
Upcoming Special Seminar:
Wednesday Apr. 13th
12:00 pm
Rm. 318, Hennings Building, UBC
Julio ParraMartinez (Caltech) "Causality constraints on corrections to Einstein gravity"
Abstract: In this talk I will describe constraints from causality and unitarity on 2ā2 graviton scattering in fourdimensional weaklycoupled effective field theories. Together, causality and unitarity imply dispersion relations that connect lowenergy observables to highenergy data. Using such dispersion relations, I will explain how to derive twosided bounds on gravitational Wilson coefficients in terms of the mass M of new higherspin states. Such bounds have many implications. For instance, they show that gravitational interactions must shut off uniformly in the limit Gā0, 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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