susy searches with the atlas detector

SUSY searches with the ATLAS detector

Jeanette Lorenz

Ludwig-Maximilians-Universität MünchenExcellence Cluster Universe

12.12.2014 / GDR Terascale@Heidelberg

Supersymmetry (SUSY)

Supersymmetry: symmetry relatingfermions and bosons

• Only possible extension of Poincarespace-time symmetry.

• Minimal Supersymmetic Standard Model(MSSM): each Standard Model particlereceive a supersymmetric partner.

• Extended Higgs sector required.

Motivations for Supersymmetry (selection):

Can provide a dark matter candidate.Solves hierarchy problem if masses ofSUSY particles not too high. Unification of gauge couplings

Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 2

Production of supersymmetric particles at the LHC

10-3

10-2

10-1

1

10

200 400 600 800 1000 1200 1400 1600

νeν

e* l

ele*

t1t1

*

qq

qq*

gg

qg

χ2ogχ

2oχ

1+

maverage

[GeV]

σtot

[pb]: pp → SUSY

√S = 8 TeV

[Prospino, http://www.thphys.uni-heidelberg.de/~plehn/includes/prospino/prospino_lhc8.eps]

Strong production of quarks(1st and 2nd generation) andgluinos→ high cross section if masses nottoo high

→ Expected limits ∼ 1.2 (0.7) TeVfor gluinos (squarks)

Strong production of thirdgeneration squarks→ Expected limits up to 0.7 TeV.

Electroweak production ofsleptons and eletroweakinos→ might be most copiouslyproduced at the LHC if squarks andgluinos heavy but electroweakinoslight.

→ Expected limits ∼ 0.2 -0.5 TeV


http://www.thphys.uni-heidelberg.de/~plehn/includes/prospino/prospino_lhc8.eps

http://www.thphys.uni-heidelberg.de/~plehn/includes/prospino/prospino_lhc8.eps

Categorization of SUSY events

R-parity

→ Forbid baryon and lepton number violation by requiring R-parity conservation:

R-parity = (−1)3(B−L)+2S =

{+1 for Standard Model particles−1 for SUSY particles

B: baryon number, L: lepton number, S: spin

→ Distinguish different categories: R-parity conserved, R-parity violated and long lived scenarios

If R-parity conserved:• SUSY particles produced in pairs and

decay until lightest supersymmetric particle(LSP) reached.

• LSP stable, only weakly interacting, neutral→ dark matter candidate.

• LSP escapes detection→ (large) EmissT .

ATLAS search strategy

[https://indico.cern.ch/event/352689/material/slides/0.pdf]


https://indico.cern.ch/event/352689/material/slides/0.pdf

https://indico.cern.ch/event/352689/material/slides/0.pdf

Searches for strong production

g

gp

p

χ01

q

q

χ01

q

q

q

q

χ±1

χ∓1

p

p

q

χ01

W

q

χ01

W

g

g

χ±1

˜/ν

χ02

˜/νp

p

q q ν/`

`/ν

χ01

qq `/ν

`/ν

χ01

g

g

t

t

p

p

t

χ01

t

t

χ01

t

⇒ Final states with (many) jets, possibly leptons and a (more or less) high EmissT

Analyses (selection):

• 0-lepton + 2-6 jets [JHEP 09 (2014) 176]• 0 or 1-lepton + 3 b-jets [JHEP 10 (2014) 024]• 2 same-sign leptons/3-leptons [JHEP 06 (2014)

035]• 1 or 2 soft or hard lepton(s) + jets (to be published

soon,https://indico.cern.ch/event/352689/)

• ...

All searches use the full 2012 statistics of∼ 20 fb−1 collected by the ATLASdetector in pp collisions at 8 TeV.

(incl.) [GeV]effm0 500 1000 1500 2000 2500 3000 3500 4000

Eve

nts

/ 1

00

Ge

V

1

10

210

3101

L dt = 20.3 fb∫ = 8 TeV)sData 2012 (

SM Total

)=2650

1χ∼

)=465,m(±1

χ∼

)=665,m(q~

m(q~

q~

)=6520

1χ∼

)=1087,m(g~

m(g~

g~

Multijets

W+jets

(+X) & single toptt

Z+jets

Diboson

ATLAS

SR 5j

(incl.) [GeV]effm

0 500 1000 1500 2000 2500 3000 3500 4000

Da

ta /

MC

00.5

11.5

22.5

[JHEP 09 (2014) 176]


https://indico.cern.ch/event/352689/

Searches in final states with one or two leptonshttps://indico.cern.ch/event/352689/

Four different analyses, requiring 1 or 2 electrons or muons:• A ‘soft’ lepton ( 6/7 < pT(e/µ) < 25 GeV)→ compressed scenarios

• A ‘hard’ lepton (pT> 25 GeV)→ medium to large mass splittings

• Two hard leptons→ longer decay chains

• Two soft muons→ specialized to minimal Universal Extra Dimensions

Signal discriminated wrt background by requirements on jet multiplicity, mT, EmissT , meff

[GeV]missTE

100 200 300 400 500 600

[G

eV

]T

m

0

50

100

150

200

SR5J SR3J

VR3 region)

miss

T(high E

VR

1 r

egio

n)

T(m

VR

2 r

eg

ion

)m

iss

T(in

term

. E

CR

ATLAS Preliminary

(Example from the soft 1-lepton analysis)

Nor

mal

izatio

n vi

a lik

elih

ood

fitCR1

CR N

Inte

rpre

tatio

n us

ing

log-

likel

ihoo

d ra

tio

CR1

CR N

SR 1

SR N

SignalVR 1

VR N

Initial predicted background

Normalizedbackground

Background extra-polated to SR

Validation of extrapolatedbackground fit result

Transferfactor

Transferfactor

[arXiv:1410.1280]

Major backgrounds (t t , W+jets, Z+jets)estimated by:

• Defining control regionsdominated by backgrounds to beestimated.

• Fit background modelsimultaneously to data in allcontrol regions.

• Extrapolation to validation andsignal regions.



Searches in final states with one or two leptonshttps://indico.cern.ch/event/352689/

Results in agreement withStandard Modelexpectations.

[GeV]TmissE

250 300 350 400 450 500 550

Eve

nts

/ 100

GeV

0

5

10

15

20

25

30

35

ATLAS Preliminary-1=8 TeV, 20.3 fbs

µhard 1L e/6-jet SR

Data

Standard Model

Top Quarks

V+jets

Fake Leptons

Dibosons

)=0

1χ∼, ±

1χ∼, g~ 1-step, m(g~g~

(1025, 545, 65) GeV

Events

/ 1

00 G

eV

1

10

210

310

ATLAS Preliminary1=8 TeV, 20 fbs

bvetoµµ 2L ee/≥

jet SR3≥

Data

Standard Model

Top Quarks

Z+jets

Fake Leptons

Dibosons

)=0

1χ∼

, ν∼

/l~

, 0

2χ∼

/±

1χ∼

, q~

2step, m(q~

q~

(825, 465, 285, 105) GeV

’ [GeV]R

M200 400 600 800 1000 1200

Data

/ S

M

0

1

2

Results interpreted in multiple supersymmetric models (both simplified and phenomenological).

) [GeV]q~

m(

400 600 800 1000 1200

) [G

eV

]10

χ∼m

(

100

200

300

400

500

600

700

800

900

1000

, x=1/20

1χ∼0

1χ∼ qqWW→ q

~q

~

ATLAS Preliminary

1=8 TeV, 20 fbs

Combination)1

0χ∼

) < m

(

q~m(

)theory

SUSYσ1 ±Observed limit (

)expσ1 ±Expected limit (

Hard 1lepton obs./exp.

Soft 1lepton obs./exp.

PRD 86 (2012) 092002

All limits at 95% CL

q

q

χ±1

χ∓1

p

p

q

χ01

W

q

χ01

W

) [GeV]g~

m(

400 600 800 1000 1200 1400

) [G

eV

]10

χ∼m

(

100

200

300

400

500

600

700

800

900

1000

0

1χ∼0

1χ∼)νννν/ννν/lνν/llν qqqq(llll/lll→g

~g~

decays via sleptons/sneutrinos: g~

g~

ATLAS Preliminary

1=8 TeV, 20 fbs

Combination)1

0

χ∼

) < m

(

g~m

(

)theory



Hard 1lepton obs./exp.

2lepton obs./exp.


g

g

χ±1

˜/ν

χ02

˜/νp

p

q q ν/`

`/ν

χ01

qq `/ν

`/ν

χ01

Signalregions/analysesstatistically combinedto increase sensitivity.

Gluino masses & 1.2 TeV/squark masses & 700 GeV excluded for massless LSP, independently of the specific model.



Interpretations in cMSSM/MSUGRA

Interpretations also providedin full phenomenologicalmodels, e.g. incMSSM/MSUGRA (4parameters plus 1 sign):

• m0 (unified scalar mass atMGUT)

• m1/2 (unified gauginomass at MGUT)

• tanβ

• A0 (unified tri-linearcoupling at MGUT)

• sign of µ [GeV]0m0 1000 2000 3000 4000 5000 6000

[GeV

]1/

2m

300

400

500

600

700

800

900

1000

(2400 GeV

)q ~

(1600 GeV

)q ~

(1000 GeV)g~

(1400 GeV)g~

h (122 GeV

)

h (124 GeV

)

h (126 GeV

)

ExpectedObservedExpected

ObservedExpectedObserved

ExpectedObservedExpected

ObservedExpectedObserved

> 0µ, 0 = -2m0

) = 30, AβMSUGRA/CMSSM: tan( Status: ICHEP 2014

ATLAS Preliminary = 8 TeVs,

-1 L dt = 20.1 - 20.7 fb∫

τ∼

LSP not included.theory

SUSYσ95% CL limits.

0-lepton, 2-6 jets

0-lepton, 7-10 jets

0-1 lepton, 3 b-jets

1-lepton + jets + MET

1-2 taus + 0-1 lept. + jets + MET

3 b-jets≥2SS/3 leptons, 0 -

arXiv: 1405.7875

arXiv: 1308.1841

arXiv: 1407.0600

ATLAS-CONF-2013-062

arXiv: 1407.0603

arXiv: 1404.2500

Gluino masses below 1.3 TeV excluded for all m0 values.

→ Analyses nicely complementary.


Gluino mediated stop quark productionIn ‘natural’ SUSY models: stop masses to be below ∼ 1TeV and gluino masses below ∼ 2-3 TeV.(If stops and gluinos heavier, significant fine-tuning required and SUSY

cannot provide a full solution to the hierarchy problem.)

→ Search for direct and gluino-mediated stopproduction.

Gluino-mediated stop production: Busy final state withfour top quarks and Emiss

T

g

g

t t

ttp

p

χ01

b Wb

W

χ01

b

W

b W

→ Four b-jets in thefinal state.

→ Analyses requiringb-jets particularlysensitive - as theanalysis (inturquoise) requiring3 b-jets in final stateswith 0 or 1 lepton.

mt > mg : Gluino masses up to 1.4 TeV excluded(depending on the LSP mass).

[GeV]g~m600 700 800 900 1000 1100 1200 1300 1400 1500 1600

[GeV

]10 χ∼

m

200

400

600

800

1000

forb

idden

10χ∼t t

→g~

= 8 TeVs), g~) >> m(q~, m(1

0χ∼t t→g~ production, g~g~ ICHEP 2014

ATLASPreliminary

ExpectedObservedExpectedObservedObservedExpected

10 jets≥0-lepton, 7 -

3 b-jets≥0-1 lepton,

3 b-jets≥2SS/3 leptons, 0 -

arXiv: 1308.1841

arXiv: 1407.0600

arXiv: 1404.2500

]-1 = 20.3 fbint

[L

]-1 = 20.1 fbint

[L

]-1 = 20.3 fbint

[L

not included.theorySUSYσ95% CL limits.

) [GeV]g~

m(

500 600 700 800 900 1000 1100 1200 1300 1400

) [G

eV

]10

χ∼m

(

100

200

300

400

500

600

700

800

900

1000)g

~) >> m(t

~, m(

0

1χ∼t t→g

~ production, g

~g

~

)theory



1=8 TeV, 20 fbs

Hard 1lepton only

forb

idden

0

1χ∼t t→ g~


ATLAS Preliminary


Searches for direct stop production

t

t

χ±1

bW

χ∓1

bWp

p

χ01

c

χ01

c

t

t

χ±1

χ∓1

p

p

b

χ01

W

b

χ01

W

t

tp

p

χ01

t

χ01

t

Till Eifert -- Naturalness, Searches for top squarks August 2013, Freiburg U., Germany

Stop decays

1

[GeV]

[GeV]

0100 200 300

100

m(t)

Δm > m

(t)

m(W)+m(b)

Δm > m

(W)+m(b)

1 Introduction

�m = m(t1) � m(�01)

m(�01)

m(t1)

t1 ! t + �01

t1 ! b + �±1

t1 ! b +W + �01

t1 ! b +W⇤ + �01

t1 ! c + �01

1

1 Introduction

�m = m(t1) � m(�01)

m(�01)

m(t1)

t1 ! t + �01

t1 ! b + �±1

t1 ! b +W + �01

t1 ! b +W⇤ + �01

t1 ! c + �01

1

1 Introduction

�m = m(t1) � m(�01)

m(�01)

m(t1)

t1 ! t + �01

t1 ! b + �±1

t1 ! b +W + �01

t1 ! b +W⇤ + �01

t1 ! c + �01

1

1 Introduction

m(t1) < m(�01)

�m = m(t1) � m(�01)

m(�01)

m(t1)

t1 ! t + �01

t1 ! b + �±1

t1 ! b +W + �01

t1 ! b +W⇤ + �01

t1 ! c + �01

1

0

Figur

e1.

Illus

trationof

topsqua

rkde

caymod

esin

themassplan

esp

anne

dby

thetopsqua

rk

(t 1)an

dlig

htestne

utralin

o(�01),

whe

reth

elatter

isassu

med

tobe

thelig

htestsu

persym

metric

particle.

left/

right

stop

mixingan

dth

ene

utralin

o/ch

argino

sector.Noteth

atth

eLE

Plowe

rlim

it

1 onth

elig

htestch

argino

mass(m

(�±1)>

103.5G

eVat

95%

confi

denc

eleve

l [25

])im

plies

2 that

thet 1!

b�±1de

cayis

kine

matically

open

only

ifth

estop

massis

abov

eth

islim

it.

3 LHC

search

esfor e

lectrowe

akpr

oduc

tionof

chargino

andne

utralin

opa

irs(�±1�02) c

anpu

sh

4 themasslim

itup

toab

out70

0GeV

(see

forex

ampleRef. [26

]).How

ever, t

hese

strin

gent

5 limits

depe

ndup

onassu

mpt

ions

which

max

imise

thesearch

sens

itivity,su

chas

ade

cay

6 mod

eviasle

pton

s,alow-m

ass�01, a

ndne

arly

mass-de

gene

rate�±1�02states

with

thefie

ld

7 conten

tsetto

yieldahigh

prod

uctio

ncrosssection.

8

Thisartic

lepr

esen

tsa

search

fordirect

t 1pa

irpr

oduc

tion

infin

alstates

with

one

9 isolatedlept

on(electronor

muo

n1 ),

seve

ral jets,

andasig

nific

ant a

mou

ntof

miss

ingtran

s-

10 versemom

entu

m(the

mag

nitu

deof

which

isreferred

toas

Emiss

T

).The

potentially

large

11 Emiss

T

isge

nerated

byth

etw

oun

detected

LSPs

and

neut

rino(s).

All

top

squa

rkde

cay

12 scen

ariosde

scrib

edab

oveex

cept

forth

efla

vour

-cha

ngingmod

esareco

nsidered

.Heavy

13 flavo

urtagg

inginform

ation

isut

ilised

inth

eev

entselections

, and

forco

nstruc

tingkine

-

14 matic

varia

bles.The

search

for a

heav

ystop

exploits

ade

dica

tedtech

niqu

eof

large-radius

15 (large-R)jets.

Furthe

rmore,

low-m

omen

tum

lept

ons(referred

toas

soft-

lept

ons)

arere-

16 cons

truc

tedan

diden

tified

toen

hanc

eth

esens

itivity

tosearch

fort 1!

b�±1de

cays

with

17 nearly

mass-de

gene

rate�01an

d�±1states.

18

Search

esfor d

irect

t 1pa

irpr

oduc

tionha

vepr

evious

lybe

enrepo

rted

byth

e ATLA

S[27–

19 32] a

ndCMS

[33–

36] c

ollabo

ratio

ns,as

well

asby

theCDF

and

DØ

colla

boratio

nssas-

20 suming

di↵e

rent

SUSY

masssp

ectra

and

decay

mod

es(see

forex

ampleRefs.

[37,

38]).

21 Indirect

search

esfor s

tops

, med

iatedby

gluino

pair

prod

uctio

n,ha

vebe

enrepo

rted

byth

e

22 ATLA

S[39–

43] a

ndCMS[44]

colla

boratio

ns.

23

t 1!

t�01

1

t 1!

b�±1

21 El

ectron

san

dmuo

nsfrom

taude

cays

areinclud

ed.

–3–

t 1!

bW�01

3

t 1!

bff0 �01

4

t 1!

c�01

5

2The

ATLA

Sde

tector

andda

tasamples

6

The

ATLA

Sex

perim

ent[45]

isamulti-

purp

osepa

rticle

physicsde

tector

with

nearly

4⇡

7 cove

rage

insolid

angle.

Itco

nsist

sof

inne

rtracking

devices(ID),

electrom

agne

tican

d

8 hadr

onic

calorim

etrie

san

damuo

nsp

ectrom

eter

(MS)

with

four

supe

rcon

ductingmag

net

9 system

s,which

compr

iseath

insoleno

idsu

rrou

ndingth

eID

, and

aba

rrel

andtw

oen

d-ca

p

10 toroids p

roviding

themag

netic

field

for t

hemuo

nsp

ectrom

eter. T

heID

cons

ists o

f asil

icon

11 pixe

l detector,

asil

icon

microstrip

detector

andastraw

tube

tracke

r (for a

pseu

dorapidity

2

12 of|⌘|

<1.9).

Itpr

ovides

precisi

ontracking

and

mom

entu

mmea

suremen

tof

charge

d

13 particles f

or|⌘|

<2.5an

dallows e�cien

t b-je

t ide

ntifica

tion.

High-gran

ularity

liquid-argo

n

14 (LAr)

samplingelectrom

agne

ticca

lorim

eterscove

rin

theps

eudo

rapidity

rang

e|⌘|

<3.2.

15 The

hadr

onic

calorim

eter

system

isba

sed

ontw

odi↵e

rent

tech

nologies,scintil

latin

g-til

e

16 samplingca

lorim

eter

(|⌘| <

1.7)

and

LArsamplingca

lorim

eter

(1.5

<|⌘|

<4.9).

The

17 muo

nsp

ectrom

eter

hassepa

rate

trigge

ran

dhigh

-precisio

ntracking

cham

bers, t

helatter

18 prov

idingmuo

niden

tifica

tionan

dmom

entu

mmea

suremen

tfor|⌘|

<2.7.

19

The

data

sampleus

edin

this

analysis

wastake

ndu

ring

thepe

riod

from

March

to

20 Decem

ber20

12with

theLH

Cop

eratingat

app

centre-of-m

assen

ergy

ofp s

=8

TeV.

21 Afte

rap

plication

ofbe

am,de

tector

and

data-qua

lity

requ

iremen

ts,th

etotalintegrated

22 luminosity

is20

.3fb�1 w

ithan

uncertaintyof

±2.8%

.The

uncertaintyis

deriv

edfollo

wing

23 thesamemetho

dology

asth

atde

taile

din

Ref. [46

],fro

mapr

elim

inaryca

libratio

nof

the

24 luminosity

scalede

rived

from

beam

-sep

arationscan

spe

rform

edin

Nov

embe

r20

12.

25

The

datasetus

edforth

isan

alysis

wasreco

rded

usingth

eedi↵e

rent

type

sof

trigge

rs

26 basedon

requ

iring

asin

gle-electron

, asin

gle-muo

n,or

largeEmiss

T

. Can

dida

teev

ents

inth

e

27 electron

(muo

n)ch

anne

l are

colle

cted

usingalogica

l-OR

combina

tionof

thesin

gle-electron

28 (single-muo

n)an

dEmiss

T

trigge

rs.The

single-lept

ontrigge

rsha

veatran

sverse

mom

entu

m

29 (pT)th

resh

old

of24

GeV

. Aseco

ndsetof

complem

entary

single-lept

ontrigge

rswith

pT

30 thresh

olds

at60

GeV

(36G

eV)forth

eelectron

(muo

n)ca

serecove

rssm

alline�

cien

cies

31 associated

with

thelowe

rth

resh

oldsin

gle-lept

ontrigge

rsdu

eto

lept

oniso

latio

ncrite

ria.

32 The

Emiss

T

trigge

rha

sa

thresh

old

of80

GeV

and

reache

sfull

e�cien

cyforev

ents

with

33 o✏ineEmiss

T

abov

e15

0GeV

. Dur

ingth

ebe

ginn

ingof

2012

data

taking

, the

Emiss

T

trigge

r

34 waspa

rtly

kept

disabled

,ca

using

aloss

ofab

out2 p

b�1 in

integrated

luminosity

.The

35 combine

dtrigge

re�

cien

cyis

>98

%forth

elept

onan

dEmiss

T

selection

crite

riaap

plied

1 inth

ean

alysis.

Forth

esoft-

lept

onselections

, the

single-lept

ontrigge

rth

resh

olds

aretoo

2 largerend

eringth

esetrigge

rsus

eless.

All

cand

idateev

ents

areth

ereforereco

rded

using

32 AT

LASus

esarig

ht-han

dedco

ordina

tesystem

with

itsorigin

atth

eno

minal

interactionpo

intin

the

centre

ofth

ede

tector

and

thez-ax

isalon

gth

ebe

ampipe

.Cylindr

ical

coordina

tes(r,�

)areus

edin

the

tran

sverse

plan

e,�

beingth

eaz

imut

hal a

ngle

arou

ndth

ebe

ampipe

.The

pseu

dorapidity⌘is

defin

edin

term

sof

thepo

laran

gle✓by

⌘=� ln

tan(✓/

2), a

nd�R

=

p (�⌘)2 +

(��)2

–4–

t 1!

bW�01

3

t 1!

bff0 �01

4

t 1!

c�01

5

2The

ATLA

Sde

tector

andda

tasamples

6

The

ATLA

Sex

perim

ent[45]

isamulti-

purp

osepa

rticle

physicsde

tector

with

nearly

4⇡

7 cove

rage

insolid

angle.

Itco

nsist

sof

inne

rtracking

devices(ID),

electrom

agne

tican

d

8 hadr

onic

calorim

etrie

san

damuo

nsp

ectrom

eter

(MS)

with

four

supe

rcon

ductingmag

net

9 system

s,which

compr

iseath

insoleno

idsu

rrou

ndingth

eID

, and

aba

rrel

andtw

oen

d-ca

p

10 toroids p

roviding

themag

netic

field

for t

hemuo

nsp

ectrom

eter. T

heID

cons

ists o

f asil

icon

11 pixe

l detector,

asil

icon

microstrip

detector

andastraw

tube

tracke

r (for a

pseu

dorapidity

2

12 of|⌘|

<1.9).

Itpr

ovides

precisi

ontracking

and

mom

entu

mmea

suremen

tof

charge

d

13 particles f

or|⌘|

<2.5an

dallows e�cien

t b-je

t ide

ntifica

tion.

High-gran

ularity

liquid-argo

n

14 (LAr)

samplingelectrom

agne

ticca

lorim

eterscove

rin

theps

eudo

rapidity

rang

e|⌘|

<3.2.

15 The

hadr

onic

calorim

eter

system

isba

sed

ontw

odi↵e

rent

tech

nologies,scintil

latin

g-til

e

16 samplingca

lorim

eter

(|⌘| <

1.7)

and

LArsamplingca

lorim

eter

(1.5

<|⌘|

<4.9).

The

17 muo

nsp

ectrom

eter

hassepa

rate

trigge

ran

dhigh

-precisio

ntracking

cham

bers, t

helatter

18 prov

idingmuo

niden

tifica

tionan

dmom

entu

mmea

suremen

tfor|⌘|

<2.7.

19

The

data

sampleus

edin

this

analysis

wastake

ndu

ring

thepe

riod

from

March

to

20 Decem

ber20

12with

theLH

Cop

eratingat

app

centre-of-m

assen

ergy

ofp s

=8

TeV.

21 Afte

rap

plication

ofbe

am,de

tector

and

data-qua

lity

requ

iremen

ts,th

etotalintegrated

22 luminosity

is20

.3fb�1 w

ithan

uncertaintyof

±2.8%

.The

uncertaintyis

deriv

edfollo

wing

23 thesamemetho

dology

asth

atde

taile

din

Ref. [46

],fro

mapr

elim

inaryca

libratio

nof

the

24 luminosity

scalede

rived

from

beam

-sep

arationscan

spe

rform

edin

Nov

embe

r20

12.

25

The

datasetus

edforth

isan

alysis

wasreco

rded

usingth

eedi↵e

rent

type

sof

trigge

rs

26 basedon

requ

iring

asin

gle-electron

, asin

gle-muo

n,or

largeEmiss

T

. Can

dida

teev

ents

inth

e

27 electron

(muo

n)ch

anne

l are

colle

cted

usingalogica

l-OR

combina

tionof

thesin

gle-electron

28 (single-muo

n)an

dEmiss

T

trigge

rs.The

single-lept

ontrigge

rsha

veatran

sverse

mom

entu

m

29 (pT)th

resh

old

of24

GeV

. Aseco

ndsetof

complem

entary

single-lept

ontrigge

rswith

pT

30 thresh

olds

at60

GeV

(36G

eV)forth

eelectron

(muo

n)ca

serecove

rssm

alline�

cien

cies

31 associated

with

thelowe

rth

resh

oldsin

gle-lept

ontrigge

rsdu

eto

lept

oniso

latio

ncrite

ria.

32 The

Emiss

T

trigge

rha

sa

thresh

old

of80

GeV

and

reache

sfull

e�cien

cyforev

ents

with

33 o✏ineEmiss

T

abov

e15

0GeV

. Dur

ingth

ebe

ginn

ingof

2012

data

taking

, the

Emiss

T

trigge

r

34 waspa

rtly

kept

disabled

,ca

using

aloss

ofab

out2 p

b�1 in

integrated

luminosity

.The

35 combine

dtrigge

re�

cien

cyis

>98

%forth

elept

onan

dEmiss

T

selection

crite

riaap

plied

1 inth

ean

alysis.

Forth

esoft-

lept

onselections

, the

single-lept

ontrigge

rth

resh

olds

aretoo

2 largerend

eringth

esetrigge

rsus

eless.

All

cand

idateev

ents

areth

ereforereco

rded

using

32 AT

LASus

esarig

ht-han

dedco

ordina

tesystem

with

itsorigin

atth

eno

minal

interactionpo

intin

the

centre

ofth

ede

tector

and

thez-ax

isalon

gth

ebe

ampipe

.Cylindr

ical

coordina

tes(r,�

)areus

edin

the

tran

sverse

plan

e,�

beingth

eaz

imut

hal a

ngle

arou

ndth

ebe

ampipe

.The

pseu

dorapidity⌘is

defin

edin

term

sof

thepo

laran

gle✓by

⌘=� ln

tan(✓/

2), a

nd�R

=

p (�⌘)2 +

(��)2

–4–

t 1!

bW�01

3

t 1!

bff0 �01

4

t 1!

c�01

5

2The

ATLA

Sde

tector

andda

tasamples

6

The

ATLA

Sex

perim

ent[45]

isamulti-

purp

osepa

rticle

physicsde

tector

with

nearly

4⇡

7 cove

rage

insolid

angle.

Itco

nsist

sof

inne

rtracking

devices(ID),

electrom

agne

tican

d

8 hadr

onic

calorim

etrie

san

damuo

nsp

ectrom

eter

(MS)

with

four

supe

rcon

ductingmag

net

9 system

s,which

compr

iseath

insoleno

idsu

rrou

ndingth

eID

, and

aba

rrel

andtw

oen

d-ca

p

10 toroids p

roviding

themag

netic

field

for t

hemuo

nsp

ectrom

eter. T

heID

cons

ists o

f asil

icon

11 pixe

l detector,

asil

icon

microstrip

detector

andastraw

tube

tracke

r (for a

pseu

dorapidity

2

12 of|⌘|

<1.9).

Itpr

ovides

precisi

ontracking

and

mom

entu

mmea

suremen

tof

charge

d

13 particles f

or|⌘|

<2.5an

dallows e�cien

t b-je

t ide

ntifica

tion.

High-gran

ularity

liquid-argo

n

14 (LAr)

samplingelectrom

agne

ticca

lorim

eterscove

rin

theps

eudo

rapidity

rang

e|⌘|

<3.2.

15 The

hadr

onic

calorim

eter

system

isba

sed

ontw

odi↵e

rent

tech

nologies,scintil

latin

g-til

e

16 samplingca

lorim

eter

(|⌘| <

1.7)

and

LArsamplingca

lorim

eter

(1.5

<|⌘|

<4.9).

The

17 muo

nsp

ectrom

eter

hassepa

rate

trigge

ran

dhigh

-precisio

ntracking

cham

bers, t

helatter

18 prov

idingmuo

niden

tifica

tionan

dmom

entu

mmea

suremen

tfor|⌘|

<2.7.

19

The

data

sampleus

edin

this

analysis

wastake

ndu

ring

thepe

riod

from

March

to

20 Decem

ber20

12with

theLH

Cop

eratingat

app

centre-of-m

assen

ergy

ofp s

=8

TeV.

21 Afte

rap

plication

ofbe

am,de

tector

and

data-qua

lity

requ

iremen

ts,th

etotalintegrated

22 luminosity

is20

.3fb�1 w

ithan

uncertaintyof

±2.8%

.The

uncertaintyis

deriv

edfollo

wing

23 thesamemetho

dology

asth

atde

taile

din

Ref. [46

],fro

mapr

elim

inaryca

libratio

nof

the

24 luminosity

scalede

rived

from

beam

-sep

arationscan

spe

rform

edin

Nov

embe

r20

12.

25

The

datasetus

edforth

isan

alysis

wasreco

rded

usingth

eedi↵e

rent

type

sof

trigge

rs

26 basedon

requ

iring

asin

gle-electron

, asin

gle-muo

n,or

largeEmiss

T

. Can

dida

teev

ents

inth

e

27 electron

(muo

n)ch

anne

l are

colle

cted

usingalogica

l-OR

combina

tionof

thesin

gle-electron

28 (single-muo

n)an

dEmiss

T

trigge

rs.The

single-lept

ontrigge

rsha

veatran

sverse

mom

entu

m

29 (pT)th

resh

old

of24

GeV

. Aseco

ndsetof

complem

entary

single-lept

ontrigge

rswith

pT

30 thresh

olds

at60

GeV

(36G

eV)forth

eelectron

(muo

n)ca

serecove

rssm

alline�

cien

cies

31 associated

with

thelowe

rth

resh

oldsin

gle-lept

ontrigge

rsdu

eto

lept

oniso

latio

ncrite

ria.

32 The

Emiss

T

trigge

rha

sa

thresh

old

of80

GeV

and

reache

sfull

e�cien

cyforev

ents

with

33 o✏ineEmiss

T

abov

e15

0GeV

. Dur

ingth

ebe

ginn

ingof

2012

data

taking

, the

Emiss

T

trigge

r

34 waspa

rtly

kept

disabled

,ca

using

aloss

ofab

out2 p

b�1 in

integrated

luminosity

.The

35 combine

dtrigge

re�

cien

cyis

>98

%forth

elept

onan

dEmiss

T

selection

crite

riaap

plied

1 inth

ean

alysis.

Forth

esoft-

lept

onselections

, the

single-lept

ontrigge

rth

resh

olds

aretoo

2 largerend

eringth

esetrigge

rsus

eless.

All

cand

idateev

ents

areth

ereforereco

rded

using

32 AT

LASus

esarig

ht-han

dedco

ordina

tesystem

with

itsorigin

atth

eno

minal

interactionpo

intin

the

centre

ofth

ede

tector

and

thez-ax

isalon

gth

ebe

ampipe

.Cylindr

ical

coordina

tes(r,�

)areus

edin

the

tran

sverse

plan

e,�

beingth

eaz

imut

hal a

ngle

arou

ndth

ebe

ampipe

.The

pseu

dorapidity⌘is

defin

edin

term

sof

thepo

laran

gle✓by

⌘=� ln

tan(✓/

2), a

nd�R

=

p (�⌘)2 +

(��)2

–4–

Compressed scenarios:

→ mono-jet searches

→ soft lepton analyses

Can exploit final states with 0- 2 leptons

• Usage of complex discriminating variables

• e.g. exploit boosted topology to reject top background

Often long andcomplicated decaychains.

Usually final states withmany b-jets


Two examples for stop searches

Search for stops in final states with 1 lepton + 3-4 jets + EmissT

JHEP11(2014)118

• 15 signal regions covering many topologies:direct stop to LSP decay, 3- and 4-body decays,...

• Using a large collection of dedicated variables,including soft leptons and boosted jets.

• Sensitivity to stop masses up to 650 GeV. [GeV]

1t~m

200 300 400 500 600 700 800

[GeV

]10

r¾m

0

50

100

150

200

250

300

350

400 10

r¾ t A1t~ /

10

r¾ W b A1t~ /

10

r¾ b f f’ A1t~ production, 1t

~1t

~

10

r¾

+mt <

m1t~

m

10

r¾

+ m

W

+ m

b

< m

1t~m

10

r¾

+ m

b

< m

1t~m

)expm1 ±Expected limit (

)theorySUSYm1 ±Observed limit (ATLAS

All limits at 95% CLTmiss1-lepton + jets + E

=8 TeVs, -1 L dt = 20 fb0

Constraints from precision measurements of the ttbar cross section on light stops

Eur.Phys.J.C74 (2014) 3109

• Most searches have no sensitivity to stop massesclose to the top mass.

• Can access this region through precisionmeasurement of the t t cross section.

• Exclude stop masses below 180 GeV. [GeV]

1t~

m

170 180 190 200 210 220 230µ

95%

CL

limit

on s

igna

l str

engt

h 0.5

1

1.5

2

2.5

3

3.5

4ATLAS

-1 = 7 TeV, 4.6 fbs-1 = 8 TeV, 20.3 fbs

expσ1 ±Expected limit

theorySUSYσ1 ±Observed limit

)=1 GeV1

0χ∼, m(1

0χ∼ t →1t~


Summary on stop searches

[GeV]1t

~m

200 300 400 500 600 700

[G

eV

]10

χ∼m

0

50

100

150

200

250

300

350

400

450

500

1

0χ∼ t →

1t~

1

0χ∼ t →

1t~

1

0χ∼ t →

1t~

1

0χ∼ W b →

1t~

1

0χ∼ c →

1t~

1

0χ∼b f f’

1

0χ∼

+mt

< m

1t~m

1

0χ∼

+ m

W

+ m

b

< m

1t~m

1

0χ∼

+ m

c

/mb

< m

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: ICHEP 2014

ATLAS Preliminary

1 = 4.7 fbintL 1 = 20 fbintL1

0χ∼W b

1 = 20.3 fbintL

1

0χ∼c

1

0χ∼b f f’

1 = 20.3 fbintL

Observed limits Expected limits


=8 TeVs 1 = 20 fbintL =7 TeVs 1 = 4.7 fbintL

0L [1406.1122]

1L [1407.0583]

2L [1403.4853]

1L [1407.0583], 2L [1403.4853]

0L [1407.0608]

0L [1407.0608], 1L [1407.0583]

0L [1208.1447]

1L [1208.2590]

2L [1209.4186]

Various analyses tocover gaps at top (andW ) mass (difficult toaccess):

• t t cross sectionmeasurements.

• Search for t2 with Zin final state. →Eur.Phys.J.C (2014)

74:2883

• Measurement ofspin correlation in t tevents. →ATLAS-CONF-2014-056

→ Searches sensitive up to stop masses of ∼ 700 GeV


Searches for directly produced electroweakinos→ Direct chargino/neutralino/slepton production can dominate at the LHC ifsquarks/gluinos much heavier.

χ±1

χ∓1

˜

˜

p

p

ν

`

χ01

ν`

χ01

χ±1

χ02

τ /ντ

τ /ντ

p

p

ντ/τ

τ/ντ

χ01

τ/ντ

τ/ντ

χ01

χ±1

χ02

W

Zp

p

χ01

q

q

χ01

`

`

χ±1

χ02

W

hp

p

χ01

`

ν

χ01

b

b

Clean signatures with: leptons (including taus), W /Z bosons and Higgs bosons +Emiss

T , low jet multiplicity

E.g. searches in:

• 3 leptons (e,µ,τ ) + EmissT [JHEP 04 (2014)169]

• 2 leptons (e,µ) + EmissT [JHEP 05 (2014) 071]

• 2 taus + EmissT [JHEP 10 (2014) 096]

• 4 leptons + EmissT [Phys.Rev.D.90, 052001]


Searches for electroweak SUSY with a Higgs boson[ATLAS-CONF-2014-062]

Searches in 3 different channels:

• 1-lepton + 2 b-jets

• 2 same-sign leptons

• 1-lepton + 2 photons

Discriminating variables:

χ±1

χ02

W

hp

p

χ01

`

ν

χ01

b

b

EmissT , mT, mCT, mbb

χ±1

χ02

W

hp

p

χ01

`±

ν

χ01

`±ν

qq

Emiss,relT , meff , maximal

mT, mlj , mljj

χ±1

χ02

W

hp

p

χ01

`

ν

χ01

γ

γ

EmissT , mT(Wγi ),

∆φ(W , h)

Combining the three searches + 3-lepton search:

Limits up to 250GeV on theelectroweakinomass formassless LSP


Status of searches for electroweakinos

) [GeV]2

0χ∼ (=m1

±χ∼ m

100 200 300 400 500 600 700

[GeV

]0 1χ∼

m

0

100

200

300

400

500

600Expected limits

Observed limits

arXiv:1402.7029 3l, , ν∼/ Ll~ via 0

2χ∼±

1χ∼

arXiv:1403.5294, µ 2e/ , ν∼/ Ll~ via −

1χ∼ +

1χ∼

arXiv:1402.7029 3l, , τν∼/ Lτ∼ via 02

χ∼±1

χ∼

arXiv:1407.0350, τ2≥ , τν∼/ Lτ∼ via 02

χ∼±1

χ∼

arXiv:1407.0350, τ2≥ , τν∼/ Lτ∼ via −1

χ∼ +1

χ∼

arXiv:1403.5294+3l, µ 2e/ via WZ, 02

χ∼±1

χ∼

ATLAS-CONF-2013-093bb, µ e/ via Wh, 02

χ∼±1

χ∼

arXiv:1402.7029 3l, via Wh, 02

χ∼±1

χ∼

arXiv:1403.5294, µ 2e/ via WW, −1

χ∼ +1

χ∼


=8 TeV Status: ICHEP 2014s, -1 Preliminary 20.3 fbATLAS

)2

0χ∼ + m 1

0χ∼ = 0.5(m ν∼/ L

τ∼/ Ll~m

10χ∼

= m

20χ∼m

Z

+ m

10χ∼

= m

20χ∼m

h

+ m

10χ∼

= m

20χ∼m

1

0χ∼ = 2m

2

0χ∼m

(Be aware that in this plot many different simplified models are showntogether.)

• If decays are mediatedby sleptons: limits up to720 GeV.

• If via WZ : limits up to ∼450 GeV.

• Little or now sensitivityto compressedscenarios.


R-parity violating SupersymmetryIf R-parity violated:

• Condition: either lepton or baryon numberconserved.

• LSP can decay (thus no dark matter candidate).

• No large EmissT as signature, but usually high

object multiplicities.

χ01

χ01

˜

˜

p

p

`

λ

`

ν

`

λ`

ν

χ±1

χ∓1

χ01

χ01

p

p

W

λ

`

`

ν

W

λ

`

`

ν

4-leptons Phys.Rev.D. 90, 052001 (2014)

[GeV]g~m600 800 1000 1200 1400 1600 1800

[GeV

]0 1χ∼

m

0

200

400

600

800

1000

1200

1400

1600

1800

1

0χ∼ < m

g~m

0≠ 121λ 0≠ 122λ 0≠ 133λ 0≠ 233λ

)theory

σ 1 ±Observed (Expected

ATLAS

=8 TeVs, -1

L dt = 20.3 fb∫

;0

1χ∼ q q

0

1χ∼q q → g~g~ →pp

- l+ lν →

0

1χ∼


• Analysis requiring 4 leptons, Z-vetoand high meff.

• Backgrounds depending onτ -multiplicity in final state:

I Irreducible for 0 τ : ZZ , VVV , t tZ , HiggsI Reducible for 1-2 τ : Z+jets, t t , WZ

• Limits reaching up to ∼ 1.4 TeV inthe gluino mass→ comparable toRPC searches.


Searches for long-lived particlesLong-lived particles appear in different cases, e.g.:

• Small RPV couplings.

• RPC: compressed scenarios.

• RPC: meta-stable and long-lived gluinos due to heavy squarks.

• RPC: long-lived sleptons/neutralinos due to small coupling togravitino.

Result in distinctive signatures depending on lifetime:

• Displaced vertices, disappearing or kinked tracks.

• Leptons/photons not pointing to the primary vertex.

• Delayed decays of massive particles, ...

[Phys.Rev.D 88, 112006 (2013)]

Heavy long-lived particles [arXiv:1411.6795]

• Predicted by Split SUSY, GMSB, LeptoSUSY etc.

• Long-lived sleptons, gluinos, squarks and charginos in thefinal state.

• Significantly slower than light.

→ m = p/βγ used as discriminating variable.

• Main background: high pT mismeasured muons. mass [GeV]g~

400 600 800 1000 1200 1400 1600

Cro

ss-s

ectio

n [fb

]

1

10

210

full-detector gluinoR-Hadrons

ATLAS-1 = 8 TeV, 19.1 fb s

theory prediction

σ 1±expected limit

σ 2±expected limit

observed limit


Summary

Limits on:

• Gluinos: ∼ 1.2 - 1.3TeV

• First two generationsquarks: ∼ 800 GeV

• Stops: ∼ 700 GeV

• Electroweakinos:∼ 400 - 700 GeV.

... in the most extreme casesonly!

Limits much weaker incertain scenarios:Compressed models,...

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

ge

n.

sq

ua

rks

dir

ect

pro

du

ctio

nE

Wd

ire

ct

Lo

ng

-liv

ed

pa

rtic

les

RP

VO

the

r

MSUGRA/CMSSM 0 2-6 jets Yes 20.3 m(q)=m(g) 1405.78751.7 TeVq, g

MSUGRA/CMSSM 1 e, µ 3-6 jets Yes 20.3 any m(q) ATLAS-CONF-2013-0621.2 TeVg

MSUGRA/CMSSM 0 7-10 jets Yes 20.3 any m(q) 1308.18411.1 TeVg

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

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 1 e, µ 3-6 jets Yes 20.3 m(χ

01)<200 GeV, m(χ

±)=0.5(m(χ

01)+m(g)) ATLAS-CONF-2013-0621.18 TeVg

gg, g→qq(ℓℓ/ℓν/νν)χ01

2 e, µ 0-3 jets - 20.3 m(χ01)=0 GeV ATLAS-CONF-2013-0891.12 TeVg

GMSB (ℓ NLSP) 2 e, µ 2-4 jets Yes 4.7 tanβ<15 1208.46881.24 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 m(χ01)>50 GeV ATLAS-CONF-2014-0011.28 TeVg

GGM (wino NLSP) 1 e, µ + γ - Yes 4.8 m(χ01)>50 GeV ATLAS-CONF-2012-144619 GeVg

GGM (higgsino-bino NLSP) γ 1 b Yes 4.8 m(χ01)>220 GeV 1211.1167900 GeVg

GGM (higgsino NLSP) 2 e, µ (Z) 0-3 jets Yes 5.8 m(NLSP)>200 GeV ATLAS-CONF-2012-152690 GeVg

Gravitino LSP 0 mono-jet Yes 10.5 m(G)>10−4 eV ATLAS-CONF-2012-147645 GeVF1/2 scale

g→bbχ01 0 3 b Yes 20.1 m(χ

01)<400 GeV 1407.06001.25 TeVg

g→ttχ01 0 7-10 jets Yes 20.3 m(χ

01) <350 GeV 1308.18411.1 TeVg

g→ttχ01

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

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

01)=55 GeV 1208.4305, 1209.2102110-167 GeVt1

t1 t1(light), t1→Wbχ01

2 e, µ 0-2 jets Yes 20.3 m(χ01) =m(t1)-m(W)-50 GeV, m(t1)<<m(χ

±1 ) 1403.4853130-210 GeVt1

t1 t1(medium), t1→tχ01

2 e, µ 2 jets Yes 20.3 m(χ01)=1 GeV 1403.4853215-530 GeVt1

t1 t1(medium), t1→bχ±1 0 2 b Yes 20.1 m(χ

01)<200 GeV, m(χ

±1 )-m(χ

01)=5 GeV 1308.2631150-580 GeVt1

t1 t1(heavy), t1→tχ01

1 e, µ 1 b Yes 20 m(χ01)=0 GeV 1407.0583210-640 GeVt1

t1 t1(heavy), t1→tχ01 0 2 b Yes 20.1 m(χ

01)=0 GeV 1406.1122260-640 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 Yes 20.3 m(χ±1 )=m(χ

02), m(χ

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

1 , χ0

2

χ±1χ02→Wχ

01h χ

01

1 e, µ 2 b Yes 20.3 m(χ±1 )=m(χ

02), m(χ

01)=0, sleptons decoupled ATLAS-CONF-2013-093285 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

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 ATLAS-CONF-2013-069270 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

GMSB, stable τ, χ01→τ(e, µ)+τ(e, µ) 1-2 µ - - 15.9 10<tanβ<50 ATLAS-CONF-2013-058475 GeVχ0

1

GMSB, χ01→γG, long-lived χ

01

2 γ - Yes 4.7 0.4<τ(χ01)<2 ns 1304.6310230 GeVχ0

1

qq, χ01→qqµ (RPV) 1 µ, displ. vtx - - 20.3 1.5 <cτ<156 mm, BR(µ)=1, m(χ

01)=108 GeV ATLAS-CONF-2013-0921.0 TeVq

LFV pp→ντ + X, ντ→e + µ 2 e, µ - - 4.6 λ′311

=0.10, λ132=0.05 1212.12721.61 TeVντLFV pp→ντ + X, ντ→e(µ) + τ 1 e, µ + τ - - 4.6 λ′

311=0.10, λ1(2)33=0.05 1212.12721.1 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

g→qqq 0 6-7 jets - 20.3 BR(t)=BR(b)=BR(c)=0% ATLAS-CONF-2013-091916 GeVg

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

Scalar gluon pair, sgluon→qq 0 4 jets - 4.6 incl. limit from 1110.2693 1210.4826100-287 GeVsgluon

Scalar gluon pair, sgluon→tt 2 e, µ (SS) 2 b Yes 14.3 ATLAS-CONF-2013-051350-800 GeVsgluon

WIMP interaction (D5, Dirac χ) 0 mono-jet Yes 10.5 m(χ)<80 GeV, limit of<687 GeV for D8 ATLAS-CONF-2012-147704 GeVM* scale

Mass scale [TeV]10−1 1√s = 7 TeV

full data

√s = 8 TeV

partial data

√s = 8 TeV

full data

ATLAS SUSY Searches* - 95% CL Lower LimitsStatus: ICHEP 2014

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.


Expectations for Run 2 and the HL-LHCExtrapolations to 13/14 TeV

→ Expect to be sensitive to yet unexplored SUSY territorywith few fb−1!

HL-LHC [ATL-PHYS-PUB-2014-010]

→ Discovery reach up to 2.5-3 TeV

Looking forward to Run 2!


Backup

ATLAS detector


Razor variables

Also exploit the longitudinal information of an event.

• Both sparticles are pair-produced, the initial heavysparticles are assumed here to have the same masses orto be at the same mass scale

→ Both decay chains are symmetric if going into the framewhere the initial heavy sparticle is at rest

→ Can group all visible particles of one decay chain into amega-jet; both mega-jets should have the same energy

Variables to benefit from this configuration:

• Characteristic mass of the event:M′R =

√(j1.E + j2,E )2 − (j1,L + j2,L)2

(E : energy, L: longitudinal component, j1 and j2: four-vectors of the two mega-jets)

• Transverse information of the event:

MRT =

√|~Emiss

T |(|~j1,T|+|~j2,T|)+~EmissT ·(~j1,T+~j2,T)

2

• Razor:R =

MRT

M′R


Variables used in the different analysesSelection...

• Effective mass: mincleff =

∑pjet

T + pleptonT + Emiss

T

• Transverse mass:mT =

√2 · Emiss

T · pT(lepton) · (1− cos ∆φ(~EmissT , ~pT(lepton)))

• Cotransverse mass: mCT =√

(Eb1T + Eb2

T )2 − (~pb1T − ~p

b2T )2

• Emiss,relT =

{Emiss

T ∆φ > π/2Emiss

T sin ∆φ ∆φ < π/2


Gauge Mediated SUSY Breaking→ Further possibility to break SUSY.

GMSB:

• Breaking of SUSY via messenger interactions.• SM flavor symmetry naturally protected.• Gravitino lightest supersymmetric particle.

• Detector signature determined by nature of NLSP (can be χ01, τ , lR )

• NLSP decays to LSP (G) and the SM superpartner of the NLSP.• Parameters for minimal GMSB: Λ (SUSY breaking scale),N5 (# messenger fields), tan β, sign of µ, Cgrav (G mass scale

factor), Mmes.

General Gauge Mediation (GGM):

• No specific SUSY mass hierarchy for (un)colored states→ any MSSM sparticle can be the NLSP.• Nature of neutralino depends on M1, M2, µ and tan β.

Natural Gauge Mediation:

• All sparticles not related to fine-tuning of Higgs sector decoupled.• Stop and gluino only light colored sparticles.

[See also: M.Tripiana, SUSY13, http://cds.cern.ch/record/1596518/files/ATL-PHYS-SLIDE-2013-496.pdf]


http://cds.cern.ch/record/1596518/files/ATL-PHYS-SLIDE-2013-496.pdf

Selected results in GGM models

4-leptons [Phys.Rev.D. 90, 052001 (2014)]

The RPV 4-lepton analysis alsointerprets in GGM models.

[GeV]µ200 300 400 500 600 700 800 900

[G

eV

]g~

m

600

700

800

900

1000

1100

1200

µ <

g~m

= 1.5βGGM tan

300 400 500 600 700 ) [GeV]1

0χ∼m(

ATLAS =8 TeVs, 1

L dt = 20.3 fb∫)

theoryσ1 ±Observed limit (

)σ1 ±Expected limit (


Diphoton+EmissT [ATLAS-CONF-2014-001]

• Analysis specifically designedfor GGM models.

• Event selection based on highEmiss

T , meff or HT, and by cuttingon minimal angles φ betweenphotons/jets and Emiss

T .) [GeV]

1

0χ∼ m (

200 400 600 800 1000 1200 1400

) [G

eV

]g~

m (

1000

1100

1200

1300

1400

1500

1600ATLAS Preliminary

= 8 TeVs, 1

L dt = 20.3 fb∫

< 0.1 mmτ = 1.5, cβGGM: binolike neutralino, tan

) For

bidd

en

g~

) > m

(

1

0χ∼

m (

)TheorySUSYσ 1 ±Observed (

) Exp.

σ 1 ±Expected (

) Exp.

σ 2 ±Expected (


Monophoton[arXiv:1411.1559]

q

q χ

χ

γ Events with only a mono-photon appear in variousscenarios:

• Large extra spatial dimensions.

• Direct production of weakly interacting massive particlesthrough interaction with quarks via a heavy mediator.

• Very compressed SUSY scenarios, e.g. with pair-wiseproduced squarks and direct decay to LSPs. (Masses ofsquarks and LSPs then very close.)

q

q

γχ01

χ01

q

q

q

q∗

Interpretations

[GeV]χm1 10

2103

10

4510

4210

3910

3610

3310

3010

COUPP 90%CLSIMPLE 90%CLPICASSO 90%CLSuperK 90%CL

90%CL

W+

IceCube W

90%CLπD9: ATLAS 8TeV g=4

D9: ATLAS 8TeV g=1 90%CL



)χχ(γD9: ATLAS 7TeV


= 8 TeVs 1

L dt = 20.3 fb∫

spindependent

[GeV]χm1 10

2103

10

]2

N c

ross s

ection [cm

χ

4410

4010

3610

3210

2810




σDAMA/LIBRA, 3 σCRESST II, 2

CoGeNT, 99%CL σCDMS, 1

σCDMS, 2 CDMS, low mass

LUX 2013 90%CL Xenon100 90%CL

spinindependent

ATLAS

[GeV]q~

m

100 150 200 250 300

[G

eV

]0 1χ∼

mq~

m

5

10

15

20

25

30

35

40

45

50

51.0

75.4

39.2

49.3

31.1

39.6

25.6

31.0

24.3

27.5

218 92 61.3

305 162 116

ATLAS = 8 TeV,s1

Ldt = 20.3 fb∫

)theo

σ 1 ±Observed limit (

)expσ 1 ±Expected limit (

Nu

mb

ers

giv

e 9

5%

CL

exclu

de

d c

ross s

ectio

n [

fb]


susy searches with the atlas detector

Documents