Subthreshold $K^+$ meson production in proton–nucleus reactions and nucleon spectral function

S.V. Efremov; E.Ya. Paryev

doi:doi:10.1007/s100500050037

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Hadrons and Nuclei

Eur. Phys. J. A 1, 99-114

Subthreshold K⁺ meson production in proton-nucleus reactions and nucleon spectral function

S.V. Efremov¹ - E.Ya. Paryev²

¹ Bonner Nuclear Laboratory, Rice University, P.O. Box 1892, Houston, TX 77005-1892, USA
² Institute for Nuclear Research, Russian Academy of Sciences, Moscow 117312, Russia

Received: 2 April 1997 / Revised version: 7 August 1997

Abstract
The inclusive K⁺ meson production in proton-nucleus collisions in the near threshold and subthreshold energy regimes is analyzed with respect to the one-step ( $pN \to K^+YN$ , $Y=\Lambda,\Sigma$ ) and two-step ( $pN \to NN\pi, NN2\pi;$ $\pi N \to K^+Y$ ) incoherent production processes on the basis of an appropriate new folding model, which takes properly into account the struck target nucleon removal energy and momentum distribution (nucleon spectral function), extracted from recent quasielastic electron scattering experiments and from many-body calculations with realistic models of the NN interaction. Comparison of the model calculations of the K⁺ total and double differential cross sections for the reaction p+C¹² with the existing experimental data is given, illustrating both the relative role of the primary and secondary production channels at considered incident energies and those features of the cross sections which are sensitive to the high momentum and high removal energy part of the nucleon spectral function that is governed by nucleon-nucleon short-range and tensor correlations. It is found that the in-medium modifications of the available for pion and kaon production invariant energies squared due to the respective optical potentials are needed to account for considered experimental data.