Speaker
Description
A proper transverse momentum-dependent (TMD) factorization for quarkonium production at low transverse momentum necessitates the convolution of the TMD parton distribution function (TMDPDF) with an additional transverse momentum-dependent function, known as the TMD shape function (TMDShF). We present a phenomenological study of the impact of the TMDShF on quarkonium production in electron-proton collisions, comparing our results with predictions from the standard nonrelativistic QCD (NRQCD) framework. Our analysis demonstrates that the inclusion of the TMDShF provides a qualitative explanation for the HERA data, particularly at low transverse momentum, where standard NRQCD predictions fail. Furthermore, we discuss the implications of a proper treatment of the TMDShF for the extraction of long-distance matrix elements (LDMEs) in the low-to-intermediate transverse momentum regime.
