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Nuclear Parity Violation

S.R. Beane and M.J. Savage

Our understanding of nuclear parity violation is limited by our present inability to compute hadronic matrix elements of the parity-violating four-quark operators that arise in the low-energy effective theory of the weak interaction. Further, a consistent picture at the hadronic level is yet to emerge from experimental measurements due to nuclear uncertainties. We motivate lattice QCD studies of the parity-violating pion-nucleon coupling constant and extend flavor-conserving hadronic parity-violation from QCD to partially-quenched QCD. The parity-violating pion-nucleon coupling and the anapole form factor (and moment) of the proton are computed to one-loop order in the partially-quenched chiral expansion. For the parity-violating pion-nucleon interaction, we include the contributions from total derivative operators necessary to match the kinematics that will be used in lattice simulations.

Figure 3: Tree-level contributions to the parity-violating vertex with lattice kinematics. The crossed circle denotes an insertion of the parity-violating pion-nucleon operators. The solid square denotes an insertion of the energy-momentum dependent operators. The crossed-box denotes an insertion of energy-momentum at the weak vertex.
\begin{figure}\centerline{{\epsfxsize=3.5in \epsfbox{weakcounter.eps}}}\vskip 0.15in
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next up previous contents
Next: Strange Matrix Elements Up: Lattice QCD Previous: The Potential   Contents
Martin Savage 2003-08-06