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Evolution of twist-three parton distributions in QCD beyond the large N_c limit

V. M. Braun·G. P. Korchemsky·A. N. Manashov
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Abstract

We formulate a consistent 1/N_c^2 expansion of the QCD evolution equations for the twist-three quark distributions g_2(x,Q^2), h_L(x,Q^2) and e(x,Q^2) based on the interpretation of the evolution as a three-particle quantum-mechanical problem with hermitian Hamiltonian. Each distribution amplitude can be decomposed in contributions of partonic components with DGLAP-type scale dependence. We calculate the 1/N_c^2 corrections to the evolution of the dominant component with the lowest anomalous dimension - the only one that survives in the large-N_c limit - and observe a good agreement with the exact numerical results for N_c=3. The 1/N_c^2 admixture of operators with higher anomalous dimensions is shown to be concentrated at a few lowest partonic components and in general is rather weak.

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V. M. Braun, G. P. Korchemsky, A. N. Manashov. 2000-01-14. Evolution of twist-three parton distributions in QCD beyond the large N_c limit. https://doi.org/10.1016/s0370-2693(00)00131-3

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