##### Institut "Ruðer Bo¹koviæ",  ZAVOD ZA TEORIJSKU FIZIKU

SEMINAR ZAVODA ZA TEORIJSKU FIZIKU
(Zajednièki seminari Zavoda za teorijsku fiziku,
Zavoda za eksperimentalnu fiziku i  Zavoda za teorijsku fiziku PMF-a)

Generalized Parton Distributions

Dr. D. Mueller
Institut fuer theoretische Physik, Universitaet Regensburg, Germany

Datum:  srijeda, 13. srpanj 2005.
Vrijeme: 15.00 sati (c.t.),
Mjesto: IRB, I. krilo, seminar teorijske fizike
Sa¾etak:
Generalized parton distributions and their analog, contained by crossing, generalized distribution amplitudes are non-perturbative functions that are accessible in certain hard exclusive, however, inelastic processes such as the hard electroproduction of photons and mesons on a nuclei or nucleus target or the hadron pair production by two photon fusion in $e^+ e^-$ colliders. These functions are related to parton densities, form factors, and distribution amplitudes and contain on the other hand new non-perturbative information about the internal structure of hadrons and also nuclei that can not be revealed from inclusive or elastic exclusive measurements. In this talk, I present a new representation of generalized parton distributions and generalized distribution amplitudes that is based on the partial wave decomposition with respect to the {\em complex} collinear conformal spin. This decomposition leads to a versatile parametrization of these non-perturbative functions in terms of conformal moments, which are measurable for integer conformal spin on the lattice. There are several advantages of this representation, namely, basic properties and crossing relations are implemented, a rather flexible parametrization of ans\"atze for these non-perturbative distributions, simple numerical treatment of evolution and convolution with the hard-scattering part, and analytic approximation of scattering amplitudes.
Voditelj seminara: Dr. Bla¾enka Meliæ