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⋅10−16θe⋅cm. The electric dipole moment of the proton is exactly the opposite.
Theta dependence in holographic QCD / Bartolini, Lorenzo; Bigazzi, Francesco; Bolognesi, Stefano; Cotrone, Aldo L.; Manenti, Andrea. - In: JOURNAL OF HIGH ENERGY PHYSICS. - ISSN 1029-8479. - ELETTRONICO. - 2017:(2017), pp. 029-080. [10.1007/JHEP02(2017)029]
Theta dependence in holographic QCD
BIGAZZI, FRANCESCO;COTRONE, ALDO LORENZO;
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⋅10−16θe⋅cm. The electric dipole moment of the proton is exactly the opposite.I documenti in FLORE sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.