21,763 research outputs found
Affinity for Scalar Fields to Dissipate
The zero temperature effective equation of motion is derived for a scalar
field interacting with other fields. For a broad range of cases, involving
interaction with as few as one or two fields, dissipative regimes are found for
the scalar field system. The zero temperature limit constitutes a baseline
effect that will be prevalent in any general statistical state. Thus, the
results found here provide strong evidence that dissipation is the norm not
exception for an interacting scalar field system. For application to
inflationary cosmology, this provides convincing evidence that warm inflation
could be a natural dynamics once proper treatment of interactions is done. The
results found here also may have applicability to entropy production during the
chiral phase transition in heavy ion collision.Comment: 21 pages, 4 figures (uses epsf, RevTeX). Just minor changes. Version
in press Physical Review D (2001
Corrugation of relativistic magnetized shock waves
As a shock front interacts with turbulence, it develops corrugation which
induces outgoing wave modes in the downstream plasma. For a fast shock wave,
the incoming wave modes can either be fast magnetosonic waves originating from
downstream, outrunning the shock, or eigenmodes of the upstream plasma drifting
through the shock. Using linear perturbation theory in relativistic MHD, this
paper provides a general analysis of the corrugation of relativistic magnetized
fast shock waves resulting from their interaction with small amplitude
disturbances. Transfer functions characterizing the linear response for each of
the outgoing modes are calculated as a function of the magnetization of the
upstream medium and as a function of the nature of the incoming wave.
Interestingly, if the latter is an eigenmode of the upstream plasma, we find
that there exists a resonance at which the (linear) response of the shock
becomes large or even diverges. This result may have profound consequences on
the phenomenology of astrophysical relativistic magnetized shock waves.Comment: 14 pages, 9 figures; to appear in Ap
Symmetry breaking patterns of the 3-3-1 model at finite temperature
We consider the minimal version of an extension of the standard electroweak
model based on the gauge symmetry (the
3-3-1 model). We analyze the most general potential constructed from three
scalars in the triplet representation of , whose neutral components
develop nonzero vacuum expectation values, giving mass for all the model's
massive particles. {}For different choices of parameters, we obtain the
particle spectrum for the two symmetry breaking scales: one where the group is broken down to and a lower scale
similar to the standard model one. Within the considerations used, we show that
the model encodes two first-order phase transitions, respecting the pattern of
symmetry restoration. The last transition, corresponding to the standard
electroweak one, is found to be very weak first-order, most likely turning
second-order or a crossover in practice. However, the first transition in this
model can be strongly first-order, which might happen at a temperature not too
high above the second one. We determine the respective critical temperatures
for symmetry restoration for the model.Comment: 13 pages, 8 figures. Minor changes to match published versio
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