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82
Largevolume flux compactifications: Moduli spectrum and D3/D7 soft supersymmetry breaking
 SYSTEMATICS OF MODULI STABILISATION IN CALABIYAU FLUX COMPACTIFICATIONS,” JHEP 0503 (2005) 007 [ARXIV:HEPTH/0502058]. – 42
, 2005
"... We present an explicit calculation of the spectrum of a general class of string models, corresponding to CalabiYau flux compactifications with h1,2> h1,1> 1 with leading perturbative and nonperturbative corrections, in which all geometric moduli are stabilised as in hepth/0502058. The volum ..."
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Cited by 129 (20 self)
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We present an explicit calculation of the spectrum of a general class of string models, corresponding to CalabiYau flux compactifications with h1,2> h1,1> 1 with leading perturbative and nonperturbative corrections, in which all geometric moduli are stabilised as in hepth/0502058. The volume is exponentially large, leading to a range of string scales from the Planck mass to the TeV scale, realising for the first time the large extra dimensions scenario in string theory. We provide a general analysis of the relevance of perturbative and nonperturbative effects and the regime of validity of the effective field theory. We compute the spectrum in the moduli sector finding a hierarchy of masses depending on inverse powers of the volume. We also compute soft supersymmetry breaking terms for particles living on D3 and D7 branes. We find a hierarchy of soft terms corresponding to ‘volume dominated ’ Fterm supersymmetry breaking. Fterms for Kähler moduli dominate both those for dilaton and complex
Symmetry breaking and axionic strings in the warped deformed conifold
 JHEP 0409
"... We interpret Dstrings at the bottom of the warped deformed conifold as axionic strings in the dual cascading SU(N + M) × SU(N) gauge theory. The axion is a massless pseudoscalar glueball which we find in the supergravity fluctuation spectrum and interpret as the Goldstone boson of spontaneously b ..."
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Cited by 73 (10 self)
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We interpret Dstrings at the bottom of the warped deformed conifold as axionic strings in the dual cascading SU(N + M) × SU(N) gauge theory. The axion is a massless pseudoscalar glueball which we find in the supergravity fluctuation spectrum and interpret as the Goldstone boson of spontaneously broken U(1) baryon number symmetry. The existence of this massless glueball, anticipated in hepth/0101013, supports the idea that the cascading gauge theory is on the baryonic branch, i.e. the U(1)B global symmetry is broken by expectation values of baryonic operators. We also find a massless scalar glueball, which is a superpartner of the pseudoscalar. This scalar mode is a mixture of an NSNS 2form and a metric perturbation of the warped deformed conifold of a type first considered in hepth/0012034.
Proeyen, FayetIliopoulos terms in supergravity and cosmology
"... We clarify the structure of N = 1 supergravity in 1+3 dimensions with constant Fayet–Iliopoulos (FI) terms. The FI terms gξ induce nonvanishing Rcharges for the fermions and the superpotential. Therefore the Dterm inflation model in supergravity with constant FI terms has to be revisited. We pres ..."
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Cited by 59 (3 self)
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We clarify the structure of N = 1 supergravity in 1+3 dimensions with constant Fayet–Iliopoulos (FI) terms. The FI terms gξ induce nonvanishing Rcharges for the fermions and the superpotential. Therefore the Dterm inflation model in supergravity with constant FI terms has to be revisited. We present all corrections of order gξ/M 2 P to the classical supergravity action required by local supersymmetry and provide a gaugeanomalyfree version of the model. We also investigate the case of the socalled anomalous U(1) when a chiral superfield is shifted under U(1). In such a case, in the context of string theory, the FI terms originate from the derivative of the Kähler potential and they are inevitably fielddependent. This raises an issue of stabilization of the relevant field in applications to cosmology. The recently suggested equivalence between the Dterm strings and Dbranes of type II theory shows that braneantibrane systems produce FI terms in the effective 4d theory, with the RamondRamond axion shifting under the U(1) symmetry. This connection gives the possibility to interpret many unknown properties of D− ¯ D systems in the more familiar language of 4d supergravity Dterms, and vice versa. For instance, the shift of the axion field in both cases restricts the possible
Braneworld gravity
 Living Rev. Rel
"... The observable universe could be a 1 + 3surface (the “brane”) embedded in a 1 + 3 + ddimensional spacetime (the “bulk”), with Standard Model particles and fields trapped on the brane while gravity is free to access the bulk. At least one of the d extra spatial dimensions could be very large relati ..."
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Cited by 37 (0 self)
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The observable universe could be a 1 + 3surface (the “brane”) embedded in a 1 + 3 + ddimensional spacetime (the “bulk”), with Standard Model particles and fields trapped on the brane while gravity is free to access the bulk. At least one of the d extra spatial dimensions could be very large relative to the Planck scale, which lowers the fundamental gravity scale, possibly even down to the electroweak ( ∼ TeV) level. This revolutionary picture arises in the framework of recent developments in M theory. The 1+10dimensional M theory encompasses the known 1 + 9dimensional superstring theories, and is widely considered to be a promising potential route to quantum gravity. General relativity cannot describe gravity at high enough energies and must be replaced by a quantum gravity theory, picking up significant corrections as the fundamental energy scale is approached. At low energies, gravity is localized at the brane and general relativity is recovered, but at high energies gravity “leaks ” into the bulk, behaving in a truly higherdimensional way. This introduces significant changes to gravitational dynamics and perturbations, with interesting and potentially testable implications for highenergy astrophysics, black holes, and cosmology. Braneworld models offer a phenomenological way to test some of the novel predictions and corrections to general relativity that are implied by M theory. This review discusses the geometry, dynamics and perturbations of simple braneworld models for cosmology and astrophysics, mainly focusing on warped 5dimensional braneworlds based on the Randall–Sundrum models. c©Max Planck Society and the authors. Further information on copyright is given at
Closer towards inflation in string theory,” Phys
 Inflation in realistic Dbrane models,” JHEP 0409, 033 (2004), hepth/0403119 ; A. Buchel
, 2004
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Modified Gravity and Cosmology
, 2012
"... In this review we present a thoroughly comprehensive survey of recent work on modified theories of gravity and their cosmological consequences. Amongst other things, we cover General Relativity, ScalarTensor, EinsteinAether, and Bimetric theories, as well as TeVeS, f(R), general higherorder theo ..."
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Cited by 28 (0 self)
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In this review we present a thoroughly comprehensive survey of recent work on modified theories of gravity and their cosmological consequences. Amongst other things, we cover General Relativity, ScalarTensor, EinsteinAether, and Bimetric theories, as well as TeVeS, f(R), general higherorder theories, HořavaLifschitz gravity, Galileons, Ghost Condensates, and models of extra dimensions including KaluzaKlein, RandallSundrum, DGP, and higher codimension braneworlds. We also review attempts to construct a Parameterised PostFriedmannian formalism, that can be used to constrain deviations from General Relativity in cosmology, and that is suitable for comparison with data on the largest scales. These subjects have been intensively studied over the past decade, largely motivated by rapid progress in the field of observational cosmology that now allows, for the first time, precision tests of fundamental physics on the scale of the observable Universe. The purpose of this review is to provide a reference tool for researchers and students in cosmology and gravitational physics, as well as a selfcontained, comprehensive and uptodate introduction to the subject as a whole.
Symmetrybreaking vacua and baryon condensates in ads/cft
, 2008
"... We study the gravity duals of symmetrybreaking deformations of superconformal field theories, AdS/CFT dual to Type IIB string theory on AdS5 × Y where Y is a SasakiEinstein manifold. In these vacua both conformal invariance and baryonic symmetries are spontaneously broken. We present a detailed di ..."
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Cited by 26 (7 self)
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We study the gravity duals of symmetrybreaking deformations of superconformal field theories, AdS/CFT dual to Type IIB string theory on AdS5 × Y where Y is a SasakiEinstein manifold. In these vacua both conformal invariance and baryonic symmetries are spontaneously broken. We present a detailed discussion of the supergravity moduli space, which involves flat form fields on asymptotically conical CalabiYau manifolds, and match this to the gauge theory vacuum moduli space. We discuss certain linearised fluctuations of the moduli, identifying the Goldstone bosons associated with spontaneous breaking of nonanomalous baryonic symmetries. The remaining moduli fields are related to spontaneous breaking of anomalous baryonic symmetries. We also elaborate on the proposal that computing condensates of baryon operators is equivalent to computing the partition function of a noncompact Euclidean D3brane in the background supergravity
Cosmic f and dstrings
"... Macroscopic fundamental and Dirichlet strings have several potential instabilities: breakage, tachyon decays, and confinement by axion domain walls. We investigate the conditions under which metastable strings can exist, and we find that such strings are present in many models. There are various pos ..."
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Cited by 23 (0 self)
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Macroscopic fundamental and Dirichlet strings have several potential instabilities: breakage, tachyon decays, and confinement by axion domain walls. We investigate the conditions under which metastable strings can exist, and we find that such strings are present in many models. There are various possibilities, the most notable being a network of (p,q) strings. Cosmic strings give a potentially large window into string physics. 1 1
Chiral Symmetry Breaking with nonSUSY
 D7branes in ISD backgrounds,” arXiv:0904.0988 [hepth
"... Supersymmetric probe branes satisfy the κsymmetry condition which ensures that the action is minimized with respect to both variations of the embedding and of the worldvolume gauge field. We observe that the κsymmetry condition for a D7brane in an imaginary selfdual (ISD) background can be gene ..."
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Cited by 22 (7 self)
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Supersymmetric probe branes satisfy the κsymmetry condition which ensures that the action is minimized with respect to both variations of the embedding and of the worldvolume gauge field. We observe that the κsymmetry condition for a D7brane in an imaginary selfdual (ISD) background can be generalized yielding minimization of the action with respect to variations of the gauge field only but not of the embedding. This provides a new way to construct nonBPS solutions for D7branes once the embedding extremizes the geometrical volume of the brane. We then apply this method to the KlebanovStrassler background and find a new D7 − ¯ D7 brane configuration that realizes the spontaneous breaking of flavor chiral symmetry as evidenced by the Goldstone boson identified in the spectrum. This result generalizes our previous construction for the KlebanovWitten model. We compare our setup with the SasakiSugimoto model and discuss possible applications to QCDlike physics. Contents
Perturbations in generalized multifield inflation
 JCAP 0804, 017 (2008) [arXiv:0801.1085 [hepth
"... We study the linear perturbations of multifield inflationary models governed by a Lagrangian which is a general function of the scalar fields and of a global kinetic term combining their spacetime gradients with an arbitrary field space metric. Our analysis includes kinflation, DBI inflation and i ..."
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Cited by 22 (0 self)
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We study the linear perturbations of multifield inflationary models governed by a Lagrangian which is a general function of the scalar fields and of a global kinetic term combining their spacetime gradients with an arbitrary field space metric. Our analysis includes kinflation, DBI inflation and its multifield extensions which have been recently studied. For this general class of models, we calculate the action to second order in the linear perturbations. We decompose the perturbations into an (instantaneous) adiabatic mode, parallel to the background trajectory, and entropy modes. We show that all the entropy modes propagate with the speed of light whereas the adiabatic mode propagates with an effective speed of sound. We also identify the specific combination of entropy modes which sources the curvature perturbation on large scales. We then study in some detail the case of two scalar fields: we write explicitly the equations of motion for the adiabatic and entropy modes in a compact form and discuss their quantum fluctuations and primordial power spectra.