1,034 research outputs found
Renormalization Group Equations for the CKM matrix
We derive the one loop renormalization group equations for the
Cabibbo-Kobayashi-Maskawa matrix for the Standard Model, its two Higgs
extension and the minimal supersymmetric extension in a novel way. The derived
equations depend only on a subset of the model parameters of the
renormalization group equations for the quark Yukawa couplings so the CKM
matrix evolution cannot fully test the renormalization group evolution of the
quark Yukawa couplings. From the derived equations we obtain the invariant of
the renormalization group evolution for three models which is the angle
of the unitarity triangle. For the special case of the Standard Model
and its extensions with we demonstrate that also the shape
of the unitarity triangle and the Buras-Wolfenstein parameters
and
are conserved. The invariance of the angles of the unitarity triangle means
that it is not possible to find a model in which the CKM matrix might have a
simple, special form at asymptotic energies.Comment: 9 page
Rare top decay and CP violation in THDM
We discuss the formalism of two Higgs doublet model type III with CP
violation from CP-even CP-odd mixing in the neutral Higgs bosons. The flavor
changing interactions among neutral Higgs bosons and fermions are presented at
tree level in this type of model. These assumptions allow the study rare top
decays mediated by neutral Higgs bosons, particularly we are interested in
. For this process we estimated upper bounds of the
branching ratios of the order of
for a neutral Higgs boson mass of 125 GeV and
, 1.5, 2, 2.5. For the case of the
number of possible events is estimated from 1 to 10 events which could be
observed in future experiments at LHC with a luminosity of 300
and 14 GeV for the energy of the center of mass. Also we
estimate that the number of events for the process in
different scenarios is of order of .Comment: 8 pages, 5 figure
Rare top decay t-> c l+l- as a probe of new physics
The rare top decay t-> c l+l-, which involves flavor violation, is studied as
a possible probe of new physics. This decay is analyzed with the simplest
Standard Model extensions with additional gauge symmetry formalism. The
considered extension is the Left-Right Symmetric Model, including a new neutral
gauge boson Z' that allows to obtain the decay at tree level through Flavor
Changing Neutral Currents (FCNC) couplings. The neutral gauge boson couplings
are considered diagonal but family non-universal in order to induce these FCNC.
We find the $BR(t-> c l+l-)~10^{-13} for a range 1 TeV < M_{Z'} < 3 TeV.Comment: 9 pages, 6 figure
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