Search for SUGRA at

Silke DuensingSUSY 2003, June 10 th

Interactions

p p

~1 TeV ~1 TeVu

d

u

qq

u

u

d

SUGRA@Tevatron

p p

~1 TeV ~1 TeVu

d

u

qq

u

u

d

Sparticles are produced in pairs

R-parity conservation: decay into the “partner” +LSP

LSP->missing energy, mET at Tevatron

Squark/gluino pair production

Jets + Missing ET is generic signature for squark/gluino production in SUGRA

Typical cross-sections (pb)

m [GeV]

Jets + Missing ET

Typical cross-sections (pb)

m [GeV]

– Offline: • leading jet has pT > 100 GeV , leading two jets are central

– insures full efficiency of trigger

• mET calculated by adding all calorimeter towers with E>200 MeV

– Used are (the first) ~ 4 pb-1

• Selection : >=2 jets + mET – Trigger:

• >=1 jet with pT > 65 GeV

Jets + Missing ET

• Selection : >=2 jets + mET – Background (I) - Physics:

• PYTHIA-generated and fully simulated samples for physics backgrounds (real mET)

– Background (II) - Instrumental: • Ensure good quality of data• Require ||(mET, jet1,2)>0.15

– reject events where mET results from mismeasured Jet pT

• fit to low mET region to estimate QCD background

– mismeasured mET

g~

Fit interval 40-65 GeV

mET

(GeV)

QCD Bkg.

Total Bkg

Data 95%CL (pb)

≥ 70 17.48.4 18.48.4 7 4.2

≥ 80 8.55.3 9.5 5.3 6 3.8

≥ 90 4.23.2 5.1 3.2 4 3.1

≥ 100 2.01.8 2.7 1.8 3 2.7

Jets + Missing ET

Fit interval 40-65 GeV

• Error is sum of:– Statistical error of QCD bkg

• From error of fit parameters

– Systematic error of QCD bkg• From different fit ranges

– (much smaller) statistics of MC sample of physics background

• Neutralinos/charginos– trilepton channel

• Electron-muon channel– Low SM background

WW, ttbar, Z/WW, ttbar, Z/** -> ->

– gain compared to Run I for DØ:improved particle identification

pp ˜ i˜ j

, ˜ i0 ˜ j

, ˜ i0 ˜ j

0

Final States with Leptons

– Provides model independent limit on NP cross section

• require pT >15 GeV for both leptons (e/)

• physics background from Monte Carlo

• Instrumental background (fake rates) from data

• Quote cross-section limits as function of mET

Njet

mET

PT

einclusive search

e inclusive

~30 pb-1

Process Size

ZeWW ett e jj

5.6 ± 0.4

1.0 ± 0.1

0.02 ± 0.01

QCD + W+jets

3.01 ± 2.7

All 9.6 ± 2.7

Data 13

No jets ET > 15 GeVNo missing ET cut

Ø

mET DATA TOT BKG

> 0 13 9.6 2.7

> 5 10 7.4 2.2

> 10 7 4.6 1.6

> 15 6 3.0 1.3

> 20 3 2.3 1.1

> 25 3 1.9 1.0

> 30 2 1.6 0.8

> 40 0 1.4 0.7

> 45 0 1.1 0.5

100 fb

e - Limits on New Physics

Z dominates

Instrumental + WW

A(WWe

Chargino-Neutralino production

Tri-Lepton signature

Look at lee

Typical cross-sections (pb)

pp ˜ i˜ j

l1, 2, 3 ET X

2 points in Minimal2 points in Minimal

SUGRASUGRA

mm ≈≈2m2m

2m 2m ≈≈ 90 and 125 GeV90 and 125 GeV

~

01

~

01

~

Tri-lepton eel - pre-selection

1) At least 2 electrons (leading e p1) At least 2 electrons (leading e pTT>15 GeV >15 GeV 22ndnd e p e pTT>10 GeV) >10 GeV)

• Start from di-electron sample– understand trigger,

reconstruction, simulation

– verify determination of QCD fake background

• from data with inverted identification cuts

L = 42.0 pb-1

Tri-lepton eel-event selection

1) At least 2 electrons (leading e p1) At least 2 electrons (leading e pTT>15 GeV >15 GeV 22ndnd e p e pTT>10 GeV)>10 GeV)2)2) 10<Mee<70 GeV10<Mee<70 GeV

3) M3) MTT(e,mE(e,mETT)>15 GeV)>15 GeV

Tri-lepton eel- cross section limit

1) At least 2 electrons (leading e p1) At least 2 electrons (leading e pTT>15 GeV >15 GeV 22ndnd e p e pTT>10 GeV)>10 GeV)2) 10<Mee<70 GeV2) 10<Mee<70 GeV3) M3) MTT(e,mET)>15 GeV(e,mET)>15 GeV4) A third isolated track P4) A third isolated track PTT>5 GeV,|>5 GeV,||<3.0|<3.05) mET>15 GeV5) mET>15 GeV

typical selection efficiency for SUGRA 2-4%

Tri-lepton eel- cross section limit

1) At least 2 electrons (leading e p1) At least 2 electrons (leading e pTT>15 GeV >15 GeV 22ndnd e p e pTT>10 GeV)>10 GeV)2) 10<Mee<70 GeV2) 10<Mee<70 GeV3) M3) MTT(e,mET)>15 GeV(e,mET)>15 GeV4) A third isolated track P4) A third isolated track PTT>5 GeV,|>5 GeV,||<3.0|<3.05) mET>15 GeV5) mET>15 GeV

Cuts Sum Bkg Data

1) 3216 43 3132

2) 660 19 721

3) 96 8 123

4) 3.2 2.3 3

5) 0.0 1.4 0

x BR(3lepton) < 3.5 pb (95% CL)

……sensitivity still about factor of 7 away from extending excluded area in the parameter space

work in progress more data

Trilepton - eee mET event

Summary

• The Run II Era for searches has begun at DØ…– with a search for squarks/gluinos in Jet mET

– with a look at the e final state– with a trilepton - search containing electrons– So far - nothing beyond SM … but:

• all this will be updated with improved analyses, more channels and

more luminosity

-, PT = 45 GeV

e+, PT = 21 GeV

Missing ET = 33.5 GeV

Highest mET e event