Köln 2004 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 46: Theory VII

HK 46.6: Talk

Thursday, March 11, 2004, 18:15–18:30, D

Gluonic currents and the scaling of nucleon electro-magnetic form factors — •M.M. Kaskulov and P. Grabmayr — Physikalisches Institut der Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen

The ratio µ_pG_E^p/G_M^p decreases for four-momentum transfer Q² larger than ∼1 GeV² indicating different spatial distributions for charge and for magnetization inside the proton. Gluon-exchange currents can explain this behaviour [1]. The SU(6) breaking induced by gluonic currents predicts furthermore the scaling violation in other ratios: the ratio of neutron to proton magnetic form factors µ_pG_Mⁿ/µ_nG_M^p falls and ratio of neutron electric to magnetic form factors µ_nG_Eⁿ/G_Mⁿ rises with increasing Q². We show that the new JLab data are consistent with our expectations.

[1] M.M. Kaskulov and P. Grabmayr, Phys. Rev. C67 (2003) 042201(R)