For
finite system, one of the concerns in the topic is how to classify a specific
transition as being of first, second, or even of a higher order, according to
the Ehrenfest classification. The partition function provides all the
thermodynamic information about the physical system, and a phase transition can
be identified by the complex temperature where it is equal to zero. In
addition, the pattern of the zeros on the complex temperature plan can provide
evidences of the order of the transition. In this manuscript, we present an
analytical and simulational study connecting the microcanonical analysis of the
unstable region of the entropy to the canonical partition function zeros. We
show that for the first-order transition the zeros accumulate uniformly in a
vertical line on the complex inverse temperature plane as discussed in previous
works. We illustrated our calculation using the particles Lennard-Jones
cluster.Comment: 18 pages, 8 figure
Three nontrivial solutions for nonlocal anisotropic inclusions under nonresonance
In this article, we study a pseudo-differential inclusion driven by a nonlocal anisotropic operator and a Clarke generalized subdifferential of a nonsmooth potential, which satisfies nonresonance conditions both at the origin and at infinity. We prove the existence of three nontrivial solutions: one positive, one negative and one of unknown sign, using variational methods based on nosmooth critical point theory, more precisely applying the second deformation theorem and spectral theory. Here, a nosmooth anisotropic version of the Hölder versus Sobolev minimizers relation play an important role
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