München 2006 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 58: Theorie

HK 58.1: Vortrag

Freitag, 24. März 2006, 14:00–14:15, B

The Nucleon to Delta Transition in chiral effective field theory — •Tobias A. Gail and Thomas R. Hemmert — Institut für theoretische Physik T39, Physik Department der TU-München

Based on a nonrelativistic approach of chiral effective field theory with explicit Δ degrees of freedom [1,2] we discuss the three form factors parameterizing the isovector N to Δ transition matrix element. We present predictions for the momentum-dependence of the magnetic dipole as well as the electric- and charge quadrupole contributions to the total transition current [3]. Non-zero values for quadrupole transition form factors are typically discussed in terms of non-spherical components in the nucleon wave function. We compare our results with recent experimental data and phenomenological models .
Furthermore we explore the possibility of utilizing these ChEFT results for studying the quark mass dependence of the transition form factors and discuss the chiral extrapolation of recent lattice data of ref.[4].

[1] T.Hemmert, B.Holstein and J.Kambor, J.Phys. G24:1831.(1998)

[2] G.Gellas, T.Hemmert, C.Ktorides and G.Poulis, Phys.Rev., D60:054022 (1999).

[3] T.Gail and T.Hemmert, forthcoming.

[4] C.Alexandrou et al., Phys.Rev. D69:114506 (2004).