出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：We carry out a feasibility study toward a lattice QCD calculation of the neutron electric dipole moment
(NEDM) in the presence of the q term using two different approaches. In the first method,
we calculate the CP-odd electromagnetic form factor F3, which becomes the NEDM in the zero
momentum transfer limit. At the first order in q , we derive a formula connecting the lattice
three-point function to the CP-odd electromagnetic form factor. In the second method we directly
extract the NEDM from the energy difference between spin-up and spin-down neutron states in
the presence of a constant electric field, without expanding a small but non-zero q . We test both
approaches numerically, employing the domain-wall quark action with the RG improved gauge
action in quenched QCD at a 1
2 GeV on a 163
32 16 lattice, and further applying the
second method to the clover quark action at a similar lattice spacing and nucleon mass. We obtain
good signals from both approaches. In particular the second method works well with both
fermion formulations.
