منابع مشابه
Helicity dependent parton distributions
The helicity dependent parton distributions describe the number density of partons with given longitudinal momentum x and given polarization in a hadron polarized longitudinally with respect to its motion. After the discovery , more than 70 years ago , that the proton is not elementary , the observation of Bjorken scaling in the late 1960s lead to the idea of hadrons containing almost pointlike...
متن کاملHelicity-dependent generalized parton distributions and composite constituent quarks
An approach recently proposed to calculate the nucleon generalized parton distributions (GPDs) in a constituent quark model (CQM) scenario, considering the constituent quarks as complex systems, is used here to obtain helicitydependent GPDs. They are obtained from the wave functions of the non relativistic CQM of Isgur and Karl, convoluted with the helicity-dependent GPDs of the constituent qua...
متن کاملGeneralized Parton Distributions with Helicity Flip
We show that for both quarks and gluons there are eight generalized parton distributions in the proton: four which conserve parton helicity and four which do not. We explain why time reversal invariance does not reduce this number from eight to six, as previously assumed in the literature.
متن کاملModel study of generalized parton distributions with helicity flip
Generalized parton distributions with helicity flip are studied in the quark sector, within a simple version of the MIT bag model, assuming an SU(6) wave function for the proton target. In the framework under scrutiny it turns out that only the generalized transversity distribution, H T , is non vanishing. For this quantity, the forward limit is properly recovered and numerical results are foun...
متن کاملHelicity-flip Off-forward Parton Distributions of the Nucleon
We identify quark and gluon helicity-flip distributions defined between nucleon states of unequal momenta. The evolution of these distributions with change of renormalization scale is calculated in the leading-logarithmic approximation. The helicity-flip gluon distributions do not mix with any quark distribution and are thus a unique signature of gluons in the nucleon. Their contribution to the...
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ژورنال
عنوان ژورنال: Scholarpedia
سال: 2011
ISSN: 1941-6016
DOI: 10.4249/scholarpedia.10226