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Upcoming and Archived: Conferences | Lectures on Quantum Phenomena

Upcoming Special Seminar:

Wednesday Apr. 13th
12:00 pm
Rm. 318, Hennings Building, UBC

Julio Parra-Martinez (Caltech)
"Causality constraints on corrections to Einstein gravity"

Abstract: In this talk I will describe constraints from causality and unitarity on 2ā†’2 graviton scattering in four-dimensional weakly-coupled effective field theories. Together, causality and unitarity imply dispersion relations that connect low-energy observables to high-energy data. Using such dispersion relations, I will explain how to derive two-sided bounds on gravitational Wilson coefficients in terms of the mass M of new higher-spin states. Such bounds have many implications. For instance, they show that gravitational interactions must shut off uniformly in the limit Gā†’0, prove the scaling with M expected from dimensional analysis, and impose a species bound on theories with a large number of matter fields. In addition they demonstrate the gravity must be weakly coupled at all scales below Planck. Time permitting, I will also comment on the experimental implications of the bounds.


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