dorsal/arxiv
View SchemaElectromagnetic properties of ground and excited state pseudoscalar mesons
| Authors | A. Hoell, A. Krassnigg, P. Maris, C. D. Roberts, S. V. Wright |
|---|---|
| Categories | |
| ArXiv ID | nucl-th/0503043 |
| URL | https://arxiv.org/abs/nucl-th/0503043 |
| DOI | 10.1103/PhysRevC.71.065204 |
| Journal | Phys.Rev.C71:065204,2005 |
Abstract
The axial-vector Ward-Takahashi identity places constraints on particular properties of every pseudoscalar meson. For example, in the chiral limit all pseudoscalar mesons, except the Goldstone mode, decouple from the axial-vector current. Nevertheless, all neutral pseudoscalar mesons couple to two photons. The strength of the \pi_n^0 \gamma \gamma coupling, where n=0 denotes the Goldstone mode, is affected by the Abelian anomaly's continuum contribution. The effect is material for n \neq 0. The \gamma* \pi_n \gamma* transition form factor, T_{\pi_n}(Q^2), is nonzero for all n, and T_{\pi_n}(Q^2) \approx (4\pi^2/3) (f_{\pi_n}/Q^2) at large Q^2. For all pseudoscalars but the Goldstone mode, this leading contribution vanishes in the chiral limit. In this instance the ultraviolet power-law behaviour is 1/Q^4 for n \neq 0, and we find numerically T_{\pi_1}(Q^2) \simeq (4\pi^2/3) (-<\bar q q>/Q^4). This subleading power-law behaviour is always present. In general its coefficient is not simply related to f_{\pi_n}. The properties of n \neq 0 pseudoscalar mesons are sensitive to the pointwise behaviour of the long-range piece of the interaction between light-quarks.
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"abstract": "The axial-vector Ward-Takahashi identity places constraints on particular\nproperties of every pseudoscalar meson. For example, in the chiral limit all\npseudoscalar mesons, except the Goldstone mode, decouple from the axial-vector\ncurrent. Nevertheless, all neutral pseudoscalar mesons couple to two photons.\nThe strength of the \\pi_n^0 \\gamma \\gamma coupling, where n=0 denotes the\nGoldstone mode, is affected by the Abelian anomaly\u0027s continuum contribution.\nThe effect is material for n \\neq 0. The \\gamma* \\pi_n \\gamma* transition form\nfactor, T_{\\pi_n}(Q^2), is nonzero for all n, and T_{\\pi_n}(Q^2) \\approx\n(4\\pi^2/3) (f_{\\pi_n}/Q^2) at large Q^2. For all pseudoscalars but the\nGoldstone mode, this leading contribution vanishes in the chiral limit. In this\ninstance the ultraviolet power-law behaviour is 1/Q^4 for n \\neq 0, and we find\nnumerically T_{\\pi_1}(Q^2) \\simeq (4\\pi^2/3) (-\u003c\\bar q q\u003e/Q^4). This subleading\npower-law behaviour is always present. In general its coefficient is not simply\nrelated to f_{\\pi_n}. The properties of n \\neq 0 pseudoscalar mesons are\nsensitive to the pointwise behaviour of the long-range piece of the interaction\nbetween light-quarks.",
"arxiv_id": "nucl-th/0503043",
"authors": [
"A. Hoell",
"A. Krassnigg",
"P. Maris",
"C. D. Roberts",
"S. V. Wright"
],
"categories": [
"nucl-th",
"hep-ex",
"hep-lat",
"hep-ph",
"nucl-ex"
],
"doi": "10.1103/PhysRevC.71.065204",
"journal_ref": "Phys.Rev.C71:065204,2005",
"title": "Electromagnetic properties of ground and excited state pseudoscalar mesons",
"url": "https://arxiv.org/abs/nucl-th/0503043"
},
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