Contribution of the QCD $\Theta$-term to nucleon electric dipole moment

Understand

We present a calculation of the contribution of the $\Theta$-term to the neutron and proton electric dipole moments using seven 2+1+1-flavor HISQ ensembles.

• We also estimate the topological susceptibility for the 2+1+1 theory to be $\chi_Q = (66(9)(4) \rm MeV)^4$ in the continuum limit at $M_\pi = 135$ MeV.
• The calculation of the nucleon three-point function is done using Wilson-clover valence quarks.
• The CP-violating form factor $F_3$ is calculated by expanding in small $\Theta$.