133 research outputs found
Nonabelian Fields in Exact String Solutions
Within the framework of "anomalously gauged" Wess-Zumino-Witten (WZW) models,
we construct solutions which include nonabelian fields. Both compact and
noncompact groups are discussed. In the case of compact groups, as an example
of background containing nonabelian fields, we discuss conformal theory on the
coset, which is the natural generalization of the 2D monopole
theory corresponding to the coset. In noncompact case, we
consider examples with and cosets.Comment: 15 pages, Late
Coulomb Phase Gluon Scattering at Strong Coupling
We calculate corrections to gluon scattering amplitudes in a Coulomb phase
using gauge/string duality. The Coulomb phase considered is a maximal rank
breaking of . This problem
therefore has 3 scales involved: 1) the scale of the massive fields
arising from the spontaneous breaking of the gauge group; 2) The scale of the
scattering, characterized by the Mandelstam variables ; 3) The IR
regulator . We find corrections in the hard scattering limit , and also find below threshold corrections
with . We find that the corrections in the second case
are finite, and so are IR regulator independent.Comment: 17+17 pages, 3 figure
Ambipolar gate effect and low temperature magnetoresistance of ultrathin La0.8Ca0.2MnO3 Films
Ultrathin La0.8Ca0.2MnO3 films have been measured in a field-effect geometry.
The electric field due to the gate produces a large ambipolar decrease in
resistance at low temperatures. This is attributed to the development of a
pseudogap in the density of states and the couple of localized charge to
strain. The gate effect and mangetoresistance are interpreted in a consistent
framework. The implications for the low temperature behavior of a manganite
film in the two dimensional limit are discussed.Comment: 4 pages, 3 figure
The Heterotic Enhancon
The enhancon mechanism is studied in the heterotic string theory. We consider
the N_L=0 winding strings with momentum (NS1-W*) and the Kaluza-Klein dyons
(KK5-NS5*). The NS1-W* and KK5-NS5* systems are dualized to the D4-D0* and
D6-D2* systems, respectively, under the d=6 heterotic/IIA S-duality. The
heterotic form has a number of advantages over the type IIA form. We study
these backgrounds and obtain the enhancon radii by brane probe analysis. The
results are consistent with S-duality.Comment: 21 pages, 1 figure, LaTe
The a-theorem and conformal symmetry breaking in holographic RG flows
We study holographic models describing an RG flow between two fixed points
driven by a relevant scalar operator. We show how to introduce a spurion field
to restore Weyl invariance and compute the anomalous contribution to the
generating functional in even dimensional theories. We find that the
coefficient of the anomalous term is proportional to the difference of the
conformal anomalies of the UV and IR fixed points, as expected from anomaly
matching arguments in field theory. For any even dimensions the coefficient is
positive as implied by the holographic a-theorem. For flows corresponding to
spontaneous breaking of conformal invariance, we also compute the two-point
functions of the energy-momentum tensor and the scalar operator and identify
the dilaton mode. Surprisingly we find that in the simplest models with just
one scalar field there is no dilaton pole in the two-point function of the
scalar operator but a stronger singularity. We discuss the possible
implications.Comment: 50 pages. v2: minor changes, added references, extended discussion.
v3: we have clarified some of the calculations and assumptions, results
unchanged. v4: published version in JHE
Control of mating preferences in mice by genes in the major histocompatibility complex.
On Field Theory Thermalization from Gravitational Collapse
Motivated by its field theory interpretation, we study gravitational collapse
of a minimally coupled massless scalar field in Einstein gravity with a
negative cosmological constant. After demonstrating the accuracy of the
numerical algorithm for the questions we are interested in, we investigate
various aspects of the apparent horizon formation. In particular, we study the
time and radius of the apparent horizon formed as functions of the initial
Gaussian profile for the scalar field. We comment on several aspects of the
dual field theory picture.Comment: 31 pages, 17 figures; V2 Some figures corrected, minor revision.
arXiv admin note: substantial text overlap with arXiv:1106.233
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