Color coherence effects in the reaction $d(p,2p)n$

TL;DR

This paper investigates color transparency effects in high-energy proton-deuteron reactions, confirming previous findings at lower energies and exploring new oscillatory behaviors at beam momenta up to 75 GeV/c, with implications for nuclear filtering and polarization observables.

Contribution

It extends the analysis of color transparency effects to higher beam energies up to 75 GeV/c, revealing oscillatory behavior in nuclear transparency due to valence quark configuration interference.

Findings

Confirmation of previous transparency dependence on transverse momentum and azimuthal angle at energies below 20 GeV/c

Identification of oscillations in transparency at beam energies above 50 GeV/c due to quark configuration interference

Estimation of event rates at NICA-SPD for experimental validation

Abstract

The hard proton knock-out by the proton from the deuteron at relativistic energies is considered with a focus on the color transparency (CT) effect which influences the initial and final state interactions. The calculations are performed in the framework of the generalized eikonal approximation supplemented by the quantum diffusion model of CT. The main results of the previous calculations [1] at the beam momentum below 20 GeV/c are confirmed, including the dependence of the nuclear transparency on the transverse momentum of the spectator neutron, $p_{st}$, and on the relative azimuthal angle $\phi$ between proton and neutron: absorption at $p_{st} < 0.2$ GeV/c and enhancement at $p_{st} > 0.3$ GeV/c due to rescattering on the neutron, the change of $\phi$-dependence between these two regions, and the enhancement of CT effects with $p_{\rm lab}$. The study is then generalized to higher beam momenta, up to 75 GeV/c. It is shown that such behavior of the transparency is mainly preserved up to $p_{\rm lab}\simeq 50$ GeV/c, but changes significantly at higher beam momenta due to the interference of valence quark configurations of small and large sizes. As a result, the transparency at small $p_{st}$ exhibits oscillations as a function of the beam momentum (the nuclear filtering effect). The tensor analyzing power due to the longitudinal polarization of the deuteron is calculated. The event rate at NICA-SPD is estimated.