New constraints on a light CP-odd Higgs boson and related NMSSM Ideal Higgs Scenarios

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Recent BaBar limits on (Υ(3S)→ a→ τ+τ-) and (Υ(3S)→ a→ μ+μ-) provide increased constraints on the a b b coupling of a CP-odd Higgs boson, a, with mₐ<MΥ₍₃ₛ₎. We extract these limits from the BaBar data and compare to the limits previously obtained using other data sets, especially the CLEO-III (Υ(1S)→ →τ+τ-) limits. Comparisons are made to predictions in the context of "ideal"-Higgs NMSSM scenarios, in which the lightest CP-even Higgs boson, h₁, can have mass below 105 (as preferred by precision electroweak data) and yet can escape old LEP limits by virtue of decays to a pair of the lightest CP-odd Higgs bosons, h₁→ a₁a₁, with mₐ₁<2mB. Most such scenarios with mₐ₁<2mτ are eliminated, but the bulk of the mₐ₁>7.5 scenarios, which are theoretically the most favored, survive. We also outline the impact of the new ALEPH LEP results in the → Z+4τ channel. For β≥ 3, only NMSSM ideal Higgs scenarios with mₕ₁ 98 and mₐ₁ close to 2mB satisfy the ALEPH limits. For β 2, the ALEPH limits are easily satisfied for the most theoretically preferred NMSSM scenarios, which are those with mₐ₁ close to 2mB and mₕ₁ 90-100.