The Charm of the Proton and the $Lambda _c^{+}$ Production.pdf

a r X i v : h e p - p h / 9 7 0 2 2 5 7 v 1 5 F e b 1 9 9 7 The Charm of the Proton and the Λ + c Production 1 J. dos Anjos, G. Herrera2, J. Magnin and F.R.A. Sima?o CBPF, Rua Dr. Xavier Sigaud 150, CEP 22290-180 - Urca RJ, Rio de Janeiro, Brazil Abstract. We propose a two component model for charmed baryon production in pp collisions consisting of the conventional parton fusion mechanism and frag- mentation plus quarks recombination in which a ud valence diquark from the proton recombines with a c-sea quark to produce a Λ+c . Our two-component model is compared with the intrinsic charm two-component model and experi- mental data. INTRODUCTION The production mechanism of hadrons containing heavy quarks is not well understood. Although the fusion reactions gg → QQ? and qq → QQ? are sup- posed to be the dominant processes, they fail to explain important features of heavy quark hadro-production like the leading particle effects observed in D± produced in π?p collisions [1], Λ+c production in pp interactions [2] [3] and in others baryons containing heavy quarks [4], the J/Ψ cross section at large xF observed in πp collisions [5], etc. The above mentioned effects have been explained using a two-component model [6] consisting of the parton fusion mechanism calculable in perturbative QCD plus the coalescence of intrinsic charm [7]. In hadron-hadron collisions the recombination of valence spectator quarks with c-quarks present in the sea of the initial hadron is a possible mechanism for charmed hadron production. Here we explore that possibility for the Λ+c ’s production in pp interactions. We will assume that in addition to the usual parton fusion processes, a ud diquark recombines with c-sea quark both from the incident proton. 1) This work was partially supported by Centro Latino Americano de F??sica (CLAF). 2) Permanent address: CINVESTAV, Apdo Postal 14-740 Me?xico DF,Me?xico c? 1995 American Institute of Physics 1 2We compare our results with those of the intrins