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arXiv · 0712.2770

Automatic generation of quarkonium amplitudes in NRQCD

P. Artoisenet·F. Maltoni·T. Stelzer
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Abstract

We present a simple method to automatically evaluate arbitrary tree-level amplitudes involving the production or decay of a heavy quark pair QQbar in a generic {2S+1}L_J^[1,8] state, i.e., the short distance coefficients appearing in the NRQCD factorization formalism. Our approach is based on extracting the relevant contributions from the open heavy quark-antiquark amplitudes through an expansion with respect to the quark-antiquark relative momentum and the application of suitable color and spin projectors. To illustrate the capabilities of the method and its implementation in MadGraph a few applications to quarkonium collider phenomenology are presented.

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P. Artoisenet, F. Maltoni, T. Stelzer. 2007-12-17. Automatic generation of quarkonium amplitudes in NRQCD. https://doi.org/10.1088/1126-6708%2F2008%2F02%2F102

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