Kinematic effects in energy spectra of quarkonia production and decay

por Stefan Wolf (Departamento de Fisica Teorica)

jueves 25 ene. 2001 12:30 → 13:30 Europe/Madrid

Sala Seminarios (Dpto. de Física Teórica (UVEG))

In this talk we present the energy (momentum) distributions in J/Psi photoproduction and J/Psi production in B meson decay. In particular the upper endpoint region of these spectra is examined where the effect of soft gluon emission from the ccbar pair becomes important. Constructing a model which is consistent with the so-called shape function formalism we consider these fragmentation effects and show that they weaken the so-called Hera problem, i.e. the steep raise of the octet contributions towards high J/psi energies which is predicted by naive NRQCD. Furthermore we consider the influence of possible colour octet contributions to the upper endpoint region of the photon energy spectrum in radiative Upsilon decays.