Intrinsic charm content of the nucleon and charmness-nucleon sigma term

Abstract

In the extended chiral constituent quark model, the intrinsic cc content of the nucleon is investigated. The probabilities of the quark-antiquark components in the nucleon wave functions are calculated by taking the nucleon to be admixtures of three-and five-quark components, with the relevant transitions handled via the 3 P 0 mechanism. Predictions for the probability of the cc in the nucleon wave function and the charmness-nucleon sigma term are presented. Our numerical results turn out to be consistent with the predictions from various other approaches reported in the literature.

Orbital angular momentum of the proton and intrinsic five-quark Fock states

“…Same as in [32], here the parameters V for Goldstone boson exchange model are taken to be the empirical values [35]. E 0 = 2127 MeV is also an empirical value [32], and V was determined by fitting [32,33] the sea flavor asymmetry of the proton I exp a = 0.118 ± 0.012 [1], resulting in…”

“…The only adjusted parameter, V in Eq. (19), for the Goldstone boson exchange model, was determined by fitting [32,33] the experimental data for the sea flavor asymmetry I a =d −ū = 0.118 ± 0.012 of the proton [1]. This ensemble allowed us postdicting, on the one hand, the strangeness magnetic moment µ s and the strangeness magnetic moment G s M of the proton [37], and on other hand, shedding a light [38] on the measured [39] quark-antiquark ratios r ℓ = uū/dd, r s = ss/dd, and the strangeness content of the proton κ s = 2ss/(uū + dd).…”

“…As shown in [32,33], considering possible pentaquark components, the wave function of the proton can be expressed as follows:…”

“…Lattice QCD calculations is an ongoing long endeavor; see, e.g., [29,30]. Recently, the intrinsic sea flavor content includingū,d,s andc in the nucleon were investigated employing our formalism, within which all the possible five-quark Fock components in the nucleon wave function were taken into account [32,33], coupling between the threeand five-quark components was assumed to be via 3 P 0 quark-antiquark pair creation mech-anism [27], and the coupling strength was fixed by fitting [32,33] the sea flavor asymmetry of the proton [1]. The corresponding obtained pion-nucleon, strangeness-nucleon [34], and charm-nucleon sigma terms [33] were found to be reasonably consistent with predictions by the lattice QCD and chiral perturbation theory.…”

“…Analogous to the meson-cloud description for the nucleon, the five-quark components in the baryons' wave functions naturally contribute to the OAM of the proton, required by the angular momentum conservation law. Consequently, in the present work we study the contributions to the proton' OAM from different quark flavors, by taking into account all possible five-quark Fock components, based on the results obtained in [32,33].…”