A5102920675- Cosmology and Gravitation Theories
- Dark Matter and Cosmic Phenomena
- Black Holes and Theoretical Physics
- Galaxies: Formation, Evolution, Phenomena
- Particle physics theoretical and experimental studies
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- Computational Physics and Python Applications
- Shoulder Injury and Treatment
- Astronomy and Astrophysical Research
- Astrophysics and Cosmic Phenomena
- Shoulder and Clavicle Injuries
- Pulsars and Gravitational Waves Research
- Radio Astronomy Observations and Technology
- Relativity and Gravitational Theory
- Earth Systems and Cosmic Evolution
- Hip and Femur Fractures
- Cardiac, Anesthesia and Surgical Outcomes
- Pelvic and Acetabular Injuries
- Orthopedic Surgery and Rehabilitation
- Superconducting and THz Device Technology
- Scientific Research and Discoveries
- Quantum Mechanics and Applications
- Nerve Injury and Rehabilitation
- Particle Detector Development and Performance
University of Toronto
2006-2025
Institute for Christian Studies
2025
Syracuse University
2013-2024
University of South Carolina
2024
University of Waterloo
2022
Prisma Health
2015-2021
Oregon Health & Science University
2021
University of Michigan
2008-2018
Tokyo Institute of Technology
2017
Steadman Clinic
2015
This book lays out the scientific goals to be addressed by next-generation ground-based cosmic microwave background experiment, CMB-S4, envisioned consist of dedicated telescopes at South Pole, high Chilean Atacama plateau and possibly a northern hemisphere site, all equipped with new superconducting cameras. CMB-S4 will dramatically advance cosmological studies crossing critical thresholds in search for B-mode polarization signature primordial gravitational waves, determination number...
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 take an Effective Field Theory (EFT) approach to unifying existing proposals for the origin of cosmic acceleration and its connection cosmological observations. Building on earlier work where EFT methods were used with observations constrain background evolution, we extend this program level perturbations — following example from Inflation. Within framework, construct general theory around assumed which will typically be chosen mimic ΛCDM, identify parameters interest constraining dark...
A critical review and summary of string gas cosmology is presented. pedagogical derivation the effective action starting from theory, emphasizing necessary approximations that must be invoked, included. Working in at late times it not possible to stabilize extra dimensions by a massive winding modes demonstrated. Additional gases are considered contain so-called enhanced symmetry states. These very heavy initially, but drive moduli locations minimize energy pressure gas. Both classical...
Light scalar fields with only gravitational strength couplings are typically present in UV complete theories of physics beyond the Standard Model. In early universe it is natural for these to dominate energy density, and their subsequent decay, if prior BBN, will yield some dark matter particles decay products. this paper we make observation that a Non-thermal WIMP `Miracle' may result: is, simplest solution cosmological moduli problem, non-thermally produced WIMPs can naturally account...
We investigate constraints on the abundance of primordial black holes (PBHs) in mass range ${10}^{15}--{10}^{17}\text{ }\text{ }\mathrm{g}$ using data from cosmic microwave background (CMB) and MeV extragalactic gamma-ray (EGB). Hawking radiation PBHs with lifetime greater than age Universe leaves an imprint CMB through modification ionization history damping anisotropies. Using a model for redshift-dependent energy injection efficiencies, we show that combination temperature polarization...
A bstract The double copy relates scattering amplitudes in gauge and gravity theories, has also been extended to classical solutions. In this paper, we study solutions three spacetime dimensions, where the may be expected problematic due absence of propagating degrees freedom for graviton, lack a Newtonian limit. particular, examine theory point charge. This is vacuum solution theory, but leads non-vacuum gravity, which show consistent with previously derived constraints. Furthermore,...
Satellite data is accumulating that suggests and constrains dark matter physics. We argue there a very well motivated theoretical preexisting framework consistent with annihilation being observed by the PAMELA satellite detector. The (mainly) neutral W boson superpartner, wino mass below 200 GeV. Using program GALPROP we study products backgrounds together. Antimatter gammas from annihilating winos contribute this energy. explain why does not imply no antiproton signal was or earlier...
We examine the evolution of cosmological perturbations in a nonthermal inflationary history with late-time matter domination period prior to big bang nucleosynthesis. Such cosmology could arise naturally well-motivated moduli scenario context supersymmetry (SUSY)---in particular models split SUSY. Subhorizon dark grow linearly during dominated phase before reheating and can lead an enhancement growth substructure on small scales, even presence annihilations. This suggests that new scale (the...
Basicervical peritrochanteric fractures are relatively rare, with 1.8% to 7.6% of hip being identified as true basicervical fractures. The compression screw traditionally has been considered the "gold standard" for operative fixation fractures, generally good results. purpose this study was report outcomes proximal part femur treated cephalomedullary nailing (CMN).We reviewed medical records and radiographs all patients at our institution a fracture CMN from 2010 2012 (246 patients)....
We review the notion of Higgs effect in context string theory. find that by including this time dependent backgrounds, one is led to a natural mechanism for stabilizing moduli at points enhanced gauge symmetry. consider case radion (size extra dimensions) and as decompactification large spatial dimensions takes place will remain stabilized self-dual radius. discuss how can be incorporated into models cosmology brane inflation resolve some outstanding problems. also address issues regarding...
By considering the effects of string winding and momentum modes on a time dependent background, we find method by which six compact dimensions become stabilized naturally at self-dual radius while three grow large.
Recently the PAMELA satellite-based experiment reported an excess of galactic positrons that could be a signal annihilating dark matter. The data may admit interpretation as from winolike lightest supersymmetric particle mass about 200 GeV, normalized to local relic density, and mainly into $W$ bosons. This possibility requires current conventional estimate for energy loss rate too large by roughly factor 5. Data antiprotons gamma rays also provide tension with this interpretation, but there...
We present a unified framework for the study of late time cosmic acceleration. Using methods effective field theory, we show that existing proposals acceleration can be subsumed in single framework, rather than many compartmentalized theories. construct most general action consistent with symmetry principles, derive background and perturbation evolution equations, demonstrate special choices our parameters reproduce results already literature. Lastly, lay foundation future work placing...
We investigate the validity of effective field theory methods and decoupling heavy fields during inflation. Considering models inflation in which inflaton is coupled to a (super-Hubble) degree freedom initially its vacuum state, we find that violations are absent unless there breakdown slow-roll conditions. Next allow for temporary departure from resulting period non-adiabaticity known fail. locality event energy conservation lead tight bound on size effects field. discuss implications power...
We study the cosmological consequences of codecaying dark matter---a recently proposed mechanism for depleting density matter through decay nearly degenerate particles. A generic prediction this framework is an early dominated phase in history Universe, that results enhanced growth perturbations on small scales. compute duration and show are robust against washout from free streaming. The small-scale structure expected to survive today form compact microhalos can lead significant boost...
Within the Minimal Supersymmetric Standard Model (MSSM), LHC bounds suggest that scalar superpartner masses are far above electroweak scale. Given a high mass, nonthermal dark matter is viable alternative to WIMP generated via freezeout. In presence of moduli fields production associated with long dominated phase, modifying spectral index and primordial tensor amplitude relative those in thermalized universe. Nonthermal can have higher self-interaction cross-section than its thermal...
Bird, et. al. and Sasaki, have recently proposed the intriguing possibility that black holes detected by LIGO could be all or part of cosmological dark matter. This offers an alternative to WIMPs axions, where matter comprised solely Standard Model particles. The mass range lies within observationally viable window predicted merger rate can tested future observations. In this paper, we argue non-thermal histories favor production near -- with heavier ones unlikely form in early universe...