Gravity seminar - Claudio Corianò Seminar

 

We use a semiclassical approach to gravitational lensing, where the perturbative corrections to neutrino and photon scattering, evaluated at one-loop in the Standard Model, are compared with the Einstein formula for the deflection using an impact parameter formulation. For this purpose, we use the renormalized expression of the graviton/fermion/fermion and graviton/photon/photon vertices. We show the agreement between the deflection in classical GR and the semiclassical formulations for values of the impact parameter b_h of the neutrinos of the order of b_h ~ 20, measured in units of the Schwarzschild radius. Our analysis covers in energy most of the photon spectrum, from the cosmic microwave background up to very high energy gamma rays, and scatterings with any value of the photon impact parameter. We also study the helicity-flip photon amplitude, which is of O(α2) in the weak coupling α, and its massless fermion limit, which involves the exchange of a conformal anomaly pole. The corresponding cross section is proportional to the Born level result and brings to a simple renormalization of Einsten's formula.

JHEP 1507 (2015) 160 (arXiv:1504.01322)

JHEP 1501 (2015) 091 (arXiv:1411.2804)

JHEP 1403 (2014) 136 (arXiv:1312.7657)