  Recent direct searches for new massive particles place constraints on the
free parameters of the Littlest Higgs model. Depending on the choice of model
free parameters, the direct search limit on the global symmetry breaking scale
f can range from as low as a few hundred GeV to in excess of 4.5 TeV. The most
stringent constraints are from exclusion of the A_H using high-mass dilepton
resonance searches. The Z_H provides the best constraint in parameter regions
where the A_H decouples from leptons. Current top pair resonance data approach
but do not yet reach a useful limit in the anomaly-cancelling case, but do
provide a constraint for a limited range of parameters in other cases. A
neutral gauge boson is shown to be undetectable in dilepton resonances for a
significant range of parameter space due to decoupling from Standard Model
leptons, providing a counterexample to broad claims that a new neutral gauge
boson (sometimes generically referred to as a Z') is ruled out to a high mass
scale.
