Electromagnetic properties of the {Delta}(1232)
- Institut fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)
We calculate the electromagnetic moments and radii of the {Delta}(1232) in the nonrelativistic quark model, including two-body exchange currents. We show that two-body exchange currents lead to nonvanishing {Delta} and N{r_arrow}{Delta} transition quadrupole moments even if the wave functions have no D-state admixture. The usual explanation based on the single-quark transition model involves D-state admixtures but no exchange currents. We derive a parameter-free relation between the N{r_arrow}{Delta} transition quadrupole moment and the neutron charge radius, namely Q{sub N{r_arrow}{Delta}}=(1/{radical}(2))r{sub n}{sup 2}. Furthermore, we calculate the M1 and E2 amplitudes for the process {gamma}+N{r_arrow}{Delta}. We find that the E2 amplitude receives sizable contributions from exchange currents. These are more important than the ones that result from D-state admixtures due to tensor forces between quarks if a reasonable quark core radius of about 0.6 fm is used. We obtain a ratio of E2/M1={minus}3.5{percent}. {copyright} {ital 1997} {ital The American Physical Society}
- OSTI ID:
- 435282
- Journal Information:
- Physical Review, C, Vol. 55, Issue 1; Other Information: PBD: Jan 1997
- Country of Publication:
- United States
- Language:
- English
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