PPC07, May 2007 Dan Tovey 1 Dark Matter Searches at ATLAS Dan Tovey University of Sheffield Dan...

11 PPC07, May 2007PPC07, May 2007Dan ToveyDan Tovey

Dark Matter Searchesat ATLAS

Dark Matter Searchesat ATLAS

Dan Tovey

University of Sheffield

Dan Tovey

University of Sheffield


ATLASATLAS

Length: ~45 m Radius: ~12 m Weight: ~7000 tons


First cosmic muonsobserved by ATLAS in the underground cavernon June 20th 2005(recorded by hadronTilecal calorimeter)

Tower energies:~ 2.5 GeV

First Astroparticle Data…First Astroparticle Data…


• Main asset of LHC: huge event statistics thanks to high s and L• Allows precision measurements/tests of SM• Searches for new particles with unprecedented precision.

Event RatesEvent Rates

Process Events/s Events per year Total statistics collected at previous machines by 2008

W e 15 108 104 LEP / 107 Tevatron

Z ee 1.5 107 107 LEP

tt 1 107 104 Tevatron

bb 106 1012 – 1013 109 Belle/BaBar?

gg~~

H m=130 GeV 0.02 105 ?

m= 1 TeV 0.001 104 ---

Black holes 0.0001 103 ---m > 3 TeV (MD=3 TeV, n=4)

L = 1033 cm-2 s-1


Dark Matter @ ATLASDark Matter @ ATLAS• Characteristic signature

for Dark Matter production at ATLAS: Missing Transverse Energy (‘MET’)

• Valid for any DM candidate (not just SUSY)

• Observation of MET signal necessary but not sufficient to prove DM signal (DM particle could decay outside detector)

MET

01

01

~

~

Conclusive proof of both existence and identity of DM by

combining LHC data with astroparticle data


ComplementarityComplementarity

psi

h2

ZEPLIN-MAX

GENIUSXENON

ZEPLIN-4

ZEPLIN-2

EDELWEISS 2

CRESST-II

ZEPLIN-I

EDELWEISS

CDMSDAMA • Aim to test compatibility of e.g.

SUSY signal with DM hypothesis (data from astroparticle experiments)– Fit SUSY model parameters to

ATLAS measurements – Use to calculate DM parameters h2, m, p

si etc.

• Measurements at ATLAS complementary to direct and indirect astroparticle searches / measurements– Uncorrelated systematics

– Measures different parameters

p

si (

cm

2)

log10 (psi / 1pb)h2

No

. M

C E

xpe

rim

ents

DM particle mass m (GeV)

Polesello et al JHEP 0405 (2004) 071

CDMS-II

Provides strongest possible test of Dark Matter model

psi

m


SUSY DM StrategySUSY DM Strategy

1) SUSY Discovery phase

2) Inclusive Studies (measurement of SUSY Mass Scale, comparison of significance in inclusive channels).

3) Exclusive studies and interpretation within specific model framework (e.g. Constrained MSSM / mSUGRA)

– Specific model needed to calculate e.g. relic density general SUSY studies will be less model dependent.

4) Less model-dependent interpretation– Relax model-dependent assumptions

SUSY Dark Matter studies at ATLAS will proceed in four stages:


Stage 1:

SUSY Discovery


SUSY SignaturesSUSY Signatures• Q: What do we expect SUSY events @ LHC to look like?• A: Look at typical decay chain:

• Strongly interacting sparticles (squarks, gluinos) dominate production.

• Heavier than sleptons, gauginos etc. cascade decays to LSP.• Long decay chains and large mass differences between SUSY states

– Many high pT objects observed (leptons, jets, b-jets).

• If R-Parity conserved LSP (lightest neutralino in mSUGRA) stable and sparticles pair produced.– Large ET

miss signature (c.f. Wl).

• Closest equivalent SM signature tWb.

lqq

l

g~ q~ l~

~ ~

p p


ATLAS

5

• Use 'golden' Jets + n leptons + ETmiss discovery channel.

• Map statistical discovery reach in mSUGRA m0-m1/2 parameter space.

• Sensitivity only weakly dependent on A0, tan() and sign().

• Syst.+ stat. reach harder to assess: focus of current & future work.

Inclusive SearchesInclusive Searches

ATLAS

5


Background SystematicsBackground Systematics• Z + n jets, W l + n jets, W +

(n-1) jets ( fakes jet)• Estimate from Z l+l- + n jets (e or )• Tag leptonic Z and use to validate MC

/ estimate ETmiss from pT(Z) & pT(l)

• Alternatively tag W l + n jets and replace lepton with 0l): – higher stats

– biased by presence of SUSY

ATLAS

Preliminary

ATLAS

Preliminary

(Zll)

(Wl)


Stage 2:

Inclusive Studies


• Question 2: Is the LSP the lightest neutralino?– Natural in many MSSM models

– If YES then test for consistency with astrophysics

– If NO then what is it?

– e.g. Light Gravitino DM from GMSB models (not considered here)

• Following any discovery of SUSY next task will be to test broad features of potential Dark Matter candidate.

• Question 1: Is R-Parity Conserved?– If YES possible DM candidate

– LHC experiments sensitive only to LSP lifetimes < 1 ms (<< tU ~ 13.7 Gyr)

Inclusive StudiesInclusive Studies

Non-pointingphotons from 0

1G~ ~

GMSB Point 1b(Physics TDR)

LHC Point 5(Physics TDR)

R-Parity Conserved

R-Parity Violated

~

ATLAS

ATLAS


Measuring ParametersMeasuring Parameters• First indication of mSUGRA

parameters from inclusive channels– Compare significance in jets + ET

miss + n leptons channels

• Detailed measurements from exclusive channels when accessible.

• Consider here two specific example points studied previously:

ATLAS

LHC Point 5 (A0 =300 GeV, tan()=2, >0)

Point SPS1a (A0 =-100 GeV, tan()=10, >0) Sparticle Mass (LHC Point 5) Mass (SPS1a)

qL ~690 GeV ~530 GeV

02 233 GeV 177 GeV

lR 157 GeV 143 GeV

01 122 GeV 96 GeV

~

~

~

~

Point m0 m1/2 A0 tan() sign() LHC Point 5 100 300 300 2 +1 SPS1a 100 250 -100 10 +1


Stage 3:

Exclusive studies and interpretation within specific model framework


Exclusive StudiesExclusive Studies• With more data will attempt to measure weak scale SUSY parameters (masses etc.) using exclusive channels.

• Different philosophy to TeV Run II (better S/B, longer decay chains) aim to use model-independent measures.

• Two neutral LSPs escape from each event – Impossible to measure mass of each sparticle using one channel alone

• Use kinematic end-points to measure combinations of masses.

• Old technique used many times before ( mass from decay spectrum, W (transverse) mass in Wl).• Difference here is we don't know mass of neutral final state particles.

lqql

g~ q~ lR

~~

~p p


Dilepton Edge MeasurementsDilepton Edge Measurements

~~02

~01

l ll

e+e- + +-

~

~

30 fb-1

atlfast

Physics TDR

Point 5

e+e- + +- - e+- - +e-

5 fb-1

SU3

ATLAS ATLAS

•m0 = 100 GeV•m1/2 = 300 GeV•A0 = -300 GeV•tan() = 6•sgn() = +1

• When kinematically accessible canundergo sequential two-body decay to via a right-slepton (e.g. LHC Point 5).

• Results in sharp OS SF dilepton invariant mass edge sensitive to combination of masses of sparticles.

• Can perform SM & SUSY background subtraction using OF distribution

e+e- + +- - e+- - +e-

• Position of edge measured with precision ~ 0.5%

(30 fb-1).


Measurements With SquarksMeasurements With Squarks• Dilepton edge starting point for reconstruction of decay chain.• Make invariant mass combinations of leptons and jets.• Gives multiple constraints on combinations of four masses. • Sensitivity to individual sparticle masses.

~~~

l ll

qL

q

~

~~

bh

qL

q

~

b

llq edge1% error(100 fb-1)

lq edge1% error(100 fb-1)

llq threshold2% error(100 fb-1)

bbq edge

TDR,Point 5

TDR,Point 5

TDR,Point 5

TDR,Point 5

ATLAS ATLAS ATLAS ATLAS

1% error(100 fb-1)


‘Model-Independent’ Masses‘Model-Independent’ Masses

• Combine measurements from edges from different jet/lepton combinations to obtain ‘model-independent’ mass measurements.

01 lR

02 qL

Mass (GeV)Mass (GeV)

Mass (GeV)Mass (GeV)

~

~

~

~

ATLAS ATLAS

ATLAS ATLAS

Sparticle Expected precision (100 fb-1)

qL 3%

02 6%

lR 9%

01 12%

~

~

~

~

LHCCPoint 5


Measuring Model ParametersMeasuring Model Parameters• Alternative use for SUSY observables (invariant mass end-points,

thresholds etc.).• Here assume mSUGRA/CMSSM model and perform global fit of model

parameters to observables– So far mostly private codes but e.g. SFITTER, FITTINO now on the market;

– c.f. global EW fits at LEP, ZFITTER, TOPAZ0 etc.

Point m0 m1/2 A0 tan() sign() LHC Point 5 100 300 300 2 +1 SPS1a 100 250 -100 10 +1

Parameter Expected precision (300 fb-1) m0 2% m1/2 0.6% tan() 9% A0 16%


Dark Matter ParametersDark Matter Parameters

Baer et al. hep-ph/0305191

LEP 2 No REWSB

LHC Point 5: >5 error (300 fb-1)

p=10-11 pb

p=10-10 pb

p=10-9 pb

• Can use parameter measurements for many purposes, e.g. estimate LSP Dark Matter properties (e.g. for 300 fb-1, SPS1a)– h2 = 0.1921 0.0053– log10(p/pb) = -8.17 0.04 SPS1a: >5

error (300 fb-1)Micromegas 1.1 (Belanger et al.)+ ISASUGRA 7.69

ATLAS

300 fb-1

p

ATLAS

300 fb-1

DarkSUSY 3.14.02 (Gondolo et al.)+ ISASUGRA 7.69

h2


Target ModelsTarget Models• SUSY (e.g. mSUGRA) parameter space strongly constrained by

cosmology (e.g. WMAP satellite) data. mSUGRA A0=0, tan() = 10, >0

'Bulk' region: t-channel slepton exchange - LSP mostly Bino. 'Bread and Butter' region for LHC Expts.

'Focus point' region: significant h component to LSP enhances annihilation to gauge bosons

~

Ellis et al. hep-ph/0303043

01

01

l

llR

~

~~

01

1

/Z/h1

~

~~

Disfavoured by BR (b s) = (3.2 0.5) 10-4 (CLEO, BELLE)

0.094 h2 0.129 (WMAP)

Slepton Co-annihilation region: LSP ~ pure Bino. Small slepton-LSP mass difference makes measurements difficult.

Also 'rapid annihilation funnel' at Higgs pole at high tan(), stop co-annihilation region at large A0


Coannihilation SignaturesCoannihilation Signatures

• ETmiss>300 GeV

• 2 OSSF leptons PT>10 GeV• >1 jet with PT>150 GeV• OSSF-OSOF subtraction applied

• ETmiss>300 GeV

• 1 tau PT>40 GeV;1 tau PT<25 GeV• >1 jet with PT>100 GeV• SS tau subtraction

• Small slepton-neutralino mass difference gives soft leptons – Low electron/muon/tau energy

thresholds crucial.

• Study point chosen within region:– m0=70 GeV; m1/2=350 GeV; A0=0;

tanß=10 ; μ>0;

• Decays of 02 to both lL and lR

kinematically allowed.– Double dilepton invariant mass edge

structure;– Edges expected at 57 / 101 GeV

• Stau channels enhanced (tan)– Soft tau signatures;– Edge expected at 79 GeV;– Less clear due to poor tau visible

energy resolution.

ATLAS

ATLAS

Preliminary

Preliminary

100 fb-1

100 fb-1

~~~


Focus Point SignaturesFocus Point Signatures• Large m0 sfermions are heavy

• Most useful signatures from heavy neutralino decay• Study point chosen within focus point region :

– m0=3550 GeV; m1/2=300 GeV; A0=0; tanß=10 ; μ>0

• Direct three-body decays 0n → 0

1 ll

• Edges give m(0n)-m(0

1) : flavour subtraction applied

~ ~~ ~

Z0 → ll

300 fb-1

→ ll~ ~ → ll~ ~

Preliminary

ATLAS

Parameter Without cuts Exp. value

M 68±92 103.35

M2-M1 57.7±1.0 57.03

M3-M1 77.6±1.0 76.41

M = mA+mB mA-mB


Stage 4:

Less model-dependent interpretation


Dark Matter in the MSSMDark Matter in the MSSM• Can relax mSUGRA constraints to obtain

more ‘model-independent’ relic density estimate.

• Much harder – needs more measurements• Not sufficient to measure relevant (co-)

annihilation channels – must exclude all irrelevant ones also …

• Stau, higgs, stop masses/mixings important as well as gaugino/higgsino parameters

Nojiri, Polesello & Tovey, JHEP 0603 (2006) 063

h2

h2

σ(m)=5 GeV

σ(m)=0.5 GeV

SPA point

300 fb-1300 fb-1

σ(h2) vs σ(m)


Heavy Gaugino MeasurementsHeavy Gaugino Measurements

• Potentially possible to identify dilepton edges from decays of heavy gauginos.

• Requires high stats.• Crucial input to reconstruction of MSSM

neutralino mass matrix (independent of SUSY breaking scenario).

ATLAS100 fb-1 ATLAS

100 fb-1

ATLAS100 fb-1

ATLAS

SPS1a

SPS1a


SummarySummary

• Following a (SUSY) discovery ATLAS will aim to test the (SUSY) Dark Matter hypothesis.

• Conclusive result only possible in conjunction with astroparticle experiments (constraints on LSP life-time).

• Estimation of relic density and direct / indirect DM detection cross-sections in model-dependent scenario will be first goal.

• Less model-dependent measurements will follow.• Ultimate goal: observation of neutralinos at LHC confirmed by

observation of e.g. signal in (in)direct detection Dark Matter experiment at predicted mass and cross-section.

This would be major triumph for both

Particle Physics and Cosmology!


BACK-UP SLIDES


SupersymmetrySupersymmetry• Supersymmetry (SUSY) fundamental

continuous symmetry connecting fermions and bosons

Q|F> = |B>, Q|B> = |F>

• {Q,Q}=-2pgenerators obey anti-commutation relations with 4-mom– Connection to space-time symmetry

• SUSY stabilises Higgs mass against loop corrections (gauge hierarchy/fine-tuning problem)– Leads to Higgs mass 135 GeV

– Good agreement with LEP constraints from EW global fits

• SUSY modifies running of SM gauge couplings ‘just enough’ to give Grand Unification at single scale.

LEPEWWGWinter 2006

mH<207 GeV (95%CL)


e

H-d

~H+

u

~H0

d

~H0

u

~0

4~0

3~0

2~0

1~

SUSY SpectrumSUSY Spectrum

• Expect SUSY partners to have same masses as SM states– Not observed

(despite best efforts!)

– SUSY must be a broken symmetry at low energy

• Higgs sector also expanded

• SUSY gives rise to partners of SM states with opposite spin-statistics but otherwise same Quantum Numbers.

H±H0A

G

e

bt

sc

du

g

W±Z

h

W±Z~ ~ ~

g~

G~

± 2~± 1

~

e

e

bt

sc

du~ ~

~

~

~ ~

~ ~ ~

~

~

~


Model FrameworkModel Framework• Minimal Supersymmetric Extension of the Standard Model (MSSM)

contains > 105 free parameters, NMSSM etc. has more difficult to map complete parameter space!

• Assume specific well-motivated model framework in which generic signatures can be studied.

• Often assume SUSY broken by gravitational interactions mSUGRA/CMSSM framework : unified masses and couplings at the GUT scale 5 free parameters(m0, m1/2, A0, tan(), sgn()).

• R-Parity assumed to be conserved.• Exclusive studies use benchmark

points in mSUGRA parameter space:• LHCC Points 1-6;

• Post-LEP benchmarks (Battaglia et al.);

• Snowmass Points and Slopes (SPS);

• etc…

LHCC mSUGRA Points

1 2

3

45


SUSY & Dark MatterSUSY & Dark Matter• R-Parity Rp = (-1)3B+2S+L

• Conservation of Rp (motivated e.g. by string models) attractive– e.g. protects proton from

rapid decay via SUSY states

• Causes Lightest SUSY Particle (LSP) to be absolutely stable

• LSP neutral/weakly interacting to escape astroparticle bounds on anomalous heavy elements.

• Naturally provides solution to dark matter problem

• R-Parity violating models still possible not covered here.

Universe Over-Closed

mSUGRA A0=0, tan() = 10, >0

Ellis et al. hep-ph/0303043

01

01

l

llR

~

~~

01

1

/Z/h1

~

~~

Disfavoured by BR (b s) = (3.2 0.5) 10-4 (CLEO, BELLE)

0.094 h2 0.129 (WMAP-1year)


Stop MassStop Mass• Look at edge in tb mass distribution.• Contains contributions from

– gtt1tb+1

– gbb1bt+1

– SUSY backgrounds

• Measures weighted mean of end-points• Require m(jj) ~ m(W), m(jjb) ~ m(t)

• Subtract sidebands from m(jj) distribution• Can use similar approach with gtt1tt0

i

– Di-top selection with sideband subtraction

• Also use ‘standard’ bbll analyses (previous slide)

~

~ ~

~ ~

~

120 fb-1

ATLAS

LHCC Pt 5 (tan()=10)

120 fb-1

ATLAS

LHCC Pt 5 (tan()=10)

mtbmax = (443.2 ± 7.4stat) GeV

Expected = 459 GeV

mtbmax = (510.6 ± 5.4stat) GeV

Expected = 543 GeV

~

~

~


Preparations for 1st PhysicsPreparations for 1st Physics• Preparations needed to ensure efficient/reliable searches

for/measurements of SUSY particles in timely manner:– Initial calibrations (energy scales, resolutions, efficiencies etc.);– Minimisation of poorly estimated SM backgrounds;– Estimation of remaining SM backgrounds;– Development of useful tools.– Definition of prescale (calibration) trigger strategy

• Different situation to Run II (no previous measurements at same s)• Will need convincing bckgrnd. estimate with little data as possible.• Background estimation techniques will change depending on

integrated lumi. • Ditto optimum search channels & cuts.• Aim to use combination of

– Fast-sim;– Full-sim;– Estimations from data.

• Use comparison between different techniques to validate estimates and build confidence in (blind) analysis.


Black Hole SignaturesBlack Hole Signatures• In large ED (ADD) scenario, when impact

parameter smaller than Schwartzschild radius Black Hole produced with potentially large x-sec (~100 pb).

• Decays democratically through Black Body radiation of SM states – Boltzmann energy distribution.

Mp=1TeV, n=2, MBH = 6.1TeV

• Discovery potential (preliminary)– Mp < ~4 TeV < ~ 1 day

– Mp < ~6 TeV < ~ 1 year

• Studies continue …

ATLAS w/o pile-up

w/o pile-up ATLAS


Sbottom/Gluino MassSbottom/Gluino Mass• Following measurement of squark, slepton

and neutralino masses move up decay chain and study alternative chains.

• One possibility: require b-tagged jet in addition to dileptons.

• Give sensitivity to sbottom mass (actually two peaks) and gluino mass.

• Problem with large error on input 01 mass

remains reconstruct difference of gluino and sbottom masses.

• Allows separation of b1 and b2 with 300 fb-1.

lbb

l

g~ b~ lR

~~

~p p 300 fb-1

~

~ ~

m(g)-0.99m(01)

= (500.0 ± 6.4) GeV

300 fb-1

ATLAS

ATLAS

SPS1a

SPS1a

m(g)-m(b1) = (103.3 ± 1.8) GeV

m(g)-m(b2) = (70.6 ± 2.6) GeV

~ ~

~ ~

~ ~


RH Squark MassRH Squark Mass• Right handed squarks difficult as rarely decay via ‘standard’ 0

2 chain

– Typically BR (qR 01q) > 99%.

• Instead search for events with 2 hard jets and lots of ETmiss.

• Reconstruct mass using ‘stransverse mass’ (Allanach et al.):mT2

2 = min [max{mT2(pT

j(1),qT(1);m),mT

2(pTj(2),qT

(2);m)}]

• Needs 01 mass measurement as input.

• Also works for sleptons.

qT(1)+qT

(2)=ETmiss

~ ~

~qRq

~

ATLAS

ATLAS

ATLAS

30 fb-130 fb-1 100 fb-1

Left sleptonRight

squark

Right squark

~

~

SPS1a

SPS1aSPS1a

Precision ~ 3%


Physics StrategyPhysics Strategy• December 2007(?): 900 GeV calibration run

– commence tuning trigger menus / in situ calibration

• Summer 2008: first 14 TeV physics run (L < 1032 cm-2 s-1, Lint ~ 1 fb-1)

– commence tuning trigger menus / in situ calibration

– First SM measurements: min bias, PDF constraints, Z / W / top / QCD

• 2008/9: physics run (L ~ 2x1033 cm-2 s-1, Lint ~ 10 fb-1)

– First B-physics measurements & rare decay searches (e.g. Bs→J/) – First searches: high mass dilepton / Z’, inclusive SUSY, Black Hole

production, Higgs in ‘easier’ channels e.g. H→4l

• 2009/10: physics run (L ~ 2x1033 cm-2 s-1, Lint = 10 fb-1/year)

– First precision SM & B-physics measurements (systematics under control)

– Improved searches sensitivity

– Light Higgs searches (ttH, H→gg, VBF qqH(H→) etc.)

• 2010/11: High luminosity running (L ~1034, Lint = 100 fb-1/year)

– High precision measurements of New Physics (e.g. Higgs/SUSY/ED properties)


Inclusive SUSYInclusive SUSY• First SUSY parameter to be measured

may be mass scale:– Defined as weighted mean of masses of

initial sparticles.

• Calculate distribution of 'effective mass' variable defined as scalar sum of masses of all jets (or four hardest) and ET

miss:

Meff=pTi| + ET

miss.

• Distribution peaked at ~ twice SUSY mass scale for signal events.

• Pseudo 'model-independent' measurement.

• With PS typical measurement error (syst+stat) ~10% for mSUGRA models for 10 fb-1 , errors much greater with ME calculation an important lesson …

Jets + ETmiss + 0 leptons

ATLAS

10 fb-1


SUSY Spin MeasurementSUSY Spin Measurement• Q: How do we know that a SUSY signal is really due to SUSY?

– Other models (e.g. UED) can mimic SUSY mass spectrum

• A: Measure spin of new particles.• One possibility – use ‘standard’ two-body slepton decay chain

– charge asymmetry of lq pairs measures spin of 02

– relies on valence quark contribution to pdf of proton (C asymmetry)

– shape of dilepton invariant mass spectrum measures slepton spin

~

150 fb -1

spin-0=flat

Point 5

ATLAS

ll

llA

mlq

Straightline distn

(phase-space)

Point 5

Spin-½, mostly winoSpin-0

Spin-½

Spin-0

Spin-½, mostly bino

Polarise

MeasureAngle

ATLAS

150 fb -1


Processing the DataProcessing the Data

• Understand/interpret data via numerically intensive simulations

– e.g. 1 event (ATLAS Monte Carlo Simulation) ~20 mins/3 MB

• Use worldwide computing Grid to solve problem

• Many events– ~109 events/experiment/year

– ~3 MB/event raw data

– several passes required

Worldwide LHC computing requirement (2007):– 100 Million SPECint2000

(=20,000 of today’s fastest processors)

– 12-14 PetaBytes of data per year (=100,000 of today’s highest capacity HDD).

16 Million channels

100 kHzLEVEL-1 TRIGGER

1 MegaByte EVENT DATA

200 GigaByte BUFFERS500 Readout memories

3 Gigacell buffers

500 Gigabit/s

Gigabit/s SERVICE LAN PetaByte ARCHIVE

Energy Tracks

Networks

1 Terabit/s(50000 DATA CHANNELS)

20 TeraIPS

EVENT BUILDER

EVENT FILTER

40 MHzCOLLISION RATE

Charge Time Pattern

Detectors

Grid Computing Service 300 TeraIPS


25 ns

Event rate in ATLAS :

N = L x (pp) 109 interactions/s

Mostly soft ( low pT ) events

Interesting hard (high-pT ) events are rare Each accompanied by 20 soft eventsAlso additional soft interactions (UE)

ATLAS


Background EstimationBackground Estimation• Inclusive signature: jets + n leptons + ET

miss

• Main backgrounds:– Z + n jets– W + n jets – QCD– ttbar

• Greatest discrimination power from ETmiss

(R-Parity conserving models)• Generic approach to background

estimation:– Select low ET

miss background calibration samples;

– Extrapolate into high ETmiss signal region.

• Used by CDF / D0• Extrapolation is non-trivial.

– Must find variables uncorrelated with ETmiss

• Several approaches being developed.

Jets + ETmiss + 0 leptons

ATLAS

10 fb-1

PPC07, May 2007 Dan Tovey 1 Dark Matter Searches at ATLAS Dan Tovey University of Sheffield Dan...

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