Final Combination of CDF’s Searches for the Higgs …trj/wc_trj_cdfhiggs_18jan_pub.pdfFinal...

Final Combination of CDF’s Searches for the Higgs Boson

Tom Junk Fermilab

On behalf of the CDF Collabora5on

1/18/13

Joint Experimental-‐Theore5cal Physics Seminar January 18, 2013

in the Standard Model and Extensions

T. Junk CDF's Higgs Searches 1

1/18/13

Tevatron Performance Proton-‐an5proton collisions with Run I: 1988 – 1996 : CDF Collects over 100 pb-‐1 of data at ECM = 1.8 TeV Run II: 2001 – 2011 : CDF Collects 10.0 W-‐1 of data at ECM = 1.96 TeV -‐-‐ 12 W-‐1 delivered. Many thanks to the Beams Division for spectacular performance of the Tevatron


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The CDF II Detector First CDF pp event: 1985 End of opera5ons: 2011


1/18/13

1

10

10 2

10 3

100 125 150 175 200 225 250 275 300mH [GeV]

(pp

H+X

) [fb]

Tevatrons=1.96 TeV

pp–H (NNLO+NNLL QCD + NLO EW)

pp–

WH (NNLO QCD + NLO EW)

pp–ZH (NNLO QCD + NLO EW)

pp– qqH (NNLO QCD + NLO EW)pp–tt–H (NLO QCD)

[GeV]HM100 200 300 400 500 1000

Higg

s BR

+ T

otal

Unc

ert

-310

-210

-110

1

LHC

HIG

GS

XS W

G 2

011

bb

cc

ttgg

Z

WW

ZZ

SM Higgs Boson Production and Decay Rates

Primary analysis modes: mH<130 GeV: VHàVbb mH>130 GeV: ggàHàWW

Addi5onal modes: Hàττ, Hàγγ, HàZZà4l cHàcbb

Gluon Fusion

Associated Produc5on

Vector Boson Fusion

t

t cH


1/18/13

Talk Outline

• Updates to CDF’s METbb Search • CDF’s Hàbb combina5on • Combined Results of all CDF SM Higgs boson searches • Fourth-‐Genera5on and Fermiophobic Results • Constraints on non-‐SM Couplings


1/18/13

Associated production VH

H

b

b!

l-

l

Jet

Jet

ν

l

ν

ν!

1)

2)

3)

V

Friday, November 9, 12

“lvbb”

“METbb” or “vvbb”

“llbb”

Drawing Credit: CMS Higgs TWiki. CDF also seeks qqHàqqbb and cHàcbb

The Main Associated Production Search Channels


1/18/13

The Status as of Summer 2012 CDF, D0, and Tevatron Publica5ons: CDF lvbb: Phys. Rev. Lec. 109, 111804 (2012) Includes new HOBIT b-‐tagger CDF llbb: Phys. Rev. Lec. 109, 111803 (2012) Includes new HOBIT b-‐tagger CDF METbb: Phys. Rev. Lec. 109, 111805 (2012) Uses old SECVTX+JetProb b-‐taggers CDF Combined Hàbb: Phys. Rev. Lec. 109, 111802 (2012) D0 lvbb: Phys. Rev. Lec. 109, 121804 (2012) D0 llbb: Phys. Rev. Lec. 109, 121803 (2012) D0 METbb: Phys. Lec. B 716, 285 (2012) D0 Combined Hàbb: Phys. Rev. Lec. 109, 121802 (2012) Tevatron Combined Hàbb: Phys. Rev. Lec. 109, 071804 (2012)


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10-4

10-3

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90 100 110 120 130 140 15010-4

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10-2

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mH (GeV/c2)

Back

grou

nd p

-val

ue ObservedExpected if SM Higgs signal

at each mH separately

Expected ±1 s.d.Expected ±2 s.d.

1

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mH (GeV/c2)

(W

H+

ZH) x

Br(H

bb– ) (fb

)

Measured±1 s.d.

±2 s.d.Predicted

At mH=125 GeV/c2, the measured rate is

! (WH + ZH )!Br(H" bb ) = 291#113+118 fb

CDF’s Hàbb Results, Summer 2012

The SM predic5on is

! (WH + ZH )!Br(H" bb ) =120±8 fb

Cross Sec5ons: Baglio, Djouadi; Harlander, Mantler, Marzani, Ozeren Branching Ra5os: LHC Cross Sec5on Working Group Denner et al., arXiv:1101.0593, arXiv:1201.3084

p-‐value using the cross sec5on as test sta5s5c: 2.7σ


Phys. Rev. Lec. 109, 111802 (2012)

1/18/13

Tevatron Hàbb Results, Summer 2012

Maximum local significance: 3.3σ at mH=135 GeV/c2 Global significance: 3.1σ Local significane at mH=125 GeV/c2 is 2.8σ

Cross sec5on fit at mH=125 GeV/c2

(!WH +! ZH )!B(H" bb ) = 230#0.080+0.090 (stat+syst) fb

SM Predic5on: 0.12 ± 0.01 pb

Phys. Rev. Lec. 109, 071804 (2012)


1/18/13

Current Status from the LHC

A Higgs-‐like par3cle is firmly established, its mass looks to be between 125 and 126 GeV, and its proper3es are consistent with the SM Higgs boson

Many more superb results are available at hcps://twiki.cern.ch/twiki/bin/view/AtlasPublic/HiggsPublicResults hcps://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResultsHIG


1/18/13

CDF’s HOBIT b-tagger – Improved Sensitivity With Respect to the SECVTX, Roma, and BNess taggers

HOBIT Tight and Loose opera5ng points chosen to have similar mistag rates as older SECVTX opera5ng points. More signal More b background Similar LF background

A neural-‐network b-‐tagger using inputs from other b-‐taggers, as well as lepton ID to include semileptonically decaying B hadrons.

J. Freeman et al., Nucl. Instrum. Methods A 697, 64 (2012). see also M. Stancari’s JETP Seminar, Mar. 7 2012

Opera3ng Point

Mistag rate

SECVTX efficiency

HOBIT efficiency

Tight 1.4% 39% 54%

Loose 2.9% 47% 59%

per-‐jet efficiencies shown


1/18/13

VHàMETbb Analysis

Select Events with 2 or 3 jets: 25 < ET,J1 < 200 GeV 20 < ET,J2 < 120 GeV If a third jet is present, 15 < ET,J3 < 100 GeV |ηjet| < 2 with at least one jet with |η|<0.9 No iden5fied lepton MET > 35 GeV ΔϕMET,J2>0.4; ΔϕMET,J3>0.4 if present

B-‐tagging: Double-‐5ght HOBIT tag (TT) Tight tag + Loose Tag (TL) One 5ght tag (1T)

Event Preselection

Inversions of the event selec5on requirements define control samples


1/18/13

Signal (and b-tagged background) gain by using HOBIT compared with SECVTX and JetProb

Categories are non-‐overlapping. The 1T category does not include TL or TT events


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Data-Based Tagged QCD Multijet Prediction Control Region: Same cuts as Preselec5on but:

•  no b-‐tag required •  35 GeV < MET < 70 GeV •  Δφ(MET,j2) < 0.4

Nearly all events are QCD mul5jet events in this sample. Measure tag frac5ons for TT, TL, 1T in this sample as func5ons of

•  HT •  missing pT •  the frac5on of charged energy in the cones of jets 1 and 2 •  the number of reconstructed primary ver5ces •  The momentum-‐weighted sum of the sines of the angles between reconstructed muon candidates and jet axes

Result is three Tag Rate Matrices. Apply these to preselected data minus W+jets, Z+jets, cbar, single top, and dibosons to model the tagged QCD mul5jet background

New for the HOBIT analysis


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)T

p, T

E(0 1 2 3

Even

ts /

0.10

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410

)2) (GeV/c2

,j1

Invariant Mass(j0 100 200 300 400

2Ev

ents

/ 8

GeV

/c

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410 Data QCD Multijet TopV + HF EWK Mistags VV

Sphericity0 0.2 0.4 0.6 0.8 1

Even

ts /

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310

410

Validation of Key Variables in the Tagged Preselection Sample

Variables also checked in •  QCD-‐enriched region: low MET, low Δφ(MET,jet) •  Electroweak control region Requires the presence of a high-‐pT isolated lepton (e or μ)


1/18/13

Signal Region: NNQCD>0.6. Retains 87% of signal while rejec5ng 90% of QCD mul5jet backgrounds

TT+TL+1T together

QCD-rejection Neural Network

Signal Region

QCDNN0 0.2 0.4 0.6 0.8 1

Even

ts /

0.03

310

210

310

410

510Data QCD Multijet TopV + HF EWK Mistags VV

10)×VH (Used to Normalize QCD

0.1 < NNQCD < 0.6 events used to normalize the QCD rate Extrapola5on uncertain5es assessed in predic5ng rates for NNQCD > 0.6. Larger uncertain5es than Moriond 2012 analysis

Signal Region


1/18/13

Predicted Yields in the Three Tagged Signal Samples

Process 1T TL TT

QCD Mul5jet 5941 ± 178 637 ± 25 222 ± 16

Top 1174 ± 158 302 ± 40 271 ± 34

V+heavy flavor jets 3124 ± 718 286 ± 83 211 ± 65

Electroweak mistags 1070 ± 386 55 ± 21 13 ± 6

Diboson 305 ± 46 48 ± 6 41 ± 5

Total expected background 11612 ± 949 1329 ± 112 759 ± 86

Observed Data 11955 1443 692

ZHàννbb, llbb (mH=125 GeV) 9.7 ± 1.0 5.4 ± 0.5 5.4 ± 0.5

WHàlνbb 9.8 ± 1.0 5.3 ± 0.5 5.3 ± 0.5


1/18/13

)2 = 125 GeV/cH

(mSIGNN0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

1T e

vent

s / 0

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1200Data QCD Multijet TopV + HF EWK Mistags VV

10)×VH (

0.8 0.85 0.9 0.95 1

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(mSIGNN0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

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vent

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vent

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Signal-Separation Neural Network Output Distributions for the Three b-tagged Signal Samples

Double Tight

Single Tight Tag

Tight+Loose


1/18/13

)2 (GeV/cHm90 100 110 120 130 140 150

95%

CL

Uppe

r Lim

it/SM

1

10

ObservedExpected

1 s.d. expected±

2 s.d. expected±

)2Higgs Mass (GeV/c90 100 110 120 130 140 150

95%

C.L

. lim

it / S

M

1

10

68% Confidence interval95% Confidence intervalExpected 95% C.L. limitObserved 95% C.L. limit

Observed and Expected Limits

This Result: HOBIT TT+TL+1T

SECVTX+JP SS+SJ+1S

Phys. Rev. Lec. 109, 111805 (2012)

At mH=125 GeV, obs = 3.06xSM exp = 3.33xSM

At mH=125 GeV, obs = 6.7xSM exp = 3.6xSM

8% sensi5vity improvement at mH=125 GeV/c2. Average expected improvement over whole mass range: 14%. Big change in observed result! New limit is a drop of 55% rela5ve to the published one at mH=125 GeV/c2


1/18/13 T. Junk CDF's Higgs Searches 20

Discussion of METbb Results

Many cross-‐checks run to assess compa5bility of the new HOBIT result and the published SECVTX+JetProb result: 1. Reanalysis of 1S, SJ, and SS tag categories using new framework, selec5on, and systema5cs 2. Valida5on of b-‐jet tagger modeling 3. Effects of Data Migra5on 4. P-‐value for the difference in observed limits using pseudoexpriments 5. Background modeling

1/18/13

Analysis Updates Besides Changing b-Taggers •  B-‐tag scale factor uncertainty handling improved – proper an5correla5ons between exclusive samples evaluated. •  QCD Mul5jet uncertain5es are larger, and improved methods for extrapola5ng from the control regions are used. •  Events with with jets with ET1>200 GeV and ET2>120 GeV now rejected •  Addi5onal MET cut at 35 GeV in early stage of analysis to get away from trigger turn-‐on now applied

•  V+heavy flavor jets backgrounds now itemized separately with independent sources of uncertainty. The charm tag rate and gluon spli�ng rates are different depending on the sample. •  Z+jets with Zàbb background model included. Re-‐Doing the SECVTX+JetProb analysis with these changes measures the impact of the changes and provides a cross check of the Winter/Summer 2012 METbb analysis


1/18/13

)2 (GeV/cHm90 100 110 120 130 140 150

95%

CL

Uppe

r Lim

it/SM

1

10

ObservedExpected

1 s.d. expected±

2 s.d. expected±

HOBIT

)2 (GeV/cHm90 100 110 120 130 140 150

95%

CL

Uppe

r Lim

it/SM

1

10

Observed [5]Expected [5]

1 s.d. expected± 2 s.d. expected±

Observed (Cross-check)Expected (Cross-check)

SECVTX+JP Published analysis + Redo Crosscheck

Results of SECVTX+JetProb Redo Cross Check

At mH=125 GeV/c2, the observed HOBIT limit is 47% lower than the Re-‐Done SECVTX+JP observed limit. (Was 55% lower than published).


1/18/13

Combine the Redone SECVTX+JetProb METbb with llbb+lvbb

1

10

90 100 110 120 130 140 150

1

10

mH (GeV/c2)

95%

CL

Lim

it/SM

CDF Run II Preliminary H bb–, L = 9.45 fb-1

Observed (w/ published METbb)Expected w/o HiggsExpected ±1 s.d.Expected ±2 s.d.

Observed (w/ Re-DoneSECVTX+JetProb METbb)

SM=1

Black Curve: Same limit curve as in Phys. Rev. Lec. 109, 111802 (2012) Red Curve: Published llbb, lvbb, and the Redone SECVTX+JetProb crosscheck P-‐value remains unchanged. at 2.7σ at mH=125 GeV/c2


CDF finds no significant issues with the previous version of the METbb analysis and stands firmly behind last summer’s published results.

CDF Combined VHàVbb limits/SM

1/18/13

B-Tag Modeling Validation: Electroweak Control Region

)2 = 125 GeV/cH

(mSIGNN0 0.2 0.4 0.6 0.8 1

TT E

vent

s / 0

.04

1

10

210 Data QCD Multijet TopV + HF EWK Mistags VV

Double-‐Tight HOBIT TT

)2 = 125 GeV/cH

(mSIGNN0 0.2 0.4 0.6 0.8 1

SS E

vent

s / 0

.04

1

10

210

Double-‐Tight SECVTX SS

Preselec5on requirements, but require a high-‐pT isolated lepton (e or μ) Look for mismodeled correla5ons between NNSIG and b-‐tagging


No modeling issues seen with either b-‐tag algorithm as a func5on of NNSIG

1/18/13

1T TL TT 1S 55% 35% 15% SJ 4% 20% 30% SS 1% 14% 51%

Data Event Overlap Fractions: NNSIG>0.8


Denominator: HOBIT analysis events

Studying the Effects of Event Migration

HOBIT Tagger is more efficient: Expect promo5on of signal events to higher tag categories.

We do not see problems in modeling: Suspect sta5s5cal fluctua5ons.

1/18/13

Event Rate Summaries – HOBIT analysis vs. SECVTX+JP

Now: 6.5 events deficit at high score. Was: spot on

Tag category Background (fit) DataTT 39.5± 4.6 33SS 37.6± 4.6 37TL 67.4± 6.8 80SJ 45.6± 5.1 62


High Score: NNSIG > 0.8 Observed Event Counts

Excesses seen in both old and new 5ght-‐loose categories


Events Gained and Lost: TL and SJ

Top three NNSIG score events in the SJ analysis are no longer selected. Two are now LL and one is 1L. Bin has high s/b and a large weight in the result. A test: We added these three events by hand to TL. SECVTX+JP(redo) vs. HOBIT limit discrepancy changes from 47% to 31% with the events added back. The NNSIG func5on is unchanged since

Moriond 2012. Selected, tagged events receive the same NNSIG scores they always did.

1/18/13

Events Gained and Lost: TT and SS


Lost More Events than Gained in the high-‐NNSIG region. Studied adding 5 extra candidates to the TT data by hand, following the background shape (not just the last bin). Change in limit discrepancy: from 47% to 33% Combined effect of TT and TL candidates: reduces discrepancy from 47% to 19% Improvement in sensi5vity is 8% at mH=125 GeV

1/18/13

How Likely is it? Compare CDF METbb HOBIT analysis with the re-‐done SECVTX+JP analysis Paired pseudoexperiments: •  HOBIT channels TT, TL, 1T •  SECVTX channels SS, SJ, 1S •  Use expected overlaps in the NNSIG < 0.8 and NNSIG > 0.8 regions to generate independent samples of events in 15 categories: TTSS, TTSJ, TT1S, TTnone TLSS, TLSJ, TL1S, TLnone 1TSS, 1TSJ, 1T1S, 1Tnone noneSS, noneSJ, none1S Calculate limit for each pair of pseudoexperiments & compare

P-‐value for |Limit difference| to be as big as observed: 7% Highly correlated over mH range: P-‐value for all limits to be low: 3-‐5%



)2 (GeV/cHm90 100 110 120 130 140 150

Ove

rlap

Frac

tion

0

0.2

0.4

0.6

0.8

1

> 0.8SIG

Overlap Fraction of Data Events with NN

= 100Hm = 125Hm = 150Hm

How Correlated are the Searches at Each mH? Limited resolu5on on input variables to NNSIG correlates results of searches at nearby masses. Between 2 and 3 independent search results over the mass range 90 < mH < 150 GeV/c2


Tag category Background (fit) DataTT 264.8± 25.1 265SS 228.8± 21.0 217TL 506.1± 38.8 506SJ 312.5± 22.6 291

Studying Backgrounds in the Intermediate NNSIG Score Region

Intermediate Score: 0.48 < NNSIG < 0.8 Background fits dominated by events at even lower NNSIG score Limits on Higgs boson signal fairly insensi5ve to these bins.

)2 = 125 GeV/cH

(mSIGNN0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

TT e

vent

s / 0

.04

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0.8 0.85 0.9 0.95 1

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No evidence for mismodeling in this region

1/18/13

Final CDF Combined VHàVbb Cross Section Measurements

The SM predic5on is

! (WH + ZH )!Br(H" bb ) =120±8 fb

0

100

200

300

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500

600

700

90 100 110 120 130 140 1500

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mH (GeV/c2)

(W

H+

ZH) x

Br(H

bb– ) (fb

)

Measured±1 s.d.

±2 s.d.Predicted

At mH=125 GeV/c2, the final measurement is

! (WH + ZH )!Br(H" bb ) = 206#104+110 fb

Final

! (WH + ZH )!Br(H" bb ) = 291#113+118 fb

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)

Measured±1 s.d.

±2 s.d.Predicted

Summer 2012

At mH=125 GeV/c2 the previous measuement is


1/18/13

Summary of the Hàbb Updates and Investigations

•  Previous METbb (SECVTX+JetProb) analysis is s5ll valid •  Analysis redone with new framework, cuts, and systema5c uncertainty handling •  Previous METbb result reproduced with small shi�s in limits •  No change in combined limits or p-‐values

•  Switching to a new b-‐tagger reclassified events – only 50% overlap with events in the old analysis in the highest-‐weight region. •  New best-‐fit cross sec5ons are lower. •  We must choose the more sensi5ve analysis: HOBIT METbb is 8% more sensi5ve than the previous version at mH=125 GeV/c2, and 14% stronger on average in 90 < mH < 150 GeV



Predicted Event Overlap Fractions, signal MC

Roman font – normalized to HOBIT yields. Italics: Normalized to SECVTX+JP yields

Combining the SECVTX+JetProb Analysis and HOBIT Analysis? Reasons to do it: •  More sta5s5cal power •  Observed results may be intermediate between published and new results

Reasons not to do it: •  Expected sensi5vity gain is very small – signal events are expected to remain tagged, merely shuffled from one category to another •  More exclusive tag categories (15 instead of 3). Smaller data control samples mean higher systema5c uncertain5es •  HOBIT uses SECVTX variables as inputs, among others. It’s already a combina5on. •  Combining HOBIT and SECVTX+JetProb was not on our original menu of analysis improvements, for the above reasons. We made the decision to switch all analyses from SECVTX+JetProb to HOBIT without knowledge of the data outcome. Switching a posteriori would bias the final result.

1/18/13

Updates Since the last full CDF SM Higgs Combination

•  Revert to the published 6.0 W-‐1 Hàττ Search. 8.3 W-‐1 preliminary result not published.

•  Update the cH search: train MVA’s at each mH. •  Improve correla5ons/an5correla5ons in b-‐tag uncertain5es in llbb / lvbb analyses •  Upgraded the Central-‐Central Hàγγ search to use an MVA instead of mγγ. Searches including plug photons and conversions s5ll use mγγ. CDF’s SM combina5on last done for Winter 2012 conferences.


1/18/13

All CDF SM Search Channels


1/18/13

1

10

0 2 4 6 8 10 12 14Integrated Luminosity (fb-1)

Expe

cted

Lim

it/SM Summer 2005

Summer 2006Summer 2007Winter 2008Fall 2008

Fall 2009Summer 2010Summer 2011Winter 2012

mH=115 GeV/c2

SM=1

1

10

0 2 4 6 8 10 12 14Integrated Luminosity (fb-1)

Expe

cted

Lim

it/SM Summer 2004

Summer 2005Summer 2007Winter 2008Fall 2008

Spring 2009Fall 2009Summer 2010Summer 2011Winter 2012

mH=160 GeV/c2

SM=1

Sensitivity Evolution over Time

We collected data, and we also learned how to get more out of the data. •  Becer MVA’s •  Becer Event Selec5on •  Becer lepton ID •  Becer jet energy resolu5on •  More triggers •  More analysis categories •  Sharing improvements between analyses


1/18/13

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SM Combined Data Summaries at mH=125 and 165 GeV/c2

Background Hypothesis fit to data Bins of similar s/b added together


1/18/13

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SM Combined Data Summaries at mH=125 and 165 GeV/c2

Same as before, but ficed background subtracted from the data. Data error bars are sqrt(s+bfit)



Sensitivity of the Main Search Channels

1

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10 2

100 110 120 130 140 150 160 170 180 190 200

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mH (GeV/c2)

R95m

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Htt–H tt–tb–

VH Vbb–

H ZZ 4lH W+W-

Combined

SM=1

1/18/13

1

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100 120 140 160 180 200

1

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mH (GeV/c2)

R95 Expected if no Higgs

ObservedExpected ±1 s.d.Expected ±2 s.d.

Expected if mH=125 GeV/c2

SM=1

CDF’s Final SM Higgs Rate Limits

Excluded regions: 90 < mH < 102 GeV/c2 and 149 < mH < 172 GeV/c2 Expect to exclude if no Higgs: 90 < mH < 94 GeV/c2, 96 < mH < 106 GeV/c2, and 153 < mH < 175 GeV/c2


1/18/13

SM/Best Fit 0 1 2 3 4 5 6 7 8 9 10 11

b VbVH

-+ H

-W+ WH

Hbbt tHtt

2 = 125 GeV/cHmCombined (68%) Single Channel

0

0.5

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mH (GeV/c2)

Rfit

Observed±1 s.d.±2 s.d.

Expected ifmH=125 GeV/c2

Best-Fit Cross Sections at mH=125 GeV/c2

ttH! ttbb : 9.49"6.28+6.60 #SM

H! !! : 7.81"4.42+4.61 #SM

H!W +W " : 0.00"0.00+1.78 #SM

H! ! +! " : 0.00"0.00+8.44 #SM

VH!Vbb : 1.72"0.87+0.92 #SM

Combined : 1.54!0.73+0.77 "SM


SM Combina5on

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10-4

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Back

grou

nd p

-val

ue ObservedExpected if SM Higgs signal

at each mH separately

Expected if mH=125 GeV/c2

Expected ±1 s.d.Expected ±2 s.d.

1

2

3

CDF’s Combined SM Higgs Boson Search p-value Observed local significance at mH=125 GeV/c2 is 2.0σ Expected significance at mH=125 GeV/c2 is 1.6σ assuming a signal is present.

2.5σ local significance at mH=120 GeV/c2

Look-‐Elsewhere Effect: •  mH~125 GeV has been firmly established by the LHC •  CDF’s mass resolu5on is not very sharp -‐-‐ ~2 independent search results in Hàbb, ~2 in HàWW •  Technical challenge – MVA’s trained at each mH separately. Histograms of predic5ons exchanged. Would need to exchange correlated pseudoexperiments to compute LEE exactly.


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Extensions to the SM: Fourth-Generation Models (SM4)

A heavy fourth genera5on of quarks would scale the gg→H produc5on rate at colliders by a factor of ~9. But watch out for H→ν4ν4 decays. E. Arik et al., Acta Phys. Polon. B 37, 2839 (hep-‐ph/0502050)

Kribs, Spannowsky, Plehn, Tait, Phys. Rev. D 76, 075016 (2007) T. Junk CDF's Higgs Searches 44

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. Lim

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w m

ass)

pre

dict

ion

SM4(low mass)=1

ExpectedObservedExpected ±1 s.d.Expected ±2 s.d.SM4(high mass)

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mH (GeV/c2)

(gg

H)×

Br(H

W+ W

- ) (pb

)

Exp. 95% C.L. limitObs. 95% C.L. limit±1 s.d. exp. limit±2 s.d. exp. limitSM4 (low mass)SM4 (high mass)

Searches for ggàHàWW – Model Independent and SM4 interpretation

SM4 Cross Sec5ons computed at NNLO in QCD by Anastasiou, Boughezal, and Furlan

Searches op5mized specifically for ggàH (NN’s not trained with WH, ZH, or VBF). Limit on cross sec5on 5mes b.r. shown along with SM4 model predic5ons.

Low-‐Mass scenario: ml4=100 GeV, mv4=80 GeV High-‐Mass scenario: ml4=mv4=1 TeV Both Scenarios: md4=400 GeV, mu4=450 GeV

Low-‐mass scenario exclusions: Expected exclusion: 123 < mH < 231 GeV/c2 Observed exclusion: 124 < mH < 203 GeV/c2


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1

10

100 110 120 130 140 150 160 170 180 190 200

1

10

mH (GeV/c2)

R95

f

Expected if no Higgs

Observed

Expected ±1 s.d.

Expected ±2 s.d.

FHM=1

A Test of the Fermiophobic Higgs Model Model tested: Assume SM-‐like behavior for the Higgs boson, except switch off all couplings to fermions. Decays for Hàbb, Hàττ, and Hàgg are highly suppressed. ggàH produc5on is neglibly small. WH, ZH, VBF produc5on cross sec5ons are as predicted by the SM HàWW, ZZ par5al widths are as predicted by the SM. Hàγγ is modified – loss of the fermion loop increases the decay rate. Hàγγ search is re-‐op5mized for this search because the pT spectrum of the H is harder in WH and ZH than for ggàH Branching ra5os recomputed using the modified decay widths.

Included channels: Hàγγ, HàWW, HàZZà4l

Observed exclusion: 100 < mH< 113 GeV/c2 Expected exclsuion: 100 < mH< 122 GeV/c2


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Constraining the Couplings of the Higgs Boson to Fermions and Gauge Bosons

We follow the procedures and nota5on of the LHC Higgs Cross Sec5on WG A. David et al., arXiv:1209.0040

The model: SM-‐like, but Hff couplings are scaled together by κf HWW coupling is scaled by κW HZZ coupling is scaled by κZ For some studies, we scale the HWW and HZZ couplings by κW=κZ=κV Standard Model is recovered if κf = κW = κZ = 1


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Step 1: Scale cross sec3ons for each process according to couplings -‐-‐ Precy much by defini5on! Unless NNLO VBF includes the EW ggH piece. From Bolzoni, Moch, Maltoni, and Zaro’s papers, it seems as if the EW ggH piece is not in the NNLO VBF calcula5on.

LO rela5ons, but mostly true at higher order (most QCD affects the colored ini5al-‐state par5cles. There is ggàWH at higher order, however.)

Constraining Couplings

! (gg!H ) =! SM (gg!H )(0.95" f2 + 0.05" f"V )

! (WH ) =! SM (WH )"V2

! (ZH ) =! SM (ZH )"V2

! (VBF) =! SM (VBF)"V2

A. David et al., LHCHXSWG-‐2012-‐001. arXiv:1209.0040


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Aglie�, Bonciani, Degrassi and Vicini, arXiv:hep-‐ph/0610033 Anastasiou, Boughezal, Petriello, JHEP 0904 003 (2009) Ac5s, Passarino, Sturm, Uccira5 PLB 670, 12 (2008) Grazzini and de Florian PLB 674, 291 (2009)

Two-Loop Electroweak Contributions to the ggH Coupling

•  Approximately a 5% contribu5on to the ggàH produc5on cross sec5on at mH=125 GeV/c2. Main contribu5on is from interference with the LO process. •  Contribu5on not included in VBF calcula5on (HAWK: Denner, Dicmaier, Mück)


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Step 2: Recompute all Higgs boson decay branching ra3os from scaled par3al widths α and β come from Spira et al., arXiv:hep-‐ph/9504378 α=1.28 β = -‐0.21

Constraining Couplings

!(H" gg) = !SM (H" gg)(0.95! f2 + 0.05! f!V )

!(H"W +W # ) = !SM (H"W +W # )!V2

!(H" bb ) = !SM (H" bb )! f2

!(H" " +" # ) = !SM (H" " +" # )! f2

!(H" cc ) = !SM (H" cc )! f2

!(H" ZZ ) = !SM (H" ZZ )!V2

!(H" ## ) = !SM (H" ## )$!V +%! f2

Br(H! XX) = "(H! XX)"i

i#

Other modes, like Hàμ+μ-‐ and HàZγ have very small widths


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Some work from theorists Espinosa, Grojean, Mühlleitner, and Troc, “First Glimpse at Higgs’ Face”, arXiv:1207.1717v2 (updated Aug. 21 with post-‐ICHEP data) JHEP 1212, 045 (2012).

a=κV, c=κF T. Junk CDF's Higgs Searches 51


More Complete Treatment of Signal Scalings Example: HWW Search. All Signals have HàWW, but different mixtures of produc5on mechanisms in each search channel.

Pie charts show rela5ve contribu5ons.

ggH WH ZH VBF

ggH WH ZH VBF

ggH

WH

ZH

VBF

Zero Jets

One Jet

Two or More Jets

Same Sign di-‐ leptons

Tri-‐Leptons Z-‐rejected

ggH WH ZH VBF

ggH WH ZH VBF ggH WH ZH VBF

Tri-‐Leptons Z-‐selected

Each signal contribu5on should be scaled by the appropriate factor

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Signal Rate Enhancement Factors for ggàHàWW and WH->lvbb


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Signal Rate Enhancement Factors for ttHàttbb and WH->WWW

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Posterior Constraint on the Hff Coupling Factor κf

•  Uniform prior assumed •  κW = κZ = 1 assumed

Excess in the Hàγγ searches drives the asymmetry from posi5ve and nega5ve coupling scale factors



W-2 -1 0 1 2

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sity

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Posterior Constraint on the HWW Coupling Factor κW

•  Uniform prior assumed •  κf = κZ = 1 assumed

Excess in the Hàγγ searches drives the asymmetry from posi5ve and nega5ve coupling scale factors


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Posterior Constraint on the HWW Coupling Factor κZ

•  Uniform prior assumed •  κf = κW = 1 assumed

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Two-Dimensional Constraints: Bosons vs. Fermions


Uniform prior assumed Large κV with small κf constrained by trileptons, same-‐sign dileptons Large κf and small κV constrained by cHàcbb


W

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floatingf

Two-Dimensional Constraints: W vs. Z Couplings

Uniform prior assumed κf integrated over (“marginalized”) Less constraint on HZZ than on HWW All couplings consistent with SM predic5ons

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Summary (1) •  CDF’s Searches for the Higgs boson in the SM, SM4, and Fermiophobic models are now finalized •  Publica5ons on the final METbb (HOBIT) search plus the combina5on are being submiced. •  Previous METbb (SECVTX+JP) analysis is s5ll valid – no mistakes affec5ng the Summer 2012 result were found. •  Switching to a new b-‐tagger reclassified events – only 50% overlap with events in the old METbb analysis in the highest-‐NNSIG region. •  New best-‐fit cross sec5ons are somewhat lower. •  We must choose the more sensi5ve analysis: HOBIT METbb is 8% more sensi5ve than the previous version at mH=125 GeV/c2


1/18/13

Excess of events persists in the SM Higgs search near mH=125 GeV/c2. Higgs boson does not look like those of the FP model, or SM4. Couplings to W, Z, and fermions are consistent with SM predic5ons Extrac5ng coupling informa5on from the data requires full predic5ons of signal rates and shapes in all channels. Channels that contribute licle to the total SM sensi5vity can have outsized impacts on exo5c coupling scenario tests.

Summary (2)


Final Combination of CDF’s Searches for the Higgs …trj/wc_trj_cdfhiggs_18jan_pub.pdfFinal...

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