Radiative corrections: from medium to high energy experiments.

Radiative corrections are crucial for modern high-precision physics experiments, and are an area of active research in the experimental and theoretical community. Here we provide an overview of the state of the field of radiative corrections with a focus on several topics: lepton-proton scattering, QED corrections in deep-inelastic scattering, and in radiative light-hadron decays. Particular emphasis is placed on the two-photon exchange, believed to be responsible for the proton form-factor discrepancy, and associated Monte-Carlo codes.

Two-photon exchange in (muonic) deuterium at N3LO in pionless effective field theory.

We present a study of the two-photon-exchange (2 -exchange) corrections to the -levels in muonic ( D) and ordinary (D) deuterium within the pionless effective field theory (EFT). Our calculation proceeds up to next-to-next-to-next-to-leading order (N3LO) in the EFT expansion. The only unknown low-energy constant entering the calculation at this order corresponds to the coupling of a longitudinal photon to the nucleon-nucleon system.

Dissecting the Hadronic Contributions to (g-2)_{μ} by Schwinger's Sum Rule.

The theoretical uncertainty of (g-2)_{μ} is currently dominated by hadronic contributions. In order to express those in terms of directly measurable quantities, we consider a sum rule relating g-2 to an integral of a photoabsorption cross section. The sum rule, attributed to Schwinger, can be viewed as a combination of two older sum rules: Gerasimov-Drell-Hearn and Burkhardt-Cottingham.