Nuclear Physics Seminar
Description of hard-exclusive processes in terms of Transition
Distribution Amplitudes
Jean-Philippe Lansberg (Ecole Polytechnique, France)
In a first part, I shall introduce the concept of Transition Distribution
Amplitudes (TDAs) by underlining some similarities and differences
compared to Generalised Parton Distributions (GPDs). In the case of "meson
to photon" transitions, I will define the leading-twist TDAs and show how
a simple model in terms of Double Distributions, inspired from those used
to model GPDs, already enable to show that these TDAs can be
experimentally studied in photon-photon collisions and provides us with a
complementary description of these reactions to that of GDAs. In a second
part, I shall focus on the baryonic case, which can be used to study
backward DVCS on proton as well as backward electroproduction of a meson.
In the latter case, I will discuss our first estimate of some cross
sections that may be measured at JLab and Hermes.
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