Searches for charged Higgs bosons, supersymmetry, and exotica with tau leptons with the ATLAS and...

Ryan Reece

[email protected]

University of Pennsylvania

September 20, 2012Tau 2012, Nagoya, Japan

Searches for charged Higgs bosons,

supersymmetry, and exotica with

tau leptons with the ATLAS and

CMS detectors at the LHC

on behalf of the ATLAS and CMS collaborations

Ryan Reece (Penn)

Outline

2

• Motivational questions about the SM

• Large Hadron Collider, ATLAS, and CMS

• Charged Higgs searches

• SUSY searches

• Exotics: Leptoquark and Z’ searches

... all with taus.

Ryan Reece (Penn)

Why the Standard Model?

3

• Why the gauge group SU(3)C × SU(2)L × U(1)Y ?

• Why are there 3 generations of quarks and leptons?

• Why are lepton and hadron charges quantized in the

same units? Why the existing hypercharges?

Is it because...

• the gauge group of Nature is actually bigger?

SO(10) → SU(5) × U(1) Georgi-Glashow

SO(10) → SU(4)C × SU(2)L × SU(2)R Pati-Salam

• e.g. Pati-Salam SO(10): QEM = T3L + T3R + 1/2(B − L)

• lifetime of the proton > 1033 years ⇒ if unification happens it must suppress proton decay, e.g. it happens at a high energy scale

QEM = T3L + Y/2

Ryan Reece (Penn)

Gauge coupling unification

4

Using renormalization group equations one can evolve

the electroweak and strong coupling constants, as

measured at LEP.[Amaldi, de Boer, and Furstenau 1991]

SUSY allows

for unification

Ryan Reece (Penn)

GUT Motivations

5

It is interesting that:

• the structure of SM can be embedded in larger groups, and this

could explain the SM hypercharges,

• the SM couplings apparently converge when run to very high

energies.

Motivates the possibility of grand unification.

Avenues of discovery:

• Higgs sector

• supersymmetry

• leptoquarks

• Z’

102 GeV1016 GeV

The LHC,

ATLAS, and CMS

Ryan Reece (Penn) 7

Ryan Reece (Penn) 8

Ryan Reece (Penn) 9tt → bb(µν)(τhν) candidate

Ryan Reece (Penn) 10

Datasets

• Analyses reported here use 2-5 fb-1 of the data collected in 2011 at √s = 7 TeV.

• In 2012, ATLAS and CMS each have collected over 14 fb-1 so far at √s = 8 TeV.

[TWiki:CMSPublic/LumiPublicResults, ATLAS-CONF-2012-042]

Number of Vertices

0 5 10 15 20 25 30A

rbitra

ry U

nits

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

> = 15µData 2011, <

> = 29µData 2011, <

> = 32µData 2011, <

ATLAS Preliminary

= 7 TeVs

Ryan Reece (Penn)

High-pT τh reconstruction

11

Isolation

annulus

pile-up

tau

UE

Count # tracks

in core cone

!"#$

"%&'()*'

+"#$

"%&'()*'

,*-./'

0)().(1*

2-*(3.%)45%16

• τh reco seeded by calorimeter jets

• associate tracks in ∆R < 0.2, select 1 or 3

• combine calorimeter and tracking

information in a BDT or likelihood

discriminant, preferring narrow clustering,

hadronic activity[ATLAS-CONF-2011-152, CMS PAS TAU-11-001]

• particle-flow reconstructs constituent 4-vectors

• τh reco seeded by particle-flow hadrons

• Hadron Plus Strip (HPS) algorithm for

counting π0s

• isolation cone for rejecting QCD jets

•Hadronic decays dominantly to 1 or 3 π± and possibly a few additional π0s

•Decay in beam-pipe: cτ ≈ 90 µm

Charged

Higgs f

f′g

g

g

ντ

τ+

H+

W-

t

t

b

b

Ryan Reece (Penn)

Charged Higgs

• 2HDM, five spin-0 states:

CP-even H±, CP-even H and h, CP-odd A

• Necessary for MSSM

• tan β = vu/vd

• For tan β > 2, H+→τν

dominant decay

• Produced through top

decays: t→bH+ (for mH+ < mt)

• Look for tt with enhanced τ.

13

f

f′g

g

g

ντ

τ+

H+

W-

t

t

b

b

-

Ryan Reece (Penn)

Charged Higgs: bbqqτh ‘

14[arxiv:1204.2760]

3.2 tt → bbW∓H±→ bb(qq)(τhν)

Emiss

T

0.5 GeV1/2·

√

∑

pT> 13;

[GeV]Tm

0 50 100 150 200 250 300 350 400

Events

/ 2

0 G

eV

0

10

20

30

40

50

60

70

80

) = 5%+

bH→tB(

Data 2011

τTrue

misidτ→Jet

misidτ→e

Multi-jets

SM + uncertainty

= 130 GeV+H

m

-1 Ldt = 4.6 fb∫

= 7 TeVs

ATLAS

+jetsτ

Ryan Reece (Penn)

Charged Higgs

15[arxiv:1204.2760]

[GeV]+H

m

90 100 110 120 130 140 150 160

+ b

H→

t B

-210

-110

1

Observed CLsExpected

σ 1±σ 2±

ATLAS

Data 2011

= 7 TeVs

-1Ldt = 4.6 fb∫

combined

[GeV]+H

m

90 100 110 120 130 140 150 160

βta

n

0

10

20

30

40

50

60

Median expected exclusion

Observed exclusion 95% CL

theoryσObserved +1

theoryσObserved -1

-1Ldt = 4.6 fb∫Data 2011

=7 TeVs maxh

m

ATLAS

Ryan Reece (Penn)

Charged Higgs

16[arvix:1205.5736]

Ryan Reece (Penn)

Supersymmetry

18

• Could help explain: observed , ,

, ...

• Especially interesting large parameter space when the is

the Next-to-Lightest-Supersymmetric-Particle ( )

• The possible consistent

extension to the symmetries of 4-D QFT from

. [Haag–Lopuszanski–Sohnius theorem, 1975]

• No observed SUSY partners yet ⇒ SUSY is broken at a high energy scale.

Ryan Reece (Penn)

SUSY signatures

19

• R-parity-conserving: require high-ETmiss and high-HT

HT = ∑pT(jets)

• R-parity-violating: require high-ST

no stable LSP ⇒ less ETmiss discrim.ST = HT + ∑pT(isolated leptons) + ETmiss

• Why add taus?

• B(N2→ ττN1) or B(C1→ τνN1) can be higher than

other flavors when tan β is high.

• Improve stats even without enhancement

• Constrain all couplings λijk

• CMS incorporates taus into their general multi-lepton search.

• ATLAS and CMS perform dedicated searches with taus.

Ni f

f f

N1

~ ~ ~ ~

1

2λijkLiLjEk

N1 ℓ

ℓ ℓ′

ν′′

λ

Ryan Reece (Penn) [arxiv:1206.3949]

Events

0

10

20

30

40

50

60

70

Events

0

10

20

30

40

50

60

70CMS -1 = 4.98 fb

int=7 TeV Ls

Data

Charge Mis-Id

Prompt-Prompt(irreducible)

Nonprompt-Nonprompt

Prompt-Nonprompt

Region 1: Region 2: Region 3: Region 4: Region 5:

> 80 GeVTH > 200 GeVTH > 450 GeVTH > 450 GeVTH > 450 GeVTH

> 120 GeVmiss

TE > 120 GeVmiss

TE > 50 GeVmiss

TE > 120 GeVmiss

TE > 0 GeVmiss

TE

TH

igh p

)µ

/eµ

µ(e

e/

TLow

p

)µ

/eµ

µ(e

e/

TH

igh p

)µ

/eµ

µ(e

e/

TLow

p)

µ/e

µµ

(ee/

TH

igh p

)µ

/eµ

µ(e

e/

TLow

p

)µ

/eµ

µ(e

e/

TH

igh p

)µ

/eµ

µ(e

e/

Tau c

hannels

)ττ/

τµ/

τ(e

TH

igh p

)µ

/eµ

µ(e

e/

(GeV)T

H0 200 400 600 800 1000 1200 1400

(G

eV

)m

iss

TE

0

50

100

150

200

250 µµ

eeµe

τµ

τe

ττ

Regio

n 1

Regio

n 2

Region 4

Region 3

Region 5

CMS -1 = 4.98 fbint.

= 7 TeV, Ls

SUSY: Same-sign dileptons + jets + MET

20

ETmiss

Ryan Reece (Penn)

• Significantly

extends LEP and

CMS 2010 results.

• Gluino masses

500-1000 GeV

excluded.

• Similar result in

opposite-sign

(in back up). (GeV)0m

500 1000 1500 2000 2500

(G

eV

)1/2

m

100

200

300

400

500

600

700

800

900

1000CMS = 7 TeVs, -1 = 4.98 fbint.L

± l~ LEP2

±

1χ∼ LEP2

No EWSB

= L

SP

τ∼

Non-Convergent RGE's

) = 500g~m(

) = 1000g~m(

) = 1500g~m(

) = 2000g~m(

) = 1000

q~m(

) = 1500

q~m(

) = 2000

q~m(

) = 2500

q~m

(

)=10βtan(

= 0 GeV0

A

> 0µ

= 173.2 GeVt

m

Observed Limit (NLO+NLL with uncertainties)

Expected Limit (NLO+NLL)

)-1 = 35 pbint

NLO Obs. Limit (L

SUSY: Same-sign dileptons + jets + MET

21[arxiv:1206.3949]

ETmiss

CMSSM exclusion

Ryan Reece (Penn)

SUSY: multi-lepton

22[arxiv:1106.0933, CMS PAS SUS-11-013, arvix:1204.5341]

) 2 (GeV/cq~

m600 800 1000 1200 1400

)

2

(G

eV

/cg~

m

600

800

1000

1200

140095% C.L. Limits:

CMS observed

σ 1±CMS expected

σ 2±CMS expected

CMS = 7 TeVs, -1 = 35 pbintL

123λ

122λ

• Harder to exclude couplings to 3rd gen. because of tau ID.

• Exclude squark and gluino masses in 1 TeV range in models with

neutralino LSP decaying through RPV.

• Categorize all events with 3-4 leptons, binning in N(lep), N(τh),

ETmiss , HT, Z/no-Z, no-OSSF, ST ⇒ 114 signal regions (GeV)

q~m

1000 1500 2000

(G

eV

)

g~m

1000

1500

2000

95% C.L. CLs Limits

NLO observed

σ1±NLO expected

σ2±NLO expected

-1 = 7 TeV, L = 4.98 fbsCMS

λ123

λ123

λ122

Ryan Reece (Penn)

! +~

! "

! #

χ1

0

G~

Multileptons and Strong Production

CMS multilepton search with 35/pbq~g~

χ1

0

R ±~

χ1

±

!L ±~

q~g~

SUSYcascade

[arvix:1203.6580, arvix:1204.3852]

SUSY: + jets + taus ,

23

ETmiss

Gauge-Mediated Supersymmetry

Breaking (GMSB) motivated

LSP: very light (∼keV) gravitino (G)

~

τ+µ

muon/muon+jet

pµ

T> 18 GeV

pjet

T> 10 GeV

≥1 jet (50 GeV)

—

1 µ (20 GeV)

≥1 med. (20 GeV)

me, µ

T> 100 GeV

meff > 1000 GeV

Event selection

trig:

ST

= HT + ∑pT(!,τ) + ETmiss

∑

ective mass meff =

~

0 200 400 600 800 1000

Events

/ 5

0 G

eV

-110

1

10

210

310

410ATLAS Preliminary

=7 TeVs -1

L dt = 4.7 fb∫Data 2011

Standard ModelMultijetsW+jetsZ+jetsTop

DiBosonsDrell-Yan

= 50TeVΛGMSB - = 40β tan

= 50TeVΛGMSB - = 20β tan

[GeV]effm0 200 400 600 800 1000

Data

/MC

1

2

>

Ryan Reece (Penn)


24[arvix:1203.6580, arvix:1204.3852]

ETmiss

• Combine channels:

1τh+!+jets,

1τh+jets, ≥2τh+jets

• Interpret with GMSB

• Λ = “SUSY breaking

scale”

• OPAL:

Λ > 26 TeV

• ATLAS:

Λ > 47-58 TeV [TeV]Λ

10 20 30 40 50 60 70 80 90 100

βta

n

10

20

30

40

50

60=1grav>0, Cµ=3, 5=250 TeV, NmessGMSB: M

1

0χ∼

1τ∼

CoNLSP

Rl~

Theoryexcl.

(2000 G

eV)

g~

(1800 G

eV)

g~

(1600 G

eV)

g~

(1400 G

eV)

g~

(1200 G

eV)

g~

(1000 G

eV)

g~

(800 G

eV)

g~

(600 G

eV)

g~

(400 G

eV)

g~

1

0χ∼ Rl~

Theoryexcl.

(600 G

eV)

g~

(400 G

eV)

g~

(600 G

eV)

g~

(400 G

eV)

g~

1

0χ∼

Theoryexcl.

ATLAS Preliminary

=7 TeVs, -1 dt = 4.7 fb∫

)theorySUSYσ1 ± limit (

SObserved 95% CL

)expσ1 ±Expected limit (

ATLAS 95% CL limit τ 2-12.05fb

)1τ∼OPAL 95% CL (

)R

µ∼OPAL 95% CL (

OPAL 95% CL

Exotica

Ryan Reece (Penn)

3rd generation leptoquarks

26[CMS PAS EXO-12-002]

(GeV),bτM0 50 100 150 200 250 300 350 400 450

Even

ts

1

10

210

310

= 7 TeVs, -1CMS 4.8 fb

Data

ttbar

W/Z + jets

Other=450 GeV

LQSignal M

Ryan Reece (Penn)

(GeV)1t~

LQ3/M

200 300 400 500 600 700 800

(pb)

σ×

2 b

)τ

→ 1t~B

r(LQ

3/

-410

-310

-210

-110

1

10

210

310=1β with theory unc.,

theoryσ ×2β

=1333

'λ with theory unc.,

theoryσ ×2 b)τ→

1t~

Br(

with theory unc.theory

σ ×2 b)τ→Br(VLQ3

Expected 95% C.L. upper limit

Observed 95% C.L. upper limit

CMS Preliminary

-1 L dt = 4.8 fb∫

3rd generation leptoquarks

27[CMS PAS EXO-12-002]

(GeV)TS

100 200 300 400 500 600 700 800 900 1000

Even

ts

10

20

30

40

50 = 7 TeVs, -1CMS 4.8 fb

Data

ttbarW/Z + jets

+ ll)ττ*(γZ/

VV=450 GeV

LQSignal M

~

~

Ryan Reece (Penn)

) [GeV]missTE, h

τ, hτ(tot

Tm

0 500 1000 1500

Events

/ 5

0 G

eV

-210

-110

1

10

210

310

410

ATLAS Preliminary-1

dt L = 4.6 fb∫ = 7 TeVs

(a)Data 2011

Multijetττ→*γ/Z

ντ→W

Others

ττ→(1250)Z’

Z’ → ττ → τhτh

28[ATLAS-CONF-2012-067]

Ryan Reece (Penn) [ATLAS-CONF-2012-067]

) [GeV]missTE, hτ, µ(tot

Tm

0 500 1000 1500

Events

/ 5

0 G

eV

-210

-110

1

10

210

310


-1dt L = 4.6 fb∫ = 7 TeVs

(b)Data 2011

ττ→*γ/Z

+jetsW

Multijet

µµ→Z

tt

Dibosonsingle top

ττ→(1000)Z’

Z’ → ττ → µτh

29

Ryan Reece (Penn)

• τhτh: 1.25 (1.35) TeV

• µτh: 1.00 (1.05) TeV

• eµ: 0.75 (0.80) TeV

ATLAS Z’ SSM Exclusions: observed (expected) @ 95% CL

Combined limit

30[ATLAS-CONF-2012-067]

[GeV]Z’

m

500 1000 1500

[pb]

Bσ

-310

-210

-110

1

ATLAS Preliminary-1

dt L = 4.7 fb∫ = 7 TeVs

Combined

Expected limit

σ 1±Expected

σ 2±Expected

Observed limit

SSMZ’

(GeV)Z'M400 600 800 1000 1200 1400 1600

) (p

b)

ττ→

BR

(Z'

×Z

')

→(p

pσ

-310

-210

-110

1

10

210-1

= 7 TeV, 4.94 fbs CMS,

Obs. Combined 95% CL

Exp. Combined 95% CL

expected rangeσ1

expected rangeσ2

SSMZ'

ψZ'

1.4 TeV

1.3 TeV 1.4 Te

V1.1 TeV

Ryan Reece (Penn)

Conclusions

31

• The performance of the LHC, and the ATLAS and

CMS experiments have extended many exclusions

for new physics.

• Many searches will be improved with the 2012

dataset and further their reach with increases in

luminosity and energy after the coming long shutdown.

• Unification and supersymmetry remain hidden.

• A new boson is in grasp consistent with the SM

Higgs with a mass of 126 GeV, and taus will play an

important role determining its couplings to fermions!

References

Ryan Reece (Penn)

General references

• J. Beringer et al. (Particle Data Group), Phys. Rev. D86, 010001 (2012).

• U. Amaldi, W. de Boer, and H. Furstenau. “Comparison of grand unified theories

with electroweak and strong coupling constants measured at LEP.” PLB 260

(1991) 447.

• W. de Boer, C. Sander. “Global Electroweak Fits and Gauge Coupling

Unification.” (2003) [arxiv:0307049]

• S.P. Martin. “A Supersymmetry Primer” [arxiv:9709356]

33

Ryan Reece (Penn)

Charged Higgs

• ATLAS

• “Search for charged Higgs bosons decaying via H± → τ±ν in tt events using pp

collision data at √s = 7 TeV with the ATLAS detector” [arxiv:1204.2760]

• CMS

• “Search for a light charged Higgs boson in top quark decays in pp collisions at

√s = 7 TeV” [arvix:1205.5736]

34

Ryan Reece (Penn)

SUSY

• ATLAS

• “Search for events with large missing transverse momentum, jets, and at least two

tau leptons in 7 TeV proton-proton collision data with the ATLAS detector” [arxiv:

1203.6580]

• “Search for supersymmetry with jets, missing transverse momentum and at least one

hadronically decaying τ lepton in proton-proton collisions at √s = 7 TeV with the

ATLAS detector” [arxiv:1204.3852]

• CMS

• “Search for anomalous production of multilepton events in pp collisions at √s = 7

TeV” [arvix:1204.5341]

• “Search for new physics with same-sign isolated dilepton events with jets and

missing transverse energy” [arxiv:1205.6615]

• “Search for new physics in events with opposite-sign leptons, jets, and missing

transverse energy in pp collisions at √s = 7 TeV” [arxiv:1206.3949]

35

Ryan Reece (Penn)

Exotics

• ATLAS

• “A search for high-mass resonances decaying to τ+τ− in pp collisions at √s = 7

TeV with the ATLAS detector” [ATLAS-CONF-2012-067]

• CMS

• “Search for high-mass resonances decaying into τ-lepton pairs in pp collisions

at √s = 7 TeV” [arvix:1206.1725]

• “Search for pair production of third generation leptoquarks and stops that

decay to a tau and a b quark” [CMS PAS EXO-12-002]

36

Ryan Reece (Penn)

Tau performance

• ATLAS

• “Reconstruction, Energy Calibration, and Identification of Hadronically

Decaying Tau Leptons” [ATLAS-CONF-2011-077]

• “Performance of the Reconstruction and Identification of Hadronic Tau Decays

with ATLAS” [ATLAS-CONF-2011-152]

• “Z → ττ cross section measurement in proton-proton collisions at 7 TeV with

the ATLAS experiment” [ATLAS-CONF-2012-006]

37

Ryan Reece (Penn)

Tau performance• CMS

• “Performance of τ-lepton reconstruction and identification in CMS”

[arvix:1109.6034, CMS PAS TAU-11-001]

• “CMS Strategies for tau reconstruction and identification using particle-flow

techniques” [CMS PAS PFT-08-001]

• “Particle–Flow Event Reconstruction in CMS and Performance for Jets, Taus,

and ETmiss” [CMS PAS PFT-09-001]

• “Commissioning of the Particle-Flow Reconstruction in Minimum-Bias and Jet

Events from pp Collisions at 7 TeV” [CMS PAS PFT-10-002]

• “Commissioning of the particle-flow event reconstruction with leptons from

J/Psi and W decays at 7 TeV” [CMS PAS PFT-10-003]

• “Study of tau reconstruction algorithms using pp collisions data collected at

√s = 7 TeV” [CMS PAS PFT-10-004]

38

Back up:

general


ATLAS DetectorMagnets: 5 tonne central solenoid, 2T in inner detector, 4T toroid system

Muon Spectrometer: |η|<2.7, drift-tube chambers

Tracking: |η|<2.5, B=2T, precise tracking and vertexing, Si pixels, strips, and TRT straws, TR electron ID

Electromagnetic Calorimeter: |η|<3.2, 3+1 layers corrugated layers of lead and LAr

Hadronic Calorimeter: |η|<5, Central: iron/scintillator tiles, Forward: copper/tungsten-LAr

Ryan Reece (Penn)


42

Ryan Reece (Penn)


43

Ryan Reece (Penn)

Phenomenology of tau decays

44

τ−

→ e− νe ντ

µ−

νµ ντ

17.8%17.4%

}

leptonic 35.2%

π−

π0ντ

π−

ντ

π− 2π0

ντ

K− (Nπ0) (NK0) ντ

π− 3π0

ντ

25.5%10.9%9.3%1.5%1.0%

1 prong 49.5%

π−

π−

π+

ντ

π−

π−

π+

π0ντ

9.0%4.6%

}

3 prong 15.2%

Ryan Reece (Penn)

pass/f

ail

0

0.05

0.1

W CR: Inclusive, 1p

W CR: OS, 1p

W CR: SS, 1p

Tp

0 50 100 150 200 250

ratio

0

1

2

pass/f

ail

0

0.05

0.1

QCD CR: Inclusive, 1p

QCD CR: OS, 1p

QCD CR: SS, 1p

Tp

0 50 100 150 200 250

ratio

0

1

2

BDT Medium BDT Medium

Observed variance in fake-rates

45

(BDTMedium)

1. Why do quarks and gluons have different tau fake-rates?

2. How does the quark/gluon fraction vary among samples?

• Hypothesis: quarks vs gluons

• Divide the issue into two questions:

ATLAS work in progress ATLAS work in progress

Ryan Reece (Penn)

Jet width for quark/gluons

46

J. Gallicchio, M. Schwartz. “Quark and Gluon Tagging at the LHC”. arXiv:1106.3076.

• !(r) = fraction of jet

energy within ∆R < r.

• Quark jets are more

narrow than gluon jets

of the same energy.

• Tau identification prefers

narrow candidates.

• This is consistent with samples of quark-enriched jets, like

W+jet, having higher fake-rates.

Ryan Reece (Penn)

OS vs SS W+jet

47

q

Wg

q′

(a)

q W

g q′

(b)

q

q′W

g

(c)

• The charge of the quark should correlate with the

reconstructed charge of the tau candidate, therefore (a) and

(b) preferably produce opposite sign W+jet events.

• OS and SS will have different quark/gluon fractions.

Leading order W+jet production:

Ryan Reece (Penn)

Madgraph predicted Quark/Gluon

48

50 100 200 400 800 1600

Q

G

0%

100%

80%

60%

40%

20%

pT Cut on All Jets (GeV)50 100 200 400 800 1600

Q

G

0%

100%

80%

60%

40%

20%

pT Cut on All Jets (GeV)

J. Gallicchio, M. Schwartz. “Pure Samples of Quark and Gluon Jets at the LHC”. arXiv:1104.1175

50 100 200 400 800 16000%

100%

80%

60%

40%

20%

GG

QG

QQ

pT Cut on All Jets (GeV)50 100 200 400 800 1600

0%

100%

80%

60%

40%

20%

GGG

QGG

QQG

QQQ

pT Cut on All Jets (GeV)

Back up:

ATLAS tau

identification

Ryan Reece (Penn)

Tau identification variables

50

Electrmagnetic radius: REM =

∑∆Ri<0.4

i∈{EM 0−2}EEM

T,i∆Ri

∑∆Ri<0.4

i∈{EM 0−2}EEM

T,i

Track radius: Rtrack =

∑∆Ri<0.4

i pT,i ∆Ri∑∆Ri<0.4

i pT,i

Leading track momentum fraction: ftrack =

ptrackT,1

pτT

Core energy fraction: fcore =

∑∆Ri<0.1

i∈{all}EEM

T,i∑∆Ri<0.4

i∈{all}EEM

T,i

Electromagnetic fraction: fEM =

∑∆Ri<0.4

i∈{EM 0−2}EEM

T,i

∑∆Rj<0.4

j∈{all}EEM

T,j

Cluster mass: mclusters, invariant mass clusters at the EM

energy scale.

Track mass: mtracks, invariant mass of the track system.

Transverse flight path significance: SflightT

Motivation: taus tend to be collimated more than jets, have a

leading track, and often significant neutral pion deposits in the EM

calorimeter.

Ryan Reece (Penn)

[GeV] Tp

0 10 20 30 40 50 60 70 80 90 100

bkgd

ε

-210

-110

1

-1Integrated Luminosity 244 nb / Loose Cuts (Data/MC) / Medium Cuts (Data/MC) / Tight Cuts Data(MC)

PreliminaryATLAS PreliminaryATLAS

EMR

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

candid

ate

s / 0

.01

τN

um

ber

of

0

20

40

60

80

100

120

140

160

180

200

220

310×

ATLAS Preliminary = 7 TeV )sData 2010 (

Pythia QCD JetsττPythia Z->

-1Integrated Luminosity 15.6 nb

First data

51

“Reconstruction of hadronic tau candidates in QCD events at ATLAS with 7 TeV pp collisions”

[ATLAS-CONF-2010-059]

“Tau Reconstruction and Identification Performance in ATLAS”


• First comparisons of background distributions and the QCD

fake-rate between data and Monte Carlo.

• Already see that MC over-estimates the jet fake-rate. ⇒kW ≈ 0.5

Ryan Reece (Penn)

Tau discriminants

52

CutspT-parametrized cuts on REM and

Rtrack, and a cut on ftrack.

Projective likelihood

d = ln

(

LS

LB

)

=∑N

i=1 ln

(

pSi(xi)

pBi(xi)

)

Boosted decision trees (BDT)

[GeV]T

p

20 30 40 50 60 70 80 90 100

⟩tr

ack

R⟨

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

Likelihood Score

-20 -15 -10 -5 0 5 10 15 20

Arb

itra

ry U

nits

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18ττ→+Zντ→W

dijet Monte Carlo-1dt L = 23 pb∫2010 dijet data

<60 GeVT

3 prongs 15 GeV<p

ATLAS Preliminary

BDT Score

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1A

rbitra

ry U

nits

0

0.02

0.04

0.06

0.08

0.1

0.12 ττ→+Zντ→W

dijet Monte Carlo-1dt L = 23 pb∫2010 dijet data

<60 GeVT

3 prongs 15 GeV<p

ATLAS Preliminary

ATLAS work in progress

Ryan Reece (Penn)

Maturing of discriminants

53

Signal Efficiency

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

Inve

rse

Backgro

und E

ffic

ien

cy

1

10

210

310

Cuts

BDT

Likelihood

>20GeVT

1-Prong p

ATLAS Preliminary

[GeV]T

p

20 30 40 50 60 70 80 90 100

⟩E

MR⟨

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

(a) R cut curves for 1-prong

• Cuts are pt-parametrized to account for the Lorentz collimation

of boosted taus.

• Experience grows with LLH and BDT discriminants, which

become the preferred discriminants in 2011.

“Reconstruction, Energy Calibration, and Identification of Hadronically Decaying Tau Leptons

in the ATLAS Experiment” [ATLAS-CONF-2011-077, ATL-PHYS-INT-2011-068]

ATLAS work in progress

Ryan Reece (Penn)

Seeing first hadronic taus

54

Number of tracks

0 1 2 3 4 5 6 7 8 9 10

Num

ber

of

events

0

500

1000

1500

2000

2500

0 1 2 3 4 5 6 7 8 9 100

500

1000

1500

2000

2500

0 1 2 3 4 5 6 7 8 9 100

500

1000

1500

2000

2500

0 1 2 3 4 5 6 7 8 9 100

500

1000

1500

2000

2500

0 1 2 3 4 5 6 7 8 9 100

500

1000

1500

2000

2500

0 1 2 3 4 5 6 7 8 9 100

500

1000

1500

2000

2500

0 1 2 3 4 5 6 7 8 9 100

500

1000

1500

2000

2500

0 1 2 3 4 5 6 7 8 9 100

500

1000

1500

2000

2500 = 7 TeV)sData 2010 (

τν hτ →W

EW background

QCD background (B)

ATLAS Preliminary

-1 L dt = 34 pb∫

EMR

0 0.02 0.04 0.06 0.08 0.1 0.12 0.14

Num

ber

of

events

/ 0

.01

0

100

200

300

400

500

600

700

0 0.02 0.04 0.06 0.08 0.1 0.12 0.140

100

200

300

400

500

600

700

0 0.02 0.04 0.06 0.08 0.1 0.12 0.140

100

200

300

400

500

600

700

0 0.02 0.04 0.06 0.08 0.1 0.12 0.140

100

200

300

400

500

600

700

0 0.02 0.04 0.06 0.08 0.1 0.12 0.140

100

200

300

400

500

600

700

0 0.02 0.04 0.06 0.08 0.1 0.12 0.140

100

200

300

400

500

600

700

0 0.02 0.04 0.06 0.08 0.1 0.12 0.140

100

200

300

400

500

600

700

0 0.02 0.04 0.06 0.08 0.1 0.12 0.140

100

200

300

400

500

600

700 = 7 TeV)sData 2010 (

τν hτ →W

EW background

QCD background (BD)

ATLAS Preliminary

-1 L dt = 34 pb∫

• Nov 2010: Observation of W→τhν [ATLAS-CONF-2010-097]

• Feb 2011: Observation of Z→τhτl [ATLAS-CONF-2011-010]

Ryan Reece (Penn)

W→τν cross section

55

σ(W → τν) = 11.1 ± 0.3(stat.)± 1.7(sys.)± 0.4(lumi.) nb

σtheory = 10.46 ± 0.52 nb at NNLO

) [nb]lν l →(W σ

6 7 8 9 10 11 12 13 14 15 16

τν τ →W ATLAS

eν e →W ATLAS

µν µ →W ATLAS

= 7 TeV)sData 2010 (

Stat uncertainty

Stat ⊕Sys

Lumi⊕ Stat ⊕Sys

Prediction (NNLO)

Theory uncertainty

= 7 TeV)sData 2010 (

Stat uncertainty

Stat ⊕Sys

Lumi⊕ Stat ⊕Sys

Prediction (NNLO)

Theory uncertainty

ATLAS Preliminary

) [nb]lν l →(W σ

6 7 8 9 10 11 12 13 14 15 16

τν τ →W ATLAS

eν e →W ATLAS

µν µ →W ATLAS

Dominant systematics

τh efficiency 10.3%

τh energy scale 8.0%

τh + MET trigger

efficiency 7.0%

luminosity 3.4%

acceptance 2.3%

“Measurement of the W→τν cross section in pp collisions at sqrt(s)= 7 TeV with the ATLAS experiment”

[arXiv:1108.4101]

Ryan Reece (Penn)

Z→ττ cross section

56

σcombined = 0.97 ± 0.07(stat.)± 0.07(sys.)± 0.03(lumi.) nb

σtheory = 0.96 ± 0.05 nb at NNLO

<116 GeV) [nb]inv

ll, 66<m→(Z σ0.6 0.8 1 1.2 1.4 1.6

-136pb

combinedττ →Z

-133-36pb

µµ ee/→Z

hτ µτ

hτ eτ

µτ eτ

µτ µτ

Stat

Stat ⊕Syst

Lumi⊕ Stat ⊕Syst

Theory (NNLO)

Stat

Stat ⊕Syst

Lumi⊕ Stat ⊕Syst

Theory (NNLO)

ATLAS Preliminary

<116 GeV) [nb]inv

ll, 66<m→(Z σ0.6 0.8 1 1.2 1.4 1.6

-136pb

combinedττ →Z

-133-36pb

µµ ee/→Z

hτ µτ

hτ eτ

µτ eτ

µτ µτ


τh energy scale 11%

τh efficiency 8.6%

µ efficiency 8.6%

e efficiency 3-10%

acceptance 3%

luminosity 3.4%

“Measurement of the Z→ττ cross section in pp collisions at sqrt(s)= 7 TeV with the ATLAS detector”

[arXiv:1108.2016]

Ryan Reece (Penn)

First systematic recommendations

57

• Systematic uncertainties estimated with dedicated Monte Carlo

with shifts in UE, hadronization, and detector-related effects.

• The efficiency measurement has been superseded with data-

driven measurements from Z→ττ and W→τν tag-and-probe.[ATLAS-CONF-2011-077]

20 40 60 80 100

Ta

u e

ffic

ien

cy

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Looser Cuts working point

1 prong

ATLAS Preliminary

Nominal

Detector Material

Hadronic ShowerUnderlying Event

Noise threshold

Total sys. error

of truth tau [GeV]T

Visible p20 40 60 80 100

Ratio

0.8

0.9

1

1.1

1.2

Ta

u e

ffic

ien

cy 1

[GeV]gen

Tp

10 20 30 40 50 60 70

)gen

T/p

TE

S

T(p

∆

-0.04

-0.02

0

0.02

0.04

0.06

0.08 Underlying eventHadronic showerDetector materialNoise thresholdEM ScaleNon-closureTotal sys. error

Underlying eventHadronic showerDetector materialNoise thresholdEM ScaleNon-closureTotal sys. error






ATLAS Preliminary 1.3≤| η1 prong: |

)

Ryan Reece (Penn)

W→τν tag-and-probe

58

Number of tracks0 2 4 6 8 10 12 14 16

Events

0

200

400

600

800

1000

1200

ATLAS Preliminary

Before tau ID

)-1Data 2010 (34 pb

)ντ → (Wτ

)ν e→e (W

Jet background

Number of tracks0 2 4 6 8 10 12 14 16

Events

0

100

200

300

400

500

600

700

800

ATLAS Preliminary

After tau ID

(Looser Cuts working point)

)-1Data 2010 (34 pb

)ντ → (Wτ

)ν e→e (W

Jet background

Tag jet + MET events, probe for tau.

Tau identification efficiency scale factor0.5 1 1.5

0

7

Boosted decision trees 0.13(sys)± 0.07(stat) ±0.94 (Cross section)

Likelihood 0.16(sys)± 0.04(stat) ±1.02 (Cross section)

Cuts 0.13(sys)± 0.05(stat) ±1.00 (Cross section)

Boosted decision trees 0.05(sys)± 0.06(stat) ±1.05 (Tag&Probe)

Likelihood 0.05(sys)± 0.09(stat) ±1.02 (Tag&Probe)

Cuts 0.04(sys)± 0.06(stat) ±1.04 (Tag&Probe)

Looser identification working point-1L = 34 pbATLAS Preliminary

apply

ID

“Measurement of hadronic tau identification efficiency with W→τν events”


Back up:

CMS tau

identification

Ryan Reece (Penn)

CMS Particle Flow

60

!"#$%&'()*)+,&-

!"#$%!&'()&*+

!"#$%!&'()&*+

,"#$%!&'()&*+

,"#$%!&'()&*+

.(/01'&$()+2'3$14$1&,.2

/+()+2'3$.(/01'&

1&,.2'&$5)1

0''$!"#$%6#$%789:;9;;<

• Matches track to clusters to form charged and neutral PF objects.

• PF objects are used as input for all CMS tau reconstruction.

Ryan Reece (Penn)

CMS: Hadron Plus Strip (HPS)

61

Discrimination with calorimeter based isolation ∆R < 0.5.

[CMS PAS TAU-11-001]

Ryan Reece (Penn)

CMS: Tau Neural Classifier (TaNC)

62

• Uses a shrinking core-cone:

• ∆R(photons) < 0.15 for photons

• ∆R(charged) < (5 GeV)/ET for charged hadrons

• ∆R(charged) < ∆R(isolation) < 0.5

• Immediately discarded if the candidate doesn’t match

an expected tau decay mode.

• Dedicated Neural-net classifier for each decay mode

Decay mode Resonance Mass (MeV/c2) Branching fraction (%)

τ− → h−ντ 11.6%

τ− → h−π0ντ ρ− 770 26.0%

τ− → h−π0π0ντ a

−

1 1200 9.5%

τ− → h−

h+

h−ντ a

−

1 1200 9.8%

τ− → h−

h+

h−π0ντ 4.8%


Ryan Reece (Penn)

CMS Performance

63

(GeV/c)hτ

Tgenerated p

0 50 100

effic

ien

cy

τexpecte

d

0

0.2

0.4

0.6

0.8

1

HPS loose

HPS mediumHPS tight

= 7 TeVsCMS Simulation,

(GeV/c)hτ

Tgenerated p

0 50 100

effic

ien

cy

τexpecte

d

0

0.2

0.4

0.6

0.8

1

TaNC loose

TaNC mediumTaNC tight

= 7 TeVsCMS Simulation,


0 50 100 150 200

mis

identification r

ate

for

jets

τ

-310

-210

Dataνµ→W

Simulationνµ→W

QCD Data

QCD Simulation

DataµQCD

SimulationµQCD

HPS loose

-1 = 7 TeV, 36 pbsCMS,

(GeV/c)T

jet p0 50 100 150 200

Sim

ula

tion

Data

-Sim

.

-0.2

0

0.20 50 100 150 200

mis

identification r

ate

for

jets

τ

-310

-210

Dataνµ→W

Simulationνµ→W

QCD Data

QCD Simulation

DataµQCD

SimulationµQCD

TaNC loose


(GeV/c)T

jet p0 50 100 150 200

Sim

ula

tion

Data

-Sim

.

-0.2

0

0.2

• Not trivial to

compare ATLAS and

CMS tau

performance because

we bin fake-rates in

N(track) instead of

categorizing the

decay mode.

Ryan Reece (Penn)

CMS decay mode ID

64

0.85 0.16 0.05

0.13 0.83 0.04

0.02 0.01 0.91

decay modeτgenerated

π )0π(0ππ πππ

decay m

ode

τre

constr

ucte

d

π

0ππ

πππ

= 7 TeV sCMS Simulation,

decay modeτreconstructed

π 0ππ πππ

rela

tive y

ield

0

0.2

0.4

0.6

0.8

Dataτ τ →Z

W+jets

/ewkt tQCD



Ryan Reece (Penn)

Calorimeter granularity

65

• B = 3.8 T

• ∆η ×∆! = 0.0174×0.0174

• R = 0.5 anti-kT PF-jets

• B = 2.0 T

• ∆η ×∆! = 0.025×0.0245

• R = 0.4 anti-kT topo-jets

∆ϕ = 0.0245

∆η = 0.02537.5mm/8 = 4.69 mm ∆η = 0.0031

∆ϕ=0.0245x4 36.8mmx4 =147.3mm

Trigger Tower

TriggerTower∆ϕ = 0.0982

∆η = 0.1

16X0

4.3X0

2X0

1500

mm

470

mm

η

ϕ

η = 0

Strip cells in Layer 1

Square cells in Layer 2

1.7X0

Cells in Layer 3 ∆ϕ× ∆η = 0.0245× 0.05

ATLAS

CMS

ATLAS Barrel EM Calorimeter

Granularity could fundamentally limit our capacity to

reconstruct sub-structure / π0s.

0.0250.0174

Back up:

ATLAS Charged

Higgs

Ryan Reece (Penn)

Charged Higgs: bblτh ‘

67[arxiv:1204.2760]

[GeV]miss

TE

0 50 100 150 200 250 300

Events

/ 2

0 G

eV

0

50

100

150

200

250

300

350

400

) = 5%+

bH→tB(

Data 2011

τTrue

misidτ→Jet

misidτ→e

Misid’ed lepton

SM + uncertainty

= 130 GeV+H

m

-1 Ldt = 4.6 fb∫

= 7 TeVs

µ+τ

ATLAS

3.1 tt → bbW∓

H±→ bb(l∓ν)(τhν)

Back up:

CMS Charged

Higgs

Ryan Reece (Penn)

Charged Higgs

69[arvix:1205.5736]

Back up:

ATLAS SUSY

Ryan Reece (Penn)

(GeV)0m

500 1000 1500 2000 2500

(G

eV

)1/2

m

100

200

300

400

500

600

700

800

900

1000CMS = 7 TeVs, -1 = 4.98 fbint.L

± l~ LEP2

±

1χ∼ LEP2

No EWSB

= L

SP

τ∼

Non-Convergent RGE's

) = 500g~m(

) = 1000g~m(

) = 1500g~m(

) = 2000g~m(

) = 1000

q~m(

) = 1500

q~m(

) = 2000

q~m(

) = 2500

q~m

(

)=10βtan(

= 0 GeV0

A

> 0µ

= 173.2 GeVt

m

Observed Limit (NLO+NLL with uncertainties)

Expected Limit (NLO+NLL)

)-1 = 35 pbint

NLO Obs. Limit (L

ATLAS: Same-sign dileptons + jets + MET

71[ATLAS-CONF-2012-105, arxiv:1206.3949]

ETmiss

• Select SS ee, µµ, eµ + 4 jets + ETmiss > 150 GeV

• ATLAS result does not use hadronic taus.

[GeV]0

m

500 1000 1500 2000 2500 3000 3500

[G

eV

]1/2

m

100

200

300

400

500

600

700

(600 G

eV

)

q~

(1000 G

eV

)

q~

(1400 G

eV

)

q~

(600 GeV)g~

(1000 GeV)g~

(1400 GeV)g~

>0µ= 0, 0

= 10, AβMSUGRA/CMSSM: tan

=8 TeVs, -1

L dt = 5.8 fb∫T

miss 4 jets + E≥SS dilepton +

ATLAS )theory

SUSYσ1 ±Observed limit (

)expσ1 ±Expected limit (

SAll limits at 95% CL

1

±χ∼LEP2

Non-convergent RGE

No EW SB

=7 TeVs -1SS dilepton, 2 fb

Preliminary

Ryan Reece (Penn)


72

ETmiss

Event selection

≥1τh channel

[ arvix:1204.3852]

[GeV]eff

m

0 200 400 600 800 1000 1200 1400 1600

Events

/ 1

00 G

eV

10

20

30

40

50

60Total SM

multijets

Z + Jets

W + Jets

top

Data 2011

GMSB(40,30)

GMSB(30,20)

ATLAS-1

Ldt = 2.05 fb∫

Back up:

CMS SUSY

Ryan Reece (Penn)

SUSY: multi-lepton

74[arxiv:1106.0933, CMS PAS SUS-11-013, arvix:1204.5341]

(GeV) 1

±χ∼

m500 600 700 800 900

(G

eV

)

g~m

1500

1600

1700

1800

1900

2000

95% C.L. CLs Limits

NLO observed

σ1±NLO expected

σ2±NLO expected

-1 = 7 TeV, L = 4.98 fbsCMS

• Deviation in obs. limit from slight excess in category: 4lep(1τh), ETmiss > 50 GeV, HT < 200 GeV, no Z

Expect 0.59 ± 0.17 and observed 3 events.

Ryan Reece (Penn) [arxiv:1206.3949]

SUSY: Opposite-sign dileptons + jets + MET

75

ETmiss

Events

0

10

20

30

40

50

60

70

Events

0

10

20

30

40

50

60

70CMS -1 = 4.98 fb

int=7 TeV Ls

Data

Charge Mis-Id

Prompt-Prompt(irreducible)

Nonprompt-Nonprompt

Prompt-Nonprompt

Region 1: Region 2: Region 3: Region 4: Region 5:

> 80 GeVTH > 200 GeVTH > 450 GeVTH > 450 GeVTH > 450 GeVTH

> 120 GeVmiss

TE > 120 GeVmiss

TE > 50 GeVmiss

TE > 120 GeVmiss

TE > 0 GeVmiss

TE

TH

igh p

)µ

/eµ

µ(e

e/

TLow

p

)µ

/eµ

µ(e

e/

TH

igh p

)µ

/eµ

µ(e

e/

TLow

p)

µ/e

µµ

(ee/

TH

igh p

)µ

/eµ

µ(e

e/

TLow

p

)µ

/eµ

µ(e

e/

TH

igh p

)µ

/eµ

µ(e

e/

Tau c

hannels

)ττ/

τµ/

τ(e

TH

igh p

)µ

/eµ

µ(e

e/

Ryan Reece (Penn)

(GeV)0m500 1000 1500 2000 2500 3000

(G

eV

)1/2

m

100

150

200

250

300

350

400

450

500

550

600

± l~ LEP2

±

1χ∼ LEP2

No EW

SB

= L

SP

τ∼

Non-Conve

rgent R

GE's) = 500g~m(

) = 1000g~m(

) = 1000

q~m(

) = 1

500

q ~m

(

) = 2

000

q ~m

(

) = 2

500

q ~m

(

)=10βtan( = 0 GeV

0A

> 0µ = 173.2 GeVtm

observed

theory)σ1±observed (

expected

stat)σ1±expected (

observed 2010

-1L dt 4.98 fb∫ = 7 TeV, sCMS

LM1

LM3

LM6

LM13

SUSY: Opposite-sign dileptons + jets + MET

76[arxiv:1206.3949]

ETmiss

• Similar methods

to the same-sign

search

• Slightly less

sensitive

Ryan Reece (Penn)


77[CMS PAS SUS-12-004]

ETmiss

[GeV]0m

300 400 500 600 700 800 900 1000

[GeV

]1/

2m

100

200

300

400

500

600

700

800

900

1000

± l~ LEP2

±

1χ∼ LEP2

= L

SP

τ∼

) = 500g~m(

) = 1000g~m(

) = 1500g~m(

) = 1000

q~m(

) = 1500q~m(

Obs. LimitExp. Limit

σ 1±Exp. (theory)σ 1±Obs.

)=40βtan(

= -500 GeV0A

> 0µ

= 173.2 GeVtm

(b) CMS Preliminary

= 7 TeVs, -1

4.98 fb

Back up:

ATLAS Exotics

Ryan Reece (Penn)

Data-driven multijet

79

Norm

aliz

ed e

vent

rate

/ 1

0 G

eV

0

0.05

0.1

0.15

0.2

0.25

0.3

ATLAS Preliminary-1

dt L = 4.7 fb! = 7 TeVs

Opposite Charge (OC)

Same Charge (SC)

) [GeV]missTE, h", h"(TM

200 250 300 350

OC

/ S

C

0.51

1.5

Fit same-sign (SS) data with dijet function:

Events

/ 4

0 G

eV

-110

1

10

210

310


-1dt L = 4.7 fb! = 7 TeVs

Data 2011Multijet

""#*$/Z

%"#W

Others""#(1250)Z’

) [GeV]missTE, h", h"(TM

500 1000 1500obs.

/ exp.

0.51

1.5

• OS/SS shapes agree well

• normalize in OS sideband with 200 < MT < 250 GeV[ATLAS-CONF-2012-067]

Ryan Reece (Penn)

) [GeV]µ(Tp

0 50 100 150

Muon I

sola

tion F

ake F

acto

r

0

0.05

0.1

ATLAS Preliminary-1

dt L = 4.7 fb∫ = 7 TeVs

Multijet

Inclusive

|<1.37η|

|<1.52η1.37<|

|<2.5η1.52<|

Multijet background estimation

80

Multijet control region

• In the control region, divide leptons

into pass and fail isolation.

• Define fake factor:

• Predict the number of multijet events:

fµ–iso(pT, η) ≡Npass µ–iso(pT, η)

Nfail µ–iso(pT, η)

∣

∣

∣

∣

∣

∣

multijet–CR

Nmultijet(pT, η, x) = fµ–iso(pT, η) · Nfail µ–iso

multijet(pT, η, x) .

This assumes that the ratio of the number of isolated muons to the number of non-isolated muons inx) = fµ–iso(pT, η) ·

(

Nfail µ–iso

data(pT, η, x) − N

fail µ–iso

MC(pT, η, x)

)

.

The shape of the multijet background in any kinematic variable, x M , is modeled from

Ryan Reece (Penn) ) [GeV]hτ(

Tp

0 50 100 150 200 250

Ta

u I

D F

ake F

acto

r

0

0.05

0.1

0.15

0.2

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-1dt L = 4.7 fb∫ = 7 TeVs

)+jetsνµ→(W

Inclusive

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|<2.47η1.52<|

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+jetsW

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) [GeV]missTE, µ(Tm

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/ exp.

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1.5

W+jet background estimation

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W+jet control region

• In a W+jet control region, divide tau candidates into

pass and fail identification.

• Define fake factor:

• Predict the number of W/Z+jet events:

fτ(pT, η) ≡Npass τ−ID(pT, η)

Nfail τ−ID(pT, η)

∣

∣

∣

∣

∣

∣

W–CR

NW/Z+jet(pT, η, x) = fτ(pT, η) · Nfail τ−IDW/Z+jet (pT, η, x) ,

x) = fτ(pT, η) ·(

Nfail τ−IDdata (pT, η, x) − Nfail τ−IDmultijet (pT, η, x) − N

fail τ−IDMC (pT, η, x)

)

.

Ryan Reece (Penn)

Double fake factor procedure

82

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,-.#&%$.&#$-.

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!"#$%&"'%()

!"#$%$*+&,-%#.,

• The multijet contamination is estimated from the rate of non-isolated leptons, in

both the signal region that passes tau ID, and the sample that fails.

• Then, the corrected number of tau candidates failing ID are weighted to predicted

the W+jet background.

• This way, the corrections are small at each step.

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(d)Data 2011

Dibosonττ→*γ/Z

tt+jetsW

µµ→Zττ→(750)Z’

Z’ → ττ → eµ overview

83

Event selection


Back up:

CMS Exotics

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Z’→ττ

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hτ

hτ →(750) SSMZ'

τ τ →Z

ee→Z W+jets

QCD

Searches for charged Higgs bosons, supersymmetry, and exotica with tau leptons with the ATLAS and...

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