p cornering natural susy with s = 13 tev data€¦ · t2 m 0 50 100 150 200 250 300 number of...

Cornering natural SUSY with√s = 13 TeV data

Les Rencontres de MoriondEW Interactions and Unified Theories

La Thuile, Italy 18-25 March 2017

Andreas PetridisOn behalf of the ATLAS and CMS collaborations

University of Adelaide

March 20, 2017

A. Petridis 1 / 24

Supersymmetry and NaturalnessThe most studied extension of the SM among any BSM theory. Advantages:

• Could solve the hierarchy problem through the one loop stop correction;

• Could unify the fundamental interactions of nature;

• Could provide a dark matter candidate, if R-Parity is conserved;

• Naturalness requierement by the tree-level relation in MSSM:

−m2Z

2= |µ|2 + m2

Hu

• stops expected to be light (<∼ 1 TeV);

• higgsinos with masses below 350 GeV;

• a not too heavy gluino;

10.1007/JHEP09(2012)035,arXiv:1110.6926 [hep-ph]

A. Petridis 2 / 24

https://arxiv.org/abs/1110.6926

OverviewAnalyses covered

• t̃ t̃• b̃b̃• χ̃±

1 χ̃02

Compressed spectra(∆m = mχ̃±1 /χ̃

02−mχ̃0

1< 30 GeV)

t̃ t̃χ̃±1 χ̃

02

wino-like

Eur.Phys.J. C74 (2014) 12

ATLAS

• t̃ 0-lepton (ATLAS-CONF-2017-020)

• t̃2 → t̃1 Z/H (ATLAS-CONF-2017-013)

• t̃ 1-lepton R-ParityViolation(ATLAS-CONF-2017-013)

Link to ATLAS public results

CMS

• t̃ 0-lepton (SUS-16-049)

• t̃ 2-leptons (SUS-17-001)

• 2-soft-leptons (SUS-16-042)

• HH → 4b (SUS-16-044)

• b̃ 0-lepton (SUS-16-032)

• b̃ h→ γγ (SUS-16-045)

Link to CMS public results

A. Petridis 3 / 24

https://twiki.cern.ch/twiki/bin/view/AtlasPublic/SupersymmetryPublicResults

http://cms-results.web.cern.ch/cms-results/public-results/preliminary-results/SUS/index.html

... from stops ...

... to sbottoms ...

A. Petridis 4 / 24

The stop searches: t̃1 → tχ̃01

• High mass region∆m > mt

• boosted topologies

• Intermediate region

∆m(t̃1, χ̃01) < mt

• Examine“3-body-decays”

• Compressed region

∆m(t̃1, χ̃01) < mW + mb

• Examine “4-body-decays”• Challenging region due to the soft products of the decays• high background rates

• t̃1 → cχ̃01 challenging due to charm tagging

• Dedicated searches based on the lepton multiplicities

A. Petridis 5 / 24

ATLAS Stop 0-lepton ATLAS-CONF-2017-020

High mass - ∆m(t̃1, χ̃01) > mt

• 2 inclusive SRs targeting different∆m = mt̃ −mχ̃0

1with 3 subcategories based on

t−tagged and W−tagged jets (TT, TW, T0)

• Disctriminant variables:m0,1

jet,R=1.2,mb,minT ,mb,max

T ,EmissT

• Main background contribution comesZ(νν) + jets, followed by tt̄V (whereV = W , Z) and tt̄

∆m(t̃1, χ̃01) ∼ mt

• Based on Recursive Jigsaw Reconstruction(RJR) by requiring an Initial State Radiation jet

• SRs binned in RISR (≡ EmissT /pISR

T ∼ mχ̃01/mt̃)

• Main background contribution tt̄

A. Petridis 6 / 24

https://twiki.cern.ch/twiki/bin/view/AtlasPublic/SupersymmetryPublicResults

ATLAS Stop 0L - Results ATLAS-CONF-2017-020

• Top left: Data and Standard Model (SM)predictions in Signal Regions (SRs)

• 95% CL limits in the mass planes mt̃1 −mχ̃01

for

t̃1 → tχ̃01 (top right) and mg̃ −mt̃1 (bottom

right) in fully hadronic final states

[GeV]1

t~m

200 400 600 800 1000 1200

[G

eV

]0 1

χ∼m

0

100

200

300

400

500

600

700

800

900

SRA+SRB+SRC

0

1χ∼

+ m

t

< m

1t~m

0

1χ∼

+ m

b

+ m

W

< m

1t~m

=8 TeVs, 1ATLAS 20 fb

0

1χ∼

(*) t→

1t~

Top squark pair production,

1=13 TeV, 36.1 fbs

ATLAS Preliminary)

theory

SUSYσ1 ±Observed limit (

)expσ1 ±Expected limit (

All limits at 95% CL

[GeV]g~

m

800 1000 1200 1400 1600 1800 2000

[G

eV

]1t~

m

0

200

400

600

800

1000

1200

1400

1600

1800

2000

< 0t

m1t

~ mg~m

+soft) = 100%0

1χ∼ t→

1t~

t→ g~ pair production, BR(g~

1=13 TeV, 36.1 fbs


ATLAS Preliminary)

theory

SUSYσ1 ±Observed limit (

)expσ1 ±Expected limit (1

ATLAS stop1L 13 TeV, 3.2 fb1

ATLAS incl 1L 8 TeV, 20.3 fb1

ATLAS monojet 13 TeV, 3.2 fb

A. Petridis 7 / 24

CMS Stop 0-lepton CMS-SUS-16-049

High ∆m(t̃1, χ̃01)

• Search regions are defined from differentrequirements onmT (b1,2,E

missT ), t/W−tagged jets, Njets ,

“resolved-top”, EmissT

• 51 disjoint search regions

Low ∆m(t̃1, χ̃01)

• ISR approach

• 53 disjoint regions

• Developmet of a novel soft b−taggingalgorithm based on the presence of asecondary vertex for recovering b−taggedbelow pT (b) < 20 GeV

[GeV]T

generated top p100 200 300 400 500 600

Effi

cien

cy

0

0.2

0.4

0.6

0.8

1Resolved top

(13 TeV)

CMSSimulation Preliminary

A. Petridis 8 / 24

CMS Stop 0-lepton - Results SUS-16-049

High mass

[GeV]t~

m

200 400 600 800 1000 1200

[GeV

]0 1χ∼

m

0

100

200

300

400

500

600

700

800

3−10

2−10

1−10

1

10

2100

1χ∼

+ m

W

= m

t~m

0

1χ∼

+ m

t

= m

t~m

(13 TeV)-135.9 fbCMS Preliminary

NLO+NLL exclusion1

0χ∼ t → t~, t~ t

~ →pp

theoryσ 1 ±Observed

experimentσ 1 ±Expected

95%

CL

uppe

r lim

it on

cro

ss s

ectio

n [p

b]

four-body-decay

[GeV]t~

m

300 350 400 450 500 550 600 650 700 750

) [G

eV]

0 1χ∼ , t~m

( ∆

10

20

30

40

50

60

70

80

90

100

110

1−10

1


NLO+NLL exclusion1

0χ∼' f b f → t~, t~ t

~ →pp



95%

CL

uppe

r lim

it on

cro

ss s

ectio

n [p

b]

charm-tagged

[GeV]t~

m

300 350 400 450 500 550 600 650

) [G

eV]

0 1χ∼ , t~m

( ∆

10

20

30

40

50

60

70

80

90

100

110

1−10

1

10 (13 TeV)-135.9 fbCMS Preliminary

NLO+NLL exclusion1

0χ∼ c → t~, t~ t

~ →pp



95%

CL

uppe

r lim

it on

cro

ss s

ectio

n [p

b]

• 95% CL exclusion limits on pp → t̃1t̃1 in three differenttopologies;

• High mass region: mt̃1 up to 1.04 TeV and mχ̃01

up to500 GeV are probed;

• Low mass region (∆m(t̃1, χ̃01) < mW ): mt̃1 up to 580

GeV are probed for mχ̃01

of 540 GeV;

• Bottom exclusion taken from SUS-16-032. Mass splits upto 10 GeV have been probed.

[GeV]t~

m200 300 400 500 600

[GeV

]LS

Pm

0

100

200

300

400

500

600

700

800

-110

1

10

210

= 13 TeVs, -1CMS Preliminary, 35.9 fb

NLO+NLL exclusion1

0χ∼ c → t~, t~ t

~ →pp



95%

CL

uppe

r lim

it on

cro

ss s

ectio

n (p

b)

A. Petridis 9 / 24

CMS Stop two-lepton CMS-SUS-17-001

• Searches based on different flavors of mT2 calculation (mT2(``), mT2(b`b`));

• Construct 12 disjoint SRs based on EmissT , mT2(``) and mT2(b`b`)

• Dominant background in low mT2 region comes from single top and tt̄• In high mT2 regions tt̄ + X has significant contributions with tt̄Z(νν) being

the dominant one. CRs defined inpp → tt̄Z → (t → b`±ν)(t → bjj)(Z → ``)

(ll) (GeV)T2M0 50 100 150 200 250 300

Num

ber

of E

vent

s

1−10

1

10

210

310

410

510 /single-tttZttH/W, tZq, tWZtt

multi bosonDrell-Yan

, 1 e)µdata (1 (750,1)

01χ∼ t→ t

~

(600,300)01χ∼ t→ t

~

CMS Preliminary (13 TeV)-1L=35.9 fb

(ll) (GeV)T2M0 50 100 150 200 250 300

Dat

a / M

C0.5

1

1.5

A. Petridis 10 / 24

CMS Stop two-lepton CMS-SUS-17-001

signal region number

Eve

nts

2−10

1−10

1

10

210

310

410/single-tttZtt

multi bosonotherDrell-YanData

(750,1)01χ∼ t→ t~

(600,300)01χ∼ t→ t~

CMS Preliminary (13 TeV)-1L=35.9 fb

(ll) < 140 GeVT2100 GeV < M (ll) < 240 GeVT2140 GeV < M

(ll)

> 2

40 G

eVT

2M

signal region number

Dat

a / M

C

0.5

1

1.5

0 1 2 3 4 5 6 7 8 9 10 11 12

[GeV]1t

~m200 400 600 800 1000 1200

[GeV

]0 1χ∼

m

0

100

200

300

400

500

600

700

800

3−10

2−10

1−10

1

10


NLO+NLL exclusion1

0χ∼ t → 1t~

, 1t~ 1t

~ →pp



95%

C.L

. upp

er li

mit

on c

ross

sec

tion

[pb]

• Observation agrees within errors with the Standard Model expectations

• 95% CL exclusion limits on the mass plane mt̃1−mχ̃0

1

• Interpretations on t̃ → bχ̃±1 , χ̃

±1 →W±χ̃0

1 are also available

A. Petridis 11 / 24

Summary of t̃1 → tχ̃01 searches

ATLAS

[GeV]1t

~m

200 300 400 500 600 700 800 900 1000

[GeV

]10 χ∼

m

0

100

200

300

400

500

600

700

1

0χ∼ W b →1t~

/ 1

0χ∼ t →1t~

1

0χ∼ t →1t~

1

0χ∼ W b →1t~

1

0χ∼ c →1t~

-1=8 TeV, 20 fbs

t

) < m

10

χ∼,1t~

m(

∆W

+ m

b

) < m

10

χ∼,1t~

m(

∆) <

01

0χ∼,

1t~ m

(∆

1

0χ∼ t →1t~

/ 1

0χ∼ W b →1t~

/ 1

0χ∼ c →1t~

/ 1

0χ∼ b f f' →1t~

production, 1t~1t

~ Status: Moriond 2017

ATLAS Preliminary

1

0χ∼W b

1

0χ∼c

1

0χ∼b f f'

Observed limits Expected limits All limits at 95% CL

=13 TeVs

[CONF-2017-020]-1t0L 36.1 fb

[CONF-2016-050]-1t1L 13.2 fb

[CONF-2016-076]-1t2L 13.3 fb

[1604.07773]-1MJ 3.2 fb

Run 1 [1506.08616]

CMS

[GeV]t~m

200 400 600 800 1000 1200

[GeV

]10 χ∼

m0

100

200

300

400

500

600

700

800

CMS Preliminary

10χ∼ t→ t~, t~t~ →pp Moriond/EW 2017

(13 TeV)-135.9 fbExpectedObserved)miss

TSUS-16-033, 0-lep (H)T2SUS-16-036, 0-lep (M

SUS-16-049, 0-lep stopSUS-17-001, 2-lep stop

0

1χ∼

+ m

t

= m

t~m

• Updated results from CMS are expected in time for Moriond QCD

A. Petridis 12 / 24

Complementary models studied from ATLAS and CMS

A. Petridis 13 / 24

ATLAS t̃ Z/H ATLAS-CONF-2017-019

• Searches for t̃ production with Higgs (h) or Zbosons

• t̃1 → tχ̃02, χ̃

02 → h/Z χ̃

01

• t̃2 → h/Zt̃1, t̃1 → tχ̃01. Provide additional

sensitivity in the region ∆m(t̃1, χ̃01) ∼ mt

• Final states considered:

• three-leptons plus a b−tag jet (3`1b),aiming at top squark decays involving Zboson

• Dominant backgrounds: tt̄Z , WZ .

• one-lepton plus four b − tag jet (1`4b),targeting top squark decays involving Higgsboson

• Dominant background: tt̄;

• Three overlapped SRs targeting differentmass splits (mt̃2 −mχ̃0

1) have been

designed for each final-state

A. Petridis 14 / 24

ATLAS t̃ Z/H ATLAS-CONF-2017-019

• Top: 95% CL exclusion limits onmt̃2 −mχ̃0

1for a fixed mt̃1 −mχ̃0

1= 180

GeV, assuming BR(t̃2 → Zt̃1)=1 (left)BR(t̃2 → ht̃1)=1 (right)

• Bottom right: 95% CL exclusion limitson mt̃1 −mχ̃0

2for mχ̃0

1= 0 GeV,

assuming a BR(χ̃02 → Z χ̃

01)=0.5 and

BR(χ̃02 → hχ̃

01)=0.5

A. Petridis 15 / 24

ATAS Stop RPV ATLAS-CONF-2017-013

Discussed in Emma’s talk: Pushing limits on generic squarks and gluinos at LHC at 13 TeV

• Stop Searches performed in R-ParityViolation models

• Final-state examined: 1`+ jets final state

• SRs are binned in jet multiplicity with thelower one being at five-jets

• Dominant backgrounds in Nb−tag = 0 arett̄ + jets and W + jets while for Nb−tag > 0the dominant source is tt̄ + jets

btagsN

0 1 2 3 4≥

Events

0

50

100

150tt

+ jetsW

+ jetsZ

MultijetOthers

1 = 13 TeV, 36.1 fbs

l > 40 GeV)T

10 jets (p≥ +

ATLAS Simulation Preliminary

t̃

t̃

χ̃01,2

χ̃∓1

p

p

t

λ′′323

t

bs

b

λ′′323

b

bs

) [GeV]t~

m(

600 800 1000 1200 1400

) [G

eV

]10

χ∼m

(

500

1000

15001 = 13 TeV, 36.1 fbs

LSPH~

), theory

SUSYσ 1 ±Obs. limit (

LSPH~

), exp

σ 1 ±Exp. limit (

LSPB~

), theory


LSPB~

), exp

σ 1 ±Exp. limit (

1

+χ∼ / b

1,2

0χ∼ t→ t

~

bbs→ 1

+χ∼ tbs, →

1,2

0χ∼

)1

0χ∼

m(t)

+ m(

≤) t~m(


ATLAS Preliminary

A. Petridis 16 / 24


Discussed in Emma’s talk: Pushing limits on generic squarks and gluinos at LHC at 13 TeV

• Stop Searches performed in R-ParityViolation models

• Final-state examined: 1`+ jets final state

• SRs are binned in jet multiplicity with thelower one being at five-jets

• Dominant backgrounds in Nb−tag = 0 arett̄ + jets and W + jets while for Nb−tag > 0the dominant source is tt̄ + jets

btagsN

0 1 2 3 4≥

Events

0

50

100

150tt

+ jetsW

+ jetsZ

MultijetOthers

1 = 13 TeV, 36.1 fbs

l > 40 GeV)T

10 jets (p≥ +


t̃

t̃

χ̃01,2

χ̃∓1

p

p

t

λ′′323

t

bs

b

λ′′323

b

bs

) [GeV]t~

m(

600 800 1000 1200 1400

) [G

eV

]10

χ∼m

(

500

1000

15001 = 13 TeV, 36.1 fbs

LSPH~

), theory


LSPH~

), exp

σ 1 ±Exp. limit (

LSPB~

), theory


LSPB~

), exp

σ 1 ±Exp. limit (

1

+χ∼ / b

1,2

0χ∼ t→ t

~

bbs→ 1

+χ∼ tbs, →

1,2

0χ∼

)1

0χ∼

m(t)

+ m(

≤) t~m(


ATLAS Preliminary

A. Petridis 17 / 24

... from stops ...

... to sbottoms ...

A. Petridis 18 / 24

CMS Sbottom searches CMS-SUSY-16-032

• Non-compressed (∆m(b̃1, χ̃01) >150 GeV):

• Main discriminants:Min[MT (j1,E

missT ),MT (j2,E

missT )], cotransverse

mass (mCT ) and HT (scalar sum of the two leadingjets)

• SRs binned in mCT and HT

• Compressed (∆m(b̃1, χ̃01) <150 GeV):

• Based on an ISR jet recoiling against EmissT .

• Compressed SRs are binned in EmissT and b/c−tag

jet multiplicity

P1

P2

eb⇤1

eb1

b̄

e�01

e�01

b

[GeV]CTm0 200 400 600 800 1000 1200

Eve

nts

1−10

1

10

210

MCT_totalEntries 6883

Mean 284.2

Std Dev 106.6

MCT_totalEntries 6883

Mean 284.2

Std Dev 106.6

(900,100)b~

b~

(1200,100)b~

b~

Z+jetsW+jetstopVVQCD

(13 TeV)-136 fbCMS Simulation Preliminary

dummy

SV+Nc-tags+Nb-tagsN0 1 2 3 4 5 6

Eve

nts

1−10

1

10

210

310

410

Nall_totalEntries 455655

Mean 0.5746

Std Dev 0.7098

Nall_totalEntries 455655

Mean 0.5746

Std Dev 0.7098

(250,240)t~t~

(550,500)b~

b~

Z+jetsW+jetstopVVQCD

(13 TeV)-136 fbCMS Simulation Preliminary

dummy

[GeV]b~m

400 600 800 1000 1200 [G

eV]

LSP

m100

200

300

400

500

600

700

800

900

-310

-210

-110

1

10

= 13 TeVs, -1CMS Preliminary, 35.9 fb

NLO+NLL exclusion1

0χ∼ b → b~

, b~

b~

→pp



95%

CL

uppe

r lim

it on

cro

ss s

ectio

n (p

b)

A. Petridis 19 / 24

CMS search in razor+H → γγ (sbottom) CMS-SUY-16-045

• In the MSSM Higgs bosons may be producedthrough the cascade decays of heavier sparticles;

• Search performed in H → γγ decay-mode and inassociation with at least one jet

• Approach based on razor variables and themomentum and mass resolution of the diphotonsystem

• Two main classes of background:

• SM Higgs (taken from MC)• non-resonant QCD estimated from a

data-driven technique by fitting the γγmass distribution (dominant systematicuncertainty arises from normalization andshape of that function)

b̃χ̃02

b̃χ̃02

b̄

H

χ̃01

χ̃01

H

b

HighPt

1 VARIOUS EQUATIONS

1. sbottom mass mb̃

2. neutralino mass m¬̃01

3. neutralino mass splitting ¢m0¬̃ = m¬̃0

2°m¬̃0

1= 130GeV

4. on shell mass constraint mb̃ ∏ m¬̃01+mb +130

5. on shell mass constraint m¬̃01= mb̃ °150

6. HighPt Box: p∞∞

T > 110 GeV

2

Y

H(ɣɣ)-HZ(bb)

HighRes

LowRes

Y

Y

N

N

N

1 VARIOUS EQUATIONS




2°m¬̃0

1= 130GeV




T > 110 GeV

7. HZbb Box: mHbb 2 (110,140) GeV || mZbb 2 (76,106) GeV


T > 110 GeV


T > 110 GeV

2

1 VARIOUS EQUATIONS




2°m¬̃0

1= 130GeV




T > 110 GeV



T > 110 GeV


T > 110 GeV

2

1 VARIOUS EQUATIONS




2°m¬̃0

1= 130GeV




T > 110 GeV



T > 110 GeV


T > 110 GeV

2

1 VARIOUS EQUATIONS




2°m¬̃0

1= 130GeV




T > 110 GeV


8. HighRes Box: æm∞∞/m∞∞ < 0.85 %


T > 110 GeV

2

A. Petridis 20 / 24

CMS search in razor+H → γγ (sbottom) CMS-SUY-16-045

Bin Number0 2 4 6 8 10 12

Obs

erve

d S

igni

fican

ce

6−

4−

2−

0

2

4

(13 TeV)-135.9 fb Searchγγ→Razor HCMS PreliminaryH

igh

Pt

Cat

ego

ry

HZ

bb

Cat

ego

ry

Hig

hR

es/L

ow

Res

Cat

ego

ry

[GeV]b~m

250 300 350 400 450 500 [G

eV]

10 χ∼m

0

50

100

150

200

250

300

350

400

1

10CMS Preliminary (13 TeV)-135.9 fb

1

0χ∼ bH→ 2

0χ∼ b→ b~

, b~

b~

→pp

NLO+NLL exclusion

=130 GeV1

0χ∼-m2

0χ∼mtheoryσ 1 ±Observed


95%

C.L

. upp

er li

mit

on c

ross

sec

tion

[pb]

• Left: Observed significance in units of standard deviations per search region;The yellow and green bands represent the 1σ and 2σ regions, respectively.

• Right: 95% CL exclusion limits on the mass plane mb̃ −mχ̃01

A. Petridis 21 / 24

Compressed Electroweakino searches

A. Petridis 22 / 24

CMS two-soft-lepton CMS-PAS-SUS-16-048

• Naturalness imposes constraints on the masses ofhiggsinos

• Light higgsinos would likely have a compressed massspectrum

• Experimentaly challenging signature: Muons pT down to3.5 GeV has been considered

• Results interpreted in the context of direct χ̃±1 χ̃

02 (cross

sections based on Wino scenario)

P1

P2

χ̃±1

χ̃02

W

Z

χ̃01

χ̃01

M(ll) [GeV]

Eve

nts

0

1

2

3

4

5

6DataTChi150/20tt(2l)DYVVtWFakesRarestotal bkg. unc.

CMS Preliminary (13 TeV)-135.9 fb

M(ll) [GeV]5 10 15 20 25 30 35 40 45 50

Dat

a/pr

ed.

0

1

2

3

4 stat. bkg. unc. total bkg. unc.

[GeV] ±1

χ∼, 2

0χ∼m100 120 140 160 180 200 220 240 260

) [G

eV]

10 χ∼ , 20 χ∼ m

(

∆

10

15

20

25

30

35

40

45

50

1−10

1

10

210 (13 TeV)-133.2-35.9 fbCMS Preliminary

1

0χ∼ W* → ±1

χ∼, 1

0χ∼ Z* → 0

2χ∼, ±

1χ∼ 0

2χ∼ →pp



95%

CL

uppe

r lim

it on

cro

ss s

ectio

n [p

b]

A. Petridis 23 / 24

Summary

• Both experiments have a rich program on the SUSY production of 3rd

generation squarks;

• Both experiments improved the object reconstruction and identification toobtain sensitivities in very challenging regions in the mass plane mt̃1

−mχ̃01

• Advanced techniques have also been employed to gain sensitivity in thedifferent regions;

• Current searches explore a wide range of final states and topologies;

• All searches produced null results so far;

• More data are expected to be collected in the upcoming years, stay tuned andyou never know what the data might be hiding!

Thank you

A. Petridis 24 / 24

Back-up

A. Petridis 25 / 24

Background estimation strategies

SUSY searches heavily rely on our understanding of the Standard Model processes

Reducible backgroundReceives contributions from non-prompt leptons. Estimation based on data-driventechniques (Matrix Method, Fake Factor);

Irreducible backgrounds

Normalize Monte Carlo predictions (tt̄,VV , ..) todata in dedicated Control Regions (CR);

• Extracted Normalization Factor (NF) isvalidated in Validation Regions(VR);

• Final background estimation comes from asimultaneous likelihood fit of Signal Regionsand CR;

Backgrounds producing “fake” EmissT due to jet mismeasurement

Contributions from this category are suppressed by requiring the jets and EmissT to not

point in the same direction (∆φ(jets,EmissT ))

Small backgroundsContributions from these sources ara takes directly from Monte Carlo predictions.

A. Petridis 26 / 24


• Searches performed for right-handed t̃pair production with the t̃ decaying to a

bino or higgsino χ̃01;

• χ̃01 undergoes RPV decays with a

non-zero λ′′

323 (≈ O(10−1 − 10−2))

• Final-state examined: 1`+ jets finalstate

• Three sets of jet pT thresholds (40, 60,80) have been considered to providesensitivity to a broad range of possiblesignals

• SRs are binned in jet multiplicity withthe lower one being at five-jets

• Dominant backgrounds in Nb−tag = 0are tt̄ + jets and W + jets while forNb−tag > 0 the dominant source istt̄ + jets

t̃

t̃

χ̃01,2

χ̃∓1

p

p

t

λ′′323

t

bs

b

λ′′323

b

bs

btagsN

0 1 2 3 4≥

Eve

nts

0

50

100

150tt

+ jetsW

+ jetsZ

MultijetOthers

1 = 13 TeV, 36.1 fbs

l > 40 GeV)T

10 jets (p≥ +


A. Petridis 27 / 24


• tt̄ + jets estimation based on a data-driventechnique. Extraction of an initial templateof the b−tag multiplicity spectrum in eventswith five jets and the parameterization of theevolution of this template to higher jetmultiplicities.

where xi describe the probability of oneadditional jet to be either not b−tagged(x0), b−tagged (x1) or b−tagged andleading to a second b−tagged jet to moveinto the fiducial acceptance (x2)

• Validation of the jet-scaling parameterizationin dileptonic tt̄ events

jets+1)/N

jets(N

6/5 7/6 8/7 9/8 10/9 11/10 12/11

(j)

MC

l+

jets

+je

tst t r

0.1

0.2

0.3

4/3 5/4 6/5 7/6 8/7 9/8 10/9

(j)

MC

dile

pto

n+

jets

t t r

0.1

0.2

0.3

(j)

Data

dile

pto

n

+je

tst t r 0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8 > 40 GeV

Tjet p

> 60 GeVT

jet p

> 80 GeVT

jet p

Parameterized scaling

dilepton tData t

dileptontMC t

l+jetstMC t

ATLAS Preliminary

=13 TeVs1

36.1 fb

A. Petridis 28 / 24


• Right: Expected SM background andobservation in different b−tagmultiplicities in `+ 9jets final state

btagsN

0 1 2 3 4≥

Eve

nts

0

50

100

Datatt

+ jetsW

+ jetsZ

MultijetOthers

1 = 13 TeV, 36.1 fbs

l > 60 GeV)T

+ 9 jets (p

ATLAS Preliminary

) = 500 GeV1

0χ∼

) = 2 TeV, m(g~

m(

btagsN

0 1 2 3 4≥

Data

/Model

0.60.8

11.21.4

MC

/Model

0.51

1.5

) [GeV]t~

m(

600 800 1000 1200 1400

) [G

eV

]10

χ∼m

(

500

1000

15001 = 13 TeV, 36.1 fbs

LSPH~

), theory


LSPH~

), exp

σ 1 ±Exp. limit (

LSPB~

), theory


LSPB~

), exp

σ 1 ±Exp. limit (

1

+χ∼ / b

1,2

0χ∼ t→ t

~

bbs→ 1

+χ∼ tbs, →

1,2

0χ∼

)1

0χ∼

m(t)

+ m(

≤) t~m(


ATLAS Preliminary

• Left: 95% CL limits on the mass planemt̃1 −mχ̃0

1for pure bino or pure

higgsino χ̃01

A. Petridis 29 / 24

ATLAS Stop two-leptons ATLAS-CONF-2016-076

..highlights from 2016 summer confereces

• Examining t̃1 pair production inthree-body-decays;

• Searches based on super-razor variables;

• Particularly sensitvite in

mW + mb < ∆m(t̃1, χ̃01) < mt

• Two dedicated SRs, one for ∆m(t̃1, χ̃01) ∼ mW

and the other ∆m(t̃1, χ̃01) ∼ mt

t̃

t̃

W

Wp

p

χ̃01

b `

ν

χ̃01

b `

ν

) [GeV]1t~

m(

100 150 200 250 300 350 400 450)

[GeV

] 0 1χ∼

m(

0

50

100

150

200

250

300

350

400ATLAS Preliminary

= 13 TeVs, -1L = 13.3 fb

0

1χ∼ bW→ 1t

~

3-bodyt + SR

3-bodyWSR

)theoryσ1 ±Observed limit (


ATLAS 8 TeV (WW-like)

ATLAS 8 TeV (Stop-2L)

ATLAS 8 TeV (Stop-1L)

W + mb

) < m

01χ∼,

1t~ m

(∆

t

) < m

01χ∼,

1t~ m

(∆

) < 0

01χ∼,

1t~ m

(∆

A. Petridis 30 / 24

https://cds.cern.ch/record/2206249

t̃ → bχ̃±1 , χ̃

±1 → W χ̃0

1

...motivated by gaugino universality

Searches based on fully hadronic final statesATLAS-CONF-2016-077 CMS-SUS-16-049

ATLAS

[GeV]1

t~m

200 300 400 500 600 700 800

[GeV

]0 1χ∼

m

0

50

100

150

200

250

300

350

400

450

500

SRB+SRC

+

1χ∼ + mb

< m1t~m

<103.5 GeV±

1χ∼m

-1ATLAS 1L 8 TeV, 20 fb

-1ATLAS 2L 8 TeV, 20 fb

)0

1χ∼ m× = 2 ±

1χ∼

(m0

1χ∼

(*) W→ ±

1χ∼, ±

1χ∼ b → 1t

~Stop pair production,

-1=13 TeV, 13.3 fbs

ATLAS Preliminary)

theorySUSYσ1 ±Observed limit (



CMS

[GeV]t~

m

200 400 600 800 1000 1200

[GeV

]0 1χ∼

m

0

100

200

300

400

500

600

700

800

3−10

2−10

1−10

1

10

210

0

1χ∼

+ m

t

= m

t~m

(13 TeV)-135.9 fbCMS Preliminary0

1χ∼ ± W→

1

±χ∼, 1

±χ∼ b → t~, t~ t

~ →pp

NLO+NLL exclusion

theoryσ 1 ±Observed )/20

1χ∼

+ mt~ = (m±

1χ∼m


95%

CL

uppe

r lim

it on

cro

ss s

ectio

n [p

b]

ATLAS assumption:mχ̃±1

= 2×mχ̃01

CMS assumption:mχ̃±1

= (mt̃1 + mχ̃01)/2

Searches based on one-leptonfinal states

ATLAS-CONF-2016-050CMS-PAS-SUS-16-028To be updated from both

experiments

ATLAS

[GeV]1t

~

m200 300 400 500 600 700 800 900

[GeV

]0 1χ∼

m

50

100

150

200

250

300

350

400

450

)1

0χ∼ m×

= 2

1±χ∼ ( m

1±χ∼+m

b < m1t~m

1

0χ∼ m× = 2 ±

1χ∼

, m1

±χ∼b+→1t~

production, 1t~1t

~

)thσ1±Observed limit ()expσ1±Expected limit (

ATLAS stop1L 8 TeV

ATLAS Preliminary-1 = 13 TeV, 13.2 fbs

Limit at 95% CL

CMS

[GeV]t~

m

200 400 600 800 1000 1200

[GeV

]0 1χ∼

m

0

100

200

300

400

500

600

700

3−10

2−10

1−10

1

10


1

0χ∼ ± b W→ 1

±χ∼ b → t~*, t~ t

~ →pp

NLO+NLL exclusion



)/20

1χ∼

+ mt~ = (m±

1χ∼m

95%

C.L

. upp

er li

mit

on c

ross

sec

tion

[pb]

A. Petridis 31 / 24





ATLAS Sbottom searches Eur. Phys. J. C (2016) 76:547

highlights from 2015 data sample

• Searches for b̃1 → bχ̃01;

• Examining final states with exactly two b-tagjets and Emiss

T

• Main discriminant variable:

• Bound for b̃ is given by:

mmaxCT = (m2

b̃1−m2

χ̃01)/mb̃1

A. Petridis 32 / 24

https://arxiv.org/pdf/1606.08772.pdf

CMS Stop one-lepton CMS-PAS-SUS-16-028

New results will be available on Moriond QCD

• Four main SRs with different Njets and MWT2 requirements which are then binned in

EmissT

• Main discriminants:MW

T2 : the information from on-shell W−boson is included in the mT2 calculatorModified topness variable tmod for further background rejection

350

− 25

0

450

− 35

0

450

≥

350

− 25

0

450

− 35

0

550

− 45

0

550

≥

350

− 25

0

450

− 35

0

450

≥

350

− 25

0

450

− 35

0

550

− 45

0

650

− 55

0

650

≥

Eve

nts

1

10

210

310

Lost Lepton l1→tt

(not from t)l1 νν→Z

(850,50)0

1χ∼ t→t~ (600,300)

0

1χ∼ t→t~

(750,50)±

1χ∼ b→t~

Data

> 6.4modt 2 jets

> 200 GeVWT2M

3 jets

200 GeV≤ WT2M

4 jets≥

> 200 GeVWT2M

4 jets≥


[GeV]missTED

ata

/ pre

d.

1

3

0.3 [GeV]t~

m

200 400 600 800 1000 1200

[GeV

]0 1χ∼

m

0

100

200

300

400

500

600

700

3−10

2−10

1−10

1

10


NLO+NLL exclusion1

0χ∼ t → t~*, t~ t

~ →pp



95%

C.L

. upp

er li

mit

on c

ross

sec

tion

[pb]

A. Petridis 33 / 24

https://cds.cern.ch/record/2205271/files/SUS-16-028-pas.pdf

CMS Stop one-soft-lepton CMS-PAS-SUS-16-031

• Direct t̃1t̃1 production with subsequentfour-body-decays;

• Exploring the very-low pT region of leptons

A. Petridis 34 / 24


ATLAS Stop 1-lepton ATLAS-CONF-2016-050

..highlights from 2016 summer confereces

• SR1 targets low mass splittings (decay products arefully resolved)

• tN high targets the high mass region

• mT =√

2p`TEmissT (1− cos(∆φ))

• asymmetric-mT2 is used to reject tt̄ events whereone lepton is not reconstructed;

• topness: a minimising χ2−type function quantifyingthe compatibility with a dileptonic tt̄ event

[GeV]missTE

200 250 300 350 400 450 500 550 600

even

ts /

30 G

eV

0

2

4

6

8

10

12

14

16 Data Total SMtt Z+jets

W+jets Wt

Diboson +Vtt

)=(600,200)0

1χ∼,t~m(

)=(800,1)0

1χ∼,t~m(

ATLAS Preliminary -1 = 13 TeV, 13.2 fbs

SR1

[GeV]Tm200 400 600 800 1000 1200 1400 1600

even

ts /

100

GeV

0

1

2

3

4

5 Data Total SMtt Z+jets

W+jets WtDiboson +Vtt

)=(600,200)0

1χ∼,t~m(

)=(800,1)0

1χ∼,t~m(


tN_high SR

[GeV]1t

~

m200 300 400 500 600 700 800 900 1000

[GeV

]0 1χ∼

m0

100

200

300

400

500

600

700

< 0t

- m01χ∼

- m1t~ m

0

1χ∼t+→1t

~ production, 1t

~1t

~

)thσ1±Observed limit (

)expσ1±Expected limit (

)-18 TeV + 13 TeV (3.2 fbATLAS stop1L


Limit at 95% CL

A. Petridis 35 / 24


CMS Razor+H → γγ CMS-SUS-16-045

A. Petridis 36 / 24

p cornering natural susy with s = 13 tev data€¦ · t2 m 0 50 100 150 200 250 300 number of...

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