Search for a low-mass Higgs boson (A0) at BABAR Arafat Gabareen Mokhtar (SLAC) On behalf of the BABAR Collaboration Topics Y(3S)→γA0, A0→τ+τ- arXiv:0906.2219 Submitted to PRL Y(2S,3S)→γA0, A0→μ+μ- arXiv:0905.4539 Y(3S)→γA0,A0→invisible arXiv:0808.0017 Preliminary

Introduction Minimum SM: single Higgs mass ~ 100 GeV/c2 R. Dermisek, et al., PRD 76, 051105 (R) (2007) B(Y→γA0) A0 non-singlet fraction (cosθA) Minimum SM: single Higgs mass ~ 100 GeV/c2 MSSM: additional Higgs doublets to give mass to new particles NMSSM: additional Higgs singlet to solve the hierarchy problem Linear combination of singlet with a Higgs doublet leads to CP-odd Higgs state, A0, low mass (A0) < 2mb Search for A0 in Y(nS)→γA0 mA0<2mτ 2mτ<mA0<7.5 GeV/c2 7.5 <mA0<8.8 GeV/c2 8.8 <mA0<9.2 GeV/c2 F. Wilczek, Phys. Rev. Lett. 39, 1304 (1977)

Recent Measurement from CLEO at Y(1S) In a sample of 25M Y(1S) events, search for Y(1S)→γA0, with A0→μ+μ-, 0.3 – 3.5 GeV A0→τ+τ-, 3.5 – 9.5 GeV No evidence for A0 Upper limits in the range (1- 48)×10-5 at 90% C.L. A0→τ+τ- A0→μ+μ- W. Love et. al., PRL 101, 151802 (2008) CLEO limits on Υ(1S)→γA0 90% UL B(Y(1S)→γA0)B(A0→ℓℓ) A0 mass (MeV)

Analyses of Y(nS)→gA0 Narrow initial state Radiative Y(nS) Decays: Y(1S) M= 9,469.3 ± 0.3 MeV Γ = 54.02 ± 1.25 KeV Y(2S) M=10,0233 ± 0.3 MeV Γ = 31.98 ± 2.63 KeV Y(3S) M=10,355.2± 0.5 MeV Γ = 20.32 ± 1.85 KeV Radiative Y(nS) Decays: Y(nS) → A0 g with A0→μ+μ- A0→τ+τ- A0→invisible (hint for light dark matter) In Y(nS) rest frame, photon energy measures mass of A0: Search for monochromatic photon

Search for A0→τ+τ- arXiv:0906.2219 μμ ee Search for three decays modes ττ→ee, ττ→eμ, and ττ→μμ (τ→ℓυℓυτ) Resolution Efficiency: Selection criteria optimized in five Eγ regions (background varies with Eγ) @ Eγ=0.2 GeV 8 MeV @ Eγ=4.5 GeV 55 MeV ee: 10-14 % eμ: 12-20 % μμ: 22-26 %

Inclusive Photon Spectrum at Y(3S) χb ττ→ee Eγ (GeV) ττ→eμ ττ→μμ Principal background from ee→γττ Peaking background expected at ~760 MeV: Y(3S)→γχbJ(2P), χbJ(2P)→γY(1S,2S), Y(1S,2S)→ττ No evidence for an enhancement at ~921 MeV for Y(3S)→γηb, ηb→ττ BABAR preliminary

Fits to Eγ distributions 0.2 – 2.0 GeV 2.5 – 4.5 GeV ττ→ee ττ→eμ ττ→μμ Eγ (GeV) S1 Eγ (GeV) ττ→ee ττ→eμ ττ→μμ S5 BABAR preliminary

Scan for Narrow Peaks Eγ (GeV) BABAR preliminary Subtract fitted smooth background of γ spectrum Scan in steps equivalent to the half the resolution in Eγ (307 scan points in total) Simultaneous fits (binned ML) to the 3 different ττ-final states BABAR preliminary No evidence for a structure beyond the null Higgs hypothesis…

Results of Combined Fits BABAR preliminary Y(3S)→γχbJ(2P), χbJ(2P)→γY(1S), Y(1S)→τ+τ- @ 90% C.L.

Search for Y(2S,3S)→γA0, A0→μ+μ- Exclude regions around J/ψ and ψ(2S) Y(2S) Y(3S) Combined BABAR preliminary Search for narrow enhancement: ML fit in 1955 mass intervals of 2-5 MeV, covering the range 0.212 ≤ m(A0) ≤ 9.3 GeV, No evidence for A0→μ+μ-

Search for Y(2S,3S)→γA0, A0→μ+μ- arXiv:0905.4539 Results after scan Y(2S) Y(3S) & combined BABAR preliminary No evidence for A0→μ+μ- structure beyond the null hypothesis Upper limit at 90% C.L.

Search for A0→invisible () arXiv:0808.0017 Select events with single photon Eγ>2.2 GeV and LARGE missing energy Search for a peak in Eγ spectrum No evidence for a signal was observed

Summary & Conclusions BABAR searched for a low-mass Higgs boson A0 in asample of 100M Y(2S) and 122M Y(3S) The search was performed for Y(nS)→γA0 with in the decay modes A0→μ+μ-, A0→τ+τ-, A0→invisible No evidence for A0 below 10 GeV/c2 was observed in these decay modes and this data sample Upper limits @90 % C.L. were obtained BF(ηb→μ+μ-)<0.9%, BF(ηb→τ+τ-)<8%

BACKUP SLIDES

Relevant BABAR data BABAR Run7 ~122 Million Y(3S) ~100 MillionY(2S)