Article Dans Une Revue Physics Letters B Année : 2000

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

Résumé

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.

Dates et versions

hal-00013016 , version 1 (03-11-2005)

Identifiants

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V. M. Braun, G. P. Korchemsky, A. N. Manashov. Evolution of twist-three parton distributions in QCD beyond the large N_c limit. Physics Letters B, 2000, 476, pp.455-464. ⟨hal-00013016⟩
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