N -> Delta DVCS, exclusive DIS processes and skewed quark distributions in large N_c limit

L. L. Frankfurt; M. V. Polyakov; M. Strikman

paper

N -> Delta DVCS, exclusive DIS processes and skewed quark distributions in large N_c limit

arXiv:hep-ph/9808449

Abstract

We evaluate the amplitude of Bethe-Heitler process: γ^* p -> γΔ^+ -electron bremsstrahlung of photon accompanied by the excitation of Δ $i so ba r . W es h o w t ha tt hi s ba c k g r o u n d i ss u pp r esse d a t s ma l l m o m e n t u m t r an s f er s q u a r e d tt o a p r o t o n r e l a t i v e t o t ha t f or γ^{*} p - > γ p an d γ^{*} p \to - > Δ^{+} - D V C S p r ocesses . F r o m e x p er im e n t a l p o in t o f v i e w, t hi s m e an s t ha tN - > N an d N - > Δ s k e w e d q u a r k d i s t r ib u t i o n s (S Q D^{'} s) mi g h t b e m e a s u r ab l e a t s ma l l m o m e n t u m t r an s f er . S e v er a l im pl i c a t i o n s an d a ppl i c a t i o n so f t h e QC D f a c t or i z a t i o n t h eor e m f or t h e p r ocesses γ_{L}^{*} + p - > h_{f} + h_{s} a r e d i sc u sse d w h er e h_{f} - t h e p a r t i c l e p r o d u ce d a l o n g p h o t o nm o m e n t u m$ \vec q$ maybe either a meson or a baryon. We discuss also t dependence of DVCS and exclusive meson production as the practical criteria to distinguish between soft and hard regime. Basing on the large-N_c picture of the nucleon as a soliton of the effective chiral Lagrangian we derive relations between N -> N and N ->ΔSQD's which can be used to estimate amplitude of N -> ΔDVCS .

8 pages, latex. Contribution to the Workshop " Jefferson Lab Physics and Instrumentation with 6-12 GeV Beams", Newport News, VA, June 15-18, 1998