dorsal/arxiv
View SchemaPion cloud and the $Q^2-$dependence of $\gamma^* N \leftrightarrow \Delta$ transition form factors
| Authors | S. S. Kamalov, Shin Nan Yang |
|---|---|
| Categories | |
| ArXiv ID | nucl-th/9904072 |
| URL | https://arxiv.org/abs/nucl-th/9904072 |
| DOI | 10.1103/PhysRevLett.83.4494 |
| Journal | Phys.Rev.Lett.83:4494-4497,1999 |
Abstract
Recent experiment indicates that the behavior exhibited by the ratios $E_{1^+}/M_{1^+}$ and $S_{1^+}/M_{1^+}$ of the $\gamma^* N \leftrightarrow \Delta$ transition remain small and negative for $Q^2 \le 4.0 GeV^2$. It implies that the perturbative QCD is still not applicable at these momentum transfers. We show that these data can be explained in a dynamical model for electromagnetic production of pions, together with a simple scaling assumption for the bare $\gamma^* N \Delta$ form factors. Within our model we find that the bare $\Delta$ is almost spherical and the electric E2 and Coulomb C2 quardrupole excitations of the physical $\Delta$ are nearly saturated by pion cloud contribution in $Q^2 \le 4.0 GeV^2$.
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"abstract": "Recent experiment indicates that the behavior exhibited by the ratios\n$E_{1^+}/M_{1^+}$ and $S_{1^+}/M_{1^+}$ of the $\\gamma^* N \\leftrightarrow\n\\Delta$ transition remain small and negative for $Q^2 \\le 4.0 GeV^2$. It\nimplies that the perturbative QCD is still not applicable at these momentum\ntransfers. We show that these data can be explained in a dynamical model for\nelectromagnetic production of pions, together with a simple scaling assumption\nfor the bare $\\gamma^* N \\Delta$ form factors. Within our model we find that\nthe bare $\\Delta$ is almost spherical and the electric E2 and Coulomb C2\nquardrupole excitations of the physical $\\Delta$ are nearly saturated by pion\ncloud contribution in $Q^2 \\le 4.0 GeV^2$.",
"arxiv_id": "nucl-th/9904072",
"authors": [
"S. S. Kamalov",
"Shin Nan Yang"
],
"categories": [
"nucl-th",
"hep-ph"
],
"doi": "10.1103/PhysRevLett.83.4494",
"journal_ref": "Phys.Rev.Lett.83:4494-4497,1999",
"title": "Pion cloud and the $Q^2-$dependence of $\\gamma^* N \\leftrightarrow \\Delta$ transition form factors",
"url": "https://arxiv.org/abs/nucl-th/9904072"
},
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