Searches for SUSY and BSM Higgswith ATLAS in Run II

Les Rencontres de Physique de la Vallee d’Aoste, La Thuile

Christian Ohm, on behalf ofthe ATLAS Collaboration

Lawrence Berkeley National Laboratory

March 10, 2016

1 / 28

Outline

1. Introduction

2. Supersymmetry searches1` + jets + Emiss

T

0` + 4-6 jets +EmissT

0` + 7-10 jets + EmissT

Z(``) + jets + EmissT

2 b-jets + EmissT

3-4 b-jets + EmissT

2` same-sign/3` + EmissT

3. Beyond-SM Higgs searchesH/A→ ττ(+b)High-mass γγ resonance

4. Summary & conclusions

2015 ATLAS pp data set

√s = 13 TeV,

∫L dt = 3.2 fb−1

Still more ATLAS BSM results in talks by L. Bryngemark, D. Strom, D. Lopez, and A. Cortes!

2 / 28

A brief introduction to supersymmetry

What is SUSY?

I Generalization of SM: symmetrybetween forces and matter particles

I Introduces sfermions and gauginos⇒ doubles particle content wrt SM

SUSY is attractive

I Can explain Dark Matter

I Alleviates hierarchy problem

I Allows for gauge coupling unification

but. . .

I Over 100 free parameters ⇒ widerange of possible exp. signatures

So, SUSY is theoretically appealing,

phenomenologically rich, and therefore

experimentally challenging

I Extended Higgs sector: h,H,A,H±

From 8 TeV to 13 TeV

From http://inspirehep.net/record/1326406

run 1 limit

� large increase of SUSY cross-sectionfrom 8 to 13 TeV :

• σ (g g) × 30 for m(g) =1.4 TeV

• σ (tt) × 8 for m(t) = 700 GeV

• σ (χχ) × 4 for m(χ) = 500 GeV

I focus on gluino and third generation squarks searches with 2015 data, with a discoverypotential beyond run 1 limits even with 3 fb−1 of 13 TeV data

I discovery potential of EW SUSY beyond run 1 limits will be reached with 2016 data

A. Marzin (CERN) SUSY searches with ATLAS 16 février 2016 12 / 52

(arXiv:1411.1427)

8 TeV→ 13 TeV⇒ σ(SUSY) grows:

I σ(gg)× 30 for mg = 1.4 TeV

I σ(tt)× 8 for mt = 700 GeV

I σ(χχ)× 4 for mχ = 500 GeV

In contrast: σ(tt)× 3.3⇒ S/B boost

Early Run II priorities:

I Target strong production of g and q

I Optimize for discovery, simple androbust analyses (cut & count),

3 / 28

Candidate tt event!

ATLAS in Run II - upgraded with additional innermost tracker layer (IBL)

Detector performance understood quickly with 13 TeV data

[GeV]refT

p210 310

⟩ re

f

T/p

lead

jet

T p⟨

0.8

0.85

0.9

0.95

1

1.05

1.1

1.15

1.2DataPythia8

Sherpa 2.1

DataPythia8

Sherpa 2.1

ATLAS Preliminary-1 = 13 TeV, 3.3 fbs

+jet Eventsγ R = 0.4, EM+JES (in-situ)tanti-k| < 0.8lead jetη|

[GeV]refT

p50 60 210 210×2 310

MC

/ D

ata

0.960.98

11.021.04

Jet response: data/MC agree to ∼1%

lead)µ(η

2.5− 2− 1.5− 1− 0.5− 0 0.5 1 1.5 2 2.5

[GeV

]− µ+ µ

m

90.6

90.8

91

91.2

91.4

91.6

91.8 PreliminaryATLAS -1 = 13 TeV, 3.3 fbs

Data

−µ+µ→Z

Syst. uncert.

)leadµ(η

2.5− 2− 1.5− 1− 0.5− 0 0.5 1 1.5 2 2.5

Dat

a/M

C

0.995

1

1.005

Muon pT scale

Effi

cien

cy

0.95

0.96

0.97

0.98

0.99

1ATLAS Preliminary

-1 = 13 TeV, 3.2 fbs

>15 GeVTE

Electron reconstruction

Data MC

η

-2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5

Dat

a / M

C

0.99

0.995

1

1.005

1.01

Electron efficiency

Also key for these results:

I flavor tagging

I EmissT - strong discrimination power

due to escaping DM particles!

I Variables describing event topologyand kinematics

5 / 28

General strategy for Run II: typical workflow

I Signal region: optimized for S/B

I Uses variables describing eventtopology and kinematics

I Can’t rely on perfect modeling inMC out to tails in distributions

Irreducible backgrounds : semi data-driven technique

� Principle : renormalize MC in control regions kinematically close to the signal region

� Define CRs by reverting cuts on 1 or 2 variables we believe are more reliably modelled by MC

Imore robust against potential MC mis-modelling of critical variables

I systematic uncertainties correlated between CR and SR largely cancel out

� compromise between low systematics and statistical uncertainties

� The extrapolation from the CR is validated in intermediate validation regions

Variable 1

Vari

able

2

Control

region

Signal

region

Validation

region

Validation

region

A. Marzin (CERN) SUSY searches with ATLAS 16 février 2016 21 / 52

For main irreducible BGs (tt, V+jets):

I Define

1. Control regions (CRs) ⇒MC normalization factors

2. Test extrapolation usingvalidation regions (VRs)

3. Predict yields in blindedsignal regions (SRs)

I Considerations:

I Extrapolate along reliablymodeled variables

I Uncertainties: trade-offbetween stat and syst.

Reducible backgrounds measured indata, for example:

I “Fake” EmissT , `

I Charge mis-identification for `

6 / 28

1` + jets + EmissT search ATLAS-CONF-2015-076

Target: final states with significantEmiss

T , jets and exactly one isolated e/µ

g

g

χ±1

χ∓1

p

p

q q

χ01

W

qq

χ01

W

Background estimation: tt and W+jetsdominate ⇒ normalize MC in CRs

Ex: soft-lepton 2-jet

I Regions split by requirementson Emiss

T and mT

I tt CR: ≥ 1 b-jet

I W+jets CR: no b-jets

Design of SRs:

I 4 hard-lepton SRs(large m

χ±1−mχ0

1)

I 2 soft-lepton (compressed spectra)

I Further subdivided usingnjets, E

missT ,mT,m

incleff

[GeV]missTE

200 300 400 500 600 700

[GeV

]T

m

20

40

60

80

100

120

140

160

180

200

SR

CR

TmVR

missTEVR

ATLAS PreliminarymissTE1-lepton + jets +

soft-lepton 2-jet

7 / 28

1` + jets + EmissT : results ATLAS-CONF-2015-076

I SR yields agree with bg-only hypo:

Num

ber o

f eve

nts

2

4

6

8

10

12

14

DataTotal SMtt

W+jetsdibosonsingle topOthers

ATLAS PreliminarymissT

1-lepton + jets + E-1 = 13 TeV, 3.3 fbs

4-je

t low

-x S

R

4-je

t hig

h-x

SR

5-je

t SR

6-je

t SR

2-je

t sof

t-lep

ton

SR

5-je

t sof

t-lep

ton

SR

tot

σ) /

pr

ed -

nob

s(n

2−02

I Largest deviation: 2σ excess inhard-lepton 6-jet SR:I e: exp: 1.9± 0.6, obs: 2I µ: exp: 2.5± 0.8, obs: 8

I Exclusion curves in mg-mχ01

plane ⇒I Run-I contour in gray, improved

limits now exclude up tomg = 1.6 TeV

(Throughout: only showing exampleinterpretations - more available!)

Even

ts /

80 G

eV

1−10

1

10

210

310

-1 = 13 TeV, 3.3 fbsATLAS Preliminary

Hard lepton 6-jet

DataTotal SMtt

W+jetsDibosonSingle topOthers

)=(1105,865,625) GeV1

0χ∼,

1±

χ∼,g~m(

[GeV]Tm100 150 200 250 300 350 400 450 500

Dat

a / S

M

0

1

2

[GeV]g~m400 600 800 1000 1200 1400 1600 1800 2000

[GeV

]10

χ∼m

200

400

600

800

1000

1200

1400

) ) = 1/21

0χ∼) - m(g~) ) / ( m(

1

0χ∼) - m(

1±

χ∼, x = (m(0

1χ∼

0

1χ∼qqqqWW→ g~-g~

soft-lepton 2-jet (obs./exp.)4-jet low-x (obs./exp.)5-jet (obs./exp.)6-jet (obs./exp.)

-1=13 TeV, 3.3 fbs

missT

+ jets + Eµ1 e/

10χ∼

< mg~m

-1ATLAS 8 TeV, 20.3 fb

All limits at 95% CL

ATLAS Preliminary

g

g

χ±1

χ∓1

p

p

q q

χ01

W

qq

χ01

W

8 / 28

0` + 4-6 jets +EmissT search ATLAS-CONF-2015-062

Target: g and q prod. with hadronic final states

q

qp

p

χ01

q

χ01

q

g

gp

p

χ01

q

q

χ01

q

q

g

g

χ±1

χ∓1

p

p

q q

χ01

W

qq

χ01

W

SR design:

I 2, 4, 5, 6 jets (no `!)

I Subdivided in effective mass

meff =∑jets

pT + EmissT

Backgrounds:

I W+jets: CR for W → `ν (b-jet veto) ↗I Top: CR with 1` & ≥ 1 b-jet →I Z(νν)+jets: estimated from γ+jets

I Diboson from MC

I Selection efficiently rejects multijet bg,residual estimated from CR with small∆φmin(Emiss

T , j)

(incl.) [GeV]effm1000 1500 2000 2500 3000 3500

even

ts /

100

GeV

1

10

210

PreliminaryATLAS -1=13 TeV, 3.2 fbs

CRW for SR4jtData 2015SM TotalDibosonZ+jets

(+EW) & single topttMulti−jetW+jets

(incl.) [GeV]effm1000 1500 2000 2500 3000 3500

Dat

a / M

C

00.5

1

1.52

(incl.) [GeV]effm1000 1500 2000 2500 3000 3500

even

ts /

100

GeV

1

10

210

PreliminaryATLAS -1=13 TeV, 3.2 fbs

CRT for SR4jtData 2015SM TotalDibosonZ+jetsW+jetsMulti−jet

(+EW) & single toptt

(incl.) [GeV]effm1000 1500 2000 2500 3000 3500

Dat

a / M

C

00.5

1

1.52

9 / 28

0` + 4-6 jets +EmissT : results ATLAS-CONF-2015-062

Num

ber o

f eve

nts

1

10

210

Data 2015SM TotalMulti−jetW+jets(+EW) & single toptt

Z+jetsDiboson

PreliminaryATLAS-1=13TeV, 3.2 fbs

Signal Region2jl 2jm 2jt 4jt 5j 6jm 6jt

Dat

a/Bk

g

00.20.40.60.8

11.21.41.61.8

Results

I Data agrees with bg estimate,no significant excess observed

I New limits derived:I ↙ New exclusions in mg-mχ0

1plane

I ↓ Slightly improved limits in mq-mχ01

[GeV]g~m200 400 600 800 1000 1200 1400 1600 1800 2000

[GeV

]0 1

χ∼m

0

200

400

600

800

1000

1200

1400

10χ∼

< m

g~m

01

χ∼01

χ∼ qqqq→ g~-g~

ATLAS Preliminary

-1 = 13 TeV, 3.2 fbs

missT

0-lepton + 2-6 jets + E

All limits at 95% CL

)SUSYtheoryσ1 ±Observed limit (

)expσ1 ±Expected limit (-1ATLAS 8 TeV, 20.3 fb

g

gp

p

χ01

q

q

χ01

q

q

[GeV]q~m200 400 600 800 1000 1200 1400

[GeV

]0 1

χ∼m

0

200

400

600

800

1000

1200

10χ∼

< m

q~m

01

χ∼01

χ∼ qq→ q~-q~

ATLAS Preliminary

-1 = 13 TeV, 3.2 fbs

missT

0-lepton + 2-6 jets + E

All limits at 95% CL

)SUSYtheoryσ1 ±Observed limit (

)expσ1 ±Expected limit (-1ATLAS 8 TeV, 20.3 fb

q

qp

p

χ01

q

χ01

q

10 / 28

0` + 7-10 jets + EmissT search ⇒ arXiv:1602.06194

g

g

χ±1

χ02

χ±1 χ0

2

p

p

q q W

Z

χ01

qq W

Z

χ01

g

g

χ02

χ±1

p

p

t t

χ01

Z/h

tb

χ01

W

SRs for gg with complex decays:

I 7, 8, 9, 10 jets

I Looser EmissT requirements

I Up to 2 b-jets

0 2 4 6 8 10 12 14 16 18 20

1/2

Eve

nts

/ 4 G

eV

-110

1

10

210

310

ATLAS1− = 13 TeV, 3.2 fbs

DataTotal backgroundMultijet (=6-jet data)

ql, ll→ tt + jetsν l→W

OtherpMSSM benchmark2-step benchmark

SR 10j50-0b

]1/2 [GeVTH / missTE

0 2 4 6 8 10 12 14 16 18 20

Dat

a / P

redi

ctio

n

00.5

11.5

2

Background estimation:

I Multijet: EmissT significance,

EmissT /

√HT, is ∼indep. of njets,

extract templates from 5j and 6j CRs

I Top and W+jets from MC

No significant excess ⇒Limits up to mg ∼ 1.4 TeV

) [GeV]g~m(

800 900 1000 1100 1200 1300 1400 1500 1600 1700

) [G

eV

]0 1

χ∼m

(

100

200

300

400

500

600

700

800

)]/20

1χ∼)+m(

±

1χ∼)=[m(

0

2χ∼)]/2, m(

0

1χ∼)+m(g~)=[m(

±

1χ∼; m(

0

1χ∼ qqWZ→ g~, g~­g~

ATLAS

Combinedmiss

TMultijets + E

1−=13 TeV, 3.2 fbs

All limits 95% CL

)exp

σ1 ±Expected (

)theory

SUSYσ1 ±Observed (

1−ATLAS 8 TeV, 20.3 fb

g

g

χ±1

χ02

χ±1 χ0

2

p

p

q q W

Z

χ01

qq W

Z

χ01

11 / 28

Z(``) + jets + EmissT search ATLAS-CONF-2015-082

Target: gg or qq with Z → `` in decay

g

g

χ02

χ02

p

p

q q

χ01

Z

qq

χ01

Z

Background estimation:

I tt, WW , Wt: flavor-symmetric(1:1:2 ratio for ee:µµ:eµ), estimatedfrom eµ data:

Nbg est.ee/µµ =

1

2NCReµ × kee/µµ

I WZ, ZZ, ttV from MC,checked in VR

I Z+jets: estimated from γ+jetsevents in data

Excess in 8 TeV Run I search:

I ee: 3σ, µµ: 1.7σ

[GeV]llm82 84 86 88 90 92 94 96 98 100

Eve

nts

/ 2.5

GeV

2

4

6

8

10

12

14ATLAS

-1 = 8 TeV, 20.3 fbs

SR-Z ee

DataStandard ModelFlavour SymmetricOther Backgrounds

=(700,200)GeVµ),g~m(=(900,600)GeVµ),g~m(arXiv:1503.03290

Reproduce Run I SR:

I SFOS ee/µµ with81 GeV < m`` < 101 GeV

I 2 jets with ∆φmin(EmissT , j) > 0.4

I EmissT > 225 GeV, HT > 600 GeV

12 / 28

Z(``) + jets + EmissT : results ATLAS-CONF-2015-082

[GeV]missTE

0 50 100 150 200

Dat

a/M

C

0.51

1.52

Even

ts /

10 G

eV

1

10

210

310

410Data 2015

Standard Model (SM)

+jets)γ* (from γZ/

Flavour symmetric

Rare top

WZ/ZZ

-1 = 13 TeV, 3.2 fbsµµ2L+MET+Jets ee+

ATLAS Preliminary

[GeV]llm50 100 150 200 250 300 350 400

Even

ts /

20 G

eV

0

5

10

15

20

25

30

35 Data 2015

Standard Model (SM)

+jets)γ* (from γZ/

Flavour symmetric

Rare top

WZ/ZZ

-1 = 13 TeV, 3.2 fbsµµee+

ATLASPreliminary

Final event yield for 2015 data:

I Expected: 10.3± 2.3

I Observed: 21 (10 ee, 11 µµ)⇒ 2.2σ excess

) [GeV]g~m(600 700 800 900 1000 1100 1200 1300 1400

) [G

eV]

20 χ∼m

(

200

400

600

800

1000

1200

1400

0

1χ∼ Z→

0

2χ∼, 0

2χ∼’q q→g~, g~g~

-1=13 TeV, 3.2 fbs SR-ZATLAS Preliminary )expσ1 ±Expected limit (

)theorySUSYσ1 ±Observed limit (

)02χ

∼)<m(

g~m(

g

g

χ02

χ02

p

p

q q

χ01

Z

qq

χ01

Z

Observed limitworse than expecteddue to excess!

CMS observes 12 with 12+4.0−2.8 expected (CMS-PAS-SUS-15-011)

13 / 28

2 b-jets + EmissT search ATLAS-CONF-2015-066

Targets direct b pair-production

b

bp

p

χ01

b

χ01

b

I 4 SRs forI low mχ0

1(subdivided in mCT)

I more compressed SUSY spectra

I BG from W/Z/tt estimated fromCRs with 1-2 `

No significant excess ⇒mb < 850 GeV excluded

[GeV]CTm

Eve

nts

/ 50

GeV

0

5

10

15

20

25

30

35

40

45Preliminary ATLAS Preliminary ATLAS

-1= 13 TeV, 3.2 fbsData SM totaltt

Single topOthersW + jetsZ + jets

)=10

1χ∼)=700, m(b

~m(

SRA250

Data SM totaltt

Single topOthersW + jetsZ + jets

)=10

1χ∼)=700, m(b

~m(

[GeV]CTm0 100 200 300 400 500 600

Dat

a / S

M

0

1

2

[GeV]1b

~m100 200 300 400 500 600 700 800 900 1000 1100

[GeV

]0 1χ∼

m

0

100

200

300

400

500

600

700

800

Best SR

forb

idde

n

01χ∼

b

→ 1b~

=8 TeVs, -1 + 2 b-jets, 20.1 fbTmissATLAS E

=8 TeVs, -1ATLAS monojet, 20.3 fb

0

1χ∼ b → 1b

~Bottom squark pair production,

-1=13 TeV, 3.2 fbs

ATLAS Preliminary)

theorySUSYσ1 ±Observed limit (

)expσ1 ±Expected limit (

All limits at 95% CL

14 / 28

3-4 b-jets + EmissT search ATLAS-CONF-2015-067

Target: gg with 3rd gen. decays

g

gp

p

χ01

t

t

χ01

t

t

g

gp

p

χ01

b

b

χ01

b

b

[GeV]missTE

Eve

nts

/ 50

GeV

1

10

210

310

410

510 ATLAS Preliminary-1 = 13 TeV, 3.3 fbs

Gbb pre-selection

Data 2015Total backgroundttSingle top + W/Z/htt

Z+jetsW+jetsDiboson

100)× σ = 1700, 200 (0

1χ∼

, mg~

Gbb: m

100)× σ = 1400, 800 (0

1χ∼

, mg~

Gbb: m

[GeV]missTE

200 300 400 500 600 700 800

Dat

a / S

M

0

1

2

I SR design:I 0` (b) and 1` (t)I Subdivided in Emiss

T , njets, b-jets

I BackgroundsI Dominated by tt, estimated in

lower-EmissT CRs

I Other BGs from MC

No significant excess ⇒Limits up to mg ∼ 1.7 TeV

[GeV]g~m1000 1200 1400 1600 1800 2000

[GeV

]10 χ∼

m

0

200

400

600

800

1000

1200

1400

1600-1ATLAS 8 TeV, 20.1 fb

)expσ1 ±Expected limit (

)theorySUSYσ1 ±Observed limit (

t

+ 2m0

1χ∼ < mg~m

)g~) >> m(q~, m(0

1χ∼+t t→ g~ production, g~g~

All limits at 95% CL

PreliminaryATLAS-1=13 TeV, 3.3 fbs

-1ATLAS 8 TeV, 20.1 fb

)expσ1 ±Expected limit (

)theorySUSYσ1 ±Observed limit (

g

gp

p

χ01

t

t

χ01

t

t

15 / 28

2` same-sign/3` + EmissT search arXiv:1602.09058

Target: g/q prod. w/ W → `ν decays

g

gp

p

χ01

t

t

χ01

t

t

b

b

χ±1

χ∓1

p

p

t

χ01

W

t

χ01

W

g

g

χ±1

χ02

χ±1 χ0

2

p

p

q q W

Z

χ01

qq W

Z

χ01

g

g

χ02

˜/ν

χ02

˜/νp

p

q q `/ν

`/ν

χ01

qq `/ν

`/ν

χ01

I SR design: 0, 1 and 3 b-jets

Signal region N signallept N20

b−jets N50jets Emiss

T [GeV] meff [GeV]

SR0b3j ≥3 =0 ≥3 >200 >550

SR0b5j ≥2 =0 ≥5 >125 >650

SR1b ≥2 ≥1 ≥4 >150 >550

SR3b ≥2 ≥3 - >125 >650

I BackgroundsI Charge mis-id measured in Z → ``I Fake leptons from id-based matrix

methodI Other processes from MC

[GeV]missTE

40 60 80 100 120 140 160

Eve

nts

/ 25

GeV

0

2

4

6

8

10

12

14

16

=50 GeV0

1χ∼

=600 GeV, mb~m

Charge-FlipRareWZ, WW, ZZ

cutmissTSR1b before E

DataSM TotalFake LeptonsttW, ttZ

0

1χ∼ tW→1b

~SUSY

ATLAS-1=13 TeV, 3.2 fbs

SR

> 150

[GeV]g~

m700 800 900 1000 1100 1200 1300

[GeV

]10 χ∼

m

200

400

600

800

1000

1

0χ∼

+ mZ

+ mW

< mg~m

))/21

0χ∼) + m(1

±χ∼) = (m(2

0χ∼))/2, m(1

0χ∼) + m(g~) = (m(1

±χ∼; m(1

0χ∼ qqWZ→ g~ production, g~g~

-1=13 TeV, 3.2 fbs

ATLAS Observed limit

)expσ1 ±Expected limit (

-1ATLAS 8 TeV, 20.3 fb

-1ATLAS SS/3L 8 TeV, 20.3 fb

All limits at 95% CL

g

g

χ±1

χ02

χ±1 χ0

2

p

p

q q W

Z

χ01

qq W

Z

χ01

16 / 28

H/A→ ττ(+b) search ATLAS-CONF-2015-061

Target: additional neutral Higgs bosonsA and H in MSSM from gg fusion &b-associated production ⇒

τlep-τhad

I Jets (W , QCD)faking e/µ, τestimated fromfake-factors in CRs

I Z, top from MC

τhad-τhad

I Dominant BG QCD,estimated fromfake-factor method

200 300 400 500 600 700 800 900 1000

Eve

nts

/

Ge

V

3−10

2−10

1−10

1

10

210

310 Dataττ →H/A

= 25β = 500 GeV, tanAm fakesτl,→Jet

ττ→Z, single toptt

Dibosonµµee/→Z

UncertaintyPre­fit background

ATLAS Preliminary

­1

= 13 TeV, 3.2 fbs

hadτµτ →H/A

[GeV]totTm

200 300 400 500 600 700 800 900 1000Data

/Pre

d

0

1

2

µ ch, full selection

g

g

h/H/A

g

g b

b

h/H/A

g

b

b

h/H/A

Can dominate at large tan β

[GeV]Am200 300 400 500 600 700 800 900 1000 1100 1200

βta

n10

20

30

40

50

60

70

80

= 3

00 G

eVH

m

= 8

00 G

eVH

m

= 1

000

GeV

Hm

Observed

Expected

σ1

σ2

ATLAS Run-I (Obs.)

ATLAS Run-I, SM Higgs

boson couplings (Obs.) /////////

-1=13 TeV, 3.2 fbsPreliminary, ATLAS hMSSM scenario

, 95% CL limitsττ →H/A

Improved upper tan β limit for mA > 700 GeV

17 / 28

High-mass γγ resonance search ATLAS-CONF-2015-081

I γγ key channel for discovering andmeasuring the 125 GeV Higgs

I Refined but simple analysis,selection, optimized for scalar

Selection

I Two ’tight’ photons

I Relative ET cuts:Eγ1T /mγγ > 0.4Eγ2T /mγγ > 0.3

I Isolation: ET-dependent,calo- and track-based

Signal model: double-sided Crystal Ballfunction, two width hypotheses:

I Narrow-Width Approx. (NWA)

I Large Width (LW), ≤ 25% of mγγ

Search looks for bump in mγγ , SM bg from fit of smooth function to data:

f(k)(x; b, {ak}) = (1− x1/3)bx∑kj=0 aj(log x)j , where x = mγγ/

√s

Background fit tested for several k-values, k = 0 performs sufficiently.S +B fit for mγγ > 150 GeV.

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High-mass γγ resonance: results ATLAS-CONF-2015-081

[GeV]γγm

200 400 600 800 1000 1200 1400 1600

Eve

nts

/ 40

GeV

1−10

1

10

210

310

410ATLAS Preliminary

-1 = 13 TeV, 3.2 fbs

Data

Background-only fit

[GeV]γγm200 400 600 800 1000 1200 1400 1600

Dat

a -

fitte

d ba

ckgr

ound

15−10−

5−05

1015

I Under NWA: local excess of 3.6σ,minimal p0 at mγγ ≈ 750 GeV

I [200, 2000] GeV considered ⇒compensate for look-elsewhere effect⇒ global significance 2.0σ

(PER pulled 1.5σ in NWA fit)

[GeV]Xm

200 400 600 800 1000 1200 1400 1600 1800

Loca

l p-v

alue

5−10

4−10

3−10

2−10

1−10

1

ATLAS Preliminary-1 = 13 TeV, 3.2 fbs

Observed

σ0

σ1

σ2

σ3

σ4

LW hypothesis:

I Best-fit width of 45 GeV (∼ 6%)

I Increased local significance: 3.9σ

I LEE-adjustment (mass range &width up to 10%)⇒ global significance of 2.3σ

19 / 28

Summary & conclusions

I Several searches for SUSY and additional Higgs bosons have already beenperformed by ATLAS using the 3.2 fb−1 of data from 2015

I More results presented tonight & tomorrow (Lene, David, David, Arely) -keep an eye on the ATLAS winter conference results page for updates

I For most searches the data agree well with the expectations frombackground processes. Two intriguing but inconclusive excesses observed:

I Z + jets + EmissT : 2.2σ (in ATLAS also in Run I, not in CMS)

I High-mass γγ: ∼2σ around mγγ = 750 GeV

The 25 fb−1 the LHC plans to deliver during 2016 will reveal thenature of the observed excesses - the data taking starts soon!

20 / 28

Back-up material

21 / 28

Interest in the γγ results on the arXiv since December10/03/16 09:34title tbd by adavid

Page 1 of 1http://fiddle.jshell.net/adavid/bk2tmc2m/show/light/

Date and time of last update (UTC)

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ber o

f sub

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#Run2Seminar and subsequent γγ-related arXiv submissions2016/03/07 17:55:15: Submissions: 273

0

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13 Dec 20 Dec 27 Dec 03 Jan 10 Jan 17 Jan 24 Jan 31 Jan 07 Feb 14 Feb 21 Feb 28 Feb 06 Mar 13 Mar

S

7 89101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144 145146147148149150151152153154155156157158159160161162163164165166167168169170171 172173174175176177178179180181182183184185186187188189190191192193194195196197198 199200201202203204205206207208209210211212213214215 216 217218219220221222223 224225226227228229230231232233 234235236237238239240241242243244245246247248249250251252253254255256257258259 260261262263264265266267268269270271272273

(A. David)

Number of arXiv papers related to December’s preliminary high-mass γγresults. Probably more on interpretations in Marco Nardecchia’s talk tomorrow.

There’s even a paper predicting the shape of this curve:

“. . . fits to the current data predict that the total number of paperson the topic will not exceed 310 papers by the June 1. 2016”

22 / 28

High-mass γγ resonance search: more details

Signal selection eff:I Overall signal efficiency:

I 30-40% for ggFI 30-45% for VBFI 25-35% for ttH

I In fiducial volume: 55-70%

Signal modeling:

I Optimized for narrow Higgs-likeresonances with m > 200 GeV

I Prod. via ggF, VBF, WH/ZH, ttH

Background estimation:

I Parameterized by smooth function,free parameters adjusts it to the data

I Possibility of needing more degreesof freedom considered and evaluatedwith F -test ⇒ k > 0 not needed

Fit & significance:

I Unbinned ML fit of mγγ distribution

I Local p-value for bg-only hypo fromasymptotic approximation

I LEE based on number of 2σcrossings in [200, 2000] GeV

Compatibility with 8 TeV data:within 2.2σ (1.4σ) for NWA (LW)

23 / 28

High-mass γγ resonance search: main uncertainties

Source UncertaintyBackground modeling �•

Spurious signal 2 – 10�3 events, mass-dependentBackground fit 50%– 20% of the total signal yield uncertainty,

mass- and signal-dependentSignal modeling �•

Photon energy resolution +[55�110]%�[20�40]% , mass-dependent

Signal yield •Luminosity ±5%Trigger ±0.63%

CX factors •Photon identification ±(3–2)%, mass-dependentPhoton isolation ±(4.1–1)%, mass-dependentProduction process ±3.1%

Table 1: Summary of the systematic uncertainties in the signal-plus-background likelihood fit when considering theNWA signal model. The � symbol denotes categories of uncertainties that a�ect the local p-value for the background-only hypothesis, while the • symbol denotes uncertainties that impact the limit on �fiducial ⇥ BR(X ! ��).

10 Results

Figure 1 shows the diphoton mass spectrum observed in data, with the result of an unbinned background-only fit superimposed. The uncapped local p0, as obtained by the signal-plus-background likelihoodfits under the NWA hypothesis for the signal, is shown in Figure 2. The most significant deviationfrom the background hypothesis is observed for a mass of about 750 GeV, corresponding to a localsignificance of 3.6 �, and to a global significance of 2.0 � when the LEE taking into account themass range mX 2 [200 � 2000] GeV is accounted for. The second most significant deviation from thebackground-only hypothesis is found for a mass of about 1.6 TeV, corresponding to a local significance of2.8 �.

In the region around 750 GeV, the NWA fits exhibit a⇠1.5� pull on the nuisance parameter associated withthe photon energy resolution uncertainty, indicating an excess broader than the experimental m�� invariantmass resolution. After this behavior was observed, signal-plus-background fits were also performedassuming a large width for the signal component. The largest deviation from the background-onlyhypothesis is observed for a mass around 750 GeV and ↵ ' 6%, corresponding to a width � of about 45GeV. The local significance increases when allowing the width to vary, as expected. The local (global)significance evaluated for the large width fit is about 0.3 higher than that for the NWA fit, corresponding to3.9 (2.3) �. The global significance value is obtained accounting for a 2-dimensional LEE correspondingto the scan range mX 2 [200 � 2000] GeV and ↵ 2 [1 � 10]%.5

In the excess region, defined as m�� 2 [700, 800] GeV, the numbers of fitted signal and background eventsunder both the NWA and large-width hypotheses are about equal.

5 The stability of the 2-dimensional LEE correction is evaluated by considering a larger scan range for the ↵ parameter. Whenextending the range to ↵ 2 [1� 25]% the global significance is only marginally a�ected, reducing at most by 0.05 with respectto the value obtained considering the [1 � 10]% range.

12

24 / 28

Z(``) + jets + EmissT : additional details

Background estimation:

I Flavor-symmetric: tt, WW , Wt⇒ measured in eµ dataTotal: 60% (70%, 20%, 8%)

I Z/γ∗+jets: gives EmissT due to

mismeasurements (or ν in jetfragmentation) ⇒ small but peakedat m`` ∼ mZ

I Diboson: ∼30% (from MC)

Z/γ∗+jets details:

I Exploit that Z+jets and γ+jets havesimilar topologies, Z and γ bothwell-measured, hadronic recoil

I Use (lepton-free) γ+jets sample withSRZ-like kinematics (no Emiss

T cut)

I Apply pT reweighting, smearing (µchannel only), recalculate Emiss

T

I Normalize EmissT in Z CR

[GeV]missTE

0 50 100 150 200 250+j

et/Z

γ0.5

11.5

2

Even

ts /

10 G

eV

1−10

1

10

210

310* MCγZ/

+jets MC)γ* (from γZ/

-1 = 13 TeV, 3.2 fbsµµVRZ ee+

ATLAS Simulation Preliminary

MC closure test

25 / 28

Z(``) + jets + EmissT : additional details about SR, VRs, CRs

Region EmissT HT njets m`` SF/DF ∆φ(jet12,p

missT ) mT(`3, E

missT ) nb-jets

[GeV] [GeV] [GeV] [GeV]

Signal regions

SRZ > 225 > 600 ≥ 2 81 < m`` < 101 SF > 0.4 - -

Control regions

Z normalisation < 60 > 600 ≥ 2 81 < m`` < 101 SF > 0.4 - -CR-FS > 225 > 600 ≥ 2 61 < m`` < 121 DF > 0.4 - -CRT > 225 > 600 ≥ 2 m`` /∈ [81, 101] SF > 0.4 - -

Validation regions

VRZ < 225 > 600 ≥ 2 81 < m`` < 101 SF > 0.4 - -VRT 100–200 > 600 ≥ 2 m`` /∈ [81, 101] SF > 0.4 - -VRS 100–200 > 600 ≥ 2 81 < m`` < 101 SF > 0.4 - -VR-FS 100–200 > 600 ≥ 2 61 < m`` < 121 DF > 0.4 - -VR-WZ 100–200 - - - 3` - < 100 0VR-ZZ < 100 - - - 4` - - 0VR-3L 60–100 > 200 ≥ 2 81 < m`` < 101 3` > 0.4 - -

26 / 28

Variable definitions

I Missing transverse momentum (or energy):

EmissT =

√(Emiss

x )2 + (Emissy )2

where Emissx(y) = −

∑Ex(y) summed over all calibrated e, γ, µ, τ, jets. . .

I Scalar transverse-energy sum:

HT =∑jets,`

pT

I Effective mass:m

(incl)eff =

∑jets,`

pT + EmissT

I Transverse mass (1`):

mT =

√2p`TE

missT (1− cos[∆φ(~, Emiss

T )])

I Contransverse mass (measures the masses of pair-prod. semi-invisiblydecaying heavy particles, e.g. b→ bχ0):

m2CT(υ1, υ2) = [ET(υ1) + ET(υ2)]2 − [pT(υ1)− pT(υ2)]2

27 / 28

Run I SUSY results

Model e, µ, τ, γ Jets Emiss

T

∫L dt[fb−1] Mass limit Reference

Inclu

siv

eS

ea

rch

es

3rd

ge

n.

gm

ed

.3rd

gen.

squark

sdir

ect

pro

duction

EW

dir

ect

Lo

ng

-liv

ed

pa

rtic

les

RP

V

Other

MSUGRA/CMSSM 0-3 e, µ /1-2 τ 2-10 jets/3 b Yes 20.3 m(q)=m(g) 1507.055251.8 TeVq, g

qq, q→qχ01 0 2-6 jets Yes 20.3 m(χ

01)=0 GeV, m(1st gen. q)=m(2nd gen. q) 1405.7875850 GeVq

qq, q→qχ01 (compressed) mono-jet 1-3 jets Yes 20.3 m(q)-m(χ

01 )<10 GeV 1507.05525100-440 GeVq

qq, q→q(ℓℓ/ℓν/νν)χ01

2 e, µ (off-Z) 2 jets Yes 20.3 m(χ01)=0 GeV 1503.03290780 GeVq

gg, g→qqχ01 0 2-6 jets Yes 20.3 m(χ

01)=0 GeV 1405.78751.33 TeVg

gg, g→qqχ±1→qqW±χ01 0-1 e, µ 2-6 jets Yes 20 m(χ

01)<300 GeV, m(χ

±)=0.5(m(χ

01)+m(g)) 1507.055251.26 TeVg

gg, g→qq(ℓℓ/ℓν/νν)χ01

2 e, µ 0-3 jets - 20 m(χ01)=0 GeV 1501.035551.32 TeVg

GMSB (ℓ NLSP) 1-2 τ + 0-1 ℓ 0-2 jets Yes 20.3 tanβ >20 1407.06031.6 TeVg

GGM (bino NLSP) 2 γ - Yes 20.3 cτ(NLSP)<0.1 mm 1507.054931.29 TeVg

GGM (higgsino-bino NLSP) γ 1 b Yes 20.3 m(χ01)<900 GeV, cτ(NLSP)<0.1 mm, µ<0 1507.054931.3 TeVg

GGM (higgsino-bino NLSP) γ 2 jets Yes 20.3 m(χ01)<850 GeV, cτ(NLSP)<0.1 mm, µ>0 1507.054931.25 TeVg

GGM (higgsino NLSP) 2 e, µ (Z) 2 jets Yes 20.3 m(NLSP)>430 GeV 1503.03290850 GeVg

Gravitino LSP 0 mono-jet Yes 20.3 m(G)>1.8 × 10−4 eV, m(g)=m(q)=1.5 TeV 1502.01518865 GeVF1/2 scale

gg, g→bbχ01 0 3 b Yes 20.1 m(χ

01)<400 GeV 1407.06001.25 TeVg

gg, g→ttχ01 0 7-10 jets Yes 20.3 m(χ

01) <350 GeV 1308.18411.1 TeVg

gg, g→ttχ01

0-1 e, µ 3 b Yes 20.1 m(χ01)<400 GeV 1407.06001.34 TeVg

gg, g→btχ+1 0-1 e, µ 3 b Yes 20.1 m(χ

01)<300 GeV 1407.06001.3 TeVg

b1b1, b1→bχ01 0 2 b Yes 20.1 m(χ

01)<90 GeV 1308.2631100-620 GeVb1

b1b1, b1→tχ±1 2 e, µ (SS) 0-3 b Yes 20.3 m(χ

±1 )=2 m(χ

01) 1404.2500275-440 GeVb1

t1 t1, t1→bχ±1 1-2 e, µ 1-2 b Yes 4.7/20.3 m(χ

±1 ) = 2m(χ

01), m(χ

01)=55 GeV 1209.2102, 1407.0583110-167 GeVt1 230-460 GeVt1

t1 t1, t1→Wbχ01 or tχ

01

0-2 e, µ 0-2 jets/1-2 b Yes 20.3 m(χ01)=1 GeV 1506.0861690-191 GeVt1 210-700 GeVt1

t1 t1, t1→cχ01 0 mono-jet/c-tag Yes 20.3 m(t1)-m(χ

01 )<85 GeV 1407.060890-240 GeVt1

t1 t1(natural GMSB) 2 e, µ (Z) 1 b Yes 20.3 m(χ01)>150 GeV 1403.5222150-580 GeVt1

t2 t2, t2→t1 + Z 3 e, µ (Z) 1 b Yes 20.3 m(χ01)<200 GeV 1403.5222290-600 GeVt2

ℓL,R ℓL,R, ℓ→ℓχ01 2 e, µ 0 Yes 20.3 m(χ01)=0 GeV 1403.529490-325 GeVℓ

χ+1χ−1 , χ

+1→ℓν(ℓν) 2 e, µ 0 Yes 20.3 m(χ

01)=0 GeV, m(ℓ, ν)=0.5(m(χ

±1 )+m(χ

01)) 1403.5294140-465 GeVχ±

1

χ+1χ−1 , χ

+1→τν(τν) 2 τ - Yes 20.3 m(χ

01)=0 GeV, m(τ, ν)=0.5(m(χ

±1 )+m(χ

01)) 1407.0350100-350 GeVχ±

1

χ±1χ02→ℓLνℓLℓ(νν), ℓνℓLℓ(νν) 3 e, µ 0 Yes 20.3 m(χ

±1 )=m(χ

02), m(χ

01)=0, m(ℓ, ν)=0.5(m(χ

±1 )+m(χ

01)) 1402.7029700 GeVχ±

1, χ

0

2

χ±1χ02→Wχ

01Zχ

01

2-3 e, µ 0-2 jets Yes 20.3 m(χ±1 )=m(χ

02), m(χ

01)=0, sleptons decoupled 1403.5294, 1402.7029420 GeVχ±

1, χ

0

2

χ±1χ02→Wχ

01h χ

01, h→bb/WW/ττ/γγ e, µ, γ 0-2 b Yes 20.3 m(χ

±1 )=m(χ

02), m(χ

01)=0, sleptons decoupled 1501.07110250 GeVχ±

1, χ

0

2

χ02χ03, χ

02,3 →ℓRℓ 4 e, µ 0 Yes 20.3 m(χ

02)=m(χ

03), m(χ

01)=0, m(ℓ, ν)=0.5(m(χ

02)+m(χ

01)) 1405.5086620 GeVχ0

2,3

GGM (wino NLSP) weak prod. 1 e, µ + γ - Yes 20.3 cτ<1 mm 1507.05493124-361 GeVW

Direct χ+1χ−1 prod., long-lived χ

±1 Disapp. trk 1 jet Yes 20.3 m(χ

±1 )-m(χ

01)∼160 MeV, τ(χ

±1 )=0.2 ns 1310.3675270 GeVχ±

1

Direct χ+1χ−1 prod., long-lived χ

±1 dE/dx trk - Yes 18.4 m(χ

±1 )-m(χ

01)∼160 MeV, τ(χ

±1 )<15 ns 1506.05332482 GeVχ±

1

Stable, stopped g R-hadron 0 1-5 jets Yes 27.9 m(χ01)=100 GeV, 10 µs<τ(g)<1000 s 1310.6584832 GeVg

Stable g R-hadron trk - - 19.1 1411.67951.27 TeVg

GMSB, stable τ, χ01→τ(e, µ)+τ(e, µ) 1-2 µ - - 19.1 10<tanβ<50 1411.6795537 GeVχ0

1

GMSB, χ01→γG, long-lived χ

01

2 γ - Yes 20.3 2<τ(χ01)<3 ns, SPS8 model 1409.5542435 GeVχ0

1

gg, χ01→eeν/eµν/µµν displ. ee/eµ/µµ - - 20.3 7 <cτ(χ

01)< 740 mm, m(g)=1.3 TeV 1504.051621.0 TeVχ0

1

GGM gg, χ01→ZG displ. vtx + jets - - 20.3 6 <cτ(χ

01)< 480 mm, m(g)=1.1 TeV 1504.051621.0 TeVχ0

1

LFV pp→ντ + X, ντ→eµ/eτ/µτ eµ,eτ,µτ - - 20.3 λ′311

=0.11, λ132/133/233=0.07 1503.044301.7 TeVντ

Bilinear RPV CMSSM 2 e, µ (SS) 0-3 b Yes 20.3 m(q)=m(g), cτLS P<1 mm 1404.25001.35 TeVq, g

χ+1χ−1 , χ

+1→Wχ

01, χ

01→eeνµ, eµνe 4 e, µ - Yes 20.3 m(χ

01)>0.2×m(χ

±1 ), λ121,0 1405.5086750 GeVχ±

1

χ+1χ−1 , χ

+1→Wχ

01, χ

01→ττνe, eτντ 3 e, µ + τ - Yes 20.3 m(χ

01)>0.2×m(χ

±1 ), λ133,0 1405.5086450 GeVχ±

1

gg, g→qqq 0 6-7 jets - 20.3 BR(t)=BR(b)=BR(c)=0% 1502.05686917 GeVg

gg, g→qχ01, χ

01 → qqq 0 6-7 jets - 20.3 m(χ

01)=600 GeV 1502.05686870 GeVg

gg, g→t1t, t1→bs 2 e, µ (SS) 0-3 b Yes 20.3 1404.250850 GeVg

t1 t1, t1→bs 0 2 jets + 2 b - 20.3 ATLAS-CONF-2015-026100-308 GeVt1

t1 t1, t1→bℓ 2 e, µ 2 b - 20.3 BR(t1→be/µ)>20% ATLAS-CONF-2015-0150.4-1.0 TeVt1

Scalar charm, c→cχ01 0 2 c Yes 20.3 m(χ

01)<200 GeV 1501.01325490 GeVc

Mass scale [TeV]10−1 1

√s = 7 TeV

√s = 8 TeV

ATLAS SUSY Searches* - 95% CL Lower LimitsStatus: July 2015

ATLAS Preliminary√s = 7, 8 TeV

*Only a selection of the available mass limits on new states or phenomena is shown. All limits quoted are observed minus 1σ theoretical signal cross section uncertainty.

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