Search for top squarks at Tevatron inspired by dark matter and electroweak baryogenesis

摘要

The search for the top squark ((t) over bar (1)) within the kinematic reach of Tevatron Run II is of great contemporary interest. Such a (t) over bar (1) can explain the baryon asymmetry of the universe provided 120 GeV <= m((t) over bar1) <= m(t). Moreover if Delta m m((t) over bar1) - m((chi) over bar1)(0) is small, where (chi) over bar (0)(1) is the lightest supersymmetric particle (LSP), the dark matter relic density as obtained from the WMAP data may be explained via (t) over bar (1)-LSP coannihilation. In this scenario the decay (t) over bar (1) -> c (chi) over bar (0)(1) is likely to occur with 100% branching ratio but for small Delta m the conventional di-jet + is not an element of(T) signal becomes unobservable. We propose a new search strategy based on the di-jet + is not an element of T signature accompanied by an isolated cluster of energy which arises from a decaying heavy particle with characteristic decay length. Our preliminary simulations with Pythia indicate that for 100 GeV <= m (t) over bar (1) <= 130 GeV this signal may be observable while somewhat lager m (t) over bar (1) may still provide hints of new physics. (C) 2008 Elsevier B.V. All rights reserved.