24 research outputs found
Electroweak Theory and Noncommutative Geometry
The noncommutative generalisation of the standard electroweak model due to
Balakrishna, Gursey and Wali is formulated in terms of the derivations
Der_2(M_3) of a three dimensional representation of the su(2) Lie algebra of
weak isospin. A light Higgs boson of mass about 130 GeV, together with four
very heavy scalar bosons are predicted.Comment: 11 pages, LATEX, no figures. Talk given at the 2nd Gursey Memorial
Conference, June 2000, Istanbu
Scaling Cosmologies from Duality Twisted Compactifications
Oscillating moduli fields can support a cosmological scaling solution in the
presence of a perfect fluid when the scalar field potential satisfies
appropriate conditions. We examine when such conditions arise in
higher-dimensional, non-linear sigma-models that are reduced to four dimensions
under a generalized Scherk-Schwarz compactification. We show explicitly that
scaling behaviour is possible when the higher-dimensional action exhibits a
global SL(n,R) or O(2,2) symmetry. These underlying symmetries can be exploited
to generate non-trivial scaling solutions when the moduli fields have
non-canonical kinetic energy. We also consider the compactification of
eleven-dimensional vacuum Einstein gravity on an elliptic twisted torus.Comment: 21 pages, 3 figure
Beta, Dipole and Noncommutative Deformations of M-theory Backgrounds with One or More Parameters
We construct new M-theory solutions starting from those that contain 5 U(1)
isometries. We do this by reducing along one of the 5-torus directions, then
T-dualizing via the action of an O(4,4) matrix and lifting back to
11-dimensions. The particular T-duality transformation is a sequence of O(2,2)
transformations embedded in O(4,4), where the action of each O(2,2) gives a
Lunin-Maldacena deformation in 10-dimensions. We find general formulas for the
metric and 4-form field of single and multiparameter deformed solutions, when
the 4-form of the initial 11-dimensional background has at most one leg along
the 5-torus. All the deformation terms in the new solutions are given in terms
of subdeterminants of a 5x5 matrix, which represents the metric on the 5-torus.
We apply these results to several M-theory backgrounds of the type AdS_r x
X^{11-r}. By appropriate choices of the T-duality and reduction directions we
obtain analogues of beta, dipole and noncommutative deformations. We also
provide formulas for backgrounds with only 3 or 4 U(1) isometries and study a
case, for which our assumption for the 4-form field is violated.Comment: v2:minor corrections, v3:small improvements, v4:conclusions expanded,
to appear in Class. Quant. Gra
Strings on the deformed T^{1,1}: giant magnon and single spike solutions
In this paper we find giant magnon and single spike string solutions in a
sector of the gamma-deformed conifold. We examine the dispersion relations and
find a behavior analogous to the undeformed case. The transcendental functional
relations between the conserved charges are shifted by certain gamma-dependent
term. The latter is proportional to the total momentum and thus qualitatively
different from known cases.Comment: 35 pages, no figure
On the perturbative chiral ring for marginally deformed N=4 SYM theories
For \cal{N}=1 SU(N) SYM theories obtained as marginal deformations of the
\cal{N}=4 parent theory we study perturbatively some sectors of the chiral ring
in the weak coupling regime and for finite N. By exploiting the relation
between the definition of chiral ring and the effective superpotential we
develop a procedure which allows us to easily determine protected chiral
operators up to n loops once the superpotential has been computed up to (n-1)
order. In particular, for the Lunin-Maldacena beta-deformed theory we determine
the quantum structure of a large class of operators up to three loops. We
extend our procedure to more general Leigh-Strassler deformations whose chiral
ring is not fully understood yet and determine the weight-two and weight-three
sectors up to two loops. We use our results to infer general properties of the
chiral ring.Comment: LaTex, 40 pages, 4 figures, uses JHEP3; v2: minor correction
A Massive S-duality in 4 dimensions
We reduce the Type IIA supergravity theory with a generalized Scherk-Schwarz
ansatz that exploits the scaling symmetry of the dilaton, the metric and the NS
2-form field. The resulting theory is a new massive, gauged supergravity theory
in four dimensions with a massive 2-form field and a massive 1-form field. We
show that this theory is S-dual to a theory with a massive vector field and a
massive 2-form field, which are dual to the massive 2-form and 1-form fields in
the original theory, respectively. The S-dual theory is shown to arise from a
Scherk-Schwarz reduction of the heterotic theory. Hence we establish a massive,
S-duality type relation between the IIA theory and the heterotic theory in four
dimensions. We also show that the Lagrangian for the new four dimensional
theory can be put in the most general form of a D=4, N=4 gauged Lagrangian
found by Schon and Weidner, in which (part of) the SL(2) group has been gauged.Comment: 20 pages, references adde
Semi-classical Strings in Sasaki-Einstein Manifolds
We find point-like and classical string solutions on the AdS_5 x X^5, where
X^5 are the 5-dimensional Sasaki-Einstein manifolds Ypq and Lpqr. The number of
acceptable solutions is limited drastically in order to satisfy the constraints
on the parameters and coordinates of the manifolds. The energy of the solutions
depends on the parameters of the Sasaki-Einstein manifolds and on the conserved
momenta transcendentally. A discussion on BPS solutions is presented as well.Comment: 34 pages, 9 figure
Lectures on Nongeometric Flux Compactifications
These notes present a pedagogical review of nongeometric flux
compactifications. We begin by reviewing well-known geometric flux
compactifications in Type II string theory, and argue that one must include
nongeometric "fluxes" in order to have a superpotential which is invariant
under T-duality. Additionally, we discuss some elementary aspects of the
worldsheet description of nongeometric backgrounds. This review is based on
lectures given at the 2007 RTN Winter School at CERN.Comment: 31 pages, JHEP
Probing Universality in the Gravity Duals of N=1 SYM by gamma-deformations
Recently, a one-parameter deformation of the Maldacena-Nunez dual of the N=1
SYM theory was constructed in hep-th/0505100. According to the Lunin-Maldacena
conjecture, the background is dual to pure N=1 SYM in the IR coupled to a KK
sector whose dynamics is altered by a dipole deformation that is proportional
to the deformation parameter gamma. Thus, the deformation serves to identify
the aspects of the gravity backgrounds that bear the effects of the KK sector,
hence non-universal in the dual gauge theory. We make this idea concrete by
studying a Penrose limit of the deformed MN theory. We obtain an exactly
solvable pp-wave that is conjectured to describe the IR dynamics of KK-hadrons
in the field theory. The spectrum, the thermal partition function and the
Hagedorn temperature are calculated. The Hagedorn temperature turns out to be
independent of the deformation parameter.Comment: 29 pages, 1 figure, refs. added, typos corrected, v3: discussion
extended and modified v4: discussion section modified, typos corrceted, v5:
referencing correcte