38,114 research outputs found
Mass for Plasma Photons from Gauge Symmetry Breaking
We derive the effective masses for photons in unmagnetized plasma waves using
a quantum field theory with two vector fields (gauge fields). In order to
properly define the quantum field degrees of freedom we re-derive the classical
wave equations on light-front gauge. This is needed because the usual scalar
potential of electromagnetism is, in quantum field theory, not a physical
degree of freedom that renders negative energy eigenstates. We also consider a
background local fluid metric that allows for a covariant treatment of the
problem. The different masses for the longitudinal (plasmon) and transverse
photons are in our framework due to the local fluid metric. We apply the
mechanism of mass generation by gauge symmetry breaking recently proposed by
the authors by giving a non-trivial vacuum-expectation-value to the second
vector field (gauge field). The Debye length is interpreted as an
effective compactification length and we compute an explicit solution for the
large gauge transformations that correspond to the specific mass eigenvalues
derived here. Using an usual quantum field theory canonical quantization we
obtain the usual results in the literature. Although none of these ingredients
are new to physicist, as far as the authors are aware it is the first time that
such constructions are applied to Plasma Physics. Also we give a physical
interpretation (and realization) for the second vector field in terms of the
plasma background in terms of known physical phenomena.
Addendum: It is given a short proof that equation (10) is wrong, therefore
equations (12-17) are meaningless. The remaining results are correct being
generic derivations for nonmagnetized plasmas derived in a covariant QFT
framework.Comment: v1: 1+6 pages v2: Several discussions rewritten; Abstract rewritten;
References added; v3: includes Addendu
Charge breaking bounds in the Zee model
We study the possibility that charge breaking minima occur in the Zee model.
We reach very different conclusions from those attained in simpler, two Higgs
doublet models, and the reason for this is traced back to the existence of
cubic terms in the potential. A scan of the Zee model's parameter space shows
that CB is restricted to a narrow region of values of the parameters
Strong flavour changing effective operator contributions to single top quark production
We study the effects of dimension six effective operators on the production
of single top quarks at the LHC. The operator set considered includes terms
with effective gluon interactions and four-fermion terms. Analytic expressions
for the several partonic cross sections of single top production will be
presented, as well as the results of their integration on the parton density
functions.Comment: 20 pages, 7 fig
Electron-electron interaction in a MCS model with a purely spacelike Lorentz-violating background
One considers a planar Maxwell-Chern-Simons electrodynamics in the presence
of a purely spacelike Lorentz-violating background. Once the Dirac sector is
properly introduced and coupled to the scalar and the gauge fields, the
electron-electron interaction is evaluated as the Fourier transform of the
Moller scattering amplitude (derived in the non-relativistic limit). The
associated Fourier integrations can not be exactly carried out, but an
algebraic solution for the interaction potential is obtained in leading order
in (v/s)^2. It is then observed that the scalar potential presents a
logarithmic attractive (repulsive) behavior near (far from) the origin.
Concerning the gauge potential, it is composed of the pure MCS interaction
corrected by background contributions, also responsible for its anisotropic
character. It is also verified that such corrections may turn the gauge
potential attractive for some parameter values. Such attractiveness remains
even in the presence of the centrifugal barrier and gauge invariant A.A term,
which constitutes a condition compatible with the formation of Cooper pairs.Comment: 12 pages, 3 figures, Revtex4 style, figures revised; to appear in
Phys. Rev. D (2005
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