Centrality Dependence of Deuteron Production in PbPb Collisions at 2.76 TeV via Hydrodynamics and Hadronic Afterburner

oleh: Dmytro Oliinychenko, Long-Gang Pang, Hannah Elfner, Volker Koch

Format: Article
Diterbitkan: MDPI AG 2019-04-01

Deskripsi

The deuteron binding energy is only 2.2 MeV. At the same time, its yield in Pb+Pb collisions at <inline-formula> <math display="inline"> <semantics> <msqrt> <mi>s</mi><mi>N</mi><mi>N</mi> </msqrt> </semantics> </math> </inline-formula> = 2.76 TeV corresponds to a thermal yield at the temperature around 155 MeV, which is too hot to keep deuterons bound. This puzzle is not completely resolved yet. In general, the mechanism of light nuclei production in ultra-high energy heavy ion collisions remains under debate. In a previous work we suggest a microscopic explanation of the deuteron production in central ultra-relativistic Pb+Pb collisions, the main mechanism being ppn $ pd reactions in the hadronic phase of the collision. We use a state-of-the-art hybrid approach, combining relativistic hydrodynamics for the hot and dense stage and hadronic transport for a later, more dilute stage. Deuteron rescattering in the hadronic stage is implemented explicitly, using its experimentally measured vacuum cross-sections. In these proceedings we extend our previous work to non-central collisions, keeping exactly the same methodology and parameters. We find that our approach leads to a good description of the measured deuteron transverse momentum spectra at centralities up to 40%, and underestimates the amount of deuterons at low transverse momentum at higher centralities. Nevertheless, the coalescence parameter B2, measured by ALICE collaboration, is reproduced well in our approach even for peripheral collisions.