A Covariant model for the nucleon and the Delta
Journal Article
·
· European Physical Journal A
http://dx.doi.org/10.1140/epja/i2008-10599-0
The covariant spectator formalism is used to model the nucleon and the $$\Delta$$(1232) as a system of three constituent quarks with their own electromagnetic structure. The definition of the "fixed-axis" polarization states for the diquark emitted from the initial state vertex and absorbed into the final state vertex is discussed. The helicity sum over those states is evaluated and seen to be covariant. Using this approach, all four electromagnetic form factors of the nucleon, together with the {\it magnetic\/} form factor, $$G_M^*$$, for the $$\gamma N \rightarrow \Delta$$ transition, can be described using manifestly covariant nucleon and $$\Delta$$ wave functions with {\it zero\/} orbital angular momentum $$L$$, but a successful description of $$G_M^*$$ near $Q^2=0$ requires the addition of a pion cloud term not included in the class of valence quark models considered here. We also show that the pure $$S$$-wave model
The covariant spectator formalism is used to model the nucleon and the $$\Delta$$(1232) as a system of three constituent quarks with their own electromagnetic structure. The definition of the "fixed-axis" polarization states for the diquark emitted from the initial state vertex and absorbed into the final state vertex is discussed. The helicity sum over those states is evaluated and seen to be covariant. Using this approach, all four electromagnetic form factors of the nucleon, together with the {\it magnetic\/} form factor, $$G_M^*$$, for the $$\gamma N \rightarrow \Delta$$ transition, can be described using manifestly covariant nucleon and $$\Delta$$ wave functions with {\it zero\/} orbital angular momentum $$L$$, but a successful description of $$G_M^*$$ near $Q^2=0$ requires the addition of a pion cloud term not included in the class of valence quark models considered here. We also show that the pure $$S$$-wave model
- Research Organization:
- Thomas Jefferson Lab National Accelerator Facility
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 955835
- Report Number(s):
- JLAB-THY-08-804; arXiv:0803.3034; DOE/OR/23177-0329
- Journal Information:
- European Physical Journal A, Journal Name: European Physical Journal A Vol. 36
- Country of Publication:
- United States
- Language:
- English
Similar Records
A pure $S$-wave covariant model for the nucleon
Zero-mode contribution in nucleon-delta transition
Pure S-wave covariant model for the nucleon
Journal Article
·
Mon Dec 31 23:00:00 EST 2007
· Phys.Rev.C
·
OSTI ID:883698
Zero-mode contribution in nucleon-delta transition
Journal Article
·
Mon Oct 01 00:00:00 EDT 2007
· Physical Review. D, Particles Fields
·
OSTI ID:21032336
Pure S-wave covariant model for the nucleon
Journal Article
·
Mon Jan 14 23:00:00 EST 2008
· Physical Review. C, Nuclear Physics
·
OSTI ID:21068069