Contribution of the spin-1 diquark to the nucleon’sg1structure function

Abstract

This is the final installment of a series of work that we have done in the context of the meson cloud model that investigates F 2 and g 1 structure functions. In our previous work on g 1 structure function, we showed that having a spin-0 quark-diquark for the nucleon core along with both pseudoscalar and vector meson clouds was not sufficient to reproduce experimental observation(s) consistently. For the F 2 structure function, we found that both superposition of a spin-0 diquark and a spin-1 diquark in the nucleon core along with pseudoscalar and vector meson clouds are needed to reproduce the observed F 2 (x) and the Gottfried sum rule (GSR) violation. Therefore, in the present work, we consider the contribution of a spin-1 diquark in the nucleon core to the g 1 structure function. The calculation is performed in the light-cone frame. The dressed nucleon is assumed to be a superposition of the bare nucleon plus virtual light-cone Fock states of baryon-meson pairs. For the bare nucleon, we consider different quark-diquark configurations along with the possibility that there is no diquark inside the nucleon. The initial distributions are evolved. The final results are compared with experimental results and other theoretical predictions.

Contribution of vector mesons to F2 structure function

“…Set-1 and Set-3 are quark-diquark system. For set-1 we assume that the nucleon is a quark-diquark system with spin-0 diquark and for Set-3 a superposition of spin-0 and spin-1 diquarks [1]:…”

“…where x is the fraction of the total momentum of the nucleon being carried by the quark, q, α MB are spin-flavor Clebsch-Gordan coefficients, n MB and n BM ,the splitting functions, are the probabilities of the nucleon being in state of MB or BM respectively, y is the fraction of the momentum being carried by the meson(baryon) in n MB (y)(n BM (y)). We have evaluated the splitting functions for vector mesons-baryon octet pairs [1]: 5) and vector mesons-baryon decuplet pairs [1]:…”