Leading Effects in the Spectra of ${\Lambda }_c$ and ${\bar{\Lambda }}_c$ Produced in ${\Sigma }^{-}p$, $pp$ and ${\pi }^{-}p$ Interactions

Abstract

The spectra of leading and nonleading charmed baryons (${\Lambda }_c$ and ${\bar{\Lambda }}_c$) as well as the asymmetries between these spectra measured in ${\Sigma }^{-}A$, ${\pi }^{-}A$ and pA collisions at $p_L=600GeV/c$ in the E781 experiment are simultaneously described within the framework of Quark-Gluon String Model (QGSM). It is shown that the charmed baryon spectra can be fitted by QGSM curves calculated with the parameter of diquark fragmentation, $a_f^{{\Lambda }_c}$=0.006. It was obtained in this experiment that the asymmetry between the spectra of ${\Lambda }_c$ and ${\bar{\Lambda }}_c$ in ${\pi }^{-}A$ collisions is of nonzero value. It might be described in our model only assuming that the string junction is transfered from target proton into the kinematical region of pion projectile fragmentation.

Comments: LaTeX, 12 pages, 2 epsfigures, replaced with the minor corrections in language and in references, submitted to Phys.At.Nucl. 2002