Study of low-PTspectra, sea and valence quark distributions, and correlations in 50-GeV/cπ−—emulsion-nuclei interactions

Abstract

The low-${P}_{T}$ region of secondary pions, the sea and valence quark distributions in the projectile and the target, and rapidity correlations among secondary pions are investigated in interactions of 50-GeV/c ${\ensuremath{\pi}}^{\ensuremath{-}}$ with nuclear emulsion placed in a strong magnetic field. The existence of a sharp peak in the region of ${{P}_{T}}^{2}\ensuremath{\le}0.12$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$ for positive and negative pions in the forward and backward hemispheres in the center-of-mass system is explained on the basis of resonance formation. The production of secondary pions is explained on the basis of the quark-antiquark-recombination model. We have used the valence and sea quark distributions in the pion for explaining the $\frac{{\ensuremath{\pi}}^{+}}{{\ensuremath{\pi}}^{\ensuremath{-}}}$ ratio. We find an enhancement in the number of sea quarks with an increase in nuclear-target size. Single-particle and two-particle inclusive rapidity distributions have been studied. The rapidity-difference distributions and the normalized correlation function $R$ have also been investigated. It is found that no positive correlations among secondary pions are evident at this primary energy.