TY  - JOUR
AU  - Cirigliano, V.
AU  - Jenkins, J. P.
AU  - Gonzalez-Alonso, M.
PY  - 2010
DA  - 2010//
TI  - Semileptonic decays of light quarks beyond the Standard Model
T2  - Nucl. Phys. B
JO  - Nuclear Physics B
SP  - 95
EP  - 115
VL  - 830
IS  - 1-2
PB  - Elsevier Science Bv
KW  - Semileptonic decays
KW  - CKM unitarity
KW  - Effective theory
KW  - Beyond the Standard Model
AB  - 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.
SN  - 0550-3213
UR  - http://lanl.arxiv.org/abs/0908.1754
UR  - https://doi.org/10.1016/j.nuclphysb.2009.12.020
DO  - 10.1016/j.nuclphysb.2009.12.020
LA  - English
N1  - ISI:000275150000003
ID  - Cirigliano_etal2010
ER  -