Electric dipole moment of the neutron from 2+1 flavor lattice QCD

Roger Horsley, F.K. Guo, Ulf Meissner, Yoshifumi Nakamura, Holger Perlt, Paul Rakow, Gerrit Schierholz, Arwed Schiller, James Zanotti

Research output: Contribution to journalArticlepeer-review


We compute the electric dipole moment d(n) of the neutron from a fully dynamical simulation of lattice QCD with 2 + 1 flavors of clover fermions and nonvanishing theta term. The latter is rotated into a pseudoscalar density in the fermionic action using the axial anomaly. To make the action real, the vacuum angle θ is taken to be purely imaginary. The physical value of dₙ is obtained by analytic continuation. We find dₙ = - 3.9(2)(9) x 10⁻¹⁶ theta e cm, which, when combined with the experimental limit on dₙ, leads to the upper bound |θ| ≲ 7.4 x 10⁻¹¹.
Original languageEnglish
Article number062001
Number of pages6
JournalPhysical Review Letters
Issue number6
Publication statusPublished - 3 Aug 2015


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