Backward charmonium production in πN collisions

Abstract

Abstract:The QCD collinear factorization framework allows one to describe exclusive backward production of a J/ψ meson in pion-nucleon collisions in terms of pion-to-nucleon transition distribution amplitudes. We calculate the scattering amplitude at the leading order in the strong coupling constant and estimate the cross section of this reaction in the backward kinematical region for a medium energy pion beam available at the J-Parc experimental facility.

Backward timelike Compton scattering to decipher the photon content of the nucleon

“…This crossing relation is similar to that between nucleon-to-pion (πN) and pion-to-nucleon (Nπ) TDAs established in Ref. [14] in the context of the QCD-based description of near-backward production of a J/ψ off nucleons with a pion beam.…”

“…The explicit form of the crossing relation between the Nγ and γN TDAs reads (see Appendix A of Ref. [14]):…”

Hard exclusive pion electroproduction at backward angles with CLAS

“…The considerable size of the TSSA can be most easily interpreted as a sign of the validity of the TDA-based approach. Additional evidence for the TDA-based description can be provided by observing the universality of the nucleon-to-pion TDA accessed in other reactions, which can be studied at PANDA@GSI-FAIR [33][34][35][36] J-PARC [37] as well as a variety of light meson electroproduction reactions (η, η ′ , ρ, ω) at JLab [38].…”

Baryon-to-Meson Transition Distribution Amplitudes: Formalism and Models

“…Experimentally, one may access TDAs both in the space-like domain with backward electroproduction of mesons at JLab and COMPASS and in the time-like domain in antiproton nucleon annihilation atPANDA. We also expect [30] the time-reversed π → N TDAs to be accessible at J-Parc through the reactions: π − p → J/ψ n ; π − p → γ * n → μ + μ − n. Extracting TDAs from space-like and time-like reactions will be a stringent test of their universality [31], and hence of the factorization property of hard exclusive amplitudes. This hopefully will help us to disentangle details of the complex dynamics of quark and gluon confinement in hadrons.…”