284 citations · 2.3k across the 55 of their papers we have counts for
30 papers · 1 filter
How Heavy Can Moduli Be?
Mehrdad Mirbabayi, Giovanni Villadoro
In Kaluza-Klein (KK) compactification of gravitational theories, moduli fields, which are scalar fields associated to the deformations of the compact manifold, are typically lighte…
An infrared bound on the ultraviolet bounce
Mehrdad Mirbabayi, Giovanni Villadoro
Sometimes a local minimum is known to be a metastable vacuum inside the low-energy EFT, but the true vacuum lies outside, and the bounce solution mediating the decay cannot be foun…
An Observer's Measure of De Sitter Entropy
Mehrdad Mirbabayi
The two-point correlation function of a massive field , measured along an observer's worldline in de Sitter (dS), decays exponentially as . Mea…
Probing de Sitter from the horizon
Mehrdad Mirbabayi, Flavio Riccardi
In a QFT on de Sitter background, one can study correlators between fields pushed to the future and past horizons of a comoving observer. This is a neat probe of the physics in the…
A comment about the cosmology on a bubble wall
Mehrdad Mirbabayi
The interface between a big bubble of true AdS vacuum expanding inside a false AdS vacuum is a model of an inflating dimensional universe. It looks like an interestin…
Gravity as an ensemble and the moment problem
Oliver Janssen, Mehrdad Mirbabayi, Peter Zograf
If a bulk gravitational path integral can be identified with an average of partition functions over an ensemble of boundary quantum theories, then a corresponding moment problem ca…
Low-temperature entropy in JT gravity
Oliver Janssen, Mehrdad Mirbabayi
For ensembles of Hamiltonians that fall under the Dyson classification of random matrices with , the low-temperature mean entropy can be shown to vanish as $\langle…
Markovian Dynamics in de Sitter
Mehrdad Mirbabayi
The equilibrium state of fields in the causal wedge of a dS observer is thermal, though realistic observers have only partial access to the state. To them, out-of-equilibrium state…
A 2-Replica Wormhole
Mehrdad Mirbabayi
Replica geometries are not rigid when gravity is dynamical. We numerically construct replica saddles in gravity coupled to a CFT and compare the resulting Renyi en…
Uptunneling to de Sitter
Mehrdad Mirbabayi
We propose a Euclidean preparation of an asymptotically AdS spacetime that contains an inflating dS bubble. The setup can be embedded in a four dimensional theory with a Mi…
Infrared dynamics of a light scalar field in de Sitter
Mehrdad Mirbabayi
Inertial observers in de Sitter are surrounded by a horizon and see thermal fluctuations. To them, a massless scalar field appears to follow a random motion but any attractive pote…
A Weak Gravity Theorem
Mehrdad Mirbabayi
In a gravitational theory with a massless photon the maximum charge-to-mass ratio of black holes approaches the prediction of the Einstein-Maxwell theory as black hole mass increas…
Topology of Cosmological Black Holes
Mehrdad Mirbabayi
Motivated by the question of how generic inflation is, I study the time-evolution of topological surfaces in an inhomogeneous cosmology with positive cosmological constant . If…
Asymptotic Fragility, Near Holography and
Sergei Dubovsky, Victor Gorbenko, Mehrdad Mirbabayi
We present the exact solution for the scattering problem in the flat space Jackiw-Teitelboim (JT) gravity coupled to an arbitrary quantum field theory. JT gravity results in a grav…
Shaving off Black Hole Soft Hair
Mehrdad Mirbabayi, Massimo Porrati
A recent, intriguing paper by Hawking, Perry and Strominger suggests that soft photons and gravitons can be regarded as black hole hair and may be relevant to the black hole inform…
Productive Interactions: heavy particles and non-Gaussianity
Raphael Flauger, Mehrdad Mirbabayi, Leonardo Senatore +1
We analyze the shape and amplitude of oscillatory features in the primordial power spectrum and non-Gaussianity induced by periodic production of heavy degrees of freedom coupled t…
Weinberg Soft Theorems from Weinberg Adiabatic Modes
Mehrdad Mirbabayi, Marko Simonović
Soft theorems for the scattering of low energy photons and gravitons and cosmological consistency conditions on the squeezed-limit correlation functions are both understood to be c…
Systematic Renormalization of the Effective Theory of Large Scale Structure
Ali Akbar Abolhasani, Mehrdad Mirbabayi, Enrico Pajer
A perturbative description of Large Scale Structure is a cornerstone of our understanding of the observed distribution of matter in the universe. Renormalization is an essential an…
Effective Planck Mass and the Scale of Inflation
Matthew Kleban, Mehrdad Mirbabayi, Massimo Porrati
A recent paper argued that it is not possible to infer the energy scale of inflation from the amplitude of tensor fluctuations in the Cosmic Microwave Background, because the usual…
Effective Theory of Squeezed Correlation Functions
Mehrdad Mirbabayi, Marko Simonović
Various inflationary scenarios can often be distinguished from one another by looking at the squeezed limit behavior of correlation functions. Therefore, it is useful to have a fra…
Massive Gravity: A Lorentz-Symmetric Aether
Mehrdad Mirbabayi
This is a heuristic introduction to massive gravity based on an analogy with perfect fluids. I will argue that massive gravity can be thought of as Einstein gravity in the presence…
Gravitational Waves and the Scale of Inflation
Mehrdad Mirbabayi, Leonardo Senatore, Eva Silverstein +1
We revisit alternative mechanisms of gravitational wave production during inflation and argue that they generically emit a non-negligible amount of scalar fluctuations. We find the…
Double Soft Limits of Cosmological Correlations
Mehrdad Mirbabayi, Matias Zaldarriaga
Correlation functions of two long-wavelength modes with several short-wavelength modes are shown to be related to lower order correlation functions, using the background wave metho…
Natural Tuning: Towards A Proof of Concept
Sergei Dubovsky, Victor Gorbenko, Mehrdad Mirbabayi
The cosmological constant problem and the absence of new natural physics at the electroweak scale, if confirmed by the LHC, may either indicate that the nature is fine-tuned or tha…