A5021914385- Cosmology and Gravitation Theories
- Black Holes and Theoretical Physics
- Galaxies: Formation, Evolution, Phenomena
- Dark Matter and Cosmic Phenomena
- Noncommutative and Quantum Gravity Theories
- Solar and Space Plasma Dynamics
- Relativity and Gravitational Theory
- Geophysics and Gravity Measurements
- Pulsars and Gravitational Waves Research
- Astronomy and Astrophysical Research
- Advanced Differential Geometry Research
- Particle physics theoretical and experimental studies
- Scientific Research and Discoveries
- Stellar, planetary, and galactic studies
- Statistical Mechanics and Entropy
- Vibration and Dynamic Analysis
- Computational Physics and Python Applications
- Quantum chaos and dynamical systems
- Advanced Thermodynamics and Statistical Mechanics
- Astrophysics and Cosmic Phenomena
- Fluid Dynamics and Vibration Analysis
- Quantum Chromodynamics and Particle Interactions
- Seismic Waves and Analysis
- Stochastic processes and financial applications
- Advanced Mathematical Physics Problems
The Abdus Salam International Centre for Theoretical Physics (ICTP)
2017-2024
Stanford University
2017-2021
Institute for Advanced Study
2014-2017
Albert Einstein College of Medicine
2015
New York University
2010-2013
We study the dominant effect of a long wavelength density perturbation $\ensuremath{\delta}({\ensuremath{\lambda}}_{L})$ on short distance physics. In nonrelativistic limit, result is uniform acceleration, fixed by equivalence principle, and typically has no statistical averages due to translational invariance. This same reasoning been formalized obtain ``consistency condition'' cosmological correlation functions. presence feature, such as acoustic peak at...
We present the exact solution for scattering problem in flat space Jackiw-Teitelboim (JT) gravity coupled to an arbitrary quantum field theory. JT results a gravitational dressing of theoretical amplitudes. The expression dressed $S$-matrix was previously known as solvable example novel UV asymptotic behavior, dubbed fragility. This is equivalent $T\bar{T}$ deformation initial single massless boson provides promising action formulation integrable approximation worldsheet theory confining...
A recent, intriguing paper by Hawking, Perry and Strominger suggests that soft photons gravitons can be regarded as black hole hair may relevant to the information paradox. In this note we make use of factorization theorems for infrared divergences S-matrix argue appropriately dressing in out hard states, soft-quanta-dependent part becomes essentially trivial. The paradox fully formulated terms dressed which do not depend on quanta.
Primordial black holes, formed from rare peaks in the primordial fluctuations $\zeta$, are non-rotating at zeroth order $\zeta_{\rm rms}$. We show that spin also vanishes first rms}$, suggesting dimensionless parameter $a_{\rm rms} \sim \zeta_{\rm rms}^2$. identify one quadratic contribution to by calculating (and extrapolating formation time) torque on a hole due ambient acoustic waves. For reasonable density of holes this implies percent level parameter.
We study the effect of time evolution on galaxy bias. argue that at any order in perturbations, density contrast can be expressed terms a finite set locally measurable operators made spatial and temporal derivatives Newtonian potential. This is checked an explicit third calculation. There systematic way to derive basis for these operators. spans larger space than expansion gravitational velocity potentials usually employed, although new only appear fourth order. The argued closed under...
We study the bispectrum in Effective Field Theory of Large Scale Structure, consistently accounting for effects short-scale dynamics. begin by proving that, as long theory is perturbative, it can be formulated to arbitrary order using only operators that are local time. then derive all new required cancel UV-divergences and obtain a physically meaningful prediction one-loop bispectrum. In addition new, subleading stochastic noises viscosity term needed power spectrum, we find three effective...
We argue that there is a lower bound of order <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msup><a:mn>10</a:mn><a:mrow><a:mo>−</a:mo><a:mn>19</a:mn></a:mrow></a:msup><a:mtext> </a:mtext><a:mtext> </a:mtext><a:mi>eV</a:mi></a:math> on dark matter mass if it produced after inflation via process with finite correlation length. rely nondetection free-streaming suppression and white-noise enhancement density perturbations as the observational inputs. Published by...
We apply the Effective Field Theory of Inflation to study case where continuous shift symmetry Goldstone boson \pi is softly broken a discrete subgroup. This includes and generalizes recently proposed String inspired models based on Axion Monodromy. The we have property that 2-point function oscillates as wavenumber, leading oscillations in CMB power spectrum. non-linear realization time diffeomorphisms induces some self-interactions for lead peculiar non-Gaussianity whose shape wavenumber....
We identify different helicity degrees of freedom Fierz-Paulian massive gravity around generic backgrounds. show that the two-parameter family proposed by de Rham, Gabadadze, and Tolley always propagates five therefore is free from Boulware-Deser ghost. The analysis has a number byproducts, among which (a) it shows how original decoupling limit construction ensures ghost full theory, (b) reveals an enhanced symmetry theory linearized backgrounds, (c) allows us to give algorithm for finding...
Forecasts and analyses of cosmological observations often rely on the assumption a perfect theoretical model over defined range scales. We explore how uncertainties nuisance parameters in perturbative models matter galaxy spectra affect constraints neutrino mass primordial non-Gaussianities. provide consistent treatment errors argue that their inclusion is necessary step to obtain realistic constraints. find surveys up high redshifts will allow detection minimal local non-Gaussianity order...
We analyze the shape and amplitude of oscillatory features in primordial power spectrum non-Gaussianity induced by periodic production heavy degrees freedom coupled to inflaton ϕ. find that non-adiabatic particles can contribute effects which are detectable or constrainable using cosmological data even if their time-dependent masses always heavier than scale ̇ ϕ1/2, much larger Hubble scale. This provides a new role for UV completion, consistent with criteria from effective field theory when...
Our current understanding of the Universe is established through pristine measurements structure in cosmic microwave background (CMB) and distribution shapes galaxies tracing large scale (LSS) Universe. One key ingredient that underlies cosmological observables field sources observed assumed to be initially Gaussian with high precision. Nevertheless, a minimal deviation from Gaussianityis perhaps most robust theoretical prediction models explain Universe; itis necessarily present even...
Generically, massive gravity gives a non-unique gravitational field around star. For special family of theories, we show that the stellar is unique and observationally acceptable, close to Einsteinian. The black hole solutions in this theories are also studied shown be peculiar. Black holes have near-horizon throat curvature diverging at horizon. We there exists sub-family these with non-singular horizon holes.
We revisit alternative mechanisms of gravitational wave production during inflation and argue that they generically emit a non-negligible amount scalar fluctuations. find the power is larger than tensor by factor order $1/{\ensuremath{\epsilon}}^{2}$. For an appreciable contribution, associated emission completely dominates zero-point fluctuations inflaton, resulting in tensor-to-scalar ratio $r\ensuremath{\sim}{\ensuremath{\epsilon}}^{2}$. A more quantitative result can be obtained if one...
The hot dense environment of the early universe is known to have produced large numbers baryons, photons, and neutrinos. These extreme conditions may also other long-lived species, including new light particles (such as axions or sterile neutrinos) gravitational waves. effects any such relics can be observed through their unique imprint in cosmic microwave background (CMB), large-scale structure, primordial element abundances, are important determining initial universe. We argue that future...
We point out that tensor consistency relations-i.e. the behavior of primordial correlation functions in limit a mode has small momentum-are more universal than scalar relations. They hold presence multiple fields and as long anisotropies are diluted exponentially fast. When de Sitter isometries approximately respected during inflation this is guaranteed by Higuchi bound, which forbids existence light particles with spin: De space can support hair but no curly hair. discuss two indirect ways...
Inertial observers in de Sitter are surrounded by a horizon and see thermal fluctuations. To them, massless scalar field appears to follow random motion but any attractive potential, no matter how weak, will eventually stabilize the field. We study this thermalization process static patch (the spacetime region accessible an individual observer) via truncation low frequency spectrum. focus on distribution of averaged over subhorizon region. At timescales much longer than inverse temperature...
Sphaleron heating has been recently proposed as a mechanism to realize warm inflation when inflaton is an axion coupled pure Yang-Mills. As result of heating, there friction coefficient $\gamma \propto T^3$ in the equation motion for inflaton, and thermal contribution cosmological fluctuations. Without knowledge potential, non-Gaussianity most promising way searching signatures this model. Building on earlier work by Bastero-Gil, Berera, Moss Ramos, we compute scalar three-point correlation...
Correlation functions of two long-wavelength modes with several short-wavelength are shown to be related lower order correlation functions, using the background wave method, and independently, by exploiting symmetries wavefunction Universe. These soft identities follow from non-linear extension adiabatic Weinberg, their generalization Hinterbichler et al. The is unique. A few checks presented.
The equilibrium state of fields in the causal wedge a dS observer is thermal, though realistic observers have only partial access to state. To them, out-of-equilibrium states light scalar field appear thermalize Markovian fashion. We show this by formulating systematic expansion for tracing out environment. As an example, we calculate $O(\lambda)$ correction result Starobinsky and Yokoyama relaxation exponents $\lambda \phi^4$ theory.
A bstract The two-point correlation function of a massive field ⟨ χ ( τ ) (0)⟩, measured along an observer’s worldline in de Sitter (dS), decays exponentially as → ∞. Meanwhile, every dS observer is surrounded by horizon and the holographic interpretation entropy S suggests that should stop decaying, start behaving erratically at late times. We find evidence for this expectation Jackiw-Teitelboim gravity finding topologically nontrivial saddle, which suppressed $$ {e}^{-{S}_{\textrm{dS}}}...
A perturbative description of Large Scale Structure is a cornerstone our understanding the observed distribution matter in universe. Renormalization an essential and defining step to make this physical predictive. Here we introduce systematic renormalization procedure, which neatly associates counterterms UV-sensitive diagrams order by order, as it commonly done quantum field theory. As concrete example, renormalize one-loop power spectrum bispectrum both density velocity. In addition,...