title: Neutron Electric Dipole Moment from Gauge-String Duality.
abstract: We compute the electric dipole moment of nucleons in the large N_{c} QCD model by Witten, Sakai, and Sugimoto with N_{f}=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 d_{n}=1.8×10^{-16}θ e cm. The electric dipole moment of the proton is exactly the opposite.
authors.affiliation: Dipartimento di Fisica "E. Fermi," Universitá di Pisa and INFN, Sezione di Pisa; Largo Bruno Pontecorvo 3, I-56127 Pisa, Italy.|INFN, Sezione di Firenze; Via G. Sansone 1, I-50019 Sesto Fiorentino (Firenze), Italy.|Dipartimento di Fisica e Astronomia, Università di Firenze; Via G. Sansone 1, I-50019 Sesto Fiorentino (Firenze), Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Bartolini
authors.affiliation: Dipartimento di Fisica "E. Fermi," Universitá di Pisa and INFN, Sezione di Pisa; Largo Bruno Pontecorvo 3, I-56127 Pisa, Italy.|INFN, Sezione di Firenze; Via G. Sansone 1, I-50019 Sesto Fiorentino (Firenze), Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Bigazzi
authors.affiliation: Dipartimento di Fisica "E. Fermi," Universitá di Pisa and INFN, Sezione di Pisa; Largo Bruno Pontecorvo 3, I-56127 Pisa, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Bolognesi
authors.affiliation: INFN, Sezione di Firenze; Via G. Sansone 1, I-50019 Sesto Fiorentino (Firenze), Italy.|Dipartimento di Fisica e Astronomia, Università di Firenze; Via G. Sansone 1, I-50019 Sesto Fiorentino (Firenze), Italy.
authors.forename: Aldo L
authors.initials: AL
authors.lastname: Cotrone
authors.affiliation: Dipartimento di Fisica "E. Fermi," Universitá di Pisa and INFN, Sezione di Pisa; Largo Bruno Pontecorvo 3, I-56127 Pisa, Italy.|Institute of Physics, EPFL Rte de la Sorge, BSP 728, CH-1015 Lausanne, Switzerland.
authors.forename: Andrea
authors.initials: A
authors.lastname: Manenti