T. Kono (ATLAS) - Latest Results on Searches for Dark Matter Candidates with the ATLAS Detector at the LHC

28.08.2011 - 01.09.2011 BW2011 Workshop, Serbia 1

LATEST RESULTS ON SEARCHES FOR
DARK MATTER CANDIDATES WITH THE
ATLAS EXPERIMENT AT THE LHC
Takanori Kono (University of Hamburg/DESY)

BW2011 Workshop, Serbia
28.08 – 01.09, 2011


Outline
• Standard model and supersymmetry
• LHC and ATLAS
• SUSY searches in ATLAS
• 0-lepton + missing transverse energy (w/wo b-tag)
• 1-lepton/2-lepton + missing transverse energy
• 2 photon + missing transverse energy
• Long-lived particle search
• Medium-lived particles with displaced vertex R-parity violating
• eμ resonance scenarios
• Conclusion


Standard Model of particle physics
• Standard Model (SM) is a beautiful theory
which describes nature with great precision
• Quarks, leptons and force-carrying particles
• Electroweak symmetry breaking (EMSB) is
essential to describe observed particle
masses and interactions
• Masses of W/Z bosons
• Coupling between W/Z and fermions
• Higgs field drives EWSB

Unanswered questions in SM
• 3 generation structure
• Particle mass hierarchy and mixing
• Matter-antimatter asymmetry
• Stability of the Higgs mass
• What is dark matter? (evidence from cosmology)


Extensions of the SM
• Many extensions to the SM have been proposed
• Fourth generation
• New symmetry
• Extra-dimensional models
• …..
• Supersymmetry (SUSY)
• SUSY provides an elegant solution to the hierarchy problem by
introducing a super-partner to every SM particle (fermion – boson)
• Provides a natural dark matter candidate
• Unification of gauge couplings

• If SUSY is accessible, new particles are expected to be
produced copiously at the LHC
• Production of gluinos and squarks and their decays


Supersymmetry (SUSY)
• SUSY
• Introduces a superpartner to each SM particle
which differs ½ in spin
• SUSY must be a broken symmetry
• Different symmetry breaking mechanism
leads to different phenomenologies
• Minimal Supersymmetric SM (MSSM)
• Minimal extension of the SM
• 124 free parameters
• mSUGRA (5 parameters)
m0 : common scalar mass at the GUTscale
m1/ 2 : common fermion mass at the GUTscale
A0 : trilinear coupling
Most experimental results are
tan  : sign of SUSY Higgs potential parameter interpreted in the context of
sign  : sign of SUSY Higgs potential parameter mSUGRA


Large Hadron Collider (LHC)
2011 running
• Proton-proton collision at the center-
of-mass energy of 7 TeV
• 50 ns bunch spacing
• Peak luminosity : 2.37×1033 cm-2s-1
• Delivered luminosity : >2.5 fb1
• Average pileup: ~8 collisions/bunch

• 2 general-purpose experiments (ATLAS, CMS)
• Experiments dedicated for specific physics
(ALICE, LHCb, TOTEM, LHCf)


ATLAS experiment Calorimeter
• Large acceptance and hermiticity • LAr : EM calorimeter
• Tile: Fe/Scintillator tile
• High granularity readout and
excellent resolution

Inner Detector
• Pixel (pixel detector)
• SCT (silicon strip detector)
• TRT (transition radiation tracker)

Muon spectrometer Magnet system
• MDT, CSC : precise momentum measurement • 2 T solenoid
• RPC, TGC : trigger chambers • 0.5 T toroid


Physics at the LHC
σ (proton-proton)
Total inelastic pp collision
 Minimum bias events

QCD jet production including
heavy flavors

W/Z boson production
top pair production

Higgs, SUSY and other new
physics searches

With >2 fb-1 of data we are
already probing this region


Searches for SUSY at the LHC
Characteristic SUSY production and decay• In R-parity is conserved, SUSY
particles are produced in pairs and
the lightest SUSY particle (LSP)
becomes stable
• R=(-1)3(B-L)+2s
• No direct observation of SUSY
particles, but only SM particles are
reconstructed directly
• No mass peaks
• LSP escapes the detector undetected
producing a missing transverse
energy (ETmiss)
• Evidence of SUSY is done by
establishing an excess of events in
some region of phase space
• Crucial to understand the
contribution from SM processes


Overview of SUSY searches in ATLAS
Channel Signature Integrated lumi.
0-leptons+jets+ETmiss ≥2-4 jets, large ETmiss, meff 1.04 fb-1
1-leptons+jets+ETmiss ≥3 jets, e or μ, large ETmiss, meff 1.04 fb-1
2-leptons+ETmiss Exactly 2 leptons, large ETmiss 1.04 fb-1
0-leptons+bjets+ETmiss ≥3 jets, large ETmiss, meff 0.83 fb-1
Diphoton+ETmiss γγ+ETmiss+X 1.07 fb-1
Long-lived particle Slowly moving particle 37 pb-1
eμ resonance eμ+X 0.87 fb-1
Medium-lived particle μ+displaced vertex 35 pb-1
n
• Interpretation of search results in the context of
meff   pT  ET
i miss
• mSUGRA/CMSSM model i 1
• M0, M1/2, A0, tanβ, sgn(μ)
• Simplified model


L=1.04 fb-1
ETmiss + jets + 0-lepton channel
Five signal regions are defined
to maximize sensitivities for
various production mechanisms
~~ ~   
~
q q  q10 q10
~~ ~  
~
g q  qq10 q10
~~ ~   ~
g g  qq 0 qq 0
1 1

Background sources
W+jets Leptons reconstructed as jets
Z/γ+jets γ/leptons as jets, Z+jetsνν+jets
Top Hadronic tau decay
All background estimations
QCD Mis-measurement of jets or ν from heavy are data-driven
flavor decay


L=1.04 fb-1
Entries / 100 GeV
Search in 0-lepton : Results

Entries / 150 GeV
Entries / 100 GeV
105
Data 2011 ( s = 7 TeV) 105 Data 2011 ( s = 7 TeV) Data 2011 ( s = 7 TeV)

105 ∫ L dt ~ 1.04 fb
-1 SM Total
QCD multijet
W+jets 104
∫ L dt ~ 1.04 fb
-1 SM Total
QCD multijet
W+jets
104 ∫ L dt ~ 1.04 fb
-1 SM Total
QCD multijet
W+jets
Three Jet Channel Z+jets Four Jet Channel Z+jets
Four Jet High Mass Z+jets
104 Channel
tt and single top tt and single top 103 tt and single top
SM + SU(660,240,0,10) 103 SM + SU(660,240,0,10) SM + SU(660,240,0,10)
103
ATLAS Preliminary ATLAS Preliminary 102 ATLAS Preliminary
102
102
10
10
10
1
1
1
10-1
DATA / MC

DATA / MC
2.50 500 1000 1500 2000 2500 3000 2.50 500 1000 1500 2000 2500 3000

DATA / MC
2 2.50 500 1000 1500 2000 2500 3000 2
1.5 2 1.5
1 1.5 1
0.5 1 0.5
0 0.5 0
-0.5 0 -0.5
0 500 1000 1500 2000 2500 3000 -0.5 0 500 1000 1500 2000 2500 3000
0 500 1000 1500 2000 2500 3000
meff [GeV] meff [GeV]
meff [GeV]

≥2 jets ≥3 jets ≥4 jets ≥4 jets ≥4 jets
meff>500 GeV meff>1000 GeV high mass
Total 62.3±4.3±9.2 55.0±3.8±7.3 984±39±145 33.4±2.9±6.3 13.2±1.9±2.6
expected
Data 58 59 1118 40 18

Limit on 22 (fb) 25 (fb) 429 (fb) 27 (fb) 17 (fb)
fiducial cross
section

No excess was observed


ETmiss + jets + 0-lepton : Interpretation
Phenomenological MSSM (squark-gluino) grids mSUGRA/CMSSM, A0=0, tanβ=10, μ>0
• Masses from 100 GeV to 2 TeV, m(χ01)=0
• Limits unchanged if LSP mass raised to 200 GeV
Squark-gluino-neutralino model (m = 0 GeV) MSUGRA/CMSSM: tanβ = 10, A = 0, μ>0
LSP 0
2000
squark mass [GeV]

m1/2 [GeV]
ATLAS Preliminary ATLAS Preliminary 0 lepton 2011 combined
0 lepton 2011 combined L
int
= 1.04 fb -1, s=7 TeV CLs observed 95% C.L. limit
LEP2 ∼ 1
±
CLs observed 95% C.L. limit χ CLs median expected limit
1750 600 ~, ~, tanβ=3, μ <0, 2.1 fb-1
CLs median expected limit D0 g q exp. limit 68%, 99% CL
CDF ~,~, tanβ=5, μ <0, 2 fb-1
gq Reference point
exp. limit 68%, 99% CL Theoretically excluded 2010 data PCL 95% C.L. limit
1500
2010 data PCL 95% C.L. limit
int 500
L = 1.04 fb-1, s=7 TeV

~ (140
q
1250 ~ (1200)
g
Tevatron, Run I

0)
σSUSY = 0.01 pb
CDF, Run II
D0, Run II

1000 400
~ (1000)
g

~ (10
q
σSUSY = 0.1 pb
750

00)
300
σSUSY = 1 pb ~ (800)
g
500

~ (6
q
σSUSY = 10 pb

00
200 ~ (600)
g

)
250
LEP2 ~
q

0
0 250 500 750 1000 1250 1500 1750 2000 500 1000 1500 2000 2500 3000 3500
gluino mass [GeV] m0 [GeV]

Exclude at 95 % C.L.
Exclude at 95 % C.L.
mg  800 GeV, mq  850 GeV
~ ~
if mg  mq , masses 980 GeV
~ ~
if mg  mq , masses 1075 GeV
~ ~


ETmiss + bjets + 0-lepton L=0.83 fb-1

• Analysis similar to jets+ channel but requires at least one b-jet
• Sensitive to 3rd generation squarks in R-parity conserving scenarios
• Define 4 signal regions to maximize sensitivity 1 b-tag 105

Events/ 50 GeV
ATLAS Preliminary 0-lepton,3 jets

3J-A 3J-B 3J-C 3J-D
>= 1 bjet
104 ∫ -1
L dt = 0.83 fb , s = 7 TeV Data 2011
SM Total
top production
3
10 W production
Z production
QCD production
~ 700 GeV, ~ 380 GeV
102
≥1 b-tag ≥1 b-tag ≥2 b-tag ≥2 b-tag
g b

10
meff>500 GeV meff>700 GeV meff>500 GeV meff>700 GeV 1

10-1

data / MC
2.5

Pheonomenological MSSM 2
1.5
1
0.5

mg  mb  m 0
~ ~ ~
00 200 400 600 800 1000 1200 1400
meff [GeV]
1 1

~ ~ ~ ~
g  b1b, b1  b10 (100 %)
105
2 b-tag

Events/ 50 GeV
ATLAS Preliminary 0-lepton,3 jets
>= 2 bjets
104 ∫ L dt = 0.83 fb ,-1
s = 7 TeV Data 2011

m 0  60 GeV
SM Total
top production
103 W production
~ Z production
QCD production
1 102 ~ 700 GeV, ~ 380 GeV
g b

General simplified model 10

1

• Squarks assumed to be heavy 10-1

• Gluino-gluino pair production

data / MC
2.5
2
1.5
~ ~
g  bb10 (3 - body decay)
1
0.5
00 200 400 600 800 1000 1200 1400
meff [GeV]


ETmiss + bjets : Results L=0.83 fb-1

Signal region 3J-A 3J-B 3J-C 3J-D
Total expected 356+103-92 70+24-22 79+28-25 13+5.6-5.2
Data 361 63 76 12
σ (pb) 95 % C.L. 0.288 0.061 0.078 0.017
upper limit

Phenomenological MSSM Simplified model (gluinobbχ01)
1000
~-~ + ~ -~ production, ~ → b+∼0
g g b1 b1 b1 χ
1 ∫ L dt = 0.83 fb ,
-1
s=7 TeV ~-~ production, ~→ 2b+∼0, m(~) >> m(~)
gg g χ q
1
g ∫ L dt = 0.83 fb ,
-1
s=7 TeV
mb [GeV]

mχ0 [GeV]

Maximum cross section [pb](CLs)
CLs observed limit
ATLAS Preliminary CLs expected limit 800 Observed 95% CL s limit
900 68% and 99% C.L.
107.7 102
CLs expected limits
1

1
700
~

0 lepton, 3 jets

∼
ATLAS (35 pb-1) Expected CLs limit 90.6 38.4
b-jet analyses
800 87.9 20.5 13.7
∼0 ~
m(χ ) = 60 GeV, m( 1,2)>>m(~) 600
q g ATLAS Preliminary 93.4 30.5 10.0 6.6
1
en 10
700 dd 82.4 19.0 14.0 6.3 3.8
~~
CDF b1b1 2.65 fb-1 500 0 lepton, 3 jets rbi
∼ fo
0 60.0 13.1 8.3 7.1 1.2 1.6
b-jet analyses
b+χ 1
600 ~~ ~ →2 80.6 19.0 4.5 4.7 2.2 0.9 1.1
D0 b1b1 5.2 fb-1 400 g 52.6 8.1 4.4 4.1 3.4 2.0 0.7 0.8 1
e n
500 ~
CDF ~~, → b1b 2.5 fb-1
gg idd 114.7 20.7 5.1 2.2 2.1 1.0 0.5 0.6 0.6
rb 300
~ b fo 68.2 26.0 21.0 3.5 1.3 1.0 0.7 0.3 0.4 0.5

400 ~g→b 275.0 34.4 11.8 6.3 1.7 1.0 0.7 0.4 0.3 0.3 0.5 10-1
200 136.9 97.5 17.0 5.2 2.6 1.0 0.4 0.3 0.2 0.2 0.3 0.4
Reference point
89.5 31.8 8.9 3.4 1.2 0.7 0.4 0.2 0.2 0.2 0.3 0.4
300 100
79.9 19.9 6.5 1.5 0.8 0.6 0.4 0.2 0.2 0.2 0.2 0.4
102.0 15.2 2.9 1.5 0.7 0.4 0.3 0.2 0.2 0.2 0.2 0.4
10-2
200 0
100 200 300 400 500 600 700 800 900 1000 200 300 400 500 600 700 800
mg [GeV]
~ mg [GeV]
~

Gluino masses below 720 GeV excluded Gluino masses between 200-660 GeV
for sbottom masses below 600 GeV excluded up to LSP mass of 160 GeV


ETmiss + jets + 1-lepton L=1.04 fb-1
107

Events / 10 GeV
ATLAS Preliminary Data 2011 ( s=7 TeV)

Data under/over flow = 0/0
Standard Model

Event selection
106
∫L dt = 1.04 fb
-1 multijets (data estimate)
W+jets
Z+jets
105
Electron Channel tt

• 1 lepton (electron or muon) 104
single top
Dibosons
MSUGRA m 0=500 m1/2=330

• electron pT>25 GeV or muon pT>20 GeV
miss
Δφ(ET ,jet )>0.2
103 1,2,3

• Veto second lepton if 102

• electron pT>20 GeV or
10

1
• muon pT>10 GeV 10-1

• 3 jets (>60, >25, >25 GeV)

Data / SM
2

• ∆φ(jet, ETmiss)> 0.2 for all jets
1

0

• ETmiss >125 GeV, ETmiss >0.25*Meff
0 100 200 300 400 500 600
Emiss [GeV]
T

• Meff>500 GeV

Events / 10 GeV
ATLAS Preliminary Data 2011 ( s=7 TeV)

Data under/over flow = 0/1
106 Standard Model

105
∫L dt = 1.04 fb -1 multijets (data estimate)
W+jets

4 signal regions
Z+jets
Muon Channel tt
single top
104 Dibosons

• Loose 3 jets
MSUGRA m 0=500 m1/2=330
miss
Δφ(E ,jet )>0.2
103 T 1,2,3

• Tight 3 jets 102

• Loose 4 jets 10

1

• Tight 4 jets 10-1

Data / SM
2

Main background: W+jets 1

0
0 100 200 300 400 500 600
Emiss [GeV]
T


ETmiss + 1-lepton : Interpretation L=1.04 fb-1
MSUGRA/CMSSM: tanβ = 10, A = 0, μ>0
0
500

m1/2 [GeV]
mSUGRA
ATLAS int
L = 1.04 fb-1, s=7 TeV Observed CLS 95% CL
450 Preliminary 1 lepton, combination Expected CLS

• Gluino mass<875 GeV excluded 400
~
q (900 GeV)
~
g (900 GeV)
Expected CLS ± 1σ

∼ ±
LEP2 χ
1
350 ~
~
g (800 GeV) D0 ~, ~, tanβ=3, μ<0, 2.1 fb-1
g q
q (700 GeV)

Simplified model 300 CDF ~, ~, tanβ=5, μ<0, 2 fb-1
g q

• LSP masses below 200 GeV are 250
~
q (500 GeV)
~
g (600 GeV)

excluded for gluino mass below
200 ~
g (500 GeV)
~
q (400 GeV)

150
600 GeV (for x>1/2)
~
g (400 GeV)

  
200 400 600 800 1000 1200 1400

x  m   m 0 / mq  m 0
~ ~ ~ ~
m0 [GeV]

1 1 1
800

mLSP [GeV]

Cross Section Excluded at 95% CL [pb]
1-Step Decay, x=1/2 ATLAS Preliminary
∼∼
~~→qqqqWWχ0χ0
bRPV MSUGRA: tanβ = 10, A = 0, μ>0 700 gg 1 1
102
0
500
m1/2 [GeV]

Combination
ATLAS int
L = 1.04 fb-1, s=7 TeV Observed CLS 95% CL 600 Lint = 1.04 fb-1, s=7 TeV
Preliminary 1 muon, ≥ 4 jets, tight SR Expected CLS
450
Expected CLS ± 1σ Observed 95% CL
500
Expected
~
q (900 GeV) 10
400 Expected ±1σ
400
~
g (900 GeV)

350 300
~
1
q (700 GeV)

200
300 ~
g (700 GeV)
cτ = 3 mm

cτ = 7 mm
100
250 cτ = 15 mm 10-1
100 150 200 250 300 350 400 450 500 550 600 0
m0 [GeV] 300 400 500 600 700 800
mgluino [GeV]
Constraints on Bilinear R-parity violating model


ETmiss + 2-lepton
• Several leptons may be produced in the
cascade decay of SUSY particles
• 2-lepton channel is sensitive to the pair
production of weak gauginos
~ ~ ~ ~ ~ ~ ~ ~
1  20 , 1 10 , 1 1 ,  20  20

~ ~
(a)  i0  l  
j
1 lepton on one leg
~ ~
(b)    l  0
i j
~ ~
(c)  i0  l  l   0
j
2 leptons on one leg
~ ~
(d)    l  l    (identical flavor,
i j
opposite-sign pair)
Search for ETmiss+2-leptons events with
• Same-sign leptons (SS)
• Opposite-sign leptons (OS)
• Opposite-sign, identical flavor (OS, identical flavor)


ETmiss + 2-lepton L=1.04 fb-1

SS OS
pT  25, 20 GeV
e
Events / 20 GeV

Entries / 10 GeV
∫L dt ~ 1.04 fb
ATLAS Preliminary
∫L dt ~ 1.04 fb
-1 Data 2011 ( s = 7 TeV)
104 -1

Data overflow: 1590
di-lepton [SS] Data 2011 ( s = 7 TeV)
10
6 di-lepton [OS] SM Background

Data overflow: 30
SM Background Fake leptons
Z+jets
Fake Leptons 5 Drell-Yan
10

3 ATLAS Preliminary

pT  20, 10 GeV
10 Z+jets tt
Dibosons
Drell-Yan
104 Single top
2
Diboson
10 3
10

10 102

10
1
1
-1
10 10-1
20
3 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 160 180 200
Data/MC

Data/MC
1.5
2
1 1
0 0.5
20 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 160 180 200
Mll [GeV]
Mll[GeV]
Events / 20 GeV

Entries / 10 GeV

∫L dt ~ 1.04 fb
ATLAS Preliminary
∫L dt ~ 1.04 fb
-1 Data 2011 ( s = 7 TeV)
104 -1
di-lepton [SS] Data 2011 ( s = 7 TeV)
10
6 di-lepton [OS] SM Background
Data overflow: 0

Data overflow: 0
SM Background Fake leptons
Z+jets
Fake Leptons 5 Drell-Yan
3 10
10 Z+jets tt
ATLAS Preliminary Dibosons
Drell-Yan
104 Single top
2
Diboson
10 3
10

10 102

10
1
1
-1 -1
10 10
30 50 100 150 200 250 30 50 100 150 200 250 300 350 400 450 500
Data/MC

Data/MC

2 2
1 1
0 0
0 50 100 150 200 250 0 50 100 150 200 250 300 350 400 450 500
Emiss [GeV]
T
Emiss[GeV]
T


2-lepton channel results SS, OS
Signal regions (SR)
• SS SR1 : ETmiss>100 GeV
• SS SR2 : ETmiss>80 GeV, jet pT>50,50 GeV
• OS SR1 : ETmiss>250 GeV
• OS SR2 : ETmiss>220 GeV, jet pT>80,40,40 GeV
• OS SR3 : ETmiss>100 GeV, jet pT>100,70,70,70 GeV

Limits on A×ε×σ


Flavor subtraction, OS
240
Events / 20 GeV

Events / 20 GeV
ATLAS Preliminary Data 2011 ( s = 7 TeV) SF ATLAS Preliminary Data 2011 ( s = 7 TeV) SF
250 220
Data 2011 ( s = 7 TeV) DF Data 2011 ( s = 7 TeV) DF

200
SM Background SF
SM Background DF
200
180
SM Background SF
SM Background DF
Observed value of S
Fake leptons (SF)
Z+jets (SF)
160
140
Fake leptons (SF)
Z+jets (SF) Sobs=-3.1
150 Drell-Yan (SF) Drell-Yan (SF)
tt (SF)
120 tt (SF)
Diboson (SF) 100 Diboson (SF)
100 single top (SF) 80 single top (SF)
With pseudo-experiments
∫ L dt ~ 1.04 fb ∫ L dt ~ 1.04 fb
60

Ss<4.9 (95 % CL)
-1 -1
50 40
20
0 0
Data/MC SF

Data/MC SF
2 2 3
×10

Experiments
20
1 1
ATLAS Preliminary S=0.4±4.6
18
0 0
0 50 100 150 200 250 300
>300 0 50 100 150 200 250 300
>300 16

Mll [GeV] Mll [GeV] 14
12
10

     
8

N    
Ne      6

Ne e
S  
4

 
 1  1   e 2 1  1    2 1  1   e 1    
2
0
-20 -15 -10 -5 0 5 10 15 20
Spseudo-obs

electron, muon trigger efficiency
ratio of electron and muon reconstruction efficiencies and acceptances


L=1.07 fb-1
Diphoton + ETmiss

Events / 5 GeV
104 Data 2011 ( s = 7 TeV)

• In gauge-mediated SUSY breaking
QCD
103 W→eν +jets, W →eν +γ , t t →eν +X
Z→ν ν +γ γ , W→lν +γ γ
(GMSB) models, the LSP is the gravitino GGM m~ / mχ = 800 / 400 GeV
g ∼
102
~ SPS8 Λ = 140 TeV
  G
0
1
UED 1/R = 1200 GeV
10
ATLAS Preliminary ∫ Ldt = 1.07 fb -1

• Signature: 2γ + ETmiss +X 1

10-1

• Generalized model of gauge- 10-2
0 50 100 150 200 250 300 350 400 450 500
mediated SUSY breaking (GGM) ET
miss
[GeV]
with a bino-like lightest neutralino GGM: bino-like neutralino, tanβ = 2, cτNLSP < 0.1 mm
1200
(95 % C.L.)

mg [GeV]
ATLAS Expected CL s Limit
1100
• σ<0.02 – 0.04 pb ATLAS Observed CL s Limit

~
1000 ± 1σ
• m(gluino)>776 GeV 900
ATLAS Observed CL s Limit (36 pb-1)

• Universal Extra Dimension (UED) 800
(95 % C.L.) 700
∫ Ldt = 1.07 fb-1
• σ<0.015 – 0.027 pb
s = 7 TeV
600
• 1/R>1224 GeV on the UED 500 ~ NLSP
g
ATLAS Preliminary
compactification radius 400
200 400 600 800 1000 1200
m∼ [GeV]
χ


Massive long-lived particle (LLP) search
• SUSY particles produced at the LHC may have a
long lifetime
• The particle can travel >10 meters
• This may happen when the mass difference
between the LSP is very small
• Long-lived slepton
• For example, stau as the NLSP
• Behaves like a heavy muon in the detector
• Long-lived squarks/gluinos
• Hadronizes with normal quarks or gluons
 R-hadrons Measured β from real muons

Search strategy
• Look for a slowly traveling particle reaching the muon spectrometer
• Measure the velocity (β)  m=p/(βγ)
• Timing resolution : 1-2 ns with the Tile calorimeter, 3-4 ns with the
muon spectrometers


LLP search results
Reconstructed mass distributions for
• slepton search
• R-hadron search

Consistent with BG expectation


R-parity violating SUSY

T. Kono (ATLAS) - Latest Results on Searches for Dark Matter Candidates with the ATLAS Detector at the LHC

T. Kono (ATLAS) - Latest Results on Searches for Dark Matter Candidates with the ATLAS Detector at the LHC

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T. Kono (ATLAS) - Latest Results on Searches for Dark Matter Candidates with the ATLAS Detector at the LHC