120 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
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
Heavy-flavour and quarkonium production in the LHC era: from proton-proton to heavy-ion collisions
This report reviews the study of open heavy-flavour and quarkonium production
in high-energy hadronic collisions, as tools to investigate fundamental aspects
of Quantum Chromodynamics, from the proton and nucleus structure at high energy
to deconfinement and the properties of the Quark-Gluon Plasma. Emphasis is
given to the lessons learnt from LHC Run 1 results, which are reviewed in a
global picture with the results from SPS and RHIC at lower energies, as well as
to the questions to be addressed in the future. The report covers heavy flavour
and quarkonium production in proton-proton, proton-nucleus and nucleus-nucleus
collisions. This includes discussion of the effects of hot and cold strongly
interacting matter, quarkonium photo-production in nucleus-nucleus collisions
and perspectives on the study of heavy flavour and quarkonium with upgrades of
existing experiments and new experiments. The report results from the activity
of the SaporeGravis network of the I3 Hadron Physics programme of the European
Union 7th Framework Programme
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