T-2, Nuclear and Particle Physics, Astrophysics and Cosmology

Novel Fragmentation Functions in Quarkonium Production

Thomas Mehen

Current calculations of quarkonium production within the NRQCD factorization formalism do a decent job of describing the world data on quarkonia production, but there remain outstanding puzzles, especially the polarization of quarkonia at large p_T. In this talk I describe two new ideas for high p_T quarkonium production. When quarkonium production is formulated as an expansion in m_Q/p_T, double parton fragmentation functions (DPFF) appear at subleading order. I present new evolution equations for the DPFF which will allow new resummations of large logs of m_Q/p_T. Next I discuss the production of quarkonia within jets. The energy fraction of the onia within the jet is determined a new distribution called a fragmenting jet function (FJF). I will explain how this can be calculated in NRQCD and show that measurements of these distributions can discriminate between the various NRQCD production mechanisms and test existing extractions of the NRQCD matrix elements.


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