60 research outputs found
Nonequivalent Seiberg-Witten maps for noncommutative massive U(N) gauge theory
Massive vector fields can be described in a gauge invariant way with the
introduction of compensating fields. In the unitary gauge one recovers the
original formulation. Although this gauging mechanism can be extended to
noncommutative spaces in a straightforward way, non trivial aspects show up
when we consider the Seiberg-Witten map. As we show here, only a particular
class of its solutions leads to an action that admits the unitary gauge fixing.Comment: General solutions for the map and important reference included, 6
pages, no figure
Static strings in Randall-Sundrum scenarios and the quark anti-quark potential
We calculate the energy of a static string in an AdS slice between two
D3-branes with orbifold condition. The energy for configurations with endpoints
on a brane grows linearly for large separation between these points. The
derivative of the energy has a discontinuity at some critical separation.
Choosing a particular position for one of the branes we find configurations
with smooth energy. In the limit where the other brane goes to infinity the
energy has a Coulombian behaviour for short separations and can be identified
with the Cornell potential for a quark anti-quark pair. This identification
leads to effective values for the AdS radius, the string tension and the
position of the infrared brane. These results suggest an approximate duality
between static strings in an AdS slice and a heavy quark anti-quark
configuration in a confining gauge theory.Comment: More clarifications added, typos corrected. Results unchange
DBI equations and holographic DC conductivity
We provide a simple method for writing the Dirac-Born-Infeld (DBI) equations
of a Dp-brane in an arbitrary static background whose metric depends only on
the holographic radial coordinate z. Using this method we revisit the
Karch-O'Bannon's procedure to calculate the DC conductivity in the presence of
constant electric and magnetic fields for backgrounds where the boundary is
four or three dimensional and satisfies homogeneity and isotropy. We find a
frame-independent expression for the DC conductivity tensor. For particular
backgrounds we recover previous results on holographic metals and strange
metals.Comment: 1+21 pages; v2 : references added, minor typos correcte
Physics Beyond the Standard Model: Focusing on the Muon Anomaly
We present a model based on the implication of an exceptional E_{6}-GUT
symmetry for the anomalous magnetic moment of the muon. We follow a particular
chain of breakings with Higgses in the 78 and 351 representations. We analyse
the radiative correction contributions to the muon mass and the effects of the
breaking of the so-called Weinberg symmetry. We also estimate the range of
values of the parameters of our model.Comment: 14 RevTeX pages, 5 figure
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