Since the discovery of strangeness almost five decades ago, interest in this degree of freedom has grown up and now its investigation spans the scales from quarks to nuclei. Measurements with identified strange hadrons can provide important informati
on on several hot topics in hadronic physics: the strange distribution and fragmentation functions, the nucleon tomography and quark orbital momentum, accessible through the study of the {it generalized} parton distribution and the {it transverse momentum dependent} parton distribution functions, the quark hadronization in the nuclear medium, the hadron spectroscopy and the search for exotic mesons. The CLAS12 large acceptance spectrometer in Hall B at the Jefferson Laboratory upgraded with a RICH detector together with the 12 GeV CEBAF high intensity, high polarized electron beam can open new possibilities to study strangeness in hard processes allowing breakthroughs in all those areas. This paper summarizes the physics case for a RICH detector for CLAS12. Many topics have been intensively discussed at the International Workshop Probing Strangeness in Hard Processes (PSHP2010) cite{PSHP-workshop} held in Frascati, Italy in October 2010. The authors of this papers like to thank all speakers and participants of the workshop for their contribution and very fruitful discussion.
Leading and subleading twist transverse momentum dependent parton distribution functions (TMDs) are studied in a quark model framework provided by the bag model. A complete set of relations among different TMDs is derived, and the question is discuss
ed how model-(in)dependent such relations are. A connection of the pretzelosity distribution and quark orbital angular momentum is derived.
We present studies of single-spin asymmetries for neutral pion electroproduction in semi-inclusive deep-inelastic scattering of 5.776 GeV polarized electrons from an unpolarized hydrogen target, using the CEBAF Large Acceptance Spectrometer (CLAS) at
the Thomas Jefferson National Accelerator Facility. A substantial $sin phi_h$ amplitude has been measured in the distribution of the cross section asymmetry as a function of the azimuthal angle $phi_h$ of the produced neutral pion. The dependence of this amplitude on Bjorken $x$ and on the pion transverse momentum is extracted with significantly higher precision than previous data and is compared to model calculations.
We present a summary of a recent workshop held at Duke University on Partonic Transverse Momentum in Hadrons: Quark Spin-Orbit Correlations and Quark-Gluon Interactions. The transverse momentum dependent parton distribution functions (TMDs), parton-t
o-hadron fragmentation functions, and multi-parton correlation functions, were discussed extensively at the Duke workshop. In this paper, we summarize first the theoretical issues concerning the study of partonic structure of hadrons at a future electron-ion collider (EIC) with emphasis on the TMDs. We then present simulation results on experimental studies of TMDs through measurements of single spin asymmetries (SSA) from semi-inclusive deep-inelastic scattering (SIDIS) processes with an EIC, and discuss the requirement of the detector for SIDIS measurements. The dynamics of parton correlations in the nucleon is further explored via a study of SSA in D (`D) production at large transverse momenta with the aim of accessing the unexplored tri-gluon correlation functions. The workshop participants identified the SSA measurements in SIDIS as a golden program to study TMDs in both the sea and valence quark regions and to study the role of gluons, with the Sivers asymmetry measurements as examples. Such measurements will lead to major advancement in our understanding of TMDs in the valence quark region, and more importantly also allow for the investigation of TMDs in the sea quark region along with a study of their evolution.
