Köln 2004 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 40: Theory VI

HK 40.7: Talk

Thursday, March 11, 2004, 15:30–15:45, D

Checking Lorentz-Invariance Relations Between Parton Distributions — •Marc Schlegel¹, Klaus Goeke¹, Andreas Metz¹, Pavel Pobylitsa^1,2, and Maxim Polyakov^1,2 — ¹Institut f. Theor. Physik II, Ruhr-Uni-Bochum, D-44780 Bochum, Germany — ²Petersburg Nuclear Physics Institute, Gatchina, Petersburg, 188300 Russia

Lorentz-invariance relations connecting twist-3 parton distributions with transverse momentum dependent twist-2 distributions have been proposed previously. Naively, these relations can be extracted from a covariant decomposition of the quark-quark correlator. It is argued that the derivation of the Lorentz-invariance relations fails if the path-ordered exponential, which ensures gauge invariance, is taken into account in the correlator. Our model-independent analysis is supplemented by an explicit calculation of the corresponding parton distributions in perturbative QCD with a quark target, and in a simple model of Brodsky-Hwang-Schmidt.