Parity-violating nucleon-nucleon force in the 1/N(c) expansion.
Several experimental investigations have observed parity violation (PV) in nuclear systems-a consequence of the weak force between quarks. We apply the 1/N(c) expansion of QCD to the P-violating T-conserving component of the nucleon-nucleon (NN) potential. We show there are two leading-order operators, both of which affect p[over →]p scattering at order N(c). We find an additional four operators at order N(c)(0)sin(2)θ(W) and six at O(1/N(c)). Pion exchange in the PV NN force is suppressed by 1/N(c) and sin(2)θ(W), providing a quantitative explanation for its nonobservation up to this time. The large-N(c) hierarchy of other PV NN force mechanisms is consistent with estimates of the couplings in phenomenological models. The PV observed in p[over →]p scattering data is compatible with natural values for the strong and weak coupling constants: there is no evidence of fine-tuning.
Institute of Nuclear and Particle Physics and Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701, USA.
Daniel R
DR
Phillips
Department of Applied Physics, Faculty of Sciences and Liberal Arts, Rajamangala University of Technology Isan, Nakhon Ratchasima, 30000, Thailand and Thailand Center of Excellence in Physics (ThEP), Commission on Higher Education, Bangkok 10400, Thailand.
Daris
D
Samart
Departamento de Física, FCEyN, Universidad de Buenos Aires and IFIBA, CONICET, Ciudad Universitaria, Pabellón 1, (1428) Buenos Aires, Argentina.
Carlos
C
Schat