A. MartyniukA. Martyniukaa, P. Miyagawa, P. Miyagawabb, M. Owen, M. Owencc, O. , O. TrifisTrifiscc, V. Chavda, V. Chavdacc, and U.K. Yang, and U.K. Yangcc

a: a: University of VictoriaUniversity of Victoriab: b: University of SheffieldUniversity of Sheffield

c: c: University of ManchesterUniversity of Manchester

Higgs Meeting, August 27, 2012Higgs Meeting, August 27, 2012

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Thanks to the Editorial Board: Michel Vetterli (Chair)Martin zur Nedden, Wouter Verkerke, James Ferrando

A charged Higgs boson is predicted by the Beyond SM: Two Higgs Doublet Model: H0, h0, A0, H±

Charged Higgs productions from top quark decays Huge top production, focus on H H++cs cs at low tan Complementary to HH++at high tan

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ν

W+

W/H-

b-jet

b-jet

jet

jet

t

e/

t

Dijet mass 2 fitter Semi-leptonic tt sample

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ν

W+

W/H-

b-jet

b-jet

jet

jet

t

e/

t

Likelihood Fit, Br(tH+b): Discovery or 95% Limits

Previous analysis with 35 pb-1 data (≥ 1 b-tag), comparable to the Tevatron limits ( ATL-CONF-2011-127, ATL-COM-PHYS-2011-130)

Updated analysis with 4.7 pb-1 (2011 full data) High-pt lepton with 4 jets (at least 2 b-tag)

Single lepton trigger samples Use the Top group selection cuts and have a good agreement Lep Pt>25 (e), 20 (m), Jet Pt>25, MET> 35(e), 20(m), MV1 w>0.6 The list of the full event selections cuts is in the backup slide

Supporting document ATL-COM-PHYS-2012-660

The updated analysis has a conditional approval in June, 2012 Issues with systematic Issues with fit stability

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A dijet mass 2 fitter: lepton plus 4 jets Improved the dijet mass dist. by reconstructing whole ttbar event Constrain W(e/m) and top quarks masses to be the PDG values, by

floating jet/lepton energy within their resolutions The 5th jet can be replaced as a W daughter jets with any of the two

untagged 3rd, 4th jets Remove poorly reconstructed events with 2<10

5Before Fitting After Fitting

Signals and background templates

Seven H+ signal templates from 90 to 150 GeV by 10 GeV step

SM ttbar template

Non-ttbar template (10%): Single top, W/Z+jets, QCD, and diboson

Set limits on the branching ratio to charged Higgs boson using the frequentic procedure

A likelihood function is define as

where ni: observed events, i: expected events in each bin

Limits are calculated on a test Statistics qb based on a profile Likelihood ratio

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The exp. events of ttbar bkg and H+ signal as BR(tH+b)

Missing contributions in the limits b-JES/c-JES syst. Mtop syst. Updated Stop t-ch. norm

Implementation of the syst. band in the kinematic distributions

Check the output nuisance parameters and their correlations

(N-1) limits to show the syst. effect of each item

Limits without a constraint on the (ttbar)

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Limits presented in the approval meeting in June

Raised in the Higgs Approval meeting and by the Edboard

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Missing syst. contributions (b-/c-JES, Mtop, proper Stop t-ch. norm.) are included. Their contributions are small (done)

After ICHEP deadline passed, we decided to update our analysis• Use the most updated JES calibration and it’s uncertainty ( tag 00-05-09): lower eff. for Njet>=4 cut• Use the updated luminosity with small error: 4.66 /fb with 1.8% (old:

4.71/fb with 3.4%) no change in the data, but the bkgd prediction based on the MC is reduced by 1.2%

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Implementation of the syst. band the kinematic distributions (done) Check the output nuisance parameters and their correlations (done) Limits without a constraint on the (ttbar) (done) (N-1) limits to show the syst. effect of each item (done)

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oldnew

data

SMttbar

old

new

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The fit results are consistent with null Higgs hypothesis

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Stat. Only

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mH=90 GeV mH=110 GeV

The effect of the individual syst.?

The only one syst. Item is removed in the fit, “(N-1)” limit Basically, the (N-1) limits are close to the N limits due to the

correlations with other parameters

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Groups of the correlated systematic JES, Mtop, bJES: c bTag, (ttbar) Gen, I/FSR, PS and JER

mH=90 GeV

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A group of the correlated parameters (x) is removed in the fit to check the effect of their syst. on the limits

The (N-x) limits look reasonable

In the current fit,(ttbar) is constrained with +7%/-9% uncertainties

What if we remove this constraint? basically 2 parameter fitting: Br(tH+b) and (ttbar) The limits are not changed The resulting cross sections are consistent with the SM

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The full 2011 data (4.7 fb-1) have been analyzed to search for a charged Higgs from top quark decays.

The results are consistent with null Higgs hypothesis The 95% limits on Br(tH+b) are set between 5% to 1%,

depending mHare improved by a factor of 5 to 10, with respect to the current best limits in csbar channel

The limits, equivalent to the limits from the three combined tau channels.

We plan to publish these results

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Semi-leptonic channel: e/ plus at least 4 jets (2 b-tag) Use the Top group selection cuts and have full agreement:

acceptance challenge Cuts are:

One el with ET > 25 GeV & |η| < 2.47, with a veto (1.37 < |η| < 1.52), OR one mu with pT > 20 GeV and |η| < 2.5 with single lepton triggers (EF_e20_medium,EF_e22_medium, EF_mu18, EF_mu18_medium)

Remove events tagged as e-mu overlap Require a primary vertex with at least five tracks MET > 35 GeV (el), OR MET > 20 GeV (mu) Mt(W) > 25 GeV (el) OR MET + Mt(W) > 60 GeV (mu)

≥ 4 jets with ET > 25 GeV and |η| < 2.5 and |JVF|>0.75

Events with loose bad jets with pT > 20 GeV are rejected ≥ 2 jet tagged with MV1 weight > 0.601713

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SM ttbar (~90% of the total bkgd) Use MC@NLO sample for shape and normalization with NNLO cross

section W+jets, Wbb/cc+jets, Wc+jets (~3.6% of the total bkgd)

Use ALPGEN interfaced with Herwig samples for shape and normalization

Normalized with K*cross sections plus the SFs derived from the Top W+jets group based on the W+/W- charge asymmetry in the data

Single top (~3.7% of the total bkgd) Use MC@NLO sample for Wt and s-channel, but AcerMC for t-channel

normalized with NNLO cross section (also shape) Multi-jets (~2.5% of the total bkgd)

Use anti-electron data-driven method provided by the Top fake group (normalization)

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Powheg plus Herwig vs Pythia? With Pythia AMTB1 tune: 11% difference in acceptance, disfavored

by the jet shape data. New PS syt. with Pythia Perugia 2011 C tune:3% difference in acceptance

The effect due to the PS on the limit is very minimal.

Pythia AMBT1 tune Pythia Perugia 2011 C tune