Free Meson Seminars

Modified NRQCD, Charmonium Production and the Resolution of the LHCb eta_c anomaly

by Prof. K Sridhar (Azim Premji University, Bengaluru)

Thursday, June 15, 2023 from to (Asia/Kolkata)
at AG69 and on zoom
Description Please contact rishi(at)theory(dot)tifr(dot)res(dot)in for the zoom meeting id and the password for this seminar.

Non-Relativistic QCD (NRQCD) has had considerable success in understanding charmonium production and decays but the true tests of NRQCD -- the parameter-free predictions that rely on the heavy-quark symmetry of the NRQCD Lagrangian viz., the polarisation of J/psi and psi' and the eta_c cross section -- fail miserably to conform with experiment. This has provoked us to propose a modification of NQRCD where we invoke soft, perturbative gluon emission from the intermediate colour-octet c c(bar) states. This model is able to i) provide very good fits to Tevatron data on J/psi, psi' and chi production, ii) provide parameter-free predictions for J/psi, psi' and chi production which are in excellent agreement with the data from LHC, iii) provide a possible resolution of the J/psi and psi' polarisation problem (to be yet fully explored) and iv) provide a complete resolution of the LHCb eta_c anomaly. Some preliminary results on Upsilon production at the LHC will also be presented.