Cumulative production of pions by heavy baryonic resonances in proton-nucleus collisions

TL;DR

This paper investigates how heavy baryonic resonances contribute to pion production beyond the kinematic limits in proton-nucleus collisions, emphasizing the role of successive collisions and energy-momentum conservation.

Contribution

It introduces a model where cumulative pions result from heavy baryonic resonances created in p+N reactions and subsequently excited through multiple collisions within the nucleus.

Findings

Successive collisions increase resonance masses and decrease their velocities.

The Ultra relativistic Quantum Molecular Dynamics model highlights the importance of multiple collisions.

Experimental data are needed to explore heavy hadron-like objects.

Abstract

Pion production in proton-nucleus (p+A) collisions outside the kinematical boundary of proton-nucleon (p+N) reactions, the so-called cumulative effect, is studied. Restrictions from energy-momentum conservation on the energy of pions emitted in the backward direction in the target rest frame are analyzed. It is assumed that the cumulative pions are produced in p+A reactions by heavy baryonic resonances. The baryonic resonances are first created in p+N reactions. Due to successive collisions with nuclear nucleons the masses of these resonances may then increase and, simultaneously, their longitudinal velocities decrease. We also use the Ultra relativistic Quantum Molecular Dynamics model to reveal the key role of successive collisions of baryonic resonances with nuclear nucleons for cumulative pion production in p+A reactions. Further experimental studies of cumulative hadron production in p+A reactions at high collision energies are needed to search for heavy hadron-like objects and investigate their properties.