Speaker
Prof.
Blazenka Melic
(Rudjer Boskovic Institute)
Description
The search for the Flavor Changing Neutral Current (FCNC) processes, has been one of the
leading tools to test the Standard Model (SM), in an attempt of either discovering or putting
stringent limits on the new physics scenarios.
Within the SM, there are no FCNC transitions at
tree level, mediated by the Higgs Boson. These processes are severely suppressed by the unitarity
constraints of the Cabibo-Kobayashi-Maskawa matrix. The top quark being the heaviest of all
the quarks has the largest Yukawa coupling to the Higgs boson. The large production rate of the
top quarks in the LHC, allows one to look for transition of the top quark to a quark of different
flavor but same charge. This suggests looking for rare neutral flavor changing transitions, t → cH,
t → uH, as no symmetry prohibits this decay. The SM branching ratio of this process is extremely
small, of the order BR(t → cH) SM ≈ 10 ^(−15). This is many orders of magnitude too small
to be measured in the 14 TeV LHC. Therefore an affirmative observation of the process t → qH,
well above the SM rate, will be a conclusive indication of new physics beyond the SM.
We explore the FCNC top-Higgs decays in detail at polarized linear colliders and compare results with the existing LHC searches to constrain the FCNC couplings. Moreover, we emphasis advantages of linear collider searches over the hadronic ones, in particular for discriminating between chiralites of FCNC couplings.
| I intend to submit my contribution for the proceedings | Yes |
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Primary author
Prof.
Blazenka Melic
(Rudjer Boskovic Institute)
