Local Two-Photon Couplings and the J=0 Fixed Pole in Real and Virtual Compton Scattering
The local coupling of two photons to the fundamental quark currents of a hadron gives an energy-independent contribution to the Compton amplitude proportional to the charge squared of the struck quark, a contribution which has no analog in hadron scattering reactions. We show that this local contribution has a real phase and is universal, giving the same contribution for real or virtual Compton scattering for any photon virtuality and skewness at fixed momentum transfer squared t. The t-dependence of this J = 0 fixed Regge pole is parameterized by a yet unmeasured even charge-conjugation form factor of the target nucleon. The t = 0 limit gives an important constraint on the dependence of the nucleon mass on the quark mass through the Weisberger relation. We discuss how this 1=x form factor can be extracted from high energy deeply virtual Compton scattering and examine predictions given by models of the H generalized parton distribution.
- Research Organization:
- SLAC National Accelerator Lab., Menlo Park, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC02-76SF00515
- OSTI ID:
- 943474
- Report Number(s):
- SLAC-PUB-13478; arXiv:0812.0395; TRN: US0900404
- Journal Information:
- Physical Review D, Journal Name: Physical Review D
- Country of Publication:
- United States
- Language:
- English
Similar Records
Reggeon Non_Factorizability and Fixed Pole in DVCS
Light-Cone Wavefunction Representation of Deeply Virtual Compton Scattering