A pinboard by
Rajesh Sangem

PhD, IIT Bomaby


Exploring the proton spin structure

Quarkonium (charmonium and bottomonium) production is one of the most interesting process which endows the information about the spin structure of the proton and also a promising channel to extract the nonperturbative quantities of the proton structure such as transverse momentum dependent (TMD) parton distribution functions (PDFs). TMD PDFs (in short TMDs) are function of both transverse momentum and longitudinal momentum fraction carried by the partons (quarks and gluons), and describe the 3-dimensional structure of the proton. Amongst, the eight leading twist gluon TMDs, unpolarized and linearly polarized (Boer-Mulders) gluon TMDs are the only two TMDs which describe the dynamics of gluons inside the proton. So far no experimental studies have been carried out to extract the unpolarized and Boer-Mulders TMDs from data . However, heavy-quark pair production in semi-inclusive deep inelastic and dijet production in proton-proton collision have been proposed theoretically to extract the unpolarized and linearly polarized gluon TMDs. In my thesis, we are proposing a new channel i.e., quarkonium production in unpolarized proton-proton collision at LHC and RHIC energies. To execute this work, color evaporation model and non-relativistic QCD model are used to calculate the quarkonium cross section. Significant modulation in the transverse momentum spectrum of quarkonium has been observed when taking into account the linearly polarized gluons along with the unpolarized gluons in the scattering process. The theoretical predictions are in good agreement with data. Hence quarkonium production is a handy tool to extract the unpolarized and linearly polarized gluon TMDs.