Based on the full BABAR data sample, we report improved measurements of the ratios RðDÞ ¼ BðB ! D À Þ=BðB ! D' À ' Þ and RðD Ã Þ ¼ BðB ! D Ã À Þ=BðB ! D Ã ' À ' Þ, where ' refers to either an electron or muon. These ratios are sensitive to new physics contributions in the form of a charged Higgs boson. We measure RðDÞ ¼ 0:440 AE 0:058 AE 0:042 and RðD Ã Þ ¼ 0:332 AE 0:024 AE 0:018, which exceed the standard model expectations by 2:0 and 2:7, respectively. Taken together, the results disagree with these expectations at the 3:4 level. This excess cannot be explained by a charged Higgs boson in the type II two-Higgs-doublet model. Kinematic distributions presented here exclude large portions of the more general type III two-Higgs-doublet model, but there are solutions within this model compatible with the results.
Recent investigations have suggested that the six-quark combination uuddss could be a deeply bound state (S) that has eluded detection so far, and a potential dark matter candidate. We report the first search for a stable, doubly strange six-quark state in Υ → S Λ Λ decays based on a sample of 90 × 10 6 Υ (2S) and 110 × 10 6 Υ (3S) decays collected by the BABAR experiment. No signal is observed, and 90% confidence level limits on the combined Υ (2S, 3S) → S Λ Λ branching fraction in the range (1.2 − 1.4) × 10 −7 are derived for mS < 2.05 GeV. These bounds set stringent limits on the existence of such exotic particles.
We search for the flavor-changing neutral-current decays B → K ( * ) νν, and the invisible decays J/ψ → νν and ψ(2S) → νν via B → K ( * ) J/ψ and B → K ( * ) ψ(2S) respectively, using a data sample of 471 × 10 6 BB pairs collected by the BABAR experiment. We fully reconstruct the hadronic decay of one of the B mesons in the Υ (4S) → BB decay, and search for the B → K ( * ) νν decay in the rest of the event. We observe no significant excess of signal decays over background and report branching fraction upper limits of B(B + → K + νν) < 3.7 × 10 −5 , B(B 0 → K 0 νν) < 8.1 × 10 −5 , B(B + → K * + νν) < 11.6 × 10 −5 , B(B 0 → K * 0 νν) < 9.3 × 10 −5 , and combined upper limits of B(B → Kνν) < 3.2 × 10 −5 and B(B → K * νν) < 7.9 × 10 −5 , all at the 90% confidence level. For the invisible quarkonium decays, we report branching fraction upper limits of B(J/ψ → νν) < 3.9×10 −3 and B(ψ(2S) → νν) < 15.5 × 10 −3 at the 90% confidence level. Using the improved kinematic resolution achieved from hadronic reconstruction, we also provide partial branching fraction limits for the B → K ( * ) νν decays over the full kinematic spectrum.
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