Low energy effective hamiltonian for ΔI = 1 nuclear parity violation and nucleonic strangeness

We calculate the low energy effective hamiltonian for isovector (ΔI = 1) nuclear parity violation, including the effects of heavy quarks s, c and b. At the hadronic scale, the hamiltonian contains four-quark operators of the u, d, and s quarks whose coefficients contain leading logarithmic QCD corrections from running between the weak scale and the hadronic scale. The coefficients of the operators involving the s quark are substantially larger than those of the operators involving only the u and d quarks. Recent EMC measurements of the spin-dependent proton structure functions g1^p (x) and measurements of the low-Q² axial nucleon-Z⁰ coupling from neutrino scattering indicate that the nucleon matrix element of the strange vector axial current is substantial. Assumming that the weak amplitude factorizes, this matrix element gives rise to an enhancement in the weak isovector parity violating NNρ{variant} coupling, and consequently an enhancement of hρ{variant}¹. © 1991.

Duke Scholars

Author Roxanne P. Springer Physics