Coherent states on the circle

A careful study of the physical properties of a family of coherent states on the circle, introduced some years ago by de Bi\`evre and Gonz\'alez in [DG 92], is carried out. They were obtained from the Weyl-Heisenberg coherent states in $L^2(\R)$ by means of the Weil-Brezin-Zak transformation, they are labeled by the points of the cylinder $S^1 \times \R$, and they provide a realization of $L^2(S^1)$ by entire functions (similar to the well-known Fock-Bargmann construction). In particular, we compute the expectation values of the position and momentum operators on the circle and we discuss the Heisenberg uncertainty relation.Comment: AMS-TeX file, 20 pages, 4 PostScript figures. To be published in J. Phys.

LHC bounds on lepton number violation mediated by doubly and singly-charged scalars

The only possible doubly-charged scalar decays into two Standard Model particles are into pairs of same-sign charged leptons, H ±± → l ± l ± , l = e, μ, τ , or gauge bosons, H ±± → W ± W ± ; being necessary the observation of both to assert the violation of lepton number. However, present ATLAS and CMS limits on doubly-charged scalar production are obtained under specific assumptions on its branching fractions into dileptons only. Although they can be extended to include decays into dibosons and lepton number violating processes. Moreover, the production rates also depend on the type of electroweak multiplet H ±± belongs to. We classify the possible alternatives and provide the Feynman rules and codes for generating the corresponding signals for pair and associated doubly-charged scalar production, including the leading contribution from the s -channel exchange of electroweak gauge bosons as well as the vector-boson fusion corrections. Then, using the same analysis criteria as the LHC collaborations we estimate the limits on the H ±± mass as a function of the electroweak multiplet it belongs to, and obtain the bounds on the lepton number violating processes pp → H ±± H ∓∓ → ℓ ± ℓ ± W ∓ W ∓ and pp → H ±± H ∓ → ℓ ± ℓ ± W ∓ Z , ℓ = e, μ , implied by the ATLAS and CMS doubly-charged scalar searches

A. Feinstein a,1 and M.A. Vázquez-Mozo b,c,2

hep-th/9906006 M-theory resolution of four-dimensiona

Complexity in some physical systems

The LMC-complexity introduced by López-Ruiz, Mancini and Calbet [Phys. Lett. A 209, 321-326 (1995)] is calculated for different physical situations: one instance of classical statistical mechanics, normal and exponential distributions, and a simplified laser model. We stand out the specific value of the population inversion for which the laser presents maximun complexity. 1

On the Evolution of a Large Class of Inhomogeneous Scalar Field Cosmologies

The asymptotic behaviour of a family of inhomogeneous scalar field cosmologies with exponential potential V = Λe kφ is studied. By introducing new variables we can perform an almost complete analysis of the evolution of these cosmologies. Unlike the homogeneous case (Bianchi type solutions), when k 2 < 2 the models do not isotropize due to the presence of the inhomogeneities. 1

Finite-size scaling of the left-current correlator

with non-degenerate quark masse

double commutators

A new method to solve Lindblad equations wit

Luis J. Boya†

Commutativity of missing label operators in term

and

We discuss the entropy generation in quantum tunneling of a relativistic particle under the influence of a time varying force with the help of squeezing formalism. It is shown that if one associates classical coarse grained entropy to the phase space volume, there is an inevitable entropy increase due to the changes in position and momentum variances. The entropy change can be quantified by a simple expression ∆S = ln cosh 2r, where r is the squeeze parameter measuring the “height ” and “width ” of the potential barrier. We suggest that the universe could have acquired its initial entropy in a quantum squeeze from “nothing ” and briefly discuss the implications of our proposal. One of the major problems of theoretical cosmology is to explain the present day large scale isotropy and homogeneity of the universe. The possible explanation of this puzzle must have an intimate relation to the initia

Cosmologies with Two-Dimensional Inhomogeneity

We present a new generating algorithm to construct exact non static solutions of the Einstein field equations with two-dimensional inhomogeneity. Infinite dimensional families of G1 inhomogeneous solutions with a self interacting scalar field, or alternatively with perfect fluid, can be constructed using this algorithm. Some families of solutions and the applications of the algorithm are discussed. Recently there has been a considerable interest in scalar field cosmologies. This interest is related to the studies of inflationary models where the scalar field (inflaton) acts as the main driving force for inflation. On the other hand, one of the most important issues related to the inflationary scenario is how sensitive are the inflationary models to the change in the initial conditions [1]. The dependence of the inflationary scenario on the initial conditions is usually studied either numerically or perturbatively, under some simplifying assumptions, or analytically, within the framework of exact solutions using cosmological models with a high degree of symmetry. Until now, it was only possible to study exact scalar field cosmological models with one dimensiona