Parity-violating nucleon-nucleon force in the 1/Nc expansion
Several experimental investigations have observed parity violation (PV) in nuclear systems - a consequence of the weak force between quarks. We apply the 1/Nc expansion of QCD to the P-violating T-conserving component of the nucleon-nucleon (NN) potential. We show there are two leading-order operato...
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2015
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00319007_v114_n6_p_Phillips http://hdl.handle.net/20.500.12110/paper_00319007_v114_n6_p_Phillips |
| Aporte de: |
| Sumario: | Several experimental investigations have observed parity violation (PV) in nuclear systems - a consequence of the weak force between quarks. We apply the 1/Nc 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→p scattering at order Nc. We find an additional four operators at order Nc0sin2θW and six at O(1/Nc). Pion exchange in the PV NN force is suppressed by 1/Nc and sin2θW, providing a quantitative explanation for its nonobservation up to this time. The large-Nc hierarchy of other PV NN force mechanisms is consistent with estimates of the couplings in phenomenological models. The PV observed in p→p scattering data is compatible with natural values for the strong and weak coupling constants: there is no evidence of fine-tuning. © 2015 American Physical Society. |
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