Post on 09-Nov-2021
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*
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
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 3
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]
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 4
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]
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 5
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.
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 6
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
SUSYσ1 ±Observed limit (
)expσ1 ±Expected limit (
Hard 1lepton obs./exp.
2lepton obs./exp.
All limits at 95% CL
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.
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 7
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.
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 8
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
SUSYσ1 ±Observed limit (
)expσ1 ±Expected limit (
1=8 TeV, 20 fbs
Hard 1lepton only
forb
idden
0
1χ∼t t→ g~
All limits at 95% CL
ATLAS Preliminary
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 9
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
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tan(✓/
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nd�R
=
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–4–
t 1!
bW�01
3
t 1!
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2The
ATLA
Sde
tector
andda
tasamples
6
The
ATLA
Sex
perim
ent[45]
isamulti-
purp
osepa
rticle
physicsde
tector
with
nearly
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rage
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angle.
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nsist
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electrom
agne
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onic
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etrie
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damuo
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ectrom
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roviding
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ectrom
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heID
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ists o
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l detector,
asil
icon
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andastraw
tube
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r (for a
pseu
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ovides
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ontracking
and
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entu
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suremen
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charge
d
13 particles f
or|⌘|
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dallows e�cien
t b-je
t ide
ntifica
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agne
ticca
lorim
eterscove
rin
theps
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e|⌘|
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hadr
onic
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eter
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nologies,scintil
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lorim
eter
(|⌘| <
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and
LArsamplingca
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eter
(1.5
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17 muo
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ectrom
eter
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rate
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ran
dhigh
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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.
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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
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the
24 luminosity
scalede
rived
from
beam
-sep
arationscan
spe
rform
edin
Nov
embe
r20
12.
25
The
datasetus
edforth
isan
alysis
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rded
usingth
eedi↵e
rent
type
sof
trigge
rs
26 basedon
requ
iring
asin
gle-electron
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gle-muo
n,or
largeEmiss
T
. Can
dida
teev
ents
inth
e
27 electron
(muo
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anne
l are
colle
cted
usingalogica
l-OR
combina
tionof
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gle-electron
28 (single-muo
n)an
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trigge
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veatran
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entu
m
29 (pT)th
resh
old
of24
GeV
. Aseco
ndsetof
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entary
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30 thresh
olds
at60
GeV
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eV)forth
eelectron
(muo
n)ca
serecove
rssm
alline�
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cies
31 associated
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rth
resh
oldsin
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eto
lept
oniso
latio
ncrite
ria.
32 The
Emiss
T
trigge
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sa
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GeV
and
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sfull
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ents
with
33 o✏ineEmiss
T
abov
e15
0GeV
. Dur
ingth
ebe
ginn
ingof
2012
data
taking
, the
Emiss
T
trigge
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34 waspa
rtly
kept
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out2 p
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integrated
luminosity
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35 combine
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onan
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eringth
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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
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thez-ax
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ampipe
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ical
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tes(r,�
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edin
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e,�
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imut
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ngle
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sof
thepo
laran
gle✓by
⌘=� ln
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2), a
nd�R
=
p (�⌘)2 +
(��)2
–4–
t 1!
bW�01
3
t 1!
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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
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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).
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ovides
precisi
ontracking
and
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entu
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suremen
tof
charge
d
13 particles f
or|⌘|
<2.5an
dallows e�cien
t b-je
t ide
ntifica
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High-gran
ularity
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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).
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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
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 10
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~
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 11
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
All limits at 95% CL
=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
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 12
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]
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 13
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
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
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 14
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∼
All limits at 95% CL
=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.
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 15
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∼
All limits at 95% CL
• 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.
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 16
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
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 17
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
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ea
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es
3rd
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ed
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ge
n.
sq
ua
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dir
ect
pro
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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.
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 18
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!
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 19
Backup
ATLAS detector
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 21
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
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 22
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
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 23
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]
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 24
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 (
All limits at 95% CL
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 (
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 25
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
90%CLπD8: ATLAS 8TeV g=4
D8: ATLAS 8TeV g=1 90%CL
)χχ(γD9: ATLAS 7TeV
)χχ(γD8: 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
90%CLπD5: ATLAS 8TeV g=4
D5: ATLAS 8TeV g=1 90%CL
)χχ(γD5: ATLAS 7TeV
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]
Jeanette Lorenz (LMU) SUSY searches with the ATLAS detector 12.12.2014 26