Bessel-weighted asymmetries and the Sivers effect

Leonard Gamberg, Daniël Boer, Bernhard Musch, Alexei Prokudin

Research output: Contribution to journalConference articlepeer-review


We consider the cross section 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.

Original languageEnglish (US)
JournalProceedings of Science
StatePublished - Dec 1 2012
Event6th International Conference on Quarks and Nuclear Physics, QNP 2012 - Palaiseau, Paris, France
Duration: Apr 16 2012Apr 20 2012

All Science Journal Classification (ASJC) codes

  • General


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