Measurement of quarkonium production in proton-lead and proton-proton collisions at 5.02 TeV with the ATLAS detector

Abstract

The modification of the production of

J / ψ

,

ψ ( 2 S )

, and

Υ ( n S )

(

n = 1 , 2 , 3

) in p+Pb collisions with respect to their production in pp collisions has been studied. The p+Pb and pp datasets used in this paper correspond to integrated luminosities of

28

nb

- 1

and

25

pb

- 1

respectively, collected in 2013 and 2015 by the ATLAS detector at the LHC, both at a centre-of-mass energy per nucleon pair of 5.02 TeV. The quarkonium states are reconstructed in the dimuon decay channel. The yields of

J / ψ

and

ψ (

2 S

)

are separated into prompt and non-prompt sources. The measured quarkonium differential cross sections are presented as a function of rapidity and transverse momentum, as is the nuclear modification factor,

R

p Pb

for

J / ψ

and

Υ ( n S )

. No significant modification of the

J / ψ

production is observed while

Υ ( n S )

production is found to be suppressed at low transverse momentum in p+Pb collisions relative to pp collisions. The production of excited charmonium and bottomonium states is found to be suppressed relative to that of the ground states in central p+Pb collisions.