Probing generalized parton distributions in πN→ℓ+ℓ−N

Abstract

We study the exclusive reactions π − p → ℓ + ℓ − n and π + n → ℓ + ℓ − p in view of possible future experiments with high-intensity pion beams. For large invariant mass of the lepton pair ℓ + ℓ − and small squared momentum transfer to the nucleon these are hard-scattering processes providing access to generalized parton distributions. We estimate the cross section for these reactions, explore their connection with the pion form factor, and discuss the role they can play in improving our understanding of the relevant reaction mechanisms. 1

Resumming soft and collinear contributions in deeply virtual Compton scattering

“…for hard electroproduction of mesons [21][22][23][24] and their timelike crossed versions, namely exclusive lepton pair production in photon or meson collisions with protons [25][26][27]. The future JLab-12 GeV and COMPASS-II program will provide soon bunches of data, giving a hope to get access to GPDs with a high degree of precision.…”

QCD analysis of p¯N→γ∗π in the scaling limit

“…The conditions imposed by flavour symmetry do not influence the evolution equations but lead to certain symmetry properties of TDAs. Since operators (12), (13) belong to different representations of the Lorentz group they do not mix with each other. The operators B, (12) and (13), satisfy the renormalisation group equa-…”

“…The operator H acts in different way on the operator (13) and on the operator (12). In the first case it is determined by contributions from one loop Feynman diagrams describing in the Feynman gauge the vertex corrections corresponding to gluon exchanges between quark fields and gluons forming Wilson lines as…”

Observables for Generalized TMDs of Quarks

“…We finally point out that the type of reactions discussed here could also constrain GPDs in the ERBL region, where experimental information is still sparse -see Refs. [41,42,43] for related work on GPDs.…”