Continuity of generalized parton distributions for the pion virtual Compton scattering

Abstract

We discuss a consistent treatment of the light-front gauge-boson and meson wave functions in the analyses of the generalized parton distributions(GPDs) and the scattering amplitudes in deeply virtual Compton scattering(DVCS) for the pion. The continuity of the GPDs at the crossover, where the longitudinal momentum fraction of the probed quark is same with the skewedness parameter, and the finiteness of the DVCS amplitude are ensured if the same light-front radial wave function as that of the meson bound state wave function is used for the gauge boson bound state arising from the pair-creation(or nonvalence) diagram. The frame-independence of our model calculation is also guaranteed by the constraint from the sum rule between the GPDs and the form factors.

Heavy-to-light form factors on the light cone

“…These B → P form factors have also been studied systemically in the usual light-cone quark model [5,6,7], the light cone sum rules [9] and PQCD approach [11]. Although Lattice QCD cannot give direct predictions on the B to light form factors at large recoiling, there are some studies using the extrapolations from the results at large q 2 : in quenched LQCD [37] and in unquenched LQCD [38,39].…”

“…For non-perturbative QCD, an approach which combines the advantage of light cone method with the low energy constituent quark model is more appealing. This approach, which we will call light cone quark model (LCQM), has been successfully applied to the calculation of the meson decay constants and hadronic form factors [4,5,6,7,26,27].…”

“…There are already many methods calculating the heavy-to-light transition form factors in the literature such as simple quark model [2], the light cone quark models (LCQM) [4,5,6,7] 1 , the light cone sum rules (LCSR) [8,9,10], the perturbative QCD (PQCD) approach based on k T factorization [11] etc.…”

Modelling the nucleon structure

“…A different approach consists in a direct calculation of GPDs using effective quark models. After the first calculation within the MIT bag model [103], GPDs were calculated in the χQSM [104][105][106][107][108][109][110], using covariant BetheSalpeter approaches [111][112][113][114][115][116][117][118], in the quark-target model [51,119,120], in nonrelativistic quark models [121][122][123], in light-front quark models [7,[124][125][126][127][128], in meson-cloud models [129,130], and from LFWFs inspired by AdS/QCD [131][132][133]. Although these models single out only a few features of the QCD dynamics in hadrons, they may provide some guidance on the functional dependence of GPDs, particularly if a model is constrained to reproduce electromagnetic form factors and ordinary parton distributions.…”

2004 Review of Light Cone Field Theory

“…with the known kinematic functions H 1 and H 2 given in Ref [15]. The model light front Gaussian wave functions used are…”