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arXiv · 0802.2221

Modelling light-cone distribution amplitudes from non-relativistic bound states

Guido Bell·Thorsten Feldmann
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Abstract

We calculate light-cone distribution amplitudes for non-relativistic bound states, including radiative corrections from relativistic gluon exchange to first order in the strong coupling constant. We distinguish between bound states of quarks with equal (or similar) mass, m_1 ~ m_2, and between bound states where the quark masses are hierarchical, m_1 >> m_2. For both cases we calculate the distribution amplitudes at the non-relativistic scale and discuss the renormalization-group evolution for the leading-twist and 2-particle distributions. Our results apply to hard exclusive reactions with non-relativistic bound states in the QCD factorization approach like, for instance, (B_c -> eta_c l nu) or (e^+ e^- -> J/psi eta_c). They also serve as a toy model for light-cone distribution amplitudes of light mesons or heavy B and D mesons, for which certain model-independent properties can be derived. In particular, we calculate the anomalous dimension for the B meson distribution amplitude phi_B^-(w) in the Wandzura-Wilczek approximation and derive the according solution of the evolution equation at leading logarithmic accuracy.

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Guido Bell, Thorsten Feldmann. 2008-02-25. Modelling light-cone distribution amplitudes from non-relativistic bound states. https://doi.org/10.1088/1126-6708%2F2008%2F04%2F061

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