790 research outputs found
Dirac-Born-Infeld action from spontaneous breakdown of Lorentz symmetry in brane-world scenarios
In whatever Lorentz invariant theory, the presence of extended d-dimensional
objects inside a higher dimensional bulk space-time, like for instance D-branes
in string theories, induces a spontaneous breakdown of the Poincare' invariance
of the bulk; however the effective action describing these extended objects
should still respect this larger invariance through a non-linear realization of
the full symmetry. Here the specific form of such a realization in presence of
an electromagnetic field is uncovered. The Dirac-Born-Infeld type action for a
D-brane turns out to be invariant under such transformations. Conversely it is
explicitly demonstrated in some simple cases that the most general invariant
action, as long as derivatives of the field strength (and second derivatives of
the scalars) can be neglected, is a linear combination of terms of the
Dirac-Born-Infeld type with different scale parameters. The string result is
obtained if one further assumes that the theory depends upon a single length
scale.Comment: 4 pages, no figures. v4: typos corrected; matches the published
versio
Critical exponents for higher-representation sources in 3D SU(3) gauge theory from CFT
We establish an exact mapping between the multiplication table of the
irreducible representations of SU(3) and the fusion algebra of the
two-dimensional conformal field theory in the same universality class of 3D
SU(3) gauge theory at the deconfining point. In this way the Svetitsky-Yaffe
conjecture on the critical behaviour of Polyakov lines in the fundamental
representation naturally extends to whatever representation one considers.
As a consequence, the critical exponents of the correlators of these Polyakov
lines are determined. Monte Carlo simulations with sources in the symmetric
two-index representation, combined with finite-size scaling analysis, compare
very favourably with these predictions.Comment: 15 pages, 2 figure
Self-avoiding effective strings in lattice gauge theories
It is shown that the effective string recently introduced to describe the
long distance dynamics of 3D gauge systems in the confining phase has an
intriguing description in terms of models of 2D self-avoiding walks in the
dense phase. The deconfinement point, where the effective string becomes N=2
supersymmetric, may then be interpreted as the tricritical Theta point where
the polymer chain undergoes a collapse transition. As a consequence, a
universal value of the deconfinement temperature is predicted.Comment: 7 page
The Effective String of 3D Gauge Systems at the Deconfining Transition
It is argued that the effective string of whatever 3D gauge system at the
deconfining transition is universally described by the minimal extended
superconformal theory at . A universal value of the critical temperature
is predicted.Comment: 5 page
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