We investigate the prospects for discovering axionlike particles (ALPs) via a light by scattering at two colliders, future circular collider (FCC-ee) and electron-positron (CEPC). The promising sensitivities to effective ALP-photon coupling ${g}_{a\ensuremath{\gamma}\ensuremath{\gamma}}$ are obtained. Our numerical results show that FCC-ee CEPC might be more sensitive ALPs with mass 2--8 GeV th...

We present first observations of the transversity parton distribution based on an analysis of pion-pair production in deep-inelastic scattering off transversely polarized targets. The extraction of transversity relies on the knowledge of dihadron fragmentation functions, which we take from electron-positron annihilation measurements. This is the first attempt to determine the transversity distr...

We describe the details of the evaluation of the two-loop radiative photonic corrections to Bhabha scattering. The role of the corrections in the high-precision luminosity determination at present and future electron-positron colliders is discussed. PACS numbers: 11.15.Bt, 12.20.Ds

The study of the interaction of positrons with atoms and molecules has become increasingly popular, because more and more experimental activities have become feasible. Although exchange effects are absent, the polarisation effects, caused by the attractive nature between the positron and the target electrons, make the positron-molecule collisions more difficult to handle than the corresponding ...

We report the first measurement of average electron-proton and positron-proton elastic scattering cross sections. This lepton charge-averaged section is insensitive to leading effects hard two-photon exchange, giving more robust access proton’s electromagnetic form factors. The was extracted from data taken by OLYMPUS experiment at DESY, in which alternating stored electron positron beams were ...

We outline a new kinetic theory for positrons in soft matter, which blends together cross sections for positrons scattering from single molecules, with the structure function of the medium as a whole. Numerical results are presented for positrons in liquid argon, where negative differential conductivity arises from both positron formation and the structure of the medium.

Gamma-ray burst sources with a high luminosity can produce electron-positron pair cascades in their environment as a result of back-scattering of a seed fraction of their original hard spectrum. The resulting spectral modifications offer the possibility of diagnosing not only the compactness parameter of the γ-ray emitting region but also the baryonic density of the environment external to the ...

A Monte Carlo event generator is presented. An original algorithm is developed to simulate electron–positron scattering at energies and momentum transferred much more than the electron mass. The first-order electroweak radiative corrections are included completely. Higher order corrections are taken into account by means of electron structure functions. PACS: 12.20.–m Quantum electrodynamics, 1...