Moriond ElectroWeak 2005, Gregorio Bernardi, Paris/FNAL, for the CDF and D Ø Collaborations

Gregorio Bernardi / LPNHE-Paris

CDF

Moriond ElectroWeak 2005, Gregorio Bernardi, Paris/FNAL,

for the CDF and DØ Collaborations

Tevatron/ Luminosity

CDF and DØØ

SM Higgs Searches

b-tagging / Zbb

BSM Higgs Searches

Summary

Only Results new since last Moriond are shown,i.e no unstable H++, nor H

Results on Higgs Searches @Tevatron

2Gregorio Bernardi / LPNHE-Paris

CDF Tevatron Parameters

82.32.5Interactions/ crossing

3963963500Bunch crossing (ns)

50173 Ldt (pb-1/week)

3 10329 10311.6 1030Typical L (cm-2s-1)

1.961.961.8s (TeV)

36 3636 366 6Bunches in Turn

Run IIbRun IIaRun I

Run I Run IIa Run IIb 0.1 fb-1

Since last Moriond: improvement in reliability / operating efficiency: in stores ~120 hours/week

Typical ratio of “recorded” to “delivered” luminosity is 80%-90%

So far both exper. recorded ~0.8 fb-1

Results presented on ~0.2-0.3 fb-

1

Upgrades for Run II: 2001-2009

10% energy increase: 30% higher top

integrated luminosity increase: x50

Plan (build higher antiproton stacks!)- Increase # of protons on antiproton target - Optimization of transfers, improved optics/helices - Increase p stacking/storing (mixed mode/e-cool)- Upgrade Tevatron for higher bunch intensities


CDFTevatron Run II

Performance

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10/01/03 12/31/03 03/31/04 06/30/04 09/29/04

Date

Inte

gra

ted

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min

os

ity

(p

b-1

)

Design

Base

Actual

2004 : above Design !

2005 : so far along Design

2004

2003

2002

Design for 2005 Base for 2005

Peak luminosity is above 1.1032 cm-2sec-1 Total ~0.7 fb-1 delivered in Run II

1.1032 cm-2sec-1 0.8 fb-1


CDFTevatron Long Term Luminosity

PlanCurrently expecting

delivered luminosity to each

experiment

4 - 8 fb-1

by the end of 2009 Integrated Weekly Luminosity (pb-1)

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10

20

30

40

50

60

10/1/03 9/30/04 9/30/05 9/30/06 9/30/07 9/29/08 9/29/09

electron cooling

stacktail bandwidth upgradeDesign

Base

Total Luminosity (fb-1)

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10/1/03 9/30/04 9/30/05 9/30/06 9/30/07 9/29/08 9/29/09

Design

BaseToday

Increase in number of antiprotons

key for higher luminosity

Expected peak luminosity 3.1032 cm-2sec-1 by 2007


CDF

LAr/U Calorimeter, fine-grained, hermeticNew trackers Silicon microVTX, Central Tracker (Scint Fibers)2T superconducting solenoidPre-shower detectorsUpgraded muon detectorsFaster readout electronicsNew trigger & DAQ

Total of 800,000 Silicon channels

80,000 channels in the Central Fiber Tracker

The DØ Experiment in Run II

55000 Calorimeter cells


CDFSM Higgs Production and

Decays

Production cross section in the 1.0-0.1 pb range for gg H in the 0.2-0.02 pb range for associated vector boson production

Dominant Decays bb for MH < 135 GeV WW* for MH > 135 GeV

Search strategy: MH <135 GeV associated production WH and ZH with Hbb decay

Backgrounds: top, Wbb, Zbb… MH >135 GeV gg H production with decay to WW*

Backgrounds: electroweak WW production…

Production Decays

mH (GeV/c2)

Exclu

ded


CDFExperimental Limits on Higgs

Mass

direct searches at LEP

MH >114 GeV at 95% C.L.

precision EW fits (winter 2005)

MH= 126+73-48 GeV

MH 280 GeV @ 95% C.L.

Light Higgs favoredTevatron provides:Precision measurements of mtop&

Mw

and Direct searches:

SM Higgs non-SM Higgs

LEP


CDFTevatron SM Higgs Search:

Outlook

Updated in 2003 in the low Higgs mass region

W(Z)Hl(,ll)bb to include

better detector understanding

optimization of analysis

Sensitivity in the mass region above LEP limit starts at ~2 fb-

1

Meanwhile optimizing analysis techniques understanding detectors better searching for non-SM Higgs with higher production cross sections or enhanced branching into modes with lower backgrounds

LEP

Tevatron

Ldt (fb-

1)


CDFSM “Heavy” Higgs: H WW

llSearch strategy:

2 high Pt leptons and missing Et

WW comes from spin 0 Higgs:leptons prefer to point in the same

directionW+ e+

W- e-

H

Main Background: WW ProductionGood agreement with NLO theory: 12.0-13.5 pb

Ohnemus, Campbell, R.K.EllisNow Measured at the Tevatron by both ExperimentsDØ: PRL/ hep-ex/0410062


CDF

Search in 3 channels: HWW*ll with l = ee,,e inclusive high pT lepton triggers: integrated luminosity 184 pb-1 (CDF), 147-177 pb-1(D0)

CDF: Obs: 8 evts; Bkgnd: 8.9 1 Signal: 0.17 0.02 (mH=180

GeV)

Search for H WW*

Data Selection: two isolated leptons with opposite charges with pT > 20 GeV, >25 GeV, ( , l or j) , veto on jets, light (<MH/2) invariant dilepton mass

TE TE

Maximum likelihood limit on the ll distributions for mH=140-180 GeV

*BR(H→WW)< 5.6pb For MH=160 GeV

95% CL for the 3 channels*BR(H→WW) < 5.7pb For MH=160 GeV

D: Obs: 9 evts; Bkgnd:11.1 3.2 Signal: 0.27 0.004 (mH=160

GeV)


CDF Search for WH WWW*

Search of high-pT isolated like-sign (LS) dilepton events in 193.5 pb-1 data.

leading lepton pT,1 > 20 GeV, 2nd lepton pT2 > 16 GeV, pT12=|vect.sum of 1,2| > 35 GeV. Search in the (pT,2,pT,12) plane:

- 0 events found - total exp. Backgnd: 0.95 +- 0.61(stat)

+- 0.18(syst) - bosophilic Higgs (110 GeV) exp. to be about 0.06 evts . (assuming same production x-section as SM Higgs) - SM Higgs (160 GeV) expected to be about 0.03 evts.


CDFLow Mass (<135 GeV) Higgs

Search

Also difficult at LHC (combination of several channels)

At Tevatron need to fully exploit associated productions:

WH and Z (l+l- or ) H with H bb b-tagging

Understand intrumental and SM backgrounds

W,Z+heavy flavor are backgrounds to leptonic WH,ZH

instrumental background (QCD) is difficult for H

Here after, results for b-tagging, Z and W+ Heavy Flavor,

WH, and SM Higgs prospects


CDFTagging b-quarks (B-

hadrons)

Impact Parameter Resolution

dca/s(dca)

Decay Length Resolution

Lxy/s(Lxy)

•Top, Higgs have b-quark jets

•Leptons from B meson

•Contain a B meson•Has finite life time•Travels some distance from the vertex before decaying

•~ 1mm•With charm cascade decay, about 4.2 charged tracks

Several algorithms under development/improvement:3 main categories:- Soft-lepton tagging- Impact Parameter based- Secondary Vertex reconstruction

Several algorithms under development/improvement:3 main categories:- Soft-lepton tagging- Impact Parameter based- Secondary Vertex reconstruction

B

Impact Parameter (dca)

Vertex Tagging a B(transverse plane)

Decay Lengh (Lxy)Hard Scatter

(Signed) Track


CDF

Jet Lifetime Impact Parameter

Based on signed dca Significance.

Probability distributionsP(Track from PV)Defined for each class of tracks

# of SMT Hits, pT, etc.To each jet is assigned a Probability to be a light quark: Pjet

Light Quark Fake Rate

48%

0.5%

Impact Parameter (dca) Algorithms

Another algo also used in D0: counting displaced tracks

Light jets: same flat probability for postive & negative dca significance

b jets: probability for positive dca sign. peaks at 0.


CDF SVT Algorithm

Z axis

Secondary Vertex Tagger

Reconstruct Vertices using displaced tracks

S(Lxy) = Lxy/s(Lxy).

Cut on Decay Length Significance

~50%

0.5%

Performance on signal

tt lepton+jets ~ 56%Single Top (s channel) ~ 52%Wbb ~ 52%Wj ~ 0.3%

Combining the 3 Taggers, correlations already studied

N.B.: in D0, b-tagging efficiency is defined w.r.t. “taggable” jets, i.e. results are slightly higher than if estimated w.r.t to all jets


CDF Secondary Vertex Algorithm

SecVtx tagger efficiency to tag jets in top quark MC samples, as obtained by multiplying the tag rate for such MC jets by the data/MC scale factors: 0.909±0.060 for the tight tagger and 0.927±0.066 for the loose tagger.

The bands represent the systematic error on the data/MC scale factors.

Performance on signal

42%

0.5%

Gregorio Bernardi / LPNHE-Paris

CDF

Vertex view of a low mass candidate

3 views of a high dijet mass (220 GeV) Wbb (WH) candidate

dijet mass (48 GeV)

ETmiss

Clean Events! Mass Reconstruction?

ETmiss

ETmiss

electron

b-tags


CDFFirst steps in Measuring Z

bb Dijet invariant mass of 85,794 events with both jet containing a secondary vertex b-tag.

Events are selected from 333 pb-1 of CDF data (dedicated trigger).

Two leading jets must be back-to-back in azimuth (Delta Phi>3.0), and the event must have no other jet with ET above 10 GeV.

The background shape is computed using untagged data passing the same selection.

The Z->bb signal shape is computed with Pythia

The 2 shapes are fit to the experimental data (blue points)

Fit results are in red

Fit uncertainties are stat. only.


CDFZ + Heavy Flavor

Production Z+heavy flavor is background

to ZH

Z + single b-tag– Probe of b-quark PDF– b PDF is important for hb

and single-top production

Measure (Z+b)/(Z+j)– Many systematics cancel

Selection– Z in ee and channels

(cut on mass window) 1 Jet pT>20 GeV, ||<2.5– 3458 Z+jet events


CDF (Z+b)/(Z+j)

Apply sec. vertex b-tag42 events with 1 tag8.3 from QCD

background (sideband)

Disentangle light, c, b contributions– Use light and b-tagging

efficiency from data– c-tagging efficiency from MC and

scaled for data/MC difference in b-tagging

– Nc=1.69Nb from theory

Cross checks with– Soft lepton tagging– Impact parameter tagging

0.0240.005(stat)0.005(syst)

– Theory predicts 0.018– Large part of systematic error

from tagging efficiency and background estimation

Sec. Vtx displacement/resolutionSubmitted to PRL - hep-ex/0410078

signal


CDF

174pb-1 sample with one electron and (dominant backgd for WH) TE

2540 evts (2580 630 expected)

Compared to ALPGEN, PYTHIA showering, and full detector simulation. Normalized to NLO x-section (MCFM for W+jets)

Electron: pT > 20 GeV, ||<1.1

Missing ET > 25 GeV

2 Jets: pT > 20 GeV/c, ||<2.5

Search for Wbb Production

1 tag: 76 evts (72.6 20 exp.)

Data well described by simulation

Total experimentalsyst. Error ~15 %


CDF

6 evts (4.4 1.17 expected)

95% CL upper limit of 6.6 pb on

production for b with pT

b > 20 GeV and >0.75

bWbbbR

95% CL upper limit on WH production of 9.0 - 12.2 pb for Higgs masses of 105-135 GeVPublished Run II limit better than Run I detector improvements

Accepted in PRL - hep-ex/0410062

Wbb / WH Search


CDF

162pb-1 sample with one electron or muon and TE

W+2 jet events (before b-tagging)

W+ 1b-tagged jet

2540 evts observed

62 evts (66.5 9 expected)

Data well described by simulation

Electron or muon: pT > 20 GeV/c

Missing ET > 20 GeV

2 Jets: pT > 15 GeV/c, ||<2.0

Total systematic error ~ 11%No significant peak from Higgs

Search for Wbb Production


CDF

95% CL upper limit on 5.3 (4) pb @ mH=115

(150) GeV

)bbBR(HWH)pσ(p

Wbb WH SM Higgs Prospects

Future improvements Extend b-tagging acceptance,

efficiency Additional kinematic variables

Better Mbb resolution Add bb channel


CDF

Sample Selection:- Trigger >3 jets with ET>15 GeV,- Offline cut on ET of leading jets

optimised for each Higgs mass. - 3 b-tagged jets or more Background:

“QCD heavy flavor” : bbjj, ccjj, cccc, bbcc, bbbb “QCD fakes” : jjjj “Other” : Z(bb,cc), tt

Theory/Simulation: NLO SM Higgs production (Campbell et. al., Dawson et. Al), MSSM (Carena, Mrenna, Wagner),

PYTHIA, MADGRAPH, ALPGEN

• Search for neutral Higgs in a two-Higgs-doublet MSSM SUSY model. • 260 pb-1 sample of triple b-tagged multi-jet events.• No distinction between h or H and A

Di-jet mass in 3b-tagged events260 pb-

1

No excess of events observed

bbh(bb) Search

h h

SUSY-MSSM


CDF

For mA=120 GeV: < 31 pb-1 @ 95%c.l., tan < 55 @ 95%c.l. (Max Mixing)

260 pb-1

260 pb-1

Limits on signal production cross section & in the tan β vs. mA plane:

< 70-20 pb for mA=90-150 GeV

Exclude significant portion of tan β down to 50, depending on mA and MSSM scenario:

Two benchmark MSSM scenarios:

bbh(bb) Search


CDF Search for gg h

200 pb-1 sample from triggers (lepton+isolated track): two ’s, one decaying into hadrons+n and the other to an e/m + 2n.

GeV50E|)(τp||)(τp|H T2T1TT Cuts on lepton pT, Z mass window. To remove light quark bkgnd: PYTHIA+ Tauola (signal simul.)

)Eτ,m(l, 230 evts. obs. 263.630.1 exp.

Limit on xBR extracted from likelihood fit of the “partial mass” distribution:


CDF Search for H++/H--

Predicted by some beyond SM models like Left-Right Symmetric ModelsIf short lived: prominent signature – multiple high Pt

leptons, like sign di-lepton mass peak backgrounds: WZ, W+jets, conversions (e)

If long lived (c > 3 m): two high ionization tracks

q

q

l +

l +

l -

l -

*/Z

H--

H++

MH>134GeV

D0 (113 pb-1) M(HL) > 118 GeV () at 95% C.L.CDF (240 pb-1) M(HL) > 136 GeV () at 95% C.L.

Background < 10-5


CDF Summary

Higgs search is in progress: SM Higgs sensitivity (mH >114 GeV) starts at ~2 fb-1

(Moriond 07 ?) non-SM Higgs many different models tested already see reduction in allowed phase space (Run I, LEP)

Expect substantial improvements in Higgs hunting with

~0.8 fb-1 already on tapes~8 fb-1 expected in Run II

No deviations from SM observed (yet)


CDF Backup


CDFData Collection by the

Experiments

CDF

Typical ratio of “recorded” to “delivered”luminosity is 80%-90%

As of now both exper. recorded ~0.7 fb-1

Results presented correspond to ~0.3 fb-1

Analyzed data

Analyzed data


CDF Search for H

In the SM Higgs has Br~10-3 search for SM Higgs decaying to gamma pair is not practical at Tevatron

Many SM extensions allow enhanced gamma pair decay rate largely due to suppressed coupling to fermions Fermiphobic Higgs Topcolor Higgs

Search strategy: Look for peaks in mass spectrum for high Pt isolated ’s


CDF Wbb Technicolor

CDF x-section limits for m(T

0) between 85 and 120 GeV

D rules out the m(T)=200 GeV m(T)=105 GeV combination for MV between 200 and 500 GeV

Moriond ElectroWeak 2005, Gregorio Bernardi, Paris/FNAL, for the CDF and D Ø Collaborations

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Transcript of Moriond ElectroWeak 2005, Gregorio Bernardi, Paris/FNAL, for the CDF and D Ø Collaborations