Connection between Second Class Currents and the $ΔNγ$ Form Factors $G_M^*(q^2)$ and $G_E^*(q^2)$

Milton Dean Slaughter

paper

Connection between Second Class Currents and the $Δ N γ$ Form Factors $G_{M}^{} (q^{2})$ and $G_{E}^{} (q^{2})$

arXiv:hep-ph/0412161

Abstract

An interesting connection between the nucleon weak axial-vector second class current form factor $g_{T} (q^{2})$ present in the matrix element $< p ∣ A_{π^{+}}^{μ} ∣ n >$ and the $Δ N γ$ form factors $G_{M}^{*} (q^{2})$ and $G_{E}^{*} (q^{2})$ is derived. Using a nonperturbative, relativistic sum rule approach in the infinite momentum frame, $G_{M}^{*} (q^{2})$ and $G_{E}^{*} (q^{2})$ are calculated in terms of $g_{T} (q^{2})$ and the well-known nucleon isovector Sachs form factor $G_{M}^{V}$ as input with no additional model parameters. Reasonable agreement with the data for $G_{M}^{*} (q^{2})$ may be achieved with a non-zero $g_{T} (q^{2})$ 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.

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

Connection between Second Class Currents and the ΔNγ Form Factors GM∗​(q2) and GE∗​(q2)

Abstract

Connection between Second Class Currents and the $Δ N γ$ Form Factors $G_{M}^{} (q^{2})$ and $G_{E}^{} (q^{2})$