6533b872fe1ef96bd12d43b9
RESEARCH PRODUCT
Semileptonic decays of light quarks beyond the Standard Model
Vincenzo CiriglianoMartín González-alonsoMartín González-alonsoJames Jenkinssubject
QuarkPhysicsNuclear and High Energy PhysicsParticle physicsMuonCabibbo–Kobayashi–Maskawa matrixPhysics beyond the Standard ModelElectroweak interactionHigh Energy Physics::PhenomenologyFOS: Physical sciencesObservableHigh Energy Physics - PhenomenologyOperator (computer programming)High Energy Physics - Phenomenology (hep-ph)Effective field theoryHigh Energy Physics::Experimentdescription
We describe non-standard contributions to semileptonic processes in a model independent way in terms of in SU(2)(L) x U(1)(Y) invariant effective lagrangian at the weak scale, front which we derive the low-energy effective lagrangian governing muon and beta decays. We find that the deviation from Cabibbo universality, Delta(CKM) equivalent to vertical bar V-ud vertical bar(2) + vertical bar V-us vertical bar(2) + vertical bar V-ub vertical bar(2) - 1, receives contributions from four effective operators. The phenomenological bound Delta(CKM) = (-1 +/- 6) x 10(-4) provides strong constraints on all four operators, corresponding to art effective scale Lambda > 11 TeV (90% CL). Depending on the operator, this constraint is at the same level or better then the Z pole observables. Conversely, precision electroweak constraints alone would allow universality violations as large as Delta(CKM) = -0.01 (90% CL). An observed Delta(CKM) not equal 0 at this level Could be explained in terms of a single four-fermion operator which is relatively poorly constrained by electroweak precision measurements.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2009-08-12 |