May 16 – 20, 2022
Europe/Zurich timezone

Novel broad-mass search for new scalar particles in FCNC top quark decays using the full Run 2 data of the ATLAS detector

May 17, 2022, 7:00 PM
1h
Experimental poster Top Physics Poster Session I

Speaker

Adrian Salvador Salas (The Barcelona Institute of Science and Technology (BIST) (ES))

Description

No analysis in ATLAS or CMS has so far searched for FCNC decays of top quarks into a new scalar (X) in a broad mass range probing branching ratios below $10^{-3}$. In the case of the Higgs boson, branching ratios $t\to Hu/c$ are predicted within the SM to be of about $O(10^{-17})/O(10^{-15})$. Several beyond-SM theoretical models predict new particles and enhanced branching ratios. In particular, simple SM extensions involve the Froggatt-Nielsen mechanism, which introduces a scalar field with flavour charge, the so-called flavon, featuring flavour violating interactions. Using the full Run 2 data, ATLAS has performed a search for a scalar of a mass in the range between 20 and 160 GeV and decaying into a pair of bottom quarks. In order to distinguish signal from background, a feed-forward neural network that uses kinematic variables together with various invariant masses of pairs of b-jets is used in the fits for the various mass hypotheses. The method, strategy and preliminary results for both FCNC decays $t\to cX$ and $t\to uX$ will be presented.

Primary authors

Adrian Salvador Salas (The Barcelona Institute of Science and Technology (BIST) (ES)) Andreas Korn (University College London (GB))

Presentation materials