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    Strange Asymmetries in the Nucleon

    Session IB08 - Deeply Inelastic Scattering and Hadron Structure.
    ORAL session, Tuesday morning, March 23
    Room 215E, GWCC

    Manuel Malheiro (Univ. Federal Fluminense, Rio de Janeiro), Wally Melnitchouk, Josef Speth (Forschungszentrum Juelich)

    The question of ``how much'' strangeness there is in the nucleon has been quite topical for at least the last decade. One of the earlier indicators of a non-negligible strangeness presence in the nucleon came with measurement of the strange axial matrix elements in polarised deep-inelastic scattering. Subsequently, parity-violating electron scattering experiments at MIT/Bates and more recently at Jefferson Lab have sought to measure the strange electromagnetic form factors of the nucleon at low Q^2. Any reasonable model of the non-perturbative sea quark of the nucleon must be compatible with the symmetries of QCD. One symmetry which has proved to be quite important in the study of hadronic structure and interactions is chiral symmetry. Applied to the SU(3) sector, it predicts a number of novel effects for the strange quark distributions in the nucleon, at both high and low energy scales. We outline the consequences of a kaon cloud of the nucleon for the strange elastic electromagnetic form factors, the strange axial charge, measured in elastic neutrino-nucleon scattering, and the asymmetry between the unpoalrized strange and antistrange distributions, measured in neutrino-nucleon deep-inelastic scattering. We take particular care to ensure that symmetries such as Lorentz covariance are respected in the model framework.



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