6533b835fe1ef96bd12a0054
RESEARCH PRODUCT
Isospin breaking in the nucleon mass and the sensitivity of β decays to new physics.
M Gonzalez-alonsoJ. Martin Camalichsubject
Particle physicsScalar (mathematics)Lattice field theoryNuclear TheoryGeneral Physics and AstronomyFOS: Physical sciences01 natural sciencesNuclear physicsHigh Energy Physics - Phenomenology (hep-ph)High Energy Physics - Lattice0103 physical sciencesNuclear Experiment (nucl-ex)010306 general physicsNuclear ExperimentNuclear ExperimentQuantum chromodynamicsPhysicsIsovector010308 nuclear & particles physicsHigh Energy Physics - Lattice (hep-lat)Lattice QCDQC0793PseudoscalarHigh Energy Physics - PhenomenologyIsospinHigh Energy Physics::ExperimentNucleondescription
We discuss the consequences of the approximate conservation of the vector and axial currents for the hadronic matrix elements appearing in beta decay if non-standard interactions are present. In particular the isovector (pseudo)scalar charge g_S(P) of the nucleon can be related to the difference (sum) of the nucleon masses in the absence of electromagnetic effects. Using recent determinations of these quantities from phenomenological and lattice QCD studies we obtain the accurate values g_S=1.02(11) and g_P=349(9) in the MS-bar scheme at mu=2 GeV. The consequences for searches of non-standard scalar interactions in nuclear beta decays are studied, finding epsilon_S=0.0012(24) at 90%CL, which is significantly more stringent than current LHC bounds and previous low-energy bounds using less precise g_S values. We argue that our results could be rapidly improved with updated computations and the direct calculation of certain ratios in lattice QCD. Finally we discuss the pion-pole enhancement of g_P, which makes beta decays much more sensitive to non-standard pseudoscalar interactions than previously thought.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2013-09-17 | Physical review letters |