Flavor decomposition with precision pion and kaon cross sections
2017 December 31
2018 January 16
Key properties of the nucleon are encoded in the correlation between their longitudinal momentum and their transverse position, such as the orbital angular momentum. This correlation is expressed through Generalised Parton Distributions (GPDs), which can be understood as spatial densities at different values of the longitudinal momentum of the quark, and due to the space-momentum correlation information encoded in the GPDs can link through the Ji sum rule to a parton's angular momentum. Transverse Momentum-dependent parton Distributions (TMDs) are functions of both the longitudinal and transverse momentum of partons, and they offer a momentum tomography of the nucleon complementary to the spatial tomography of GPDs. The GPD and TMD programs are at the heart of the scientific motivation of the 12 GeV Jefferson Lab. Recent data and prospects for deep exclusive pion and kaon electroproduction are presented, which conceptually would allow for flavour separations. Experimental tests of our theoretical understanding of the reaction mechanism are shown including longitudinal-transverse separated charged-pion cross section data and ratios. The prospects to use projected charged- and neutral pion data to further determine the spin, charge-parity and flavour of GPDs, including the helicity-flip GPDs, are discussed.