Results 11  20
of
29
Coupling hybrid inflation to moduli
 JCAP 0609 (2006) 012 [hepth/0606140
"... Abstract. Hybrid inflation can be realised in lowenergy effective string theory, as described using supergravity. We find that the coupling of moduli to the hybrid inflation sector in supergravity leads to a slope and a curvature for the inflaton potential. The ǫ and η parameters receive contributi ..."
Abstract

Cited by 8 (5 self)
 Add to MetaCart
(Show Context)
Abstract. Hybrid inflation can be realised in lowenergy effective string theory, as described using supergravity. We find that the coupling of moduli to the hybrid inflation sector in supergravity leads to a slope and a curvature for the inflaton potential. The ǫ and η parameters receive contributions at tree and one loop level which are not compatible with slow roll inflation. Furthermore the coupling to the moduli sector can even prevent inflation from ending at all. We show that introducing shift symmetries in the inflationary sector and taking the moduli sector to be noscale removes most of these problems. If the moduli fields are fixed during inflation, as is usually assumed, it appears that viable slowroll inflation can then be obtained with just one finetuning of the moduli sector parameters. However, we show this is not a reasonable assumption, and that the small variation of the moduli fields during inflation gives a significant contribution to the effective inflaton potential. This typically implies that η ≈ −6.
Seeing through the String Landscape  a String Hunter’s Companion
 in Particle Physics and Cosmology,” JHEP 0903, 149 (2009) arXiv:0904.4601 [hepth
"... Abstract: In this article we will overview several aspects of the string landscape, namely intersecting Dbrane models and their statistics, possible model independent LHC signatures of intersecting brane models, flux compactification, moduli stabilization in type II compactifications, domain wall s ..."
Abstract

Cited by 4 (0 self)
 Add to MetaCart
(Show Context)
Abstract: In this article we will overview several aspects of the string landscape, namely intersecting Dbrane models and their statistics, possible model independent LHC signatures of intersecting brane models, flux compactification, moduli stabilization in type II compactifications, domain wall solutions and brane inflation.
On the chaos of Dbrane phase transitions
, 2005
"... Abstract: We study small instanton (and brane recombination) phase transitions in phenomenological models built with Dbranes. By explicitly describing the cosmological dynamics of the moduli and matter fields, we show that these transitions do not occur smoothly, but are typically chaotic with the ..."
Abstract

Cited by 2 (0 self)
 Add to MetaCart
(Show Context)
Abstract: We study small instanton (and brane recombination) phase transitions in phenomenological models built with Dbranes. By explicitly describing the cosmological dynamics of the moduli and matter fields, we show that these transitions do not occur smoothly, but are typically chaotic with the gauge group of the low energy theory fluctuating in time. We comment on the potential implications for cosmological questions such as inflation. Keywords: Dbranes, Compactification and String Models. Contents 1. Introduction: phase transitions on Dbranes 1 2. Instantons in Dbrane physics 4 3. The small instanton transition in type II brane world models 6
On branes and . . .
, 2003
"... Novel theories appear on the worldvolume of branes by orienting B fields along various directions of the branes. We review some of the earlier developments and explore many new examples of these theories. In particular, among other things, we study the pinning effect of branes near conifold like si ..."
Abstract
 Add to MetaCart
Novel theories appear on the worldvolume of branes by orienting B fields along various directions of the branes. We review some of the earlier developments and explore many new examples of these theories. In particular, among other things, we study the pinning effect of branes near conifold like singularities and braneantibrane theories with different fluxes on their worldvolumes. We show that all these theories arise from different limits of an Mtheory configuration with appropriately chosen Gfluxes. This gives us a way to
Article The Dark Energy Properties of the Dirac–Born–Infeld Action
, 2012
"... entropy ..."
(Show Context)
HIP200813/TH Disorder on the landscape
, 804
"... Disorder on the string theory landscape may significantly affect dynamics of eternal inflation leading to the possibility for some vacua on the landscape to become dynamically preferable over others. We systematically study effects of a generic disorder on the landscape starting by identifying a sec ..."
Abstract
 Add to MetaCart
(Show Context)
Disorder on the string theory landscape may significantly affect dynamics of eternal inflation leading to the possibility for some vacua on the landscape to become dynamically preferable over others. We systematically study effects of a generic disorder on the landscape starting by identifying a sector with builtin disorder – a set of de Sitter vacua corresponding to compactifications of the Type IIB string theory on CalabiYau manifolds with a number of warped KlebanovStrassler throats attached randomly to the bulk part of the CalabiYau. Further, we derive continuum limit of the vacuum dynamics equations on the landscape. Using methods of dynamical renormalization group we determine the late time behavior of the probability distribution for an observer to measure a given value of the cosmological constant. We find the diffusion of the probability distribution to significantly slow down in sectors of the landscape where the number of nearest neighboring vacua for any given vacuum is small. We discuss relation of this slowdown with phenomenon of Anderson localization in disordered media.
Five Easy Pieces: The Dynamics of Quarks in Strongly Coupled Plasmas
, 2009
"... We revisit the analysis of the drag a massive quark experiences and the wake it creates at a temperature T while moving through a plasma using a gravity dual that captures the renormalisation group runnings in the dual gauge theory. Our gravity dual has a black hole and seven branes embedded via Ouy ..."
Abstract
 Add to MetaCart
(Show Context)
We revisit the analysis of the drag a massive quark experiences and the wake it creates at a temperature T while moving through a plasma using a gravity dual that captures the renormalisation group runnings in the dual gauge theory. Our gravity dual has a black hole and seven branes embedded via Ouyang embedding, but the geometry is a deformation of the usual conifold metric. In particular the gravity dual has squashed two spheres, and a small resolution at the IR. Using this background we show that the drag of a massive quark receives corrections that are proportional to powers of log T when compared with the drag computed using AdS/QCD correspondence. The massive quarks map to fundamental strings in the dual gravity theory. We use the perturbation produced by these strings to compute the wake and compare with the results obtained using AdS/QCD correspondence. We also study the shear viscosity in the theory with running couplings, analyze the viscosity to entropy ratio and compare the result with the bound derived from AdS backgrounds. In the presence of higher order curvature square corrections from the backreactions of the embedded D7 branes, we argue the possibility of the entropy to viscosity bound being violated. Finally, we show that our setup could inprinciple allow us to study a family of gauge theories at the boundary by cutting off the dual geometry respectively at various points in the radial direction. All these gauge theories can have well defined UV completions, and more interestingly, we demonstrate that any thermodynamical quantities derived from these theories would be completely independent of the cutoff scale and only depend on the temperature at which we define these theories. Such a result would justify the holographic renormalisabilities of these theories which we, in turn, also demonstrate. We give physical interpretations of these results and compare them with more realistic scenarios.
and
, 2002
"... In this paper we describe the heterotic dual of the type IIB theory compactified to four dimensions on a toroidal orientifold in the presence of fluxes. The type IIB background is most easily described in terms of an Mtheory compactification on a fourfold. The heterotic dual is obtained by perform ..."
Abstract
 Add to MetaCart
(Show Context)
In this paper we describe the heterotic dual of the type IIB theory compactified to four dimensions on a toroidal orientifold in the presence of fluxes. The type IIB background is most easily described in terms of an Mtheory compactification on a fourfold. The heterotic dual is obtained by performing a series of Udualities. We argue that these dualities preserve supersymmetry and that the supergravity description is valid after performing them. The heterotic string is compactified on a manifold that is no longer Kähler and has torsion. These manifolds have to satisfy a number of constraints, for example, existence of an holomorphic threeform, size limits, torsional equations etc. We give an explicit form of the background and study the constraints associated to them.
unknown title
, 2003
"... hepth/0312019 K3 × T 2 /Z2 orientifolds with fluxes, open string moduli and critical points ..."
Abstract
 Add to MetaCart
(Show Context)
hepth/0312019 K3 × T 2 /Z2 orientifolds with fluxes, open string moduli and critical points