Search for BSM Higgs at the Tevatron

1. Search for BSM Higgs at the Tevatron Anton Anastassov (Northwestern University) For the CDF and DØ Collaborations • Aspen 2008 Winter Conference: • "Revealing the Nature of Electroweak Symmetry Breaking" • January 15, 2008

2. BSM Higgs Searches • Look for particles consistent with the expected physical manifestation of extended Higgs models: • 2HDM, Higgs triplets • Add SUSY  a range SUSY models • Little Higgs models • …anything that goes beyond the SM Higgs • Production/final states may be: • Unique to the BSM models • Similar to SM, but with modified production rate/BR’s Many search possibilities, but… finite manpower  the CDF and DØ programs concentrate on: • Modes/models seen as most promising at the Tevatron • Final states that can be efficiently triggered on Search for BSM Higgs at the Tevatron - Anton Anastassov

3. The Tevatron Collider and Detectors CDF and D0: • General purpose detectors, axial and forward-backward symmetric • Precision tracking (incl silicon detectors) • Hadronic and EM calorimeters • Muon chambers • TOF systems Recorded more than 3 fb-1 / experiment of quality data (results in this presentation use up to 1.8 fb-1) Search for BSM Higgs at the Tevatron - Anton Anastassov

4. The tools of the searches The searches described in the following rely on good particle identification: • Electrons • Muons • B-jets • Photons • Taus (hadronic decays)  • Very well understood • Use characteristic energy in the EM and HAD calorimeters; • hits in the muon chambers (m) • Easily accessible standard candles (Z, W) • (see J. Zhu’s presentation on EW results at the Tevatron) • Displaced secondary vtx associated with the jet • Probability of tracks in the jet not originating from the IP • Soft leptons (e, m) in jets • Wealth of information  apply multivariate techniques • (see Weiming Yao’s talk for detailed discussion) • Energy deposition in the EM calorimeter • not associated with a track • Shower shape to discriminate against p0’s Search for BSM Higgs at the Tevatron - Anton Anastassov

5. Tau Reconstruction (hadronic decays) Spectrum of taus from a W sample Two-cone algorithm for tracks and p0’s: • Common axis: direction of a “seed” track • Signal cone  reconstruct • Isolation annulus  implement jet veto Spectrum of taus from Z after background subtraction NN selection • Variables: • Shower Profile • Calorimeter, track isolation • Charged fraction • Opening Angle • etc. • Define 3 types: • p-like, r-like, multi-pion Similar reconstruction/misidentification rates at CDF and DØ Search for BSM Higgs at the Tevatron - Anton Anastassov

6. Review of Direct BSM Higgs Searches at CDF and DØ • Doubly-charged Higgs • Fermiophobic Higgs (hfgg) • MSSM Higgs (CP-conserving) • Charged • Neutral

7. Searches for H±± • H±± predicted Higgs triplet, L/R symmetric models • H++ can be light: ~100 GeV • DY-like H++H-- pair production • Decays to same/different-flavor leptons • Most resent Tevatron search:DØ: H±±mm (1.1 fb-1) • Exp (obs): 3.1 (3) events  mL(R)>150 (126.5) GeV @ 95% CL • Previous searches from CDF (200-350 pb-1): ee, em, mm, et, mt • Detection modes: • 4 identified leptons • 3 ID’d leptons (+ 1 missed) • Use of tight/loose ID mL>114, 112 GeV @ 95% CL • All Tevatron searches are statistics limited • Will benefit significantly from the full data samples • After adding H±±tt the Tevatron will cover all decay modes Search for BSM Higgs at the Tevatron - Anton Anastassov

8. Search for Fermiophobic Higgsgg Searches for hfgg in Run II (1.1 fb-1) • gg+X final state: ppVVhfgg+X , pphf W(Z) mhf>90 GeV@ 95% CL (assuming SM couplings) • ggg(g)+X final state : pp hfH±  hf hfW± (suppressed VVhf couplings) • possible in 2HDM for mhf<90 GeV, mH±<200 GeV, tanb>1 • Favorable conditions: BR(H±hfW± ), BR(hfgg)≈1 Nbg=1.1±0.2, Nobs=0 sxBR(H±hfW±)xBR(hfgg)2<25.3 fb @ 95% CL (mass limit depends on assumed model) • Fermiophobic Higgs: • Suppressed couplings to fermions • Searches for hfgg: • LEP II: mhf>108.3 GeV @ 95% CL (assuming SM couplings) • Tevatron Run I: qq’V*hfZ , mhf>78.5 (82) GeV @ 95% CL DØ(CDF) Search for BSM Higgs at the Tevatron - Anton Anastassov

9. Searches for MSSM Higgs Minimal Supersymmetric Standard Model (MSSM): SUSY extension of the SM with minimal particle content • Requires two Higgs field doublets • Five physical states: H, h, A; H± • Lightest Higgs (h) mass close to EW scale • At tree level defined by mA and tanb = vu/vd • A couplings to b,t enhanced by ~tanb ! • But… complicated picture when radiative corrections are included, dependence on additional parameters:  consider “benchmark scenarios”: Search for BSM Higgs at the Tevatron - Anton Anastassov

10. Search for Charged MSSM Higgs H from t→bH+ is the most accessible mechanism at the Tevatron (can probe mH < mt-mb) • Hmodifies top BR’s (mostly at large and small tan • W± and H± decay modes differ: take advantage of different topologies in tt final states Expected number of events in the SM and MSSM for four topological final states (Lint = 192 pb-1) Search for BSM Higgs at the Tevatron - Anton Anastassov

11. Search for Charged MSSM Higgs Measurement of Rs=sl+jets/sll (1 fb-1) • Rs=1.21±0.27  consistent with the SM • H± exclusion assuming BR(H±cs)=1 BR(tbH±)<0.35 @ 95% CL Combined analysis of 4 final states Exclusive H±tn search (Lint=335 pb-1) • Final state: e(m)+t+b + X • Nbg=3.9±0.5, Nobs=6 Search for BSM Higgs at the Tevatron - Anton Anastassov

12. Neutral MSSM Higgs production Higgs decays: • bb(~90%) • tt (~9%) Search for BSM Higgs at the Tevatron - Anton Anastassov

13. Neutral MSSM Higgs • Production and decays are affected by radiative corrections * • The bb channel is more sensitive to these corrections (and therefore to the SUSY specific scenarios), while the tt channel is more robust • For large tanb h or H are almost mass degenerate with A, similar couplings • The other one is SM-like, low-mass (m<135 GeV) Db is a function of SUSY parameters * M. Carena, S. Heinemeyer, G. Weiglein, and C.E.M. Wagner, Eur.Phys.J. C45 (2006) 797-814 Search for BSM Higgs at the Tevatron - Anton Anastassov

14. Neutral MSSM Higgs Decaying to bb • Look for associated production with b(b): suppress multi-jet backgrounds • Have to pay a price • Require at least three b-tagged jets • Look for signal evidence in the mass of the two highest-ET jets Biggest challenge: predict bg, shape • Apply mistag rates to bbj events to determine shape • Normalize (outside of signal region) to the observation • Check the predicted shape using MC multijet events (flavor composition fixed to theoretical predictions) • Use MC to get shapes and biases for different flavor composition • Create 2D templates: di-jet mass vs mdifftag discriminating variable (mdifftag = m1tag+m2tag-m3tag ) • 2D fit of mjj and mdifftag used to extract signal and determines bg flavor composition Search for BSM Higgs at the Tevatron - Anton Anastassov

15. Neutral MSSM Higgs Decaying to bb Di-jet mass distribution of the two highest-ET jets in the DØ search (triple b-tagged events) The data are consistent with SM expectation. Extracted limits (Lint=0.9 fb-1) Search for BSM Higgs at the Tevatron - Anton Anastassov

16. Neutral MSSM Higgs Decaying to bb 2D fit results, projections on the two variables. The data are consistent with SM expectation. Extracted limits (Lint=0.98 fb-1) Search for BSM Higgs at the Tevatron - Anton Anastassov

17. Neutral MSSM Higgs Decaying to tt 3%  3% ee 6% e 41%, hadhad 23% ehad 23%, had • Advantages of the Higgs mode: • Lower bg’s compared to bb, probe all production modes • Weaker dependence of sensitivity on SUSY parameters: more robust Final state signatures are determined by the tau decay modes Channels used in the presented searches: tethadtmthadtetm (1.8 fb-1) tmthad (1 fb-1) previous result also used tethadtetm, being updated Major backgrounds inHiggs : • Ztt (dominant) • Bg’s from jett fakes: multi-jet, W+jet(s), g+jet(s) (tethad only) • Zee, Zmm, tt, other (small) te, tm, thad are shorthand notations for t→enn, t→mnn, and t→hadronsn, respectively. Search for BSM Higgs at the Tevatron - Anton Anastassov

18. Neutral MSSM Higgs Decaying to tt • Not enough info for full mtt reconstruction • Approximation: project ET onto vis t decay products (discussed later) Higgs/Z separation: CDF: Use partial “mass”: DØ: Form a NN using mvis and other event variables Search for BSM Higgs at the Tevatron - Anton Anastassov

19. Neutral MSSM Higgs Decaying to tt mvis (GeV/c2) mvis (GeV/c2) mvis (GeV/c2) mvis (GeV/c2) Search for BSM Higgs at the Tevatron - Anton Anastassov

20. Exclusion Limits @ 95% CL Interpretation of the limits Search for BSM Higgs at the Tevatron - Anton Anastassov

21. Neutral MSSM Higgs: Near Future at CDF and DØ Previous DØ result from the exclusive search for • Utilize the full data samples • Multivariate signal selection • Separate treatment of events with associated b-quark (for ftt) • Use full mass reconstruction (when possible) Fully reconstructed mtt at CDF • Use collinear neutrino approximation • Subset of selected events • No special optimization for these plots Search for BSM Higgs at the Tevatron - Anton Anastassov

22. Summary • Contrary to some rumors… CDF and D0 have not observed a Higgs signal yet • However, diverse (and demanding) research programs are being actively pursued • Future progress depends on both • Efficient utilization of the larger available samples • Improved analysis techniques • Following the established pattern, expect updated results at the coming winter conferences Search for BSM Higgs at the Tevatron - Anton Anastassov