Scalar dark matter search at the LHC through flavor-changing neutral current top decay

We discuss an extended standard model electroweak sector which contains a stable scalar dark matter particle, the D boson. To search for the D boson at the LHC we exploit the flavor-changing neutral current top quark decay, t→cDD, mediated by the lightest standard model-like Higgs h0 in a two Higgs doublet model framework. The branching ratio for t→cDD in this case can be as high as 10-3, after taking into account constraints arising from the D boson relic abundance. With an integrated luminosity of 10(100) fb-1, the 14 TeV LHC can explore values of this branching ratio that are one (two) order of magnitude smaller in tt production with tt→cbl-(cbl+)+EeT. For a D boson mass < or approx. 60 GeV, mh0 < or approx. 2MZ, 10 fb-1 luminosity and a branching ratio BR(t→cDD)∼10-4, the estimated number of signal events at the 14 TeV LHC is of order 80.