paper

Multiplicity dependence of (anti-)deuteron production in pp collisions at = 7 TeV

arXiv:1902.09290 · doi:10.1016/j.physletb.2019.05.028

Abstract

In this letter, the production of deuterons and anti-deuterons in pp collisions at TeV is studied as a function of the charged-particle multiplicity density at mid-rapidity with the ALICE detector at the LHC. Production yields are measured at mid-rapidity in five multiplicity classes and as a function of the deuteron transverse momentum (). The measurements are discussed in the context of hadron-coalescence models. The coalescence parameter , extracted from the measured spectra of (anti-)deuterons and primary (anti-)protons, exhibits no significant -dependence for GeV/, in agreement with the expectations of a simple coalescence picture. At fixed transverse momentum per nucleon, the parameter is found to decrease smoothly from low multiplicity pp Pb-Pb collisions, in qualitative agreement with more elaborate coalescence models. The measured mean transverse momentum of (anti-)deuterons in pp is not reproduced by the Blast-Wave model calculations that simultaneously describe pion, kaon and proton spectra, in contrast to central Pb-Pb collisions. The ratio between the -integrated yield of deuterons to protons, d/p, is found to increase with the charged-particle multiplicity, as observed in inelastic pp collisions at different centre-of-mass energies. The d/p ratios are reported in a wide range, from the lowest to the highest multiplicity values measured in pp collisions at the LHC.

24 pages, 8 captioned figures, 4 tables, authors from page 19, published version, figures at http://alice-publications.web.cern.ch/node/5117

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