We compute the electric dipole moment of nucleons in the large Nc QCD model by Witten, Sakai, and Sugimoto with Nf=2 degenerate massive flavors. Baryons in the model are instantonic solitons of an effective five-dimensional action describing the whole tower of mesonic fields. We find that the dipole electromagnetic form factor of the nucleons, induced by a finite topological θ angle, exhibits complete vector meson dominance. We are able to evaluate the contribution of each vector meson to the final result - a small number of modes are relevant to obtain an accurate estimate. Extrapolating the model parameters to real QCD data, the neutron electric dipole moment is evaluated to be dn=1.8×10-16θ e cm. The electric dipole moment of the proton is exactly the opposite.

Neutron Electric Dipole Moment from Gauge-String Duality

BARTOLINI, LORENZO;BOLOGNESI, STEFANO;MANENTI, ANDREA
2017

Abstract

We compute the electric dipole moment of nucleons in the large Nc QCD model by Witten, Sakai, and Sugimoto with Nf=2 degenerate massive flavors. Baryons in the model are instantonic solitons of an effective five-dimensional action describing the whole tower of mesonic fields. We find that the dipole electromagnetic form factor of the nucleons, induced by a finite topological θ angle, exhibits complete vector meson dominance. We are able to evaluate the contribution of each vector meson to the final result - a small number of modes are relevant to obtain an accurate estimate. Extrapolating the model parameters to real QCD data, the neutron electric dipole moment is evaluated to be dn=1.8×10-16θ e cm. The electric dipole moment of the proton is exactly the opposite.
Bartolini, Lorenzo; Bigazzi, Francesco; Bolognesi, Stefano; Cotrone, Aldo L.; Manenti, Andrea
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11568/867512
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