Jennifer Lin

Effective field theory and non-Gaussianity from general inflationary states

A bstractWe study the effects of non-trivial initial quantum states for inflationary fluctuations within the context of the effective field theory for inflation constructed by Cheung et al. which allows us to discriminate between different initial states in a model-independent way. We develop a Green’s function/path integral based formulation that incorporates initial state effects and use it to address questions such as how state-dependent is the consistency relation for the bispectrum, how many e-folds beyond the minimum required to solve the cosmological fine tunings of the big bang are we allowed so that some information from the initial state survives until late times, among others. We find that the so-called consistency condition relating the local limit of the bispectrum and the slow-roll parameter is a state-dependent statement that can be avoided for physically consistent initial states either with or without initial non-Gaussianities.

Locality of Gravitational Systems from Entanglement of Conformal Field Theories

Jennifer Lin, Matilde Marcolli, Hirosi Ooguri, 4 and Bogdan Stoica Enrico Fermi Institute and Department of Physics, University of Chicago, Chicago, IL 60637 Department of Mathematics, California Institute of Technology, 253-37, Pasadena, CA 91125 Walter Burke Institute for Theoretical Physics, California Institute of Technology, 452-48, Pasadena, CA 91125 Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo, Kashiwa 277-8583, Japan (Dated: December 8, 2014)

Conformal Phase Transitions at Weak and Strong Coupling

Abstract D3 and D7-branes intersecting in 2 + 1 dimensions give rise at low energies to N = 4 supersymmetric Yang–Mills theory coupled to defect fermions in the fundamental representation. This theory undergoes a phase transition from a conformal phase to one in which the fermions acquire a non-zero mass when the ʼt Hooft coupling of the N = 4 SYM exceeds a critical value. To study this transition, we continue the parameters of the model to a regime where a gravitational description is valid. We use it to calculate the masses of mesons and the phase diagram as a function of temperature and chemical potential. We also comment on the relation of our discussion to the transition from the non-abelian Coulomb phase to a confining one believed to occur in QCD at a critical number of flavors.

(0,2) Dynamics From Four Dimensions

We study (0,2) supersymmetric two-dimensional theories obtained by compactifying four-dimensional N=1 supersymmetric theories on a two-torus, with a magnetic field for a global U(1) symmetry, and present evidence that Seiberg duality in four dimensions leads to an identification of different models of this type.

Gravitational positive energy theorems from information inequalities

In this paper we argue that classical asymptotically anti-de Sitter spacetimes that arise as states in consistent ultraviolet completions of Einstein gravity coupled to matter must satisfy an infinite family of positive energy conditions. To each ball-shaped spatial region B of the boundary spacetime we can associate a bulk spatial region Σ_B between B and the bulk extremal surface B with the same boundary as B. We show that there exists a natural notion of a gravitational energy for every such region that is non-negative, and non-increasing as one makes the region smaller. The results follow from identifying this gravitational energy with a quantum relative entropy in the associated dual conformal field theory state. The positivity and monotonicity properties of the gravitational energy are implied by the positivity and monotonicity of relative entropy, which holds universally in all quantum systems.

Holographic walking from tachyon DBI

Abstract We use holography to study conformal phase transitions, which are believed to be realized in four dimensional QCD and play an important role in walking technicolor models of electroweak symmetry breaking. At strong coupling they can be modeled by the non-linear dynamics of a tachyonic scalar field with mass close to the Breitenlohner–Freedman bound in anti-de Sitter spacetime. Taking the action for this field to have a tachyon-Dirac–Born–Infeld form gives rise to models that resemble hard and soft wall AdS/QCD, with a dynamically generated wall. For hard wall models, the highly excited spectrum has the KK form m n ∼ n ; in the soft wall case we exhibit potentials with m n ∼ n α , 0 α ⩽ 1 / 2 . We investigate the finite temperature phase structure and find first or second order symmetry restoration transitions, depending on the behavior of the potential near the origin of field space.