On a Missed Mechanism of Dielectron Production in Nucleon-Nucleon Collisions

Abstract

We examine a new mechanism of $e^+e^-$ pair production in $NN$ collisions associated with the $NN$-decoupled dibaryon $d^\star_1$(1956) formation in the process $NN \to \gamma^\star d^\star_1$, where $\gamma^\star$ is the virtual photon which converts into a $e^+e^-$ pair. It is shown that a substantial excess of dielectron yields from $Ca+Ca$ and $C+C$ collisions at 1 GeV/A in the dielectron mass spectra in the region from 0.2 to 0.5 GeV/$c^2$ measured by the \textit{DLS Collaboration} as compared with calculated ones can be attributed to the contribution of this mechanism. A simple means for verification of the existence of such a mechanism is proposed.