Mechanisms of high energy polarized photoproduction of $π^{-}Δ^{++}$
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| Main Authors: | , , , , , , , , , |
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| Format: | Preprint |
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2026
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| _version_ | 1866908991201738752 |
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| author | Shastry, Vanamali Bibrzycki, Łukasz Mathieu, Vincent Montaña, Glòria Pilloni, Alessandro Fernández-Ramírez, César Perry, Robert J. Rodas, Arkaitz Szczepaniak, Adam P. Winney, Daniel |
| author_facet | Shastry, Vanamali Bibrzycki, Łukasz Mathieu, Vincent Montaña, Glòria Pilloni, Alessandro Fernández-Ramírez, César Perry, Robert J. Rodas, Arkaitz Szczepaniak, Adam P. Winney, Daniel |
| contents | We present an amplitude analysis of high-energy polarized photoproduction of $π^-Δ^{++}$ within a Regge exchange framework. A Regge amplitude model incorporating $π$, $ρ$, $b_1$, and $a_2$ trajectory exchanges is fit simultaneously to spin density matrix elements measured by the GlueX experiment at photon energies of $E_γ= 8.2$--$8.8$ GeV and differential cross section data from SLAC. By including SDME data, the fit constrains not only the magnitudes but also the relative phases of the helicity amplitudes. The results confirm the dominance of pion exchange at small momentum transfer, while natural parity exchanges become significant at larger $t$. We analytically continue the $s$-channel amplitude to the $t$-channel, taking care of the kinematical singularities, and isolate the dynamical residues at the meson poles. The extracted $πNΔ$ coupling constant is found to be consistent with the value obtained from the decay width of the $Δ(1232)$. For the $ρNΔ$, $b_1 NΔ$, and $a_2 NΔ$ vertices, first extractions of the relevant coupling constants are provided. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2604_22719 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Mechanisms of high energy polarized photoproduction of $π^{-}Δ^{++}$ Shastry, Vanamali Bibrzycki, Łukasz Mathieu, Vincent Montaña, Glòria Pilloni, Alessandro Fernández-Ramírez, César Perry, Robert J. Rodas, Arkaitz Szczepaniak, Adam P. Winney, Daniel High Energy Physics - Phenomenology Nuclear Theory We present an amplitude analysis of high-energy polarized photoproduction of $π^-Δ^{++}$ within a Regge exchange framework. A Regge amplitude model incorporating $π$, $ρ$, $b_1$, and $a_2$ trajectory exchanges is fit simultaneously to spin density matrix elements measured by the GlueX experiment at photon energies of $E_γ= 8.2$--$8.8$ GeV and differential cross section data from SLAC. By including SDME data, the fit constrains not only the magnitudes but also the relative phases of the helicity amplitudes. The results confirm the dominance of pion exchange at small momentum transfer, while natural parity exchanges become significant at larger $t$. We analytically continue the $s$-channel amplitude to the $t$-channel, taking care of the kinematical singularities, and isolate the dynamical residues at the meson poles. The extracted $πNΔ$ coupling constant is found to be consistent with the value obtained from the decay width of the $Δ(1232)$. For the $ρNΔ$, $b_1 NΔ$, and $a_2 NΔ$ vertices, first extractions of the relevant coupling constants are provided. |
| title | Mechanisms of high energy polarized photoproduction of $π^{-}Δ^{++}$ |
| topic | High Energy Physics - Phenomenology Nuclear Theory |
| url | https://arxiv.org/abs/2604.22719 |