On the definitions of the gamma*N -> N* helicity amplitudes

I. G. Aznauryan; V. D. Burkert; T. -S. H. Lee

On the definitions of the gammaN -> N helicity amplitudes

Nuclear Theory 2008-10-08 v2

Authors: I. G. Aznauryan , V. D. Burkert , T. -S. H. Lee

Abstract

We present definitions and formulas that may be useful for a consistent computation of helicity amplitudes for the process gamma* N -> N* in theoretical approaches. Of particular importance is the correct determination of the common sign of the amplitudes and of the relative sign between the transverse (A12,A32) and longitudinal (S12) amplitudes. This clarification is necessary to clear up confusions present in theoretical works. Using the definitions presented in this paper will enable a direct comparison with amplitudes extracted from experimental data.

Keywords

helicity amplitudes gamma* N -> N* transverse amplitudes longitudinal amplitudes sign convention theoretical approaches

Cite

@article{arxiv.0810.0997,
  title  = {On the definitions of the gamma*N -> N* helicity amplitudes},
  author = {I. G. Aznauryan and V. D. Burkert and T. -S. H. Lee},
  journal= {arXiv preprint arXiv:0810.0997},
  year   = {2008}
}

Comments

8 pages, 3 figures