QCD Sum Rules and Models for Generalized Parton Distributions
نویسنده
چکیده
I use QCD sum rule ideas to construct models for generalized parton distributions. To this end, the perturbative parts of QCD sum rules for the pion and nucleon electromagnetic form factors are interpreted in terms of GPDs and two models are discussed. One of them takes the double Borel transform at adjusted value of the Borel parameter as a model for nonforward parton densities, and another is based on the local duality relation. Possible ways of improving these Ansätze are briefly discussed.
منابع مشابه
Generalized parton distributions of the pion
Generalized Parton Distributions of the pion are evaluated in chiral quark models with the help of double distributions. As a result the polynomiality conditions are automatically satisfied. In addition, positivity constraints, proper normalization and support, sum rules, and soft pion theorems are fulfilled. We obtain explicit expressions holding at the low-energy quark-model scale, which exhi...
متن کاملHelicity-dependent Twist-two and Twist-three Generalized Parton Distributions in Light-Front QCD
We investigate the helicity dependent twist-two and twist-three generalized parton distributions in light-front Hamiltonian QCD for a massive dressed quark target. Working in the kinematical region ξ < x < 1, we obtain the splitting functions for the evolutions of twist-two quark and gluon distributions in a straightforward way. For the twist-three distribution, we find that all contributions a...
متن کاملParton-Hadron duality in QCD sum rules: quantum mechanical examples
Motivated by recent work on three-point QCD sum rules in heavy quark physics, we use the simple quantum mechanical models to study the basic issue of duality in three-point sum rules. We show that while in all of these models the duality in two-point sum rules works fine, the duality in three-point sum rules may be 100%violated, leading to completely unreliable predictions for the matrix elemen...
متن کاملViolation of Sum Rules for Twist-3 Parton Distributions in QCD
Sum rules for twist-3 distributions are reexamined. Integral relations between twist-3 and twist-2 parton distributions suggest the possibility for a δ-function at x = 0. We confirm and clarify this result by constructing hL and h 3 L (quark-gluon interaction dependent part of hL) explicitly from their moments for a one-loop dressed massive quark. The physics of these results is illustrated by ...
متن کاملA new approach to axial coupling constants in the QCD sum rule
We derive new QCD sum rules for the axial coupling constants by considering two-point correlation functions of the axial-vector currents in a one-nucleon state. The QCD sum rules tell us that the axial coupling constants are expressed by nucleon matrix elements of quark and gluon operators which are related to the sigma-terms and the moments of parton distributions. The results for the iso-vect...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2004