Abstract
We investigate the decays of the light stop in scenarios with the lightest neutralino χ˜10 being the lightest supersymmetric particle, including flavour-violating (FV) effects. We analyse the region where the three-body decay t˜1→Wbχ˜10 is kinematically allowed and provide a proper description of the transition region between the three-body decay and the four-body decay t˜1→χ˜10bff¯′. The improved treatment has been implemented in the Fortran package SUSY-HIT and is used for the analysis of this region. A scan over the parameter range including all relevant experimental constraints reveals that the FV two-body decay into charm and χ˜10 can be as important as the three-, respectively, four-body decays if not dominant and therefore should be taken into account in order to complete the experimental searches for the light stop.
Highlights
The discovery of a new scalar particle by the LHC experiments ATLAS [1] and CMS [2] has marked a milestone for particle physics
ATLAS searches in final states with two leptons have derived bounds on the stop mass under the assumption that it decays into a b-quark and an on-shell chargino, which decays via a real or virtual W boson, or that the stop decays into a top quark and the lightest neutralino [52]
We investigated in particular the mass range where the three-body decay into W bχ10 is kinematically allowed
Summary
The discovery of a new scalar particle by the LHC experiments ATLAS [1] and CMS [2] has marked a milestone for particle physics. Light stops with masses below the kinematic threshold for the decay into a top quark and the lightest neutralino, assumed to be the lightest SUSY particle (LSP), can decay through the three-body decay t1 → W bχ into the LSP, a W boson and a bottom quark b. If the t1 mass lies below the three-body decay threshold, the light stop, assumed to be the nextto-lightest SUSY particle (NLSP), can decay through a FV process into the LSP and a charm quark c or an up quark u, t1 → (u/c)χ10. ATLAS searches in final states with two leptons have derived bounds on the stop mass under the assumption that it decays into a b-quark and an on-shell chargino, which decays via a real or virtual W boson, or that the stop decays into a top quark and the lightest neutralino [52].
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