scholarly journals Searches for flavour violation and flavour changing neutral currents in top quark final states

2021 ◽  
Author(s):  
Nicolas Maximilian Köhler ◽  
2007 ◽  
Author(s):  
Γρηγόριος Βερμίσογλου

This study contains the first realistic estimate for the CMS/LHC sensitivity to Flavour Changing Neutral Currents (FCNC) in the top quark sector. The non-Standard Model decays t→Zq and t→ γ q (where q = u, c) have been studied at √s = 14 TeV exploiting the leptonic decays of the Z⁰ boson and the photon. A realistic detector simulation has been used and the most important systematic effects have been addressed. The 5-sigma discovery limits for the two decays are BR(t→qZ)= 11.4 x 10⁻⁴ and BR(t→ γ q)= 5.7 x 10⁻⁴, allowing some models of new physics to be tested.


2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Monika Blanke ◽  
Priscilla Pani ◽  
Giacomo Polesello ◽  
Giulia Rovelli

Abstract Models incorporating flavoured dark matter provide an elegant solution to the dark matter problem, evading the tight LHC and direct direction constraints on simple WIMP models. In Dark Minimal Flavour Violation, a simple framework of flavoured dark matter with new sources of flavour violation, the constraints from thermal freeze-out, direct detection experiments, and flavour physics create well-defined benchmark scenarios for these models. We study the LHC phenomenology of four such scenarios, focusing on final states where a single top quark is produced accompanied by no jets, one jet from the fragmentation of light quarks or a b-tagged jet. For each of these signatures we develop a realistic LHC analysis, and we show that the proposed analyses would increase the parameter space coverage for the four benchmarks, compared to existing flavour-conserving LHC analyses. Finally we show the projected discovery potential of the considered signatures for the full LHC statistics at 14 TeV, and for the High Luminosity LHC.


2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Nuno Castro ◽  
Mikael Chala ◽  
Ana Peixoto ◽  
Maria Ramos

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