1. A. Martyniuk a, P. Miyagawa b, M. Owen c, O. Trifis c, V. Chavda c, and U.K. Yang c a: University of Victoria b: University of Sheffield c: University of Manchester Higgs Meeting, August 27, 2012 1 Thanks to the Editorial Board: Michel Vetterli (Chair) Martin zur Nedden, Wouter Verkerke, James Ferrando

2.  A charged Higgs boson is predicted by the Beyond SM: Two Higgs Doublet Model: H 0, h 0, A 0, H ±  Charged Higgs productions from top quark decays H +  cs  Huge top production, focus on H +  cs at low tan  H +    Complementary to H +   at high tan  2 ν W+W+ W/H - b-jet jet e/ 

3.  Dijet mass  2 fitter  Semi-leptonic tt sample 3 ν W+W+ W/H - b-jet jet e/   Likelihood Fit, Br(t  H + b): Discovery or 95% Limits

4.  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 4

5.  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 5 th jet can be replaced as a W daughter jets with any of the two untagged 3 rd, 4 th jets  Remove poorly reconstructed events with  2 <10 5 Before FittingAfter Fitting

6.  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

7.  Set limits on the branching ratio to charged Higgs boson using the frequentic procedure  A likelihood function is define as where n i : observed events, i : expected events in each bin  Limits are calculated on a test Statistics qb based on a profile Likelihood ratio 7 The exp. events of ttbar bkg and H + signal as BR(t  H+b)

8.  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) 8 Limits presented in the approval meeting in June Raised in the Higgs Approval meeting and by the Edboard

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10.  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% 10  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)

11. 11 old new data SMttbar old new

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14.  The fit results are consistent with null Higgs hypothesis 14 Stat. Only

15. 15 mH=90 GeV mH=110 GeV

16.  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 16

17. 17  Groups of the correlated systematic  JES, Mtop, bJES: c  bTag,  (ttbar)  Gen, I/FSR, PS and JER mH=90 GeV

18. 18  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

19.  In the current fit,  (ttbar) is constrained with +7%/-9% uncertainties  What if we remove this constraint? basically 2 parameter fitting: Br(t  H+b) and  (ttbar)  The limits are not changed  The resulting cross sections are consistent with the SM 19

20.  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(t  H + b) are set between 5% to 1%, depending m H are 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 20

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22.  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 E T > 25 GeV & |η| 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)  M t (W) > 25 GeV (el) OR MET + M t (W) > 60 GeV (mu)  ≥ 4 jets with E T > 25 GeV and |η| 0.75  Events with loose bad jets with p T > 20 GeV are rejected  ≥ 2 jet tagged with MV1 weight > 0.601713 22

23.  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) 23

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25.  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