HERMES

The HERMES experiment collected a wealth of deep-inelastic scattering data using the 27.6 GeV polarized lepton beam at HERA and various pure gas targets, both unpolarized and polarized. This allowed for a series of diverse measurements. [...]

Exclusive $\rho^0$-meson electroproduction is studied by the HERMES experiment, using the 27.6 GeV longitudinally polarized electron/positron beam of HERA and a transversely polarized hydrogen target, in the kinematic region 1.0 GeV$^2$ < Q$^2$ < 7.0 GeV$^2$, 3.0 GeV < W < 6.3 GeV, and -t’ < 0.4 GeV$^2$. Using an unbinned maximum-likelihood method, 25 parameters are extracted. [...]

Exclusive $\rho^0$-meson electroproduction is studied by the HERMES experiment, using the 27.6 GeV longitudinally polarized electron/positron beam of HERA and a transversely polarized hydrogen target, in the kinematic region 1.0 GeV$^2$<Q$^2$<7.0 GeV$^2$, 3.0 GeV<W<6.3 GeV, and -t'<0.4 GeV$^2$. Using an unbinned maximum-likelihood method, 25 parameters are extracted. [...]

Deeply Virtual Compton Scattering (DVCS) is a key reaction to gain information on Generalized Parton Distributions. In this paper the existing measurements of DVCS on the nucleon, as well as those planned for the near future, are presented and discussed..

HERMES and COMPASS results of DVCS and DVMP are presented. Preparations for the 2016/17 COMPASS GPD run are at full swing..

The recently developed formalism of Generalized Parton Distributions (GPDs) allows connecting the experimental information of hard exclusive reactions to the spin contribution and even to the angular momentum contribution of quarks in the nucleon. By selecting different quantum numbers of the final state in exclusive productions, different GPDs can be addressed separately. [...]

The study of the quantum phase-space distribution of quarks and gluons inside nucleons in terms of TMDs and GPDs has become, in the last decade, a cutting-edge research field in hadron physics. These non-perturbative objects, respectively measurable in semi-inclusive deep-inelastic scattering and hard exclusive processes, allow to obtain 3-dimensional representations of the nu- cleon in the momentum and spatial coordinates as well as indirect insights into the still unknown parton orbital angular momentum. [...]

The study of the quantum phase-space distribution of quarks and gluons inside nucleons in terms of TMDs and GPDs has become, in the last decade, a cutting-edge research field in hadron physics. These non-perturbative objects, respectively measurable in semi-inclusive deep-inelastic scattering and exclusive processes, allow to obtain 3-dimensional representations of the nucleon in the momentum and spatial coordinates as well as indirect insights into the still unknown parton orbital angular momentum. [...]

Transverse-target-spin asymmetries as well as longitudinal beam-helicity asymmetries measured in semi-inclusive deep-inelastic scattering for charged pions and kaons and for protons and antiprotons are presented. They are extracted from data collected by the HERMES experiment using a 27.6 GeV longitudinally polarized electron and positron beam and, respectively, a transversely polarized hydrogen target and unpolarized hydrogen and deuterium targets. [...]