0000000001289655
AUTHOR
Gustavo Castelo Branco
The size of X arg(-V-ts V-tb(*) V-cs(*) V-cb) and physics beyond the standard model
We analyse the allowed range of values of chi, both in the Standard Model and in models with New Physics, pointing out that a relatively large value of chi, e.g. of order lambda, is only possible in models where the unitarity of the 3x3 Cabibbo-Kobayashi-Maskawa matrix is violated through the introduction of extra Q=2/3 quarks. We study the interesting case where the extra quark is an isosinglet, determining the allowed range for chi and the effect of a large chi on various low-energy observables, such as CP asymmetries in B meson decays. We also discuss the correlated effects which would be observable at high energy colliders, like decays t -> cZ, modifications of the cross section and for…
Small violations of unitarity, the phase in B-s(0) and visible t-> cZ decays at the LHC
We show that it is possible to accommodate the observed size of the phase in B-s(0) - (B) over bar (0)(s) mixing in the framework of a model with violation of 3 x 3 unitarity. This violation is associated to the presence of a new Q = 2/3 isosinglet quark T, which mixes both with t and c and has a mass not exceeding 500 GeV. The crucial point is the fact that this framework allows for chi equivalent to arg(-VtsVcbVtb*V-cs*) of order lambda, to be contrasted with the situation in the standard model, where chi is constrained to be of order lambda(2). We point out that this scenario implies rare top decays t -> cZ at a rate observable at the LHC and vertical bar V-tb vertical bar significantly …