What the LHC Will Teach Us About Low Energy Supersymmetryacosta/susy_aspen2003.pdf · 2003. 1....

What the LHC Will Teach Us About Low Energy

Supersymmetry

Darin Acosta

representing

ATLAS &

SUSY at the LHC, Aspen 2003 D. Acosta, University of Florida2

Outline

Introduction to SUSY, LHC, and the Detectors

Trigger strategies at start-up

Inclusive squark/gluino searches

SUSY SpectroscopyDi-lepton edgessquark and gluino reconstruction

Summary


Minimal SuperSymmetry

SUSYSymmetry between bosons and fermions

Squarks/sleptons:scalar counterparts to the fermionsCharginos/neutralinos/gluinos: fermion counterparts to SM gauge bosonsAt least two Higgs doublets (5 scalars):

Avoids fine-tuning of SM, can lead to GUTsMSSM

Usually consider RP ≡ (-1)3(B-L)+2S conserved ⇒ LSP is stable105 new parameters

mSUGRA:Require SUSY to be a local symmetryUniversal gravitational interactions break SUSY at scale F ~ (1011 GeV)25 free parameters

m0 : Common scalar massm1/2 : Common gaugino massA0 : Common scalar trilinear couplingtan β : Ratio of v.e.v. of Higgs doubletsSign(µ) : sign of Higgsino mixing parameter

Typically: M M M~ ~ ~χ χ χ1 20

102± ≈ ≈d i d i d i

M g M q M~ ~ ~a f a f a f> > χ

~,~q l

~ , ~ , ~, , , ,χ χ1 2 1 2 3 4

0± g

h H A H, , ,0 ±


Large Hadron Collider (LHC)

CMS

ATLAS

R = 4.5 kmE = 7 TeV

Two proton rings housed in same tunnel as LEP

Design luminosity: L = 1034 cm–2s–1 = 100 fb-1/year

(Pile up: ~20 collisions/crossing)

Start-up luminosity: L ~ 1033 cm–2s–1 = 10 fb-1/year

Completion: mid 2007


mSUGRA Cross Sections @ LHC~, ~q gTotal cross section

0

200

400

600

800

1000

1200

1400

0 500 1000 1500 2000m0 (GeV)

m1/

2 (

GeV

)

10 pb

1 pb

100 fb

10 fb

1 fb

EX

TH

A0 = 0 , tan β = 35 , µ > 0

Squark/gluino production dominates the total cross-section for low energy SUSYCross sections don’t vary much with µ, tanβ


Detectors

Compact Muon Solenoid (CMS)

ATLAS

muon

PbWO4 ECALFull Si tracker

4T solenoid

Cu/Scin HCAL

LAr CAL

TRT and Si tracker

Tile CAL

2T solenoidtoroids


SUSY Signatures

Complex squark/gluino decay chainsMany high-ET jetsHeavy-flavor (τ and b, especially at large tanβ)Leptons

From sleptons, charginos, W/Z, and b-jetsMissing transverse energy (MET)

From LSP and neutrinos from taus, sneutrinosExample:

CMS event simulation

m0 = 1000 GeVm1/2 = 500 GeVtan β = 35µ > 0A0 = 0


Trigger Challenge

Reduce 40 MHz bx rate (1 GHz pp) → O(100 Hz)Inclusive Jet Rate (cone algorithm, R=0.5):

Expected MET Rate:Recon. MET (hi lumi)Recon. MET (low lumi)Gen. MET (hi lumi)Gen MET (low lumi)

Full GEANT-based detector simulation on QCD background

CMS DAQ Technical Design Report CERN/LHCC 2002-26

Reconstructed MET rate below 100 GeVmainly from calorimeter energy resolution

Requiring a rate to tape of a ~few Hz implies an inclusive single jet threshold of 400–600GeV, and an inclusive MET threshold of100–200 GeV

Low lumi

High lumi


SUSY Trigger Exercise (CMS)Consider several points in the m0-m1/2 plane near the Tevatron reach (most difficult for LHC)

Consider points with and without Rp conservationFor Rp choose most difficult case:

Run full GEANT-based detector simulation on SUSY signals and SM backgrounds to evaluate trigger performance

Optimize efficiency for a rate to tape O(10 Hz)

~χ10 3→ j

(1 day of running)


Example Trigger Strategy (CMS)

Low luminosity case, L = 2×1033 cm-2s-1

Possible triggers at Level-2 (looser requirements at Level-1):

1 jet ET>180 GeV & MET>120 GeV4 jets ET>110 GeV

Overall efficiencies to pass both trigger levels for the SUSY points are:

ε=0.63, 0.63, 0.37, 0.43, 0.38, 0.23

More exclusive triggers involving angular correlations among objects can be added to further improve efficiency

Trigger becomes more efficient at high luminosity since one expects to explore higher masses

4 5 6 4R 5R 6R

With RP

1st jet

2nd jet

Background rate of ~12Hz dominated by QCD

(values at 95% gen. effic.)


Lepton and Photon Triggers

) 2

( GeV /cµµ inv M

0 20 40 60 80 100 120 140 160 180 200

)2 D

iffe

ren

tial

Rat

e (

Hz/

GeV

/c

10-4

10-3

10-2

10-1

1

10

33 L = 2x10 Minimum Bias

+ X µ → *γ Z/

+ Xµ → t t

Anticipated thresholds by ATLAS and CMS for an initial luminosity of L = 2×1033 cm-2s-1

1e: PT > 25 GeV2e: PT > 15 GeV1µ: PT > 20 GeV2µ: PT > 10 GeV1τ: PT > 85 GeV2τ: PT > 60 GeV1γ: PT > 60–80 GeV2γ: PT > 20–40 GeV

Sufficient handle on muon trigger rate:

Di-muon invariant mass at Level-3

CMS


Fast Simulation

Full simulation of signals and backgrounds like that shown for trigger exercise is too CPU intensive for complete SUSY reach determination

Require O(108) events, but full GEANT simulation takes tens of minutes per eventUse physics generators + parameterized detector performance

ATLFAST:Tracks (µ): ∆PT/PT = 0.4PT ⊕ 1% (PT in TeV)EM resolution: σ/E ~ 10%/√E ⊕ 0.3% (E in GeV)Jet resolution: σ/E ~ 60%/√E ⊕ 2% (E in GeV)

CMSJET:Tracks (µ): ∆PT/PT = 0.15PT ⊕ 0.5% (PT in TeV)EM resolution: σ/E ~ 5%/√E ⊕ 0.5% (E in GeV)Jet resolution: σ/E ~ 100%/√E ⊕ 5% (E in GeV)


Inclusive q, g Search~ ~

Counting excess events over SM backgroundDiscovery mode SUSY search at LHCExplicit sparticle reconstruction not done

6 Analyses:ET

miss: jets+MET, no lepton requirements Ol: no leptons1l: 1 lepton2lOS: 2 leptons, opposite sign2lSS: 2 leptons, same sign3l: 3 leptons

CMS Study:Common cuts:

MET>200 GeV, ≥2 jets, ETjet > 40 GeV, |η|<3

Lepton identificationElectron: PT>20 GeV, isolated, |η|<2.4Muon: PT>10 GeV, isolated or not, |η|<2.4

Vary cuts in 6 categories (~104 combinations)#Jets, MET, Jet ET, ∆φ(l,MET), Circ., µ Iso.

Optimize S/√(S+B) in a counting experimentProbe 500 (m0, m1/2) points

~106 signal events, ~108 QCD, tt, W/Z+jetsPlot 5σ sensitivity contours


CMS q, g Reach~ ~

0

200

400

600

800

1000

1200

1400

0 500 1000 1500 2000

m0 ( GeV)

m1/

2 (G

eV)

ET miss

(300 fb-1)

ET miss

0l

0l + 1l + 2l OS

1l

2l OS

2l SS3l

g~(500)

g~(1000)

g~(1500)

g~(2000)

g~(2500)

g~(3000)

q ~(2500)

q~(2000)

q ~(1500)

q ~(1000)

q~(500)

h(110)

h(123)

L dt = 100 fb-1

A0 = 0 , tan β = 35 , µ > 0

h2 = 1

h2 = 0.4

h 2 = 0.15

EX

TH

ISA

JET

7.32

+ C

MSJ

ET

4.5

Jets+MET search gives greatest sensitivityOpposite-sign leptons useful for sparticle recon.

Nucl. Phys. B547 (1999) 60


Jets+MET Reach vs. Luminosity

0

200

400

600

800

1000

1200

1400

0 500 1000 1500 2000

m0 ( GeV)

m1/

2 (G

eV)

ET miss

(1 fb-1)

ET miss

(10 fb-1)

ET miss

(100 fb-1)

ET miss

(300 fb-1)

g~(500)

g~(1000)

g~(1500)

g~(2000)

g~(2500)

g~(3000)

q ~(2500)

q~(2000)

q ~(1500)

q ~(1000)

q~(500)

h(110)

h(123)

L dt = 1, 10, 100, 300 fb-1

A0 = 0 , tan β = 35 , µ > 0

h2 = 1

h 2 = 0.4

h 2 = 0.15

EX

TH

CMS

~1 year @ L=1034

~1 year @ L=1033

~1 month @L=1033

~1 week @L=1033

(but one year for sparticle reconstruction)

Tevatron reach < 0.5 TeV

Squarks/gluinos probed to ~1.5 TeV with 1 fb-1

Up to 2.5 TeV at design luminosity (100 fb-1)


Other Parameter Choices

Similar cuts and optimization as for CMS studySensitivity for lower tanβ also derived, but lower mass Higgs inconsistent with present limits

L=10 fb–1

~1 year @ L=1033

ATLASTDR 15CERN/LHCC 99-15

0 500 1000 1500 20000

200

400

600

800

0

200

400

600

800

m0 (GeV)

2l,0j

2l,0j

3l,0j

3l,0j

1l

1l

0l

0l

SS

SS

OS

OS

3l

3l

tan β = 10, µ > 0

tan β = 10, µ < 0


R-Parity Violation

Non-conservation of RP ≡ (-1)3(B-L)+2S leads to 3 new terms in SUSY superpotential:

Choose most challenging of baryon number violation (last case):

ATLAS Study of “Point 5”m0=100 GeV, m1/2=300 GeV, tanβ=2, µ>0, A0=300MET is reduced, but still substantialNumber of jets increasesLeptons from neutralino decays

Should still be able to explore much of the parameter space as with mSUGRA

Figure 20-85 distribution for SUGRA Point 5in the case of R-parity conservation (shaded histo-gram) and R-parity violation (empty histogram).

Figure 20-86 Total jet multiplicity ( )distribution for R-parity conservation (shaded) and R-parity violation at SUGRA Point 5. The jets are recon-structed using a topological algorithm based on joiningneighbouring cells.

0 200 400 600 800 1000

Emiss (GeV)T

Eve

nts/

10 G

eV/3

0 fb

-1

10

102

103

0 2 4 6 8 10 12 14 16 18 20

Njet

Pro

babi

lity

0.16

0.14

0.12

0.10

0.08

0.06

0.04

0.02

0

ETmiss pT

jet 15GeV>

~χ10 3→ j

W L L E Q L D U L Dijk i j kc

ijk i j kc

ijk icjckc= + ′ + ′′λ λ λ


Exclusive Di-Lepton Reconstruction

Measure invariant mass distribution of OS same flavor leptons as evidence for

or

can be produced via Drell-Yan ,but more prevalent in cascade decays of

Endpoint in mass spectrum exhibits sharp edge:

This point selected by:Two OS leptons (e,µ), PT>(20,10) GeV, |η|<2.5MET>200 GeV, 4 jets: PT

1>100 GeV, PT234>50 GeV

3-body decay endpoint:2-body:

~ ~χ χ20

10→ + −l l ~ ~ ~χ χ2

010→ →+ − + −l l l l

~χ20 ~ ~χ χ1 2

0±

~, ~q g

M(l+l−) (GeV)

Eve

nts/

4 G

eV/3

0 fb

−1

SUSY e+e− + µ+µ−

SM backgroundATLAS “Point 4”:m0=800GeV m1/2=200GeVtanβ=10 µ>0 A0=0

L=30 fb–1

~ ~χ χ20

10→ + −l l

m m mllmax ~ ~= −χ χ2

010d i d i

Some Z0 from other gauginos

m m m m m mll l l lmax ~ ~ ~ ~ / ~= − −220 2 2 2

10χ χd i c he i c h d ie i c h

SM background is small


Evolution of Di-Lepton Edges

SUSY may reveal itself early through peculiarities in the the di-lepton spectraStructures tend to be less evident with increasing tanβ, where dominates

103

103

104

102

10

102

10

1 1

M(I+I-) (GeV)

m0 = 90 GeV, m1/2 = 220 GeV

mχ2 = 164 GeV, meR

= 129 GeV

Eve

nts

/ 4 G

eV

µ>0, A0 = 0

χ2

eRe / µRµ

tanβ = 2

m0 = 100 GeV, m1/2 = 190 GeVµ>0, A0 = 0

tanβ = 10

~

~ ~

~ ~0

o mχ2 = 140 GeV, meR

= 132 GeV~ ~o

mτ1 = 128 GeV~

χ2

eRe / µRµ~ ~ ~0

mτ1 = 124 GeV

χ2

τ1τ~ ~0

ee,µµ

eµ

SM SM

eµ

ee,µµ

5 fb-15 fb-1

M(I+I-) (GeV)100 0 200 300100 0 200 300

103 103

102

10

100M(I+I-) (GeV)

0 200 300 100 0 200 300

102

10

1 1

m0 = 90 GeV, m1/2 = 220 GeVµ>0, A0 = 0

tanβ = 20

m0 = 100 GeV, m1/2 = 190 GeVµ>0, A0 = 0

tanβ = 25mχ

2 = 167 GeV, meR

= 132 GeV~ ~0 mχ2 = 141 GeV, meR

= 132 GeV~ ~0

mτ1 = 103 GeV~ mτ1 = 91 GeV

D_D

_201

7c

eµ

ee,µµ

SMSM

eµ

ee,µµ

5 fb-1 5 fb-1

M(I+I-) (GeV)

~ ~χ χ τ τ20

10→ + −


Di-Tau Edge ReconstructionATLAS Physics TDR study (Full GEANT simulation)

to select hadronic tau decaysSelect narrow isolated jets: Rjet=0.2, Riso=0.4Require 0.8 GeV < Mjet < 3.6 GeV

Biased against 1-prong decays, but improves Mττ resolution (less neutrino momentum)

Di-tau efficiency is 41%Mvis = 0.66 Mττ

Additional event selection cuts4 jets: ET

1 > 100 GeV, ET2-4 > 50 GeV,

MET>100 GeV, no e,µ leptons with pT>20 GeV

0

500

1000

Eve

nts/

2.4

GeV

/10

fb-1

25 50 75 100Mττ (GeV)

0

ATLAS “Point 6”:m0=200GeV m1/2=200GeVtanβ=45 µ<0 A0=0

L=30 fb–1

BR ~ ~ .χ ττ20 99 9%→ =d i

Mvis = 40 GeVExpected edge = 60 GeV

Real τ from SUSYFake τ from SUSYSM background


Exclusive Sparticle Reconstruction

Completely reconstruct a SUSY decay chain:

ATLAS Study“Point 3” of Physics TDR

m0=200 GeV, m1/2=100 GeV, tanβ=2, µ<0, A0=0CMS Study [Chiorboli]

Investigate Points B & G of “Proposed Post-LEP Benchmarks for SUSY” (hep-ph/0106204)

B: m0=100 GeV, m1/2=250 GeV, tanβ=10, µ>0, A0=0– σTOT(SUSY) = 58 pb

G: m0=120 GeV, m1/2=375 GeV, tanβ=20, µ>0, A0=0– σTOT(SUSY) = 6.0 pb

ISASUGRA→PYTHIA→CMSJET

p

p

g~

b~

b

b

ml

±l

01

~χ

02

~χ ±l~

q~

(~~, ~~, ~~qg qq gg dominate)


Di-Lepton Edge Reconstruction

Start with reconstructing (tanβ not too large)Two OS isolated leptons, PT>15 GeV, |η|<2.4

MET>150 GeV, E(ll)>100 GeV

Select 15 GeV window around di-lepton endpoint

~χ20

p

p

g~

b~

b

b

ml

±l

01

~χ

02

~χ ±l~

q~

p

p

g~

b~

b

b

ml

±l

01

~χ

02

~χ ±l~

p

p

g~

b~

b

b

ml

±l

01

~χ

02

~χ ±l~

q~q~

~ ~

~~

~

~ ~

χ χ

χχ

χ

χ χ

10

20

20 1

0

10

20

10

1

2

at rest in rest frame

Can estimate from di - lepton endpoint and

Point B: 174 GeV,

but analysis not too sensitive to details

v

l l

vl lp

m

mp

m

m m

d i d id i d i

d id i d i

= +FHG

IKJ

≈

+ −+ −

0

100

200

300

400

500

600

700

800

900

0 25 50 75 100 125 150 175 200

M(e+e-)+M(µ+µ-) (GeV)

Eve

nts

/ 3

GeV

SUSY

tt-

Z + jet

0

10

20

30

40

50

0 20 40 60 80 100 120 140 160 180 200

M(e+e-)+M(µ+µ-)-M(e+µ-)-M(µ+e-) (GeV)

Even

ts / 2

GeVPoint B

L=10 fb–1

CMS

Subtract opposite flavors

BR=16%

Edge=79±2 GeV


b Reconstruction~

0

5

10

15

20

25

30

35

0 200 400 600 800 1000

IDEntriesMeanRMS

103 291

504.6 152.8

25.38 / 20P1 0.3074E-13P2 -0.1512E+16P3 0.2550E+13P4 0.2699E+11P5 -0.6571E-02P6 25.57P7 500.1P8 42.22

M( 20 b) (GeV)

Eve

nts

/ 28

GeV

SUSY

tt-

Add most energetic b-jet to reconstruct bEb-jet>250 GeV, |η|<2.4b-jet: ≥2 tracks with IP significance > 3σ

Require MET>150 GeVE(ll)>100 GeV

L=10 fb–1

CMS

Mass (GeV)

p

p

g~

b~

b

b

ml

±l

01

~χ

02

~χ ±l~

q~

p

p

g~

b~

b

b

ml

±l

01

~χ

02

~χ ±l~

p

p

g~

b~

b

b

ml

±l

01

~χ

02

~χ ±l~

q~q~

Result of fit:

M(b) = 500±7 GeVσM = 42 GeV

Generated masses:

M(bL) = 496 GeV

M(bR) = 524 GeV

Point B~

~~

BR ~ 5%

σ × BR dominates


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35

0 50 100 150 200 250 300

Entries 124 8.681 / 7

P1 -0.2030E-09P2 -0.2055E+09P3 0.1989E+08P4 -0.1692E+08P5 -0.2288E-01P6 27.32P7 92.41P8 16.91

M( 20 b b) - M( 2

0 b) (GeV)

Eve

nts

/ 15

GeV

SUSY

tt-

Add another b-jet closest in φ to reconstruct g&

0

5

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35

200 300 400 500 600 700 800 900 1000

IDEntriesMeanRMS

203 153

626.7 91.15

12.39 / 10P1 0.1430E-12P2 0.1678E+15P3 -0.5078E+14P4 0.1170E+12P5 -0.9486E-02P6 19.45P7 593.5P8 42.37

M( 20 b b) (GeV)

Eve

nts

/ 28

GeV

SUSY

tt-

g Reconstruction~

~

m g m b m~ ~ ~a f c h d i− is independent of :χ10

-1

5000

10000

15000

20000

Eve

nts/

4 G

eV/1

0 fb

M(χ2bb)-M(χ2b) GeV20 40 60 80 1000

0

ATLAS Point 3

Expect 20 GeV

Point BCMS

Expect 87 GeV

CMSL=10 fb–1

Mass (GeV)

Mass (GeV)

p

p

g~

b~

b

b

ml

±l

01

~χ

02

~χ ±l~

q~

p

p

g~

b~

b

b

ml

±l

01

~χ

02

~χ ±l~

p

p

g~

b~

b

b

ml

±l

01

~χ

02

~χ ±l~

q~q~

Point B

Result of fit:

M(g) = 594±7 GeVσM = 42 GeV

Generated mass:

M(g) = 595 GeV

~

~

400 600 GeV GeV< <M b~c h

BR ~ 1%


q Reconstruction~

Same di-lepton edge selection as beforeTwo jets with pT>20 GeV, |η|<2.4MET > 100 GeVVeto all b-jets

Track with second largest IP significance < 2σHelps reject sbottom and stop decays

Less luminosity required (1 fb-1)

q

CMSL=1 fb–1

Point B

Result of fit:

M(q) = 536±10 GeVσM = 60 GeV

Generated masses:

M(qL) = 543 GeV

M(qR) = 537 GeV

~

~~

Mass (GeV)

BR ~ 5%


Point G ReconstructionCross section 10× smallerSmaller branching ratios

Eb-jet>350 GeV, MET>350 GeVsbottom Result of fit:

M(b) = 720 ±26 GeVσM = 81 GeV

Generated masses:

M(bL) = 702 GeV

M(bR) = 748 GeV

~

~~

Result of fit:

M(g) = 850±40 GeVσM = 130 GeV

Generated mass:

M(g) = 860 GeV

~

~

0

2

4

6

8

10

12

14

400 600 800 1000 1200 1400

IDEntriesMeanRMS

101 89

739.9 206.3

10.13 / 9P1 0.3413E-12P2 0.3982E+14P3 -0.9041E+12P4 0.2531E+10P5 -0.5623E-02P6 9.488P7 719.7P8 81.06

M( 20 b) (GeV)

Eve

nts

/ 60

GeV

Require 300 fb-1

>1 year @ 1034

0

5

10

15

20

25

400 600 800 1000 1200 1400

IDEntriesMeanRMS

201 112

898.4 141.6

9.009 / 4P1 0.6774E-13P2 0.3944E+16P3 -0.7096E+14P4 0.1002E+12P5 -0.6384E-02P6 13.08P7 852.7P8 130.6

M( 20 b b) (GeV)

Eve

nts

/ 60

GeV

gluino


Can mSUGRA Escape LHC?

M.Battaglia et al., Eur.Phys.J. C22 (2001) 535 (hep-ph/0106204) proposed several SUSY benchmark points in the post-LEP era

Two of them would lead to sparticles beyond the reach of the LHC except for a light Higgs

squark/gluino masses > 2.5 TeV

But most other points covered well

If SUSY exists, prospects at LHC look favorable

Sparticles reconstructed in 10 fb-1

Sparticles reconstructed in 300 fb-1

Di-lepton edge not observable

X X


LHC Summary

Discovery of SUSY, if it exists, is almost assured at the LHC

Inclusive mSUGRA squark/gluino discovery reach to 1.5 TeV with 1 fb–1, 2.5 TeV with 100 fb–1

Difficult part will be untangling decay chains and measuring mass relations

Possibility to reconstruct squark/gluino/neutralinodecays in mSUGRA for several prototype analyses

Mass resolution <10% under some assumptionsGenerally require tanβ<35Generally require much more data (years)

Trigger strategies identified for efficient coverage

Many more exhaustive SUSY studies at the LHC experiments are available:

ATLAS TDR 15 CERN/LHCC 99-15CMS Note 1998/006

Looking forward to studying SUSY spectroscopy before the end of the decade !


Minimal GMSBGauge Mediated Symmetry Breaking

Uses SM gauge interactions instead of gravity to break SUSY

Solves FCNC problemSUSY breaking scale much less than mSUGRAscale √F << 1011 GeVParticles get mass from SM gauge interactions at a messenger scale Mm ~ O(1000 TeV) << MPln = number of SU(5) messenger fieldsΛ = F / Mm ~ 100 TeV

NLSP lifetime:

cτ >> detector sizeslepton ( τ ) is a long-lived heavy lepton (like µ)neutralino leads to MET, like MSSM

cτ ~ detector sizeMeasure NLSP lifetimeEstimate F

cτ << detector sizeradiative decay with γ

~

~ ~ tan )~ ~ tan )

G m

G n

G n

is LSP ( 1 GeV)

NLSP: ( = 1, low

( > 1, high 10

<<

→

→

χ γ β

βl l

cM

Fτ ~ .1 3 1001000

5 4 m GeV

TeVNLSP

FHG

IKJFHG

IKJ

~


GMSB Heavy Lepton (τ) Search~

Use drift-tube muon systems of ATLAS and CMS to measure time-of-flight for heavy leptons (σ ~ 1ns)

Measure 1/β and p ⇒ reconstruct massCMS:

Require 2 “muons” with PT>45 GeV, M>97 GeV|η|<1 for CMS drift-tube systemCan measure stau mass from 90–700 GeV:

0

10

20

30

40

50

60

70

0 100 200 300 400 500 600 700 800 900 1000

reconstructed mass (GeV)

part

icle

s / 2

0 G

eV 114GeV; L=1/fb; eff=5%

303GeV; L=10/fb; eff=15%

636GeV; L=100/fb; eff=26%

n=3, tanβ=45, Λ=50-300 TeV, M/Λ=200

CMS CR 1999/019

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 200 400 600 800 1000 1200 1400

momentum (GeV)

1/β

ATLAS


0

100

200

300

-10 -5 0 5 10

zcal o-ztrue (cm)

Eve

nts/

0.2c

m

σ =1.33 cm

10-1

1

10

10-2

10-1

1 10 102

103

cτ (m)

σ +(c

τ)/c

τ

ECAL counting

CAL counting

ECAL/ CAL

ECAL impact

CAL slope

COMBINED

L=143/fb; effkin=10%

m(N1)=291GeV

GMSB N1 Lifetime Measurement

Look for N1 decays inside detectors:1) Electromagnetic showers not pointing to vertex

Use fine angular resolution from LAr EM calorimeter (ATLAS) and PbWO4 crystals (CMS)

ATLAS: if no non-pointing γ’s in 30 fb-1 ⇒ cτ > 100km

2) Showers in muon systemIdentify showers with high hit multiplicity

CMS: Overall sensitivity to measure cτ:

~

ATLAS vertex resolution for H→γγ

~

(Λ=90 TeV, M = 500 TeV, n=1)

µ

µ

µ

What the LHC Will Teach Us About Low Energy Supersymmetryacosta/susy_aspen2003.pdf · 2003. 1....

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Transcript of What the LHC Will Teach Us About Low Energy Supersymmetryacosta/susy_aspen2003.pdf · 2003. 1....