/ Phenomenology-HEP hep-ph/0103073

Open charm enhancement by secondary interactions in relativistic nucleus-nucleus collisions?

Cassing, W. (Giessen U.) ; Kondratyuk, L.A. (Moscow, ITEP) ; Lykasov, G.I. (Dubna, JINR) ; Rzjanin, M.V. (Dubna, JINR)

Published in: Phys.Lett.
Year: 2001
Vol.: B513
Page No: 1-8
Pages: 14

Abstract: We calculate open charm production in $Pb+Pb$ reactions at SPS energies within the HSD transport approach - which is based on string, quark, diquark ($q, \bar{q}, qq, \bar{q}\bar{q}$) and hadronic degrees of freedom - including the production of open charm pairs from secondary 'meson'-'baryon' (or quark-diquark and antiquark-diquark) collisions. It is argued that at collision energies close to the $c\bar{c}$ pair threshold the dominant production mechanism is related to the two body (or quasi two body) reactions $\pi N \to \bar{D} (\bar{D^*}) \Lambda_c, (\Sigma_c)$. Estimates within the framework of the Quark-Gluon String model suggest cross sections of a few $\mu b$ for $\pi N \to \bar{D} \Lambda_c$ in the region of 1 GeV above threshold. The dynamical transport calculations for $Pb + Pb$ at 160 A$\cdot$GeV indicate that the open charm enhancement reported by the NA50 Collaboration might be due to such secondary reaction mechanisms.

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