Measurement of prompt ψ(2S) production cross sections in proton–lead and proton–proton collisions at [formula omitted].

Abstract Measurements of prompt ψ (2S) meson production cross sections in proton–lead (pPb) and proton–proton (pp) collisions at a nucleon–nucleon center-of-mass energy of s NN = 5.02 TeV are reported. The results are based on pPb and pp data collected by the CMS experiment at the LHC, corresponding to integrated luminosities of 34.6 nb − 1 and 28.0 pb − 1 , respectively. The nuclear modification factor R pPb is measured for prompt ψ (2S) in the transverse momentum range 4 < p T < 30 GeV / c and the center-of-mass rapidity range − 2.4 < y CM < 1.93. The results on ψ (2S) R pPb are compared to the corresponding modification factor for prompt J / ψ mesons. The results point to different nuclear effects at play in the production of the excited charmonium state compared to the ground state, in the region of backward rapidity and for p T < 10 GeV / c. [ABSTRACT FROM AUTHOR]