A5003256803- Cosmology and Gravitation Theories
- Black Holes and Theoretical Physics
- Dark Matter and Cosmic Phenomena
- Particle physics theoretical and experimental studies
- Noncommutative and Quantum Gravity Theories
- Galaxies: Formation, Evolution, Phenomena
- Relativity and Gravitational Theory
- Solar and Space Plasma Dynamics
- Geophysics and Gravity Measurements
- Computational Physics and Python Applications
- Quantum Electrodynamics and Casimir Effect
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Earth Systems and Cosmic Evolution
- Advanced Differential Geometry Research
- Quantum Chromodynamics and Particle Interactions
- Advanced Thermodynamics and Statistical Mechanics
- Nonlinear Waves and Solitons
- Computability, Logic, AI Algorithms
- Quantum Mechanics and Applications
- Planetary Science and Exploration
- Gamma-ray bursts and supernovae
- Cuban History and Society
- Advanced Mathematical Physics Problems
University of California, Davis
2015-2024
University of California System
2024
Bloomberg (United States)
2006
Johns Hopkins University
2006
Institut des Hautes Études Scientifiques
2005
Stanford University
1998-2004
University of California, Santa Barbara
2001-2004
European Organization for Nuclear Research
1999
University of Waterloo
1997-1998
University of New Brunswick
1997
String theory suggests the simultaneous presence of many ultralight axions possibly populating each decade mass down to Hubble scale 10^-33eV. Conversely such a plenitude (an "axiverse") would be evidence for string theory, since it arises due topological complexity extra-dimensional manifold and is ad hoc in with just four familiar dimensions. We investigate how upcoming astrophysical experiments will explore existence over vast range from 10^-33eV 10^-10eV. Axions masses between 10^-28eV...
We consider domain walls embedded in curved backgrounds as an approximation for braneworld scenarios. give a large class of new exact solutions, exausting the possibilities describing one and two cases where curvature both bulk wall are locally constant. In case walls, we find solutions each has positive tension. An interesting property these is that can be much smaller than tension, leading to significant cancellation effective cosmological constant, which however still larger observational...
We show that inflation with a quadratic potential occurs naturally in theories where an axionlike field mixes 4-form. Such axion is massive, the mass which arises from mixing being protected by shift symmetry. The 4-form backgrounds break this symmetry spontaneously and comprise minilandscape, their fluxes can change emission of membranes. Inflation begin when dominates energy density. Eventually, reduced membrane emission, roll slowly towards its minimum, as simplest version chaotic inflation.
We study an inflationary model developed by Kaloper and Sorbo, in which the inflaton is axion with a sub-Planckian decay constant, whose potential generated mixing topological 4-form field strength. This gives 4d construction of "axion monodromy inflation": winds many times over course inflation draws energy from 4-form. The classical theory equivalent to chaotic quadratic potential. Such models can produce "high scale" driven densities order $(10^{16}\ GeV)^4$, produces primordial...
The Laser Interferometer Space Antenna (LISA) has the potential to reveal wonders about fundamental theory of nature at play in extreme gravity regime, where gravitational interaction is both strong and dynamical. In this white paper, Fundamental Physics Working Group LISA Consortium summarizes current topics physics observations GWs can be expected provide key input. We briefest reviews then delineate avenues for future research directions discuss connections between working group, other...
We construct intersecting brane configurations in anit-de Sitter (AdS) space which localize gravity to the intersection region, generalizing trapping of any number n infinite extra dimensions. Since 4D Planck scale M(Pl) is determined by fundamental M(*) and AdS radius L via familiar relation M(2)(Pl) approximately M(2+n)(*)L(n), we get two kinds theories with TeV quantum submillimeter deviations from Newton's law. With submillimeter, recover phenomenology large Alternatively, if L-1 M(Pl),...
We systematically investigate the effect of short distance physics on spectrum temperature anisotropies in cosmic microwave background produced during inflation. present a general argument---assuming only low-energy locality---that size such effects is order ${H}^{2}{/M}^{2},$ where H Hubble parameter inflation and M scale high-energy physics. evaluate strength number specific string theory models. In weakly coupled field models, are far too small to be observed. phenomenologically...
We present a simple model where photons propagating in extragalactic magnetic fields can oscillate into very light axions. The oscillations may convert some of the photons, departing distant supernova, axions, making supernova appear dimmer and hence more than it really is. Averaging over different configurations field we find that dimming saturates at about one-third from supernovae large redshifts. This results luminosity distance versus redshift curve almost indistinguishable produced by...
We propose a very simple reformulation of general relativity, which completely sequesters from gravity all the vacuum energy matter sector, including loop corrections and renders contributions phase transitions automatically small. The idea is to make dimensional parameters in sector functionals 4-volume element Universe. For them be nonzero, Universe should finite spacetime. If this standard model particle physics, our mechanism prevents any its energy, classical or quantum, sourcing...
We prove that a class of solutions to Einstein's equations---originally discovered by McVittie in 1933---includes regular black holes embedded Friedmann-Robertson-Walker cosmologies. If the cosmology is dominated at late times positive cosmological constant, metric everywhere on and outside hole horizon away from big-bang singularity, asymptote future near Schwarzschild-de Sitter geometry. For without constant would-be weak null singularity.
We present a manifestly local, diffeomorphism invariant, and locally Poincaré invariant formulation of vacuum energy sequestering. In this theory, quantum generated by matter loops is canceled auxiliary fields. The fields decouple from gravity almost completely. Their only residual effect an priori arbitrary, finite contribution to the curvature background geometry, which radiatively stable. Its value be determined measurement, like part any stable UV-sensitive quantity in field theory.
We reconsider theories with low gravitational (or string) scale ${M}_{*}$ where Newton's constant is generated via new large-volume spatial dimensions, while standard model states are localized to a 3-brane. Utilizing compact hyperbolic manifolds we show that the spectrum of Kaluza-Klein modes radically altered. This allows early Universe evolve normally up substantial temperatures, and completely negates astrophysical constraints on ${M}_{*}$. Furthermore, an exponential hierarchy between...
Recently we suggested a reformulation of general relativity which completely sequesters from gravity all the vacuum energy protected matter sector, assumed to contain standard model. Here elaborate further on mechanism, presenting additional details how it cancels loop corrections and renders contributions phase transitions automatically small. We also consider cosmological consequences in more detail show that mechanism is consistent with variety inflationary models make universe big old....
Motivated by the BICEP2 observation, which may imply a sensitivity to UV completions for inflation models, effects of corrections axion monodromy models (also typically obtained from explicit string constructions), and their possible observable signatures are discussed.
We discuss how to formulate a quantum field theory of dark energy interacting with matter. show that the proposals based on assumption matter is made up heavy particles masses which are very sensitive value strongly constrained. Quintessence-generated long-range forces and radiative stability quintessence potential require such completely decoupled. However, if fraction light axions, they can have significant mixings radiatively stable perfectly consistent theory. Such models naturally occur...
We revisit the rollercoaster cosmology based on multiple stages of monodromy inflation. Working within framework effective flux field theory, we include full range strong coupling corrections to inflaton sector. find that flattened potentials $V \sim \phi^p + \ldots$ with $p \lesssim 1/2$, limited $ N 25 - 40$ efolds in first stage inflation, continue fit CMB. They yield $0.96 n_s 0.97$, and produce relic gravity waves $0.006 r 0.035$, agreement most recent bounds from BICEP/{\it Keck}. The...
We consider some aspects of inflation in models with large internal dimensions. If occurs on a 3D wall after the stabilization dimensions low unification scale $(M\ensuremath{\sim}1 \mathrm{TeV}),$ inflaton field must be extremely light. This problem may disappear an intermediate $(M\ensuremath{\sim}{10}^{11} \mathrm{GeV})$ to high $(M\ensuremath{\sim}{10}^{16} scale. However, all these cases does not provide complete solution horizon and flatness problems. To solve them, there stage bulk...
The most radical version of the holographic principle asserts that all information about physical processes in world can be stored on its surface. This formulation is at odds with inflationary cosmology, which implies our part universe do not depend boundary conditions. Also, there are some indications theory context cosmology may have problems unitarity and causality. Another principle, due to Fischler Susskind, entropy matter inside post-inflationary particle horizon must smaller than area...