Search for a low-mass Higgs boson in Y(3S) ---> gamma A0, A0 ---> tau+ tau- at BABAR

We search for a light Higgs boson A0 in the radiative decay Υ(3S)→γA0, A0→τ+τ-, τ+→e+νeν̅ τ, or τ+→μ+νμν̅ τ. The data sample contains 122×106 Υ(3S) events recorded with the BABAR detector. We find no evidence for a narrow structure in the studied τ+τ- invariant mass region of 4.03<mτ+τ-<10.10  GeV/c2. We exclude at the 90% confidence level (C.L.) a low-mass Higgs boson decaying to τ+τ- with a product branching fraction B(Υ(3S)→γA0)×B(A0→τ+τ-)>(1.5–16)×10-5 across the mτ+τ- range. We also set a 90% C.L. upper limit on the τ+τ- decay of the ηb at B(ηb→τ+τ-)<8%.