191 research outputs found
K-string tensions at finite temperature and integrable models
It has recently been pointed out that simple scaling properties of Polyakov
correlation functions of gauge systems in the confining phase suggest that the
ratios of k-string tensions in the low temperature region is constant up to
terms of order T^3. Here we argue that, at least in a three-dimensional Z_4
gauge model, the above ratios are constant in the whole confining phase. This
result is obtained by combining numerical experiments with known exact results
on the mass spectrum of an integrable two-dimensional spin model describing the
infrared behaviour of the gauge system near the deconfining transition.Comment: 22 pages, 7 figures, 1 tabl
Direct mode summation for the Casimir energy of a solid ball
The Casimir energy of a solid ball placed in an infinite medium is calculated
by a direct frequency summation using the contour integration. It is assumed
that the permittivity and permeability of the ball and medium satisfy the
condition . Upon deriving the general
expression for the Casimir energy, a dilute compact ball is considered
. In this case the
calculations are carried out which are of the first order in and take
account of the five terms in the Debye expansion of the Bessel functions
involved. The implication of the obtained results to the attempts of explaining
the sonoluminescence via the Casimir effect is shortly discussed.Comment: REVTeX, 7 pages, no figures and tables, treatment of a dilute
dielectric ball is revised, new references are adde
Bures and Statistical Distance for Squeezed Thermal States
We compute the Bures distance between two thermal squeezed states and deduce
the Statistical Distance metric. By computing the curvature of this metric we
can identify regions of parameter space most sensitive to changes in these
parameters and thus lead to optimum detection statistics.Comment: 15 pages, 1 figure (not included - obtain from Author) To appear in
Journal of Physics
Quark mixing from softly broken symmetries
Quark flavor mixing may originate in the soft breaking of horizontal
symmetries. Those symmetries, which in the simplest case are three family U(1)
groups, are obeyed only by the dimension-4 Yukawa couplings and lead, when
unbroken, to the absence of mixing. Their breaking may arise from the
dimension-3 mass terms of SU(2)-singlet vector-like quarks. Those gauge-singlet
mass terms break the horizontal symmetries at a scale much higher than the
Fermi scale, yet softly, leading to quark mixing while the quark masses remain
unsuppressed.Comment: 9 pages, plain Latex, no figure
Measuring the Higgs Sector
If we find a light Higgs boson at the LHC, there should be many observable
channels which we can exploit to measure the relevant parameters in the Higgs
sector. We use the SFitter framework to map these measurements on the parameter
space of a general weak-scale effective theory with a light Higgs state of mass
120 GeV. Our analysis benefits from the parameter determination tools and the
error treatment used in new--physics searches, to study individual parameters
and their error bars as well as parameter correlations.Comment: 45 pages, Journal version with comments from refere
Finite Density Effect in the Gross-Neveu Model in a Weakly Curved Spacetime
The three-dimensional Gross-Neveu model in spacetime is
considered at finite particles number density. We evaluate an effective
potential of the composite scalar field , which is expressed in
terms of a scalar curvature and nonzero chemical potential . We then
derive the critical values of at which the system undergoes the first
order phase transition from the phase with broken chiral invariance to the
symmetric phase.Comment: RevTeX, minor changes, new references are adde
Role of chaos for the validity of statistical mechanics laws: diffusion and conduction
Several years after the pioneering work by Fermi Pasta and Ulam, fundamental
questions about the link between dynamical and statistical properties remain
still open in modern statistical mechanics. Particularly controversial is the
role of deterministic chaos for the validity and consistency of statistical
approaches. This contribution reexamines such a debated issue taking
inspiration from the problem of diffusion and heat conduction in deterministic
systems. Is microscopic chaos a necessary ingredient to observe such
macroscopic phenomena?Comment: Latex, 27 pages, 10 eps-figures. Proceedings of the Conference "FPU
50 years since" Rome 7-8 May 200
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