TY  - JOUR
AU  - Filipuzzi, A.
AU  - Portoles, J.
AU  - Gonzalez-Alonso, M.
PY  - 2012
DA  - 2012//
TI  - U(2)^5 flavor symmetry and lepton universality violation in W -> tau(nu)over-bar(tau)
T2  - Phys. Rev. D
JO  - Physical Review D
SP  - 116010 - 10pp
VL  - 85
IS  - 11
PB  - Amer Physical Soc
AB  - The seeming violation of universality in the tau lepton coupling to the W boson suggested by LEP-II data is studied using an effective field theory (EFT) approach. Within this framework we explore how this feature fits into the current constraints from electroweak precision observables using different assumptions about the flavor structure of New Physics, namely [U(2) x U(1)](5) and U(2)(5). We show the importance of leptonic and semileptonic tau decay measurements, giving 3-4 TeV bounds on the New Physics effective scale at 90% C.L. We conclude under very general assumptions that it is not possible to accommodate this deviation from universality in the EFT framework, and thus such a signal could only be explained by the introduction of light degrees of freedom or New Physics strongly coupled at the electroweak scale.
SN  - 1550-7998
UR  - http://arxiv.org/abs/1203.2092
UR  - https://doi.org/10.1103/PhysRevD.85.116010
DO  - 10.1103/PhysRevD.85.116010
LA  - English
N1  - WOS:000305680800020
ID  - Filipuzzi_etal2012
ER  -