(at LEP) or What to do if there are too many people on the MSM Higgs Working Group

Transcription

1 Other Higgs Boson Searches (at LEP) or What to do if there are too many people on the MSM Higgs Working Group Mark Oreglia The Enrico Fermi Institute, The University of Chicago European Physical Conference, Parallel Session 7 Tampere, 999 Outline: Photonic Higgs Couplings Invisible Higgs Decays Charged Higgs Bosons Conclusions 5 July 999 M. Oreglia, EPS Tampere, Parallel 7

2 Higgs Bosons at LEP In Minimal Standard Model: production via direct limit M H > 95.2 GeV (89 GeV LEP combined) + - Yukawa production: e e ff h small in MSM (DELPHI 7-2) Next level of complexity: 2 Higgs doublet fields (2HDM) 4 ways of coupling doublets to fermions (Types I, I, II, II ) MSSM is Type II; 5 Higgs boson + - e e h A charged Higgs have large virtual effects Diphoton decay of H is of order. for M H near 8 GeV in MSM occurs via W loop enhanced in Type I model e + e - H Z 5 July 999 M. Oreglia, EPS Tampere, Parallel 7 2

3 Fermiophobia Extended Higgs sectors: avoid FCNC with constrained Yukawa couplings to fermions keep ρ = by incorporating only singlets and doublets; triplets need special care 2HDM of Type-I: all fermion couplings have the form SM cosα/sinβ, so can tune α to turn off fermion couplings 5 July 999 M. Oreglia, EPS Tampere, Parallel 7 3

4 Photonic Enhancers Mechanisms which increase photon couplings: 2HDM: Stange, Marciano, Willenbrock Eboli, Gonzalez-Garcia,Lietti, Novaes Akeroyd Higgs Triplet Model: Gunion Akeroyd; Georgi, Machacek Top-quark Condensate: Wells; Spira and Wells; Baer and Wells Pois, Weiler, Yuan Extra Dimensions: Hall and Kolda Anomalous Couplings: Hagiwara, Szalapski, Zeppenfield Gamberini, Giudice, Ridolfi Abbasabadi, et al. Hypercharge axion: Brustein, Oaknin and more! 5 July 999 M. Oreglia, EPS Tampere, Parallel 7 4

5 Photons The analyses in this section require 2 or 3 energetic photons low backgrounds photon modelling from PYTHIA was not so good for analyses in the central region; KK2F is much better, but still discrepant at the % level for hz specific modes, recoil mass cut is very effective main backgrounds from ISR and 4f vents/2 GeV E 2 OPAL E γ (GeV) cos(θ γ γ ) 5 July 999 M. Oreglia, EPS Tampere, Parallel 7 5

6 OPAL CERN EP/99-84, Tampere pb - at 89, GeV data 96.2 GeV fermiophobic limit γ) γ Upper Limit on B(h - OPAL Excluded Region M h (GeV) 5 July 999 M. Oreglia, EPS Tampere, Parallel 7 6

7 ALEPH ALEPH CONF 99-3, Tampere pb - from E cm = 9-89 GeV fermiophobic limit at 96. GeV ranching ratio B July 999 M. Oreglia, EPS Tampere, Parallel 7 7

8 L3 L3 Note 2429, Tampere pb - at 89 fermiophobic limit at 96 GeV data e + e - qq (γ) m H =95GeV 5 July 999 M. Oreglia, EPS Tampere, Parallel 7 8

9 Also from D and CDF: D contributed paper #452A 5 July 999 M. Oreglia, EPS Tampere, Parallel 7 9

10 DELPHI DEPHI 99-72, Tampere pb - from 89 GeV fermiophobic limit of 96 GeV Also, nice study of anomalous couplings photonic couplings can be enhanced by nonzero values of f B, f BB, f W, f WW there is also a scale parameter Λ these lead to nonzero Hγγ and HZγ see DELPHI s CERN-EP/99-58 (TeV -2 ) 2 / Λ F ννγγ q γ qγ DELPHI Preliminary γγγ -5 - Excluded M H (GeV/c 2 ) 5 July 999 M. Oreglia, EPS Tampere, Parallel 7

11 ! For OPAL also has Cross Section limits e + e - X Y results valid for scalar/scalar, scalar/vector γ)b(y) (pb) Y)B(X γ - X pper Limit on σ(e + e U OPAL Excluded 89 GeV a) Y hadrons Excluded b) Y l + l Excluded c) Y invisible M X (GeV) 5 July 999 M. Oreglia, EPS Tampere, Parallel 7

12 $ # " " " " Higgs Triplet Model IF the H and H do not mix, as is indicated by other constraints (see Akeroyd), then H is fermiophobic, and the preceeding analyses give good limits in the model: in 2 (Θ H ) s OPAL % Excluded from Z bb - Excluded by Direct Search M H (GeV) 5 July 999 M. Oreglia, EPS Tampere, Parallel 7 2

13 Invisible Higgs Searches for h decays into undetected particles for instance, also: but mass dependent e h + e - h h Z χ χ χ χ, χ χ Z 2 2 hz production at 2 ξ σ SM (e + e - h Z ) events characterized by large missing E and acoplanar dijet or dileptons having invariant mass close to M Z backgrounds predominantly from 4- fermion processes and WW leptons: require recoil mass = Z jets: build ANN to discriminate from irreducible background as best one can very similar to SM Higgs search 5 July 999 M. Oreglia, EPS Tampere, Parallel 7 3

14 ' ALEPH ALEPH 99-3, Tampere pb - of 89 GeV data 33 candidates, 33.6 expected background limit of 92.8 GeV (expected: 94.) 2 ξ.9.8 ALEPH PRELIMINARY 95% CL Excluded & Hadronic only 89 GeV data m h (GeV/c 2 ) 5 July 999 M. Oreglia, EPS Tampere, Parallel 7 4

15 * DELPHI DELPHI 99-83, Tampere pb - of 89 GeV data, data only muons in lepton channel 6 candidates, expected background = 69.9 mass limit = 93.8 (expected = 9.4) σ(pb) DELPHI preliminary ( observed limit ) expected limit σ SM Br(inv)=% 93.8 GeV 9.4 GeV Higgs mass (GeV/c 2) 5 July 999 M. Oreglia, EPS Tampere, Parallel 7 5

16 L3 L3 Note 2435, Tampere pb - at 89, + 83 GeV data 39 candidates, expected background = 4.6 mass limit = 95. (expected = 92.2) 8 - L3 Nevents / 2 GeV 6 4, 2 DATA 6GeV - 89 GeV BKGD 6 GeV - 89 GeV M H (GeV) 5 July 999 M. Oreglia, EPS Tampere, Parallel 7 6

17 / 2 2 OPAL PN 399 OPAL 78.4 pb - of 89 GeV data, + 83 GeV 59 candidates, expected bkgd = 6.6 mass limit = 9.6 (expected = 93.3) nearly invisible mode gives limits of 87.7 and 86.7 GeV for M = 2 and 4 GeV 2 ξ 2 OPAL GeV preliminary h χ χ 2 (nearly invisible decay) M=2 GeV M=4 GeV [GeV] M h 5 July 999 M. Oreglia, EPS Tampere, Parallel 7 7

18 Charged Higgs Bosons Pair production: e e H H Occur in all common extensions 2HDM couplings specified Triplet limits from loop corrections to Z width but H decay rate is model dependent leptonic, hadronic, and mixed modes defined by H decay final states: H 2HDM, Type I (Akeroyd): look for τν, H mature analyses: leptonic: missing E, acoplanarity hadronic: jets cs Main background: W + W - irreducible a problem τ H + but still good progress in furthering the limits by 6-9 GeV over those from 83 5 July 999 M. Oreglia, EPS Tampere, Parallel 7 8 W + A -

19 Charged Higgs Analysis Each collaboration is using something new for the 89 GeV analysis No indication of a signal Mode Data Bkgd Eff, mh=7 95% CL Limit (GeV) ALEPH 65.5 (69.5 expected) lepton % hadron % mixed % DELPHI lepton % hadron % mixed % L3 lepton % hadron % mixed % 66.9 (66.5 expected) 67.5 (7.2 expected) OPAL 68.7 (68.5 expected) lepton % (test mass = 7 GeV) hadron % mixed % 5 July 999 M. Oreglia, EPS Tampere, Parallel 7 9

20 DELPHI DELPHI 99-92, Tampere pb - at 89 GeV, plus 83 lepton channel uses τ polarization hadron mode has anti-ww likelihood 66.9 GeV limit 5 July 999 M. Oreglia, EPS Tampere, Parallel 7 2

21 L3 L3 Note 2379, Tampere pb - of 89 GeV hadron channel: 5C kinematic fit 67.5 GeV limit.8 L3 preliminary Br(H ± τν) H + H - τ + 3 ν 3 τ τ ν H 4+ H - cs 5 τ 3 ντ H 4+ H - cs c s Combined Expected M 6 ± H (GeV) τ 5 July 999 M. Oreglia, EPS Tampere, Parallel 7 2

22 7 8 : : : OPAL OPAL-PN/99-373, Tampere pb - of 89 GeV lepton: τ ANN, mass-binned analysis hadron: 5C fit limit: 68.7 GeV τ ) ν BR(H ± τ : (b) τντν qqτ 9 ν qqqq Combined Expected OPAL preliminary M ± H (GeV) 5 July 999 M. Oreglia, EPS Tampere, Parallel 7 22

23 < = < ALEPH ALEPH 99-7, Tampere pb - of 89 GeV data, plus 3-83 new lepton mode analysis hadron mode use 5C fit 65.5 GeV limit >) τ ν τ + B(H + ;.8 Excluded at 95% C.L. ALEPH Expected? Observed.4 ; m H (GeV/c 2 ± ) 5 July 999 M. Oreglia, EPS Tampere, Parallel 7 23

24 A A F 89 GeV LEP Combined 77.3 GeV combined limit for this conference: ALEPH 99-8, DELPHI 99-42, L3 Note 2442, OPAL TN-64 vents / 3 GeV E vents / 3 GeV E s = GeV LEP data combined background H + H - Signal (m H = 75 GeV) a) H + H - qq qq 8 b) 7 H + H - τν E τ qq B 6 C 7 8 D 9 Reconstructed Mass m H [GeV] 5 July 999 M. Oreglia, EPS Tampere, Parallel 7 24

25 Conclusions LEP and FNAL have searched for: h with enhanced photonic couplings charged H h into undetected particles Event candidates in all searches are (very!) consistent with Standard Model backgrounds Limits can be placed on models which extend the minimal sector, particularly the 2HDM and HTM (triplet model) worst cases: fermiophobic: M > 96 GeV charged: M > 77.3 GeV invisible: cross section limits up to 9 GeV and higher 5 July 999 M. Oreglia, EPS Tampere, Parallel 7 25