Running Coupling and Running Quark Mass Effects on the Elastic Form Factors of Nucleons
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arXiv
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2024
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| author | Yang, Bao-Yi Zhong, Hui-Hua Chen, Muyang |
| author_facet | Yang, Bao-Yi Zhong, Hui-Hua Chen, Muyang |
| contents | We study the elastic electric and magnetic form factors of the proton, neutron and the charged roper resonance ($G_E^p$, $G_M^p$, $G_E^n$, $G_M^n$, $G_E^R$ and $G_M^R$) systematically in a constituent quark model. Three ingredients are crucial in this study: i) the mixing between the pure S-wave and other components which produces a nonzero neutron electric form factor. ii) a running coupling constant that soften the form factors. iii) the running quark mass function, $M_q(p^2)$, which is responsible for the decreasing of the $μ_p G_E^p(Q^2)/G_M^p(Q^2)$ as $Q^2$ increases. The produced elastic form factors of the proton and neutron match the corresponding observed values fairly well. Our study shows that $μ_p G_E^p(Q^2)/G_M^p(Q^2) \approx M_q(Q^2/9)/M_q(0)$ upto $Q^2 \approx 4 \text{ GeV}^2$. We give predictions on the elastic form factors of the roper resonance, the electric charge and the magnetic momentum radius ratios of the roper resonance to the proton are $r^R_{E}/r^p_{E} \approx r^R_{M}/r^p_{M} \approx 1.5$. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2403_19343 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Running Coupling and Running Quark Mass Effects on the Elastic Form Factors of Nucleons Yang, Bao-Yi Zhong, Hui-Hua Chen, Muyang High Energy Physics - Phenomenology High Energy Physics - Theory We study the elastic electric and magnetic form factors of the proton, neutron and the charged roper resonance ($G_E^p$, $G_M^p$, $G_E^n$, $G_M^n$, $G_E^R$ and $G_M^R$) systematically in a constituent quark model. Three ingredients are crucial in this study: i) the mixing between the pure S-wave and other components which produces a nonzero neutron electric form factor. ii) a running coupling constant that soften the form factors. iii) the running quark mass function, $M_q(p^2)$, which is responsible for the decreasing of the $μ_p G_E^p(Q^2)/G_M^p(Q^2)$ as $Q^2$ increases. The produced elastic form factors of the proton and neutron match the corresponding observed values fairly well. Our study shows that $μ_p G_E^p(Q^2)/G_M^p(Q^2) \approx M_q(Q^2/9)/M_q(0)$ upto $Q^2 \approx 4 \text{ GeV}^2$. We give predictions on the elastic form factors of the roper resonance, the electric charge and the magnetic momentum radius ratios of the roper resonance to the proton are $r^R_{E}/r^p_{E} \approx r^R_{M}/r^p_{M} \approx 1.5$. |
| title | Running Coupling and Running Quark Mass Effects on the Elastic Form Factors of Nucleons |
| topic | High Energy Physics - Phenomenology High Energy Physics - Theory |
| url | https://arxiv.org/abs/2403.19343 |