522 research outputs found
Magnetic charge superselection in the deconfined phase of Yang-Mills theory
The vacuum expectation value of an operator carrying magnetic charge is
studied numerically for temperatures above the deconfinement temperature in
SU(2) and SU(3) gauge theory. By analyzing its finite size behaviour, this is
found to be exactly zero in the thermodynamical limit for any T > T_c whenever
the magnetic charge of the operator is different from zero. These results show
that magnetic charge is superselected in the hot phase of quenched QCD.Comment: 4 pages, 6 figures, revtex
Color confinement and dual superconductivity in full QCD
We report on evidence that confinement is related to dual superconductivity
of the vacuum in full QCD, as in quenched QCD. The vacuum is a dual
superconductor in the confining phase, whilst the U(1) magnetic symmetry is
realized a la Wigner in the deconfined phase.Comment: 4 pages, 4 eps figure
Deconfining transition in two-flavor QCD
The order and the nature of the finite-temperature phase transition of QCD
with two flavors of dynamical quarks is investigated. An analysis of the
critical exponent of the specific heat is performed through finite-size and
finite-mass scaling of various susceptibilities. Dual superconductivity of QCD
vacuum is investigated using a disorder parameter, namely the v.e.v. of a
monopole creation operator. Hybrid R simulations were run at lattice spatial
sizes of , , and and temporal size , with
quark masses in the range .Comment: Lattice2003(topology), 3 page
Relativistic deformed kinematics from momentum space geometry
We present a way to derive a deformation of special relativistic kinematics (possible low-energy signal of a quantum theory of gravity) from the geometry of a maximally symmetric curved momentum space. The deformed kinematics is fixed (up to change of coordinates in the momentum variables) by the algebra of isometries of the metric in momentum space. In particular, the well-known example of ¿-Poincaré kinematics is obtained when one considers an isotropic metric in de Sitter momentum space such that translations are a subgroup of the isometry group, and for a Lorentz covariant algebra one gets the also well-known case of Snyder kinematics. We prove that our construction gives generically a relativistic kinematics and explain how it relates to previous attempts of connecting a deformed kinematics with a geometry in momentum space
Does a deformation of special relativity imply energy dependent photon time delays?
Theoretical arguments in favor of energy dependent photon time delays from a modification of special relativity (SR) have met with recent gamma ray observations that put severe constraints on the scale of such deviations. We review the case of the generality of this theoretical prediction in the case of a deformation of SR and find that, at least in the simple model based on the analysis of photon worldlines which is commonly considered, there are many scenarios compatible with a relativity principle which do not contain a photon time delay. This will be the situation for any modified dispersion relation which reduces to E=|pâ | for photons, independently of the quantum structure of spacetime. This fact opens up the possibility of a phenomenologically consistent relativistic generalization of SR with a new mass scale many orders of magnitude below the Planck mass
ContaminaciĂłn de suelos y aguas subterraneas por vertidos industriales
In the industrialised countries, soil and groundwater contamination caused by uncontrolled spills of industrial wastes is one of the most critical environmental problem, because its removal is expensive and difficult to carry out, and the effects persist during many years. In Spain this problem is especially notorious due to an inadequate management policy derived from the absence of coordination between the different involved sectors. The treatment installations are inot enough, so it has produced spillings in streams and soils or its storage in uncontrolled landfillings.The experiences and guidelines of the Environmental Protection Agency from United States have served to the industrialised countries to evaluate this kind of contamination. This methodology is based on its identification and delimitation in soil and groundwater. After the design of a monitoring and control program it can be established the correcting measures. For this reason it is important to know the transfer processes of pollutants between the saturated and not saturated medium, for this reason it is essential the use of geochemical and geophysical methods and their combination with hydrogeological methods.In Spain, this kind of studies is only carried out recently. A case history is the contamination of the alluvial aquifer of the Besos river (Barcelona) by Cr-VI and other heavy metals and organic microcontaminants
Does a deformation of special relativity imply energy dependent photon time delays?
Theoretical arguments in favor of energy dependent photon time delays from a modification of special relativity (SR) have met with recent gamma ray observations that put severe constraints on the scale of such deviations. We review the case of the generality of this theoretical prediction in the case of a deformation of SR and find that, at least in the simple model based on the analysis of photon worldlines which is commonly considered, there are many scenarios compatible with a relativity principle which do not contain a photon time delay. This will be the situation for any modified dispersion relation which reduces to E = |pÂż| for photons, independently of the quantum structure of spacetime. This fact opens up the possibility of a phenomenologically consistent relativistic generalization of SR with a new mass scale many orders of magnitude below the Planck mass
Relativistic deformed kinematics from locality conditions in a generalized spacetime
We show how a deformed composition law of four-momenta can be used to define, at the classical level, a modified notion of spacetime for a system of two particles through the crossing of worldlines in particle interactions. We present a derivation of a generic relativistic isotropic deformed kinematics and discuss the complementarity and relations with other derivations based on kappa-Poincare Hopf algebra or on the geometry of a maximally symmetric momentum space
The deconfining phase transition in full QCD with two dynamical flavors
We investigate the deconfining phase transition in SU(3) pure gauge theory
and in full QCD with two flavors of staggered fermions. The phase transition is
detected by measuring the free energy in presence of an abelian monopole
background field. In the pure gauge case our finite size scaling analysis is in
agreement with the well known presence of a weak first order phase transition.
In the case of 2 flavors full QCD we find, using the standard pure gauge and
staggered fermion actions, that the phase transition is consistent with weak
first order, contrary to the expectation of a crossover for not too large quark
masses and in agreement with results obtained by the Pisa group.Comment: 23 pages, 11 figures, 4 tables (minor typos corrected, references
updated, accepted for publication on JHEP
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