Future of Colour Transferring and nuclear filtering

In a variety of models and experiments known as colour transparency, so-called "strongly interacting" particles can exhibit dynamically decreased interactions that defy the laws of classical strong interaction physics. Hadrons were once thought to interact by exchanging spin-0 and spin-1 mesons on a quantum mechanical basis of asymptotic states.

A non-Abelian gauge theory known as quantum chromodynamics (QCD) describes how the non-Abelian charge known as "colour" moves between and inside interacting systems. Hadrons are embedded in an infinitely bigger Hilbert space. The colour singlet operators that produce hadrons can only partially represent the Hamiltonian or the states. Hadrons are explained by QCD in terms of radically novel quark-gluon combinations, some of which coherently cancel their interactions.

There are now numerous experimental settings on the subject of colour transparency, which are briefly described below. There are now several distinctly different theoretical interpretations that have developed as a result of the necessity of making assumptions about the nature of hadrons to move forward. One could argue that the Perkins effect, which was documented in 1955, is the historical source of colour transparency.

 Although there are limits where a mechanism is introduced to make the contributions of these competing models be eliminated, the contributions due to the competing models briefly reviewed below, namely, the Landshoff process and the endpoint contribution, do not get small compared to the contribution due to the short-distance model in any limit.

The existence of several infinities of dynamical degrees of freedom is the main complexity of QCD. While it may be more convenient to just ignore them, what has been done with them must be justified by a theoretical calculation. Since the words refer to coordinate space, a guide is required because calculations are performed in the momentum space or participating quarks. The majority of the information now accessible is now understood in terms of collinear QCD factorized amplitude, where the pertinent hadronic matrix elements are generalized Parton distributions (GPDs). Examining the impact of colour transparency in such kinematics provides a way to observe how rapidly the scattered nucleons are moving through the target nucleus.

At the nexus of nuclear physics and perturbative chromodynamics (pQCD), colour transparency is a fascinating topic. Current nuclear transparency measurements demonstrate that the idea can be tested in various configurations. To shed light on the colour transparency possibility to indicate the dominance of small-distance processes at a specific kinematic position, the further experimental effort is still needed. Several processes were suggested to be examined soon at already-existing facilities, experiments, or projects in this study.

Journal Reference

Jain, P.; Pire, B.; Ralston, J.P., 2022. The Status and Future of Color Transparency and Nuclear Filtering. Physics 2022, 4, 578–589.