Since 2002 Perimeter Institute has been recording seminars, conference talks, and public outreach events using video cameras installed in our lecture theatres. Perimeter now has 7 formal presentation spaces for its many scientific conferences, seminars, workshops and educational outreach activities, all with advanced audio-visual technical capabilities. Recordings of events in these areas are all available On-Demand from this Video Library and on Perimeter Institute Recorded Seminar Archive (PIRSA). PIRSA is a permanent, free, searchable, and citable archive of recorded seminars from relevant bodies in physics. This resource has been partially modelled after Cornell University's arXiv.org.
We present a simple mechanism for obtaining large-field inflation, and hence a gravitational wave signature, from string theory compactified on twisted tori. For Nil manifolds, we obtain a leading inflationary potential proportional to phi^(2/3) in terms of the canonically normalized field phi, yielding predictions for the tilt of the power spectrum and the tensor-to-scalar ratio, $n_sapprox 0.98$ and $rapprox 0.04$ with 60 e-foldings of inflation; we note also the possibility of a variant with a candidate inflaton potential proportional to phi^(2/5).
We study effects of the neutrino yukawa coupling on neutralino dark matter observables. We found that presence of the top-like neutrino yukawa coupling does significantly affect neutralino relic density in the regions.
The cosmological constant problem and the compatibility of gravity with quantum mechanics are the two most pressing problems in all of gravitational theory. While string theory nicely addresses the latter, it has so far failed to provide any compelling solution to the former. On the other hand, while conformal gravity nicely addresses the cosmological constant problem [by naturally quenching the amount by which the cosmological constant gravitates rather than by quenching the cosmological constant itself -- Mannheim, Prog. Part. Nuc. Phys.
We discuss a quantum corrected inflation scenario driven by a generic GUT or Standard Model type particle model, whose scalar field playing the role of an inflaton has a strong non-minimal curvature coupling. We show that currently widely accepted bounds on the Higgs mass falsify the suggestion of [arXiv:0710.3755] (the work underestimating the role of radiative corrections) that the Standard Model Higgs boson can serve as the inflaton.
In SUGRA flavour models, a total sequestering is not possible and an irreducible amount of flavour and CP violation is essentially unavoidable, which renders many flavour models testable in the near future experiments.
Working in the weak tachyon region of a condensing tachyon background, we find the modified equations of motion for massless strings with conformal perturbation theory. We then estimate the backreaction on the background dilaton. In large (supercritical) dimensions, we find that the backreaction can be significant in a large region of spacetime.
WIMP dark matter candidates chi^0 have interesting signatures for direct and indirect detection in regimes where there is a near degeneracy with a heavier charged state chi^{pm}, as occurs for example along the boundary of the coannihilation strip in the CMSSM. For small splittings of O(10) MeV, the scattering of WIMPs off nuclei may be dominated by inelastic recombination processes mediated by the formation of (chi^- N) bound states, leading for example to a distinct signature for direct detection.
Parametric resonance, also known as preheating, is a plausible mechanism for bringing about the transition between the inflationary phase and a hot, radiation dominated universe. This epoch results in the rapid production of heavy particles far from thermal equilibrium and has the potential to source a significant stochastic background of gravitational radiation. Here, I present a numerical algorithm for computing the contemporary power spectrum of gravity waves generated in this post-inflationary phase transition for a large class of scalar-field driven inflationary models.
We show the nature of sequestering hidden sector in five-dimensional supergravity models, where a negative vacuum energy of the nonperturbative modulus potential is canceled by a dynamically generated F-term in the hidden sector. Soft supersymmetry breaking terms are explicitly shown in the case that both the visible and the hidden sector is quasi-localized in the extra dimension.
The phenomenology of TeV-scale physics can be modified by the existence of scale-invariant \'unparticle\' fields that can couple to the standard model sector. In particular, it has been shown that unparticles can alter gravitational interactions in a similar fashion to extra dimensions. Observable results from this mechanism -- most notably mini-black hole formation -- will be discussed, and methods of differentiating unparticles from extra dimensional models will be addressed.
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