Equal-velocity scenario for hiding dark matter at the LHC.

We consider a light supersymmetric top-quark (top-squark) scenario, where a top squark and a neutralino are the lightest supersymmetric particles and the top-squark mass is close to the sum of the neutralino mass and the top-quark mass. In this scenario, the top quark and the neutralino coming from the decay of a top squark have almost equal velocity vectors, and hence the missing transverse momentum in top-squark pair production events at colliders is suppressed, which makes the top-squark search challenging, as in the degenerate scenario where the top-squark mass and the neutralino mass are similar. In this paper, we propose a novel analysis technique aimed at discovering the top-squark pair production signal in such an "equal-velocity" scenario. The key is to look for events where the missing transverse momentum vector is proportional to the transverse momentum vector of the top-quark pair with specific values for the proportionality coefficient, as this coefficient is equal to the ratio of the neutralino mass over the top-quark mass in the equal-velocity limit. We examine the possibility that the top-squark signal can be identified at the √s = 14 TeV LHC using our analysis method. [ABSTRACT FROM AUTHOR]