English

Connection between Second Class Currents and the $\Delta N\gamma$ Form Factors $G_M^*(q^2)$ and $G_E^*(q^2)$

High Energy Physics - Phenomenology 2007-05-23 v3

Abstract

An interesting connection between the nucleon weak axial-vector second class current form factor gT(q2)g_{T}(q^{2}) present in the matrix element <pAπ+μn>< {p} | A_{\pi ^{+}}^{\mu}| {n} > and the ΔNγ\Delta N\gamma form factors GM(q2)G_{M}^{\ast}(q^{2}) and GE(q2)G_{E}^{\ast}(q^{2}) is derived. Using a nonperturbative, relativistic sum rule approach in the infinite momentum frame, GM(q2)G_{M}^{\ast}(q^{2}) and GE(q2)G_{E}^{\ast}(q^{2}) are calculated in terms of gT(q2)g_{T}(q^{2}) and the well-known nucleon isovector Sachs form factor GMVG_{M}^{V} as input with no additional model parameters. Reasonable agreement with the data for GM(q2)G_{M}^{\ast}(q^{2}) may be achieved with a non-zero gT(q2)g_{T}(q^{2}) too large to be accommodated in the Standard Model. We surmise that it is plausible that second class current-associated pion cloud effects are playing a significant role in pion electroproduction processes and perhaps must be taken into account in those methodologies which utilize effective Lagrangians.

Keywords

Cite

@article{arxiv.hep-ph/0412161,
  title  = {Connection between Second Class Currents and the $\Delta N\gamma$ Form Factors $G_M^*(q^2)$ and $G_E^*(q^2)$},
  author = {Milton Dean Slaughter},
  journal= {arXiv preprint arXiv:hep-ph/0412161},
  year   = {2007}
}

Comments

7 pages including 2 figures with captions. Several typos corrected ver. 2. Pacs Numbers typo and typo in paragraph after Eq. (6) corrected ver. 3