Particle Theory Seminar

It is organized by the Theory Group of the Laboratory for Particle Physics (LTP) at PSI.

Contact: Christoph Gnendiger, christoph.gnendiger@psi.ch, WHGA/130, Tel +41 56 310 4214.

The next seminar will take place on

Abstract: A mysterious discrepancy ("the proton radius puzzle") has been observed in the measurement of the proton charge radius in muon spectroscopy versus electron spectroscopy and electron scattering. To complement these measurements, the muon-proton scattering experiment (MUSE) is set to extract the proton radius from muon scattering. The two-photon exchange (TPE) contribution is the largest uncertainty in this experiment. In my talk, I will present the TPE box graph estimate with proton and inelastic intermediate states accounting for lepton-mass effects. I will also present the dispersion relation approach which is based on unitarity and analyticity. The future precise measurements of the ground state hyperfine splitting (HFS) in muonic hydrogen by CREMA and FAMU collaborations as well as at J-PARC will provide strict constraints on the low-energy proton structure. Exploiting the precise 1S HFS measurements in electronic hydrogen, I will show how to extract the TPE correction and make an accurate prediction for the HFS in muonic hydrogen.

The following list contains the talks scheduled in the past five years: