scholarly journals Old and new parton distribution and fragmentation functions

2001 ◽  
Vol 51 (S1) ◽  
pp. A97-A105 ◽  
Author(s):  
A. V. Efremov
Keyword(s):  
Parton Distribution ◽  
Fragmentation Functions

BESSEL-WEIGHTED ASYMMETRIES AND TRANSVERSE SPIN EFFECTS

2012 ◽  
Vol 20 ◽  
pp. 168-176
Author(s):  
LEONARD GAMBERG
Keyword(s):  
Transverse Momentum ◽  
Cross Section ◽  
Parton Distribution ◽  
Evolution Equations ◽  
Distribution Functions ◽  
Transverse Spin ◽  
High Transverse Momentum ◽  
Transverse Momentum Dependent ◽  
Fragmentation Functions ◽  
The Cross

We consider the cross section for semi-inclusive deep inelastic scattering in Fourier space, conjugate to the outgoing hadron's transverse momentum, where convolutions of transverse momentum dependent parton distribution functions and fragmentation functions become simple products. Individual asymmetric terms in the cross section can be projected out by means of a generalized set of weights involving Bessel functions. Advantages of employing these Bessel weights are that they suppress (divergent) contributions from high transverse momentum and that soft factors cancel in (Bessel-) weighted asymmetries. Also, the resulting compact expressions immediately connect to previous work on evolution equations for transverse momentum dependent parton distribution and fragmentation functions and to quantities accessible in lattice QCD. Bessel-weighted asymmetries are thus model independent observables that augment the description and our understanding of correlations of spin and momentum in nucleon structure.

scholarly journals DETECTING CORRELATED DI-HADRON PAIRS: ABOUT THE EXTRACTION OF TRANSVERSITY AND BEYOND

2014 ◽  
Vol 25 ◽  
pp. 1460045 ◽  
Author(s):  
MARCO RADICI ◽  
ALESSANDRO BACCHETTA ◽  
A. COURTOY
Keyword(s):  
Inelastic Scattering ◽  
Parton Distribution ◽  
Recent Analysis ◽  
Inclusive Production ◽  
Pion Pair ◽  
Collinear Factorization ◽  
Minkowski Space Time ◽  
Fragmentation Functions ◽  
Hadron Pairs ◽  
Θ Vacuum

We summarize the latest achievements about the extraction of the transversity parton distribution based on an analysis of pion-pair production in deep-inelastic scattering off transversely polarized targets in collinear factorization. Recently released data for proton and deuteron targets by HERMES and COMPASS allow for a flavor separation of the valence components of transversity. This extraction relies on di-hadron fragmentation functions. The latter have been taken from the first recent analysis of the semi-inclusive production of two pion pairs in back-to-back jets in e+e- annihilation. We also comment on the possibility of isolating new azimuthally asymmetric correlations of opposite pion pairs, which could arise when a fragmenting quark crosses parity-odd domains localized in Minkowski space-time and induced by the topologically nontrivial QCD background (the so-called θ vacuum).

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