Geometrical Pictures, QCD and Radii of Hadrons/ Lighter Nuclei

Abstract

Hadrons are multi-particle systems consisting of quarks and gluons. These constituents cannot escape from hadrons due to their strong interaction, which increases as they move apart. Experimental and theoretical studies of hadronic structure indicate that the extent of this confinement might vary from hadron to hadron depending upon their composition. Similar aspect has also been pointed out in case of nuclei, which needs to be probed. In our work, we have carried out a detailed survey of the experimental and theoretical approaches with special reference to quark structure. Our work is focused upon Generalized Chou Yang model (a geometrical model) and its predictive power about structure of hadrons and nuclei. In the literature, there is an indication that root mean square (rms) radii of hadrons may decrease with increasing strange quark content. In order to test this aspect, we computed rms radii of several hadrons ( , p, ) having varying strange quark content, by using electromagnetic form factors predicted by Generalized Chou Yang model. The computed results indicate that rms radii decrease with increasing strange content in the hadrons (separately for baryons and mesons). The computed rms radii of lighter nuclei are also found to decrease but with an increase in mass. This decrease in the rms radii of lighter nuclei is attributed to the increase in strength of strong interaction amongst nucleons. Greater the number of nucleons, stronger will be the binding inside nucleus, thus decreasing the rms radii or the nuclear size. An analogy is proposed amongst hadrons and nuclei: rms radii decrease as the mass of hadrons/light nuclei increase. The computed results are consistent with those from other theoretical models and experiments.