Hybrid presence c/o Euler Lecture Hall + zoom meeting. Kindly note that the maximum number of participants in presence is 17 pp.
Abstract. Positivity bounds for theories with massless spin-2 fields could have deep implications for UV physics. However, the presence of a singularity in the t-channel of the scattering amplitudes precludes the application of the standard positivity bounds. I will discuss the recent progress in working around this issue. I will show in particular how for simple renormalizable field theories coupled to gravity applying the positivity bounds to amplitudes with the t-pole subtracted leads to constraints on the low-energy coupling constants in a way which is incompatible with their actual values. This either shows that a certain degree of negativity is allowed or implies new physics at a scale parametrically smaller than expected. I will pay special attention to the case of QED and Standard Model minimally coupled to gravity.