moriond ew 2013bsm higgs searches at the tevatron 1 beyond the sm scalar boson searches in tevatron...

Moriond EW 2013 BSM Higgs Searches at the Tevatron

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Beyond the SM scalar boson searches in TeVatron

Elemér NagyCPPM

on behalf of the CDF and D0 Collaborations


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Search for Higgs bosons assuming the existence of a 4th generation of fermions

Fermiophobic Higgs searches

Search for Φbb in Minimal Supersymmetric extension of the SM

Search for heavy Higgs cascade decays

Content


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The Tevatron


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Hermetic LAr calorimeterMuon detector with large coverage in iron toroid

Central tracking system with large lever arm

Both detectors have similar structure with different particular advantages

D0 detector

)2/ln(tan

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10-year long Run II ended on Sept. 30th, 2011Total integrated luminosity delivered in Run II: ~12 fb-1 (per experiment) provided ~10 fb-1 analyzable data (per experiment)

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SM Higgs Production

GGF

VH

VBF

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SM Higgs Decays

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Higgs boson searches in the extension of the SM to a 4th generation of fermions

Additional heavy quarks u4, d4

enhance ~9 times the GGF production and makes it overwhelmingly dominant change BR’s at low MH

GGFt,u4,d4

Additional heavy leptons l4,v4

may change the BR’s at high MH

depending on their masses (ex. ml4=155 GeV, mv4=100 GeV)

Opens new sources of CP violationAllowed by precision EW data

G.D.Kribs, T.Plehn, M.Spannowsky, T.M.P. TaitarXiv:0706.3718v1

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Use event selection for SM HWW/ZZ search (mass range extended to 300 GeV)Reoptimize signal - background separation using only GGF in signalSet limit on ggHWW ignoring VH and VBF in signal and in acceptance assuming SM Br(HWW)/Br(HZZ)

Excluded regions at the Tevatron (95% CL)

Low mass scenario: ml4 = 100 GeV mv4 = 80 GeV mu4 = 450 Gev md4 = 400 GeV120 – 224 GeV (observed)118 – 272 GeV (expected)

High mass scenario:ml4 = mv4 = 1000 GeVmu4 = 450 Gev md4 = 400 GeV120 – 232 GeV (observed)118 – 291 GeV (expected)

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Fermiophobic Higgs searches

GGF

Assume Higgs couplings to fermions vanish, all other couplings as in SMCan arise in models with an extended Higgs sector like Two Higgs Doublet Model (2HDM) with parameters that make the lightest Higgs fermiophobic

Dominant decay is HWW

Hγγ is largely enhanced and provides most of the search sensitivity for MH<120 GeV

Only VH and VBF production modes are non-negligible

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SM Hγγ and HWW /ZZ searches are reinterpreted and combined taking into account only the VH and VFB production modes and BR’s either by separating them from the GGF process or by reoptimizing without the GGF signal

Excluded regions at the Tevatron (95% CL)

100 < MHf < 116 GeV (observed)

100 < MHf < 132 GeV (expected)

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At tree level the MSSM is fixed by 2 parameters: tanβ=vu/vd, MA

other MSSM parameters (e.g. µ) enter through radiative corrections (Δb)Mh has an upper bound (~135 GeV)For tanβ > 1 couplings to down-type fermions are enhanced: Br(Φbb) ~90%Associate production of Φ with b-quarks has manageable multijet background at large tanβ the production cross section is largely enhanced wrt SM

σMSSM(bbΦ)xBr(Φbb) ~ 2 σSM(bbΦ) tan2β/(1+Δb)2 with Δb ~µ tanβ

Search for Φbb in Minimal Supersymmetric extension of the SM

2 complex Higgs doublet 5 Higgs particles: h, H, A, H+, H- Φ

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3b final state 4b final state

The search goal is to find a peak in invariant mass distributions of b-jet pairs in events with multiple b-jets

CDF D0

Luminosity: 2.6 fb-1 5.2 fb-1

Trigger: ≥2 jet with b-tag info ≥3 jets with b-tag infoOffline: 3 jets pT > 20 GeV, |η|<2.0 ≥3 jets pT>20(25) GeV, |η|<2.5b-tag: sec.vtx algo NN (lifetime+IP)

Signal sample: 3 b-tagged jets 3 and 4 b-tagged jet 11,5 K events 15 and 11 K events

Signal simulation: PYTHIA events weighted by MCFM

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Di-jet mass background template shapes for different flavour composition are determined from 2 b-tagged data events

Signal is estimated from simultaneous fit of normalization of the signal and background templates to the 3 b-tagged data sample using an additional flavour separator

Multijet background is simulated with Alpgen+Pythia and its flavour composition is determined from fit to data

Likelihood ratio discriminant is used to separate signal from background

CDF D0

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Combined Tevatron cross section limit

Combined Tevatron MSSM limit

No width for Φ is assumedNo radiative corrections applied2 σ excess at 120 and 140 GeV after applying trial factors

Finite width of Φ is taken into accountRadiative corrections appliedModel parameters chosen to maximize the theoretical upper bound on Mh

Phys. Rev. D 86, 091101(R) (2012)


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Search for heavy Higgs cascade decays

CDF considers the hypothetical Higgs decay chain:

H0 H± + W (W + h0) + W W + (b b) + W

motivated by a possible existence of strongly coupled electroweak symmetry breaking sector at the TeV scale in extended Higgs sectors like 2HDM

Event selection is similar to the tt lepton+jets analyses: 1 charged lepton (e or µ) pT > 20 GeV, |η| < 1.1 ≥ 4 jets ET>15 GeV - at least 1 jet b-tagged Missing transverse momentum (MET) ≥ 20 GeV

Signal is generated by Madgraph+PYTHIA fixing Mh0=126 GeV

Background: tt and W(Z)+jet simulated by ALPGEN+PYTHIA multijet (instrumental) from low MET data control sample


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Events are reconstructed with Mjj ~ MW

Signal is serched for in Mbb

M H± +

MW

= M

H0 Cross section limits have been derived

ranging from 1300 down to 15 fb consistent with b-only expectationThey do exceed the theoretical prediction therefore no region is excluded in the MH± vs MH0 parameter space

More details in arXiv:1212.3837

M

M


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Summary

More details can be obtained from the CDF and D0 web pages

http://www-cdf.fnal.gov/physics/new/hdg/Results.htmlhttp://www-d0.fnal.gov/Run2Physics/WWW/results/higgs.htm

Higgs boson searches beyond the SM at the Tevatron were presented - assuming the existence of 4th generation fermions (CDF+D0 ≤10 fb-1) - fermiophobic Higgs bosons (CDF+D0 ≤10 fb-1), - SUSY Higgs in 3 and 4 b-quark final state (CDF+D0 ≤ 5.2 fb-1) - first study of multiple Higgs bosons in cascade decays (CDF ≤ 8.7 fb-1)

No evidence for a BSM signal has been found

We excluded - 120 < MH < 224 GeV for the mass of the Higgs boson if 4th generation fermions would exist, - 100 < MHf < 116 GeV for the mass of a fermiophobic Higgs boson, - a domain in the tanβ vs MA MSSM parameter spaceWe established upper limits on the the production cross section of heavy Higgs bosons in a specific two-doublet model


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Backup slides


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G.D.Kribs, T.Plehn, M.Spannowsky, T.M.P. TaitarXiv:0706.3718v1


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Tevatron combination of the Φττ search

Mt/Mb


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Mbb in bkg enriched region),(),(),(),( 2

2

33 bb

datab

bbMCb

bbMCb

bbpredb MDS

MDSMDSMDS

moriond ew 2013bsm higgs searches at the tevatron 1 beyond the sm scalar boson searches in tevatron...

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