Hard form factors for meson-baryon strong couplings as derived from deep inelastic lepton scattering

Abstract

As stimulated by earlier attempts for obtaining theπNN andπNδ form factors from the deep inelastic lepton scattering data, we extend the analysis by taking into account effects of additional mesons includingρ, Ω, σ,K, andK ^*, with the coupling constants fixed by the lowenergy nucleon-nucleon and hyperon-nucleon scattering data. Contrary to an earlier claim that theπ NN andπNδ form factor must be very soft (e.g., with the cutoff mass less than 500 MeV in the monopole form), we find, for example, that with all form factors parametrized in the dipole form, a universal cutoff mass of 1150 MeV in theδ/N sector and 1400 MeV in theλ/σ sector yields predictions in excellent agreement with recently published neutrino data on the momentum fractions carried by thes, Ū, and¯d quarks, as well as consistent with the sea-to-valence ratio extracted from the CDHS data and the Femilab E615 experiment. Similar results can also be obtained by using exponential cutoffs for all couplings, or by using monopole forms for some vertices while retaining dipole forms for the rest. The success of the mesonexchange picture in generating the strangeness content in a proton suggests an alternative understanding of the origin of sea quarks in the proton.