137 research outputs found
Parity Breaking Medium and Squeeze Operators
The transition between a Minkowski space region and a parity breaking medium
domain is thoroughly discussed. The requirement of continuity of the field
operator content across the separating boundary of the two domains leads to
Bogolyubov transformations, squeezed pairs states and squeeze operators that
turn out to generate a functional SU(2) algebra. According to this algebraic
approach, the reflection and transmission probability amplitude across the
separating boundary are computed. The probability rate of the emission or
absorption of squeezed pairs out of the vacuum (generalization of the
Sauter-Schwinger-Nikishov formula) is obtained.Comment: 22 pages, slightly modified, arXiv admin note: text overlap with
arXiv:1109.344
Nearly scale-invariant curvature modes from entropy perturbations during graceful exit
In this Letter, we describe how a spectrum of entropic perturbations generated during a period of slow contraction can source a nearly scale-invariant spectrum of curvature perturbations on length scales larger than the Hubble radius during the transition from slow contraction to a classical non-singular bounce (the `graceful exit' phase). The sourcing occurs naturally through higher-order scalar field kinetic terms common to classical (non-singular) bounce mechanisms. We present a concrete example in which, by the end of the graceful exit phase, the initial entropic fluctuations have become negligible and the curvature fluctuations have a nearly scale-invariant spectrum with an amplitude consistent with observations
Propagation of photons and massive vector mesons between a parity breaking medium and vacuum
The problem of propagation of photons and massive vector mesons in the
presence of Lorenz and CPT invariance violating medium is studied when the
parity-odd medium is bounded by a hyperplane separating it from the vacuum. The
solutions in both half-spaces are carefully discussed and in the case of
space-like boundary stitched on the boundary with help of the Bogolubov
transformations provided by the space-like Chern-Simons vector. The presence of
two different Fock vacua is shown and the probability amplitude for
transmission of particles from vacuum to parity breaking medium is calculated.
We have also found classical solutions and showed that the results are
consistent with ones obtained by canonical quantization formalism. In the
cases, both of entrance to and of escaping from parity-odd medium, the
probabilities for reflecting and passing through were found for each
polarization using the classical solutions. Finally, the propagator for each
polarization is obtained in the momentum space. Boundary effects under
consideration are of certain importance for registration of local parity
violation in the finite volume of heavy ion fireball and/or of a star with cold
axion condensate.Comment: 27 pages, minor revision for JHE
On asimuthal anisotropy in fragmentation of classical relativistic string
A fragmenting relativistic string is widely used for modelling particle
production via quark-gluon strings formed in hadron inelastic interactions of
high energies. In this note we focus on motion and fragmentation of
relativistic string with non-zero transverse separation of its ends and study
this scenario as a possible mechanism bringing anisotropy into the asimuthal
angle disribution of produced particles in inelastic interactions of hadrons.Comment: 12 pages, 6 figure
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