Probing top flavour-changing neutral scalar couplings at the CERN LHC

Top decays into a light Higgs boson and an up or charm quark can reach detectable levels in Standard Model extensions with two Higgs doublers or with new exotic quarks, and in the Minimal Supersymmetric Standard Model. Using both a standard and a neural network analysis we show that the CERN Large Hadron Collider will give 3 sigma evidence of decays with Br(t --> Hc) greater than or equal to 6.5 x 10(-5) or set a limit Br(t --> Hc) less than or equal to 4.5 x 10(-5) with a 95% confidence level if these decays are not observed. We also consider limits obtained from single top production associated with a neutral Higgs boson. (C) 2000 Elsevier Science B.V. All rights reserved.