15805106
String duals of two-dimensional (4,4) supersymmetric gauge theories
We study duals to field theories in two dimensions with = (4, 4) SUSY. The string backgrounds reproduce certain non-perturbative aspects of the dual field theory with a large number of colors Nc and a tunable number of flavors Nf. Different aspects of the two-dimensional field theory are discussed, among them the running of gauge couplings, the spectrum of mesons in Higgs and Coulomb branches, entanglement entropy and the non-relativistic version of our string backgrounds.
121982373
Fermionic current algebra in three dimensions
We consider the fermion-boson mapping in three dimensional space-time, in the Abelian case, from the current algebra point of view. It is shown that in a path-integral framework one can derive a general bosonization recipe leading, in the bosonic language, to the correct equal-time current commutators of the original free fermionic theory.
118385203
Towards multi-scale dynamics on the baryonic branch of Klebanov-Strassler
We construct explicitly a new class of backgrounds in type-IIB supergravity which generalize the baryonic branch of Klebanov-Strassler. We apply a solution-generating technique that, starting from a large class of solutions of the wrapped-D5system, yields the new solutions, and then proceed to study in detail their properties, both in the IR and in the UV. We propose a simple intuitive field theory interpretation of the rotation procedure and of the meaning of our new solutions within the Papadopoulos-Tseytlin ansatz, in particular in relation to the duality cascade in the Klebanov-Strassler solution. The presence in the field theory of different VEVs for operators of dimensions 2, 3 and 6 suggests that this is an important step towards the construction of the string dual of a genuinely multi-scale (strongly coupled) dynamical model.
17311968
Backreacting flavors in the Klebanov-Strassler background
In this paper we present new analytic solutions of pure Type IIB supergravity plus D7-branes describing the addition of an arbitrary number of flavors to the Klebanov-Tseytlin and Klebanov-Strassler backgrounds. We provide a precise field theory dual and a detailed analysis of the duality cascade which describes its RG flow. Matchings of beta functions and anomalies between the field theory and the string setup are presented. We give an understanding of Seiberg duality as a large gauge transformation on the RR and NSNS potentials. We also analyze the UV behavior of the field theory that, as suggested by the string background, can be associated with a duality wall.
119640171
Cosmology from String Theory
We explore the cosmological content of Salam-Sezgin six dimensional supergravity, and find a solution to the field equations in qualitative agreement with observation of distant supernovae, primordial nucleosynthesis abundances, and recent measurements of the cosmic microwave background. The carrier of the acceleration in the present de Sitter epoch is a quintessence field slowly rolling down its exponential potential. Intrinsic to this model is a second modulus which is automatically stabilized and acts as a source of cold dark matter, with a mass proportional to an exponential function of the quintessence field (hence realizing VAMP models within a String context). However, any attempt to saturate the present cold dark matter component in this manner leads to unacceptable deviations from cosmological data – a numerical study reveals that this source can account for up to about 7% of the total cold dark matter budget. We also show that (1) the model will support a de Sitter energy in agreement with observation at the expense of a miniscule breaking of supersymmetry in the compact space; (2) variations in the fine structure constant are controlled by the stabilized modulus and are negligible; (3) “fifth” forces are carried by the stabilized modulus and are short range; (4) the long time behavior of the model in four dimensions is that of a Robertson-Walker universe with a constant expansion rate (w = −1/3). Finally, we present a String theory background by lifting our six dimensional cosmological solution to ten dimensions.
118674073
Unquenched Flavor in the Gauge/Gravity Correspondence
Within the AdS/CFT correspondence, we review the studies of field theories with a large number of adjoint and fundamental fields, in the Veneziano limit. We concentrate in set-ups where the fundamentals are introduced by a smeared set of D-branes. We make emphasis on the general ideas and then in subsequent chapters that can be read independently and describe particular considerations in various different models. Some new material is presented along the various sections.
122727464
The effective action of double field theory
A bstractWe perform a generalized Scherk-Schwarz dimensional reduction of Double Field Theory on a twisted double torus. The four dimensional effective action is shown to exactly reproduce the bosonic electric sector of gauged $ \mathcal{N} $ = 4 supergravity. We present explicit expressions for the gaugings in terms of the twists, and analyze the associated string backgrounds. This framework provides a higher dimensional origin of the gaugings in terms of generalized fluxes.
122144253
Superconformal minimal models on the torus
Abstract Correlation functions for the discrete unitary series of N = 1 and N = 2 superconformal models on the torus are constructed using a Coulomb gas description. The monodromy and modular properties of the resulting conformal blocks are discussed.
14227643
Aspects of the free field description of string theory on AdS3
The near boundary limit of string theory in AdS3 is analysed using the Wakimoto free field representation of SL(2,). The theory is considered as a direct product of the SL(2,)/U(1) coset and a free boson. Correlation functions are constructed generalizing to the non-compact case the integral representation of conformal blocks introduced by Dotsenko in the compact SU(2) CFT. Sectors of the theory obtained by spectral flow manifestly appear. The formalism naturally leads to consider scattering processes violating winding number conservation. The consistency of the procedure is verified in the factorization limit.
5975372
Quantum corrections and extremal black holes
Abstract We consider static solutions of two dimensional dilaton gravity models as toy laboratories to address the question of the final fate of black holes. A nonperturbative correction to the CGHS potential tern is shown to lead classically to an extremal black hole geometry, thus providing a plausible solution to the Hawking evaporation paradox. However, the full quantum theory does not admit an extremal solution.
118270106
Minimal Hypotheses for Particle Definition in Curved Space-Time
The interaction between a quantum field and an unquantized gravitational field can be studied in the frame of a semiclassical theory in which the gravitational field enters, according to the theory of general relativity, as the background geometry, where the covariant generalizations of Klein-Gordon, Dirac, Maxwell, etc. equations are considered1. Such a theory is supposed to be a good approximation to a more general, as yet unknown, full quantum theory, when the components of the Riemann curvature tensor are small (in atomic units, h = c = 1) as compared to the Planck energy (1019 GeV) squared. One of the most striking results of this formulation is the possibility of particle- antiparticle-pairs creation by a dynamical gravitational field, the thermal radiation of black holes predicted by Hawking2 being its most popular version. Particle creation in asymptotically static universes, where the particle model (the plane waves) is perfectly defined in the far future and past, has also been studied3. But the universe has undoubtly not been static in the past; then an “in-out” theory is unrealistic.