SEMINARIO DE FISICA TEORICA I Y II

Titulo:         The 1/x form factor of the nucleon
Conferenciante: Felipe Llanes Estrada (Dpto. Fisica Teorica I, UCM)
Dia y hora:     26, 14:15 (Aula 8B)

Resumen:

Isolating the effect of individual quarks in hadron properties is a
challenging problem. We address exclusive processes in the context of
Generalized Parton Distributions and show that the collinear
factorization theorems used to justify extraction of GPD's from
experimental data fails at low transfered momentum due to Regge
behavior. The theoretical tool employed in the construction is the
parton-nucleon scattering amplitude.
Then we review the J=0 fixed pole in Compton scattering and how the
seagull diagram does reveal the pointlike charges inside hadrons. The t-
dependence is controlled by  a new, unmeasured form factor of the
nucleon, the "1/x" form factor, that can equally well be defined for
other quantum systems (we exemplify with the Hydrogen atom). In the
limit of zero t, this yields, via the Weisberger relation, the
dependence of the proton mass on the quark mass, that can be thus
extracted from experiment without resource to a quark model.