ABSTRACT
At the end of the 1960s, a collaboration of physicists from the Massachusetts Institute of Technology and the Stanford Linear Accelerator Center (SLAC) studied the inner structure of nucleons by passing a high-energy beam of electrons through liquid hydrogen. In the mid-1980s experimental results indicated that essentially none of a nucleon’s spin was attributable to its quarks’ spins. That surprise birthed the “spin crisis.” EMC deep inelastic experiment using a polarized muon beam scattering on a polarized hadron target has raised serious question about spin crisis. The proton spin crisis (sometimes called the proton spin puzzle) is a theoretical crisis precipitated by an experiment carried out by EMC (European Muon collaboration) in 1987 at CERN. This experiment has shocked the particle physics community; none or little proton’s spin can be attributed to the spin of three constituent quarks, two up and one down quark. The concept of rotating proton has been first emphasized by Chou and Yang in 1974. In continuation, there were several attempts; the baryon magnetic moment has been executed to explain the importance of constituent quark rotation. In 1999 M Casu and LM Sehgal in his paper proposed a successful model with collective quark rotation is used in discussing proton’s spin and baryon magnetic moment. After this so many attempts has been tried to get the fitting parameters to the experimental results. Li and X Cai a model with collective quark rotation is used with great success to get the better fits to the experimental results. The contribution from the orbital angular moment with some additional modifications we have calculated to better fits.
