10,143 research outputs found
COUPLING CHIRAL BOSONS TO GRAVITY
The chiral boson actions of Floreanini and Jackiw (FJ), and of McClain,Wu and
Yu (MWY) have been recently shown to be different representations of the same
chiral boson theory. MWY displays manifest covariance and also a (gauge)
symmetry that is hidden in the FJ side, which, on the other hand, displays the
physical spectrum in a simple manner. We make use of the covariance of the MWY
representation for the chiral boson to couple it to background gravity showing
explicitly the equivalence with the previous results for the FJ representationComment: 8 pages, Latex, no figure
Anomalous dimensions from rotating open strings in AdS/CFT
We propose a new entry within the dictionary of the AdS/CFT duality at strong
coupling: in the limit of a large spin or a large R-charge, the anomalous
dimension of the gauge theory operator dual to a semiclassical rotating string
is proportional to the string proper length. This conjecture is motivated by a
generalization to strings of the rule for computing anomalous dimensions of
massive particles and supergravity fields in the anti-de Sitter space. We show
that this proportionality holds for a rotating closed string in global AdS
space, representing a high spin operator made of fields in the adjoint
representation. It is also valid for closed strings rotating in
(representing operators with large R-charge), for closed strings with multiple
AdS spin, and for giant magnons. Based on this conjecture, we calculate the
anomalous dimension of operators made of fields in the fundamental
representation, associated with high spin mesons, and which are represented by
rotating open strings attached to probe D7-branes. The result is a logarithmic
dependence upon the spin, , similar to the
closed string case. We show that the operator properties --- anomalous
dimension and spin --- are obtained from measurements made by a local observer
in the anti-de Sitter space. For the open string case, this ensures that these
quantities are independent of the mass scale introduced by the D7-branes (the
quark mass), as expected on physical grounds. In contrast, properties of the
gauge theory states, like the energy, correspond to measurements by a gauge
theory observer and depend upon the mass scale --- once again, as expected.Comment: V2: two related references include
Chiral Bosons as solutions of the BV master equation 2D chiral gauge theories
We construct the chiral Wess-Zumino term as a solution for the
Batalin-Vilkovisky master equation for anomalous two-dimensional gauge
theories, working in an extended field-antifield space, where the gauge group
elements are introduced as additional degrees of freedom.
We analyze the Abelian and the non-Abelian cases, calculating in both cases
the BRST generator in order to show the physical equivalence between this
chiral solution for the master equation and the usual (non-chiral) one.Comment: 11 pages, TEX dialet, IF/UFRJ-94-
Quasinormal modes and dispersion relations for quarkonium in a plasma
Recent investigations show that the thermal spectral function of heavy and vector mesons can be described using holography.
These studies consider a bottom up model that captures the heavy flavour
spectroscopy of masses and decay constants in the vacuum and is consistently
extended to finite temperature. The corresponding spectral functions provide a
picture of the dissociation process in terms of the decrease of the quasi-state
peaks with temperature.
Another related tool that provides important information about the thermal
behaviour is the analysis of the quasinormal modes. They are field solutions in
a curved background assumed to represent, in gauge/gravity duality,
quasi-particle states in a thermal medium. The associated complex frequencies
are related to the thermal mass and width. We present here the calculation of
quasinormal modes for charmonium and bottomonium using the holographic
approach. The temperature dependence of mass and thermal width are
investigated. Solutions corresponding to heavy mesons moving into the plasma
are also studied. They provide the dependence of the real and imaginary parts
of the frequency with the quasi-particle momenta, the so called dispersion
relations.Comment: V2: enlarged version with clarifications, more comparison with
previous articles and additional references included. 11 figures, 2 tables,
62 references. Version accepted for publication in JHE
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