The strangeness form factors of the proton within nonrelativistic constituent quark model revisited

Abstract

We reexamine, within the nonrelativistic constituent quark model (NRCQM), a recent claim that the current data on the strangeness form factors indicates that the uudss¯ component in the proton is such that the uuds subsystem has the mixed spatial symmetry [31]X and flavor spin symmetry [4]FS[22]F[22]S, with s¯ in S state (configuration I). We find this claim to be invalid if corrected expressions for the contributions of the transition current to GAs and GEs are used. We show that, instead, it is the lowest-lying uudss¯ configuration with uuds subsystem of completely symmetric spatial symmetry [4]X and flavor spin symmetry [4]FS[22]F[22]S, with s¯ in P state (configuration II), which could account for the empirical signs of all form factors GEs, GMs, and GAs. Further, we find that removing the center-of-mass motion of the clusters will considerably enhance the contributions of the transition current. We also demonstrate that it is possible to give a reasonable description of the existing form factors data with a tiny probability Pss¯=0.025% for the uudss¯ component. We further see that with a small admixture of configuration I, the agreement of our prediction with the data for GAs at low-q2 region can be markedly improved. We find that without removing CM motion, Pss¯ would be overestimated by about a factor of four in the case when transition current dominates. We also explore the consequence of a recent estimate reached from analyzing the existing data on d¯−u¯, s+s¯, and u¯+d¯−s−s¯, that Pss¯ lies between 2.4–2.9%. It would lead to a large size for the five-quark system and a small bump in both GEs+ηGMs and GEs in the region of q2⩽0.1 GeV2 within the considered model.