A5058588547- Cosmology and Gravitation Theories
- Dark Matter and Cosmic Phenomena
- Astrophysics and Cosmic Phenomena
- Galaxies: Formation, Evolution, Phenomena
- Particle physics theoretical and experimental studies
- Pulsars and Gravitational Waves Research
- Neutrino Physics Research
- Astronomy and Astrophysical Research
- Geophysics and Gravity Measurements
- Computational Physics and Python Applications
- Black Holes and Theoretical Physics
- Relativity and Gravitational Theory
- Scientific Research and Discoveries
- Quantum Mechanics and Applications
- Gamma-ray bursts and supernovae
- Solar and Space Plasma Dynamics
- Stellar, planetary, and galactic studies
- Cold Atom Physics and Bose-Einstein Condensates
- Experimental and Theoretical Physics Studies
- Radio Astronomy Observations and Technology
- Space Science and Extraterrestrial Life
- Geophysics and Sensor Technology
- Superconducting and THz Device Technology
- Photocathodes and Microchannel Plates
- Quantum Information and Cryptography
UNSW Sydney
2019-2024
Liverpool John Moores University
2022-2024
Yunnan University
2024
University of Wisconsin–Madison
2014-2023
Argonne National Laboratory
2012-2014
University of Chicago
2009-2014
Ewha Womans University
2014
Lawrence Berkeley National Laboratory
2014
Fermi National Accelerator Laboratory
2009-2010
Kavli Institute for Particle Astrophysics and Cosmology
2009
We use data from our recent search for violations of the gravitational inverse-square law to constrain dilaton, radion, and chameleon exchange forces as well arbitrary vector or scalar Yukawa interactions. test interpretation PVLAS Collaboration effect a conjectured "fat-graviton" scenario gamma_{5} couplings pseuodscalar bosons power-law
If general relativity is the correct theory of physics on large scales, then there a differential equation that relates Hubble expansion function, inferred from measurements angular diameter distance and luminosity distance, to growth rate scale structure. For dark energy fluid without couplings or an unusual sound speed, deviations this consistency relationship could be signature modified gravity cosmological scales. We propose procedure based relation in order distinguish between some...
Upcoming large-scale structure surveys will measure the matter power spectrum to approximately percent level accuracy with aim of searching for evidence new physics beyond standard model cosmology. In order avoid biasing our conclusions, theoretical predictions need be at least as accurate measurements a given choice cosmological parameters. However, recent work has shown that complex physical processes associated galaxy formation (particularly energetic feedback stars and especially...
We consider how well the dark energy equation of state $w$ as a function redshift $z$ will be measured using current and anticipated experiments. use procedure which takes fair account uncertainties in functional dependence on $z$, parameter degeneracies, avoids strong prior constraints. apply to data from Wilkinson Microwave Anisotropy Probe, Sloan Digital Sky Survey, supernova searches, obtain results that are consistent with other analyses different combinations sets. The effects...
We refute recent claims in the literature that stars with relativistically deep potentials cannot exist $f(R)$ gravity. Numerical examples of stable stars, including relativistic ($G{M}_{\ensuremath{\star}}/{r}_{\ensuremath{\star}}\ensuremath{\sim}0.1$), constant density are studied. As a star is made larger, nonlinear ``chameleon'' effects screen much star's mass, stabilizing gravity at stellar center. Furthermore, we show onset this chameleon screening unrelated to strong At large central...
The chameleon scalar field is a matter-coupled dark energy candidate whose nonlinear self-interaction partially screens its fifth force at laboratory scales. Nevertheless, small-scale experiments such as the torsion pendulum can provide powerful constraints on models. Here we develop simple approximation for computing forces in Eot-Wash. We show that our agrees well with published quartic chameleon, and use it to extend these much wider range of Finally, forecast which will result from...
We report results from a search for chameleon particles created via photon-chameleon oscillations within magnetic field. This experiment is sensitive to wide class of unexplored power-law and dark energy models. These exclude 5 orders magnitude in the coupling chameleons photons covering range 4 effective mass and, individual models, between 12 couplings matter.
Standard Model extensions often predict low‐mass and very weakly interacting particles, such as the axion. A number of small‐scale experiments at intensity/precision frontier are actively searching for these elusive complementing searches physics beyond colliders. Whilst a next generation will give access to huge unexplored parameter space, discovery would have tremendous impact on our understanding fundamental physics.
Abstract We introduce a new cosmic emulator for the matter power spectrum covering eight cosmological parameters. Targeted at optical surveys, provides accurate predictions out to wavenumber <?CDATA $k\sim 5$?> Mpc −1 and redshift $z\leqslant 2$?> . In addition standard set of ΛCDM parameters, massive neutrinos dynamical dark energy state are included. The is built on sample 36 models, carefully chosen provide over wide large parameter space. For each model, we have performed high-resolution...
Cosmology in the near future promises a measurement of sum neutrino masses ∑ mν, fundamental Standard Model parameter, as well substantially-improved constraints on dark energy. We use shape BOSS redshift-space galaxy power spectrum, combination with CMB and supernova data, to constrain Essential this calculation are several recent advances non-linear cosmological perturbation theory, including fast Fourier transform methods, redshift space distortions, scale-dependent growth. Our 95%...
ABSTRACT Modern cosmological surveys are delivering data sets characterized by unprecedented quality and statistical completeness; this trend is expected to continue in the future as new ground- space-based come online. In order maximally extract information from these observations, matching theoretical predictions needed. At low redshifts, probe non-linear regime of structure formation where simulations primary means obtaining required information. The computational cost sufficiently...
ABSTRACT A number of recent studies have found evidence for a tension between observations large-scale structure (LSS) and the predictions standard model cosmology with cosmological parameters fit to cosmic microwave background (CMB). The origin this ‘S8 tension’ remains unclear, but possibilities include new physics beyond model, unaccounted systematic errors in observational measurements and/or uncertainties role that baryons play. Here, we carefully examine latter possibility using...
Abstract Observational cosmology is rapidly closing in on a measurement of the sum M ν neutrino masses, at least simplest cosmologies, while opening door to probes non-standard hot dark matter (HDM) models. By extending method effective distributions, we show that any collection HDM species, with arbitrary temperatures, and distribution functions, including massive neutrinos, may be represented as single species. Implementing this FlowsForTheMasses non-linear perturbation theory for...
We report the first results from GammeV search for chameleon particles, which may be created via photon-photon interactions within a strong magnetic field. Chameleons are hypothesized scalar fields that could explain dark energy problem. implement novel technique to create and trap reflective particles jar detect them later their afterglow as they slowly convert back into photons. These measurements provide experimental constraints on couplings of chameleons
The symmetron scalar field is a matter-coupled dark energy candidate which effectively decouples from matter in high-density regions through symmetry restoration. We consider previously unexplored regime, the vacuum mass $\mu \sim 2.4\times 10^{-3}$ eV of near scale, and coupling parameter $M 1$ TeV just beyond Standard Model energies. Such will give rise to fifth force at submillimeter distances can be probed by short-range gravity experiments. show that torsion pendulum experiment such as...
Chameleon scalar fields are dark energy candidates which suppress fifth forces in high density regions of the universe by becoming massive. We consider chameleon models as effective field theories and estimate quantum corrections to their potentials. Requiring that be small, so allow reliable predictions forces, leads an upper bound $m < 0.0073 (\rho / 10 {\rm g\, cm}^{-3})^{1/3}$eV for gravitational strength coupling whereas force experiments place a lower $m>0.0042$\,eV. An improvement...
Over the next decade, cosmological measurements of large-scale structure Universe will be sensitive to combined effects dynamical dark energy and massive neutrinos. The matter power spectrum is a key repository this information. We extend higher-order perturbative methods for computing investigate these over quasilinear scales. Through comparison with N-body simulations, we establish regime validity time-renormalization group treatment that includes also quantify accuracy standard,...
In this work we present a search for (solar) chameleons with the CERN Axion Solar Telescope (CAST). This novel experimental technique, in field of dark energy research, exploits both chameleon coupling to matter (βm) and photons (βγ) via Primakoff effect. By reducing X-ray detection threshold used axions from 1 keV 400 eV CAST became sensitive converted solar spectrum which peaks around 600 eV. Even though have not observed any excess above background, can provide 95% C.L. limit strength...
Scalar self-interactions are known to weaken considerably the current constraints on scalar-mediated fifth forces. We consider a scalar field with quartic self-interaction and gravitation-strength Yukawa couplings matter particles. After discussing phenomenology of this field, we assess ability ongoing planned experiments detect force mediated by such field. Assuming that order unity, current-generation E\"ot-Wash experiment at University Washington will be able explore an interesting subset...
The GammeV experiment has constrained the couplings of chameleon scalar fields to matter and photons. Here we present a detailed calculation afterglow rate underlying these constraints. dependence constraints on various assumptions in is studied. We discuss GammeV--CHASE, second-generation experiment, which will improve upon several major ways. Using our rate, forecast model-independent achievable by GammeV--CHASE. then apply variety models, including quartic chameleons dark energy models....
Large-scale structure surveys in the coming years will measure redshift-space power spectrum to unprecedented accuracy, allowing for powerful new tests of $\mathrm{\ensuremath{\Lambda}}$ cold dark matter ($\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$) picture as well measurements particle physics parameters such neutrino masses. We extend time-renormalization-group (RG) perturbative framework redshift space, computing ${P}_{s}(k,\ensuremath{\mu})$ massive cosmologies with time-dependent energy...
Abstract A significant challenge for modelling the massive neutrino as a hot dark matter is its large velocity dispersion. In this work, we investigate and implement multi-fluid perturbation theory that treats cosmic population collection of fluids with broad range bulk velocities. These respond linearly to clustering cold matter, which may be linear described by standard theory, or non-linear, using either higher-order N -body simulations. We verify such an alternative treatment...
We present in this work a novel and yet extremely simple method for incorporating the effects of massive neutrinos cosmological $N$-body simulations. This so-called "SuperEasy linear response" approach is based upon analytical solutions to collisionless Boltzmann equation clustering free-streaming limits, which are then connected by rational function interpolation with cosmology-dependent coefficients given algebraic expressions model parameters. The outcome {\it one-line modification}...