The Electric Dipole Moment of the Nucleons in Holographic QCD

We introduce the strong CP-violation in the framework of AdS/QCD model and calculate the electric dipole moments of nucleons as well as the CP-violating pion-nucleon coupling. Our holographic estimate of the electric dipole moments gives for the neutron d_n=1.08 X 10^{-16} theta (e cm), which is comparable with previous estimates. We also predict that the electric dipole moment of the proton should be precisely the minus of the neutron electric dipole moment, thus leading to a new sum rule on the electric dipole moments of baryons.Comment: 22 pages, no figures. v2: A reference and an acknowledgment added. v3: One more reference, to appear in JHE

Derivative corrections to the Born-Infeld action through beta-function calculations in N=2 boundary superspace

We calculate the beta-functions for an open string sigma-model in the presence of a U(1) background. Passing to N=2 boundary superspace, in which the background is fully characterized by a scalar potential, significantly facilitates the calculation. Performing the calculation through three loops yields the equations of motion up to five derivatives on the fieldstrengths, which upon integration gives the bosonic sector of the effective action for a single D-brane in trivial bulk background fields through four derivatives and to all orders in alpha'. Finally, the present calculation shows that demanding ultra-violet finiteness of the non-linear sigma-model can be reformulated as the requirement that the background is a deformed stable holomorphic U(1) bundle.Comment: 25 pages, numerous figure