CERN Accelerating science

The cross section of \psi(2S) production as a function of pt and rapidity in pp collisions at 5.02 TeV have been reported in the thesis. These results are crucial for understanding the QCD processes and production of the charmonia. The first measurement of pt and y differential cross sections at 5.02 TeV, are also shown. The production cross section ratio of \psi(2S) and J/\psi , has been studied to explore the energy dependence. Comparing with the published ALICE results at 7, 8 and 13 TeV, it is established that this ratio does not show any significant energy dependence. The cross section of \psi(2S) is described well by the NRQCD calculations except for higher pt bins. The NLO calculation based ICEM model, on the other hand overestimates the data at high pt. The ratio of inclusive \psi(2S)-to-J/\psi production cross sections integrated over pt and y is found to be 0.15+- 0.01 (stat.) +- 0.02 (syst.). The calculations based on NRQCD+CGC well reproduce the ratio as a function of pt and y for pt < 8 GeV/c. The trend of the over cross-section ratio as a function of pt and y is overestimated by the CEM model in the low pt region. The results on the inclusive production at the forward (p-going direction, 2.03 < y_cms < 3.53) and backward (Pb-going direction, -4.46 < y_cms < -2.96) rapidities in p-Pb collisions at 8.16 TeV, have been presented in the thesis in the form of production cross sections, the double cross-section ratios with respect to the J/\psi in p-Pb and pp, and the nuclear modification factors R_pPb. The analysis has been segmented in two parts: 1) pt and y differential cross-section measurement and 2) centrality dependence measurement. The main conclusion which has been drawn from the above observable is that the initial state effects, which are suffcient to explain suppression behavior, but cannot describe the suppression at the backward rapidity where it is found to be significantly suppressed. The final state effects are needed to describe \psi(2S) suppression. Apart from that, no significant energy dependence or pt dependence is observed in RpPb. The multi-differential and single-differential \psi(2S) cross-section measurements are described in the thesis. The analysis of J/\psi in Pb-Pb collisions at 5.02 TeV at forward rapidity has been performed to investigate the recombination scenario in heavy-ion collisions. The high statistics of 2015+2018 datasets made it possible to precisely show the effect of recombination which are visible only at low pt in the most central collisions. This effect induces a slope in the R_AA vs y plot in that particular bins, confirming the role of in-medium recombination of c\bar{c} pairs. The measurement of R_AA of \psi(2S) as a function of pt and centrality, has been presented. The \psi(2S) has been found to be more suppressed compared to J/\psi in semi-central and central collisions. It also shows a decreasing trend with increase of pt.