Search for MSSM Higgs Bosons at the Tevatron

1. Search for MSSM Higgs Bosons at the Tevatron Anton Anastassov (for the CDF and DØ Collaborations) HEP2005 International Europhysics Conference on High Energy PhysicsLisbon, PortugalJuly 21-27, 2005

2. What is MSSM and why is it interesting? • The simplest realistic SUSY model • Resolves the hierarchy problem • Consistent with experimental results • Higgs sector in MSSM: • Two charged bosons: H± • Two CP -even neutral bosons: h, H • One CP -odd neutral boson: A • At tree level described by mA , tanβ=vu/vd • One of the CP –even Higgses is SM-like, the other one similar to A Confirm Higgs mechanism and physics beyond the SM In case of signal Anton Anastassov – Search for MSSM Higgs Bosons at the Tevatron

3. Charged MSSM Higgs at the Tevatron • Production • Decays • Searches Anton Anastassov – Search for MSSM Higgs Bosons at the Tevatron

4. Charged MSSM Higgs Production Small cross-sections • Top decays:t →bH+ (mH < mt-mb) • qq, gg→H-H+ • bb, gg→W-H+ • gb→tH+; qq, gg→tbH+ Anton Anastassov – Search for MSSM Higgs Bosons at the Tevatron

5. Charged MSSM Higgs Decay Modes Take advantage of differences in W± and H± decays. • Major decay modes: • H+→t+n • H+→cs • H+→t*b→W+bb • H+→W+h→W+bb • BR’s depend on: • tan β • mass of H+ • Differ from W+ BR’s Anton Anastassov – Search for MSSM Higgs Bosons at the Tevatron

6. H+ Search Strategy • Check consistency of the final states with SM expectation • Interpret for several MSSM scenarios, tan β, and mH • Lint = 192 pb-1 • Look at four tt final states: • di-lepton + jets • lepton + jets (1 b-tag) • lepton + jets (≥ 2 b-tags) • lepton + tau + jets Anton Anastassov – Search for MSSM Higgs Bosons at the Tevatron

7. Search for H±: Results Consistent with the SM Will be nice to have benchmarks designed specifically for charged Higgs! No-mixing benchmark scenario mhmax benchmark scenario Anton Anastassov – Search for MSSM Higgs Bosons at the Tevatron

8. The Neutral MSSM Higgs Sector at the Tevatron • Production • Decays • Search Strategies • Results • Projections Anton Anastassov – Search for MSSM Higgs Bosons at the Tevatron

9. MSSM Higgs Production and Decays Couplings of A (and h or H) to b, t ~tanβ Gluon fusion Higgs decays: • bb(~90%) • tt(~5-13%) b-quark fusion Anton Anastassov – Search for MSSM Higgs Bosons at the Tevatron

10. DØ Searches for neutral MSSM Higgs at DØ • Search in the Higgs→bb channel • Look for associated production with b(b) (suppress multi-jet bg) • Require three b-tagged jets (identified using secondary vertex) • Form invariant mass of the two highest-ET jets • Perform binned fit of the di-jet mass spectrum Data sample: ~260 pb-1 Anton Anastassov – Search for MSSM Higgs Bosons at the Tevatron

11. DØ B-tagging, di-jet Mass Spectrum • b-tag rate estimated from data • Single b-tag + mis-tag di-jet spectrum in agreement with doubly b-tagged sample (cross-check) • Acceptance ~0.3-1% (mA=90-150) • Major sys uncertainties: • b-tagging (15%) • JES/resolution (9%), • signal simulation (5%) • trigger (9%) • luminosity (6.5%) • Bg estimation (3%) Anton Anastassov – Search for MSSM Higgs Bosons at the Tevatron

12. DØ Limits on Neutral MSSM Higgs Production • No evidence of signal found • Interpretation of the results: mhmax and no-mixing scenarios with μ<0 • The search is sensitive down to tanβ~50-55 for mA~90-120 GeV Anton Anastassov – Search for MSSM Higgs Bosons at the Tevatron

13. Search for Neutral MSSM Higgs at CDF • Search for inclusive production and subsequent Higgs decay to ττ • Tau decays: ~37% leptonic, ~63% hadronic • Event selection • One tau decays leptonically (tℓ :t→ℓnn; ℓ=e,m) • Second one hadronically (th :t→hadrons n) • Opposite charge of tℓ ,th , bg supression cuts • Acceptance ~1-2% (mA=115-250 GeV) • Dominant bg: Z/g*→tt • Z/Higgs separation: partial mass mvis(ℓ,th,ET) Anton Anastassov – Search for MSSM Higgs Bosons at the Tevatron

14. Search for Neutral MSSM Higgs at CDF Reconstruction of th: • Use two-cone algorithm (for signal & iso) • Four-momentum from trks and p0’s • Isolation veto (trk, p0) • Hadronic system: • mhad< 1.8 GeV • Ntrk = 1,3 ; charge = ±1 Before Ntrk and opposite charge cuts Anton Anastassov – Search for MSSM Higgs Bosons at the Tevatron

15. Search for Neutral MSSM Higgs at CDF • Observed 487 ev, expect 496± 5.4(stat) ± 27.7(sys) ± 24.8(lum) • Dominant systematic uncertainties: • Particle ID: th (3.5%), e (1.3%), m (4.6%) • Jet→t mis-ID estimate (20%) 3% on total bg • PDF’s (5.7%) • Luminosity measurement (6%) • Set limits by performing likelihood fit of mvis(ℓ,th,ET) distribution Example fit for mA=140 GeV Anton Anastassov – Search for MSSM Higgs Bosons at the Tevatron

16. Search for Neutral MSSM Higgs at CDF Interpret the results in mhmax and no-mixing scenarios with m<0 and m>0 The bb and tt Higgs decay channels show nice complementarity! Anton Anastassov – Search for MSSM Higgs Bosons at the Tevatron

17. What is in the (near) future? • The Tevatron has passed the 1 fb-1 mark! • Increased data sample  increased appetites • The projections are based on the current analyses techniques • A lot of improvements in the works You have not heard the last word from the Tevatron! Anton Anastassov – Search for MSSM Higgs Bosons at the Tevatron