A5055299703- Cosmology and Gravitation Theories
- Black Holes and Theoretical Physics
- Quantum, superfluid, helium dynamics
- Noncommutative and Quantum Gravity Theories
- Pulsars and Gravitational Waves Research
- Solar and Space Plasma Dynamics
- Galaxies: Formation, Evolution, Phenomena
- Geophysics and Gravity Measurements
- Relativity and Gravitational Theory
- Cold Atom Physics and Bose-Einstein Condensates
- Physics of Superconductivity and Magnetism
- Particle physics theoretical and experimental studies
- Quantum Electrodynamics and Casimir Effect
- High-Energy Particle Collisions Research
- Quantum Chromodynamics and Particle Interactions
- Computational Physics and Python Applications
- Advanced Thermodynamics and Statistical Mechanics
- Stochastic processes and financial applications
- Dark Matter and Cosmic Phenomena
- Atomic and Subatomic Physics Research
- Advanced Differential Geometry Research
- Theoretical and Computational Physics
- Experimental and Theoretical Physics Studies
- Astrophysical Phenomena and Observations
- Statistical Mechanics and Entropy
Columbia University
2015-2024
New York University
2014
Harvard University
2005-2008
Thomas Jefferson National Accelerator Facility
2007
Instituto de Estructura de la Materia
2004
Universidad Autónoma de Madrid
2004
Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
2000-2002
Scuola Normale Superiore
2001-2002
University of Pisa
2000
In the Dvali-Gabadadze-Porrati (DGP) model, ``self-accelerating'' solution is plagued by a ghost instability, which makes untenable. This fact, as well all interesting departures from general relativity (GR), are fully captured four-dimensional effective Lagrangian, valid at distances smaller than present Hubble scale. The 4D theory involves relativistic scalar $\ensuremath{\pi}$, universally coupled to matter and with peculiar derivative self-interactions. this paper, we study connection...
We develop a method for constraining the level of non-Gaussianity density perturbations when three-point function is 'equilateral' type. Departures from Gaussianity this form are produced by single field models such as ghost or Dirac–Born–Infeld inflation and in general presence higher order derivative operators effective Lagrangian inflaton. show that induced shape can be very well approximated factorizable form, making analysis practical. also that, unless one has full sky map with uniform...
The universe is smooth on large scales but very inhomogeneous small scales. Why the spacetime modeled to a good approximation by Friedmann equations? Are we sure that small-scale non-linearities do not induce backreaction? Related this, what effective theory describes scales? In this paper make progress in addressing these questions. We show for long-wavelength behaves as viscous fluid coupled gravity: integrating out short-wavelength perturbations renormalizes homogeneous background and...
We consider a Galileon field coupled to gravity. The standard no-hair theorems do not apply because of the Galileon's peculiar derivative interactions. prove that, nonetheless, static spherically symmetric black holes cannot sustain nontrivial profiles. Our theorem holds for trivial boundary conditions and cosmological ones, regardless whether there are nonminimal couplings between gravity covariant type.
We summarize the utility of precise cosmic microwave background (CMB) polarization measurements as probes physics inflation. focus on prospects for using CMB to differentiate various inflationary mechanisms. In particular, a detection primordial B‐mode would demonstrate that inflation occurred at very high energy scale, and inflaton traversed super‐Planckian distance in field space. explain how such or constraint illuminate aspects Planck scale. Moreover, can constrain scale‐dependence...
We develop a cosmological model where primordial inflation is driven by 'solid', defined as system of three derivatively coupled scalar fields obeying certain symmetries and spontaneously breaking subgroup these. The symmetry pattern differs drastically from that standard inflationary models: time translations are unbroken. This prevents our fitting into the effective field theory description adiabatic perturbations, with crucial consequences for dynamics perturbations. Most notably,...
We consider the low-energy effective field theory describing infrared dynamics of nondissipative fluids. extend previous work to accommodate conserved charges, and we clarify matching between field-theory variables thermodynamical ones. discuss systematics derivative expansion, for which offers a conceptually clear technically neat scheme. As an example, compute correction sound-wave dispersion relation coming from sample second-order term. This formalism forms basis study anomalies in...
We classify condensed matter systems in terms of the spacetime symmetries they spontaneously break. In particular, we characterize itself as any state a Poincaré-invariant theory that breaks Lorentz boosts while preserving at large distances some form spatial translations, time-translations, and possibly rotations. Surprisingly, simplest, most minimal system achieving this symmetry breaking pattern — framid does not seem to be realized Nature. Instead, Nature usually adopts more cumbersome...
We propose a novel cosmological scenario, in which standard inflation is replaced by an expanding phase with drastic violation of the Null Energy Condition (NEC): \dot H >> H^2. The model based on recently introduced Galileon theories, that allow NEC violating solutions without instabilities. unperturbed solution describes Universe asymptotically Minkowski past, expands increasing energy density until it exits regime validity effective field theory and reheats. This dynamical attractor...
Theories that attempt to explain the observed cosmic acceleration by modifying general relativity all introduce a new scalar degree of freedom is active on large scales, but screened small scales match experiments. We demonstrate if such screening occurs via chameleon mechanism, as in $f(R)$ theory, it possible have order unity violation equivalence principle, despite absence explicit microscopic action. Namely, extended objects galaxies or constituents thereof do not fall at same rate. The...
We provide a systematic coset construction of the effective field theories governing low-energy dynamics relativistic fluids and solids their ``super'' counterparts. These agree with those previously derived via different techniques. As an application our methods, we rederive Wess-Zumino term relevant for anomalous charge-carrying in ($1+1$) dimensions.
Turbulence may have been produced in the early universe by several nonequilibrium processes. Periods of cosmic turbulence left a detectable relic under form stochastic backgrounds gravitational waves. In this paper we derive general expressions for power spectrum expected signal. Extending previous works on subject, take into account effects continuous energy injection and magnetic fields. Both lead to relevant deviations from Kolmogoroff spectrum. We apply our results determine gravity...
A bstract It was recently argued that certain relativistic theories at finite density can exhibit an unconventional spectrum of Goldstone excitations, with gapped Goldstones whose gap is exactly calculable in terms the symmetry algebra. We confirm this result as well previous ones concerning gapless for non-relativistic systems via a coset construction low-energy effective field theory. Moreover, our analysis unveils additional Goldstones, naturally light others, but time model-dependent...
We introduce dissipative effects in the effective field theory of hydrodynamics. do this a model-independent fashion by coupling long-distance degrees freedom explicitly kept to generic sector that ``lives fluid,'' which corresponds physically microscopic constituents fluid. At linear order perturbations, symmetries, derivative expansion, and assumption is thermalized allow us characterize leading at low frequencies via three parameters only, correspond bulk viscosity, shear and---in...