sugra searches at the tevatron dan claes university of nebraska representing the cdf and d0...

SUGRA SUGRA Searches Searches

at the Tevatronat the Tevatron

Dan ClaesUniversity of Nebraska

representing theCDF and D0 Collaborations

The Conference on Higgs & Supersymmetry Laboratoire de l'Accélérateur Linéaire

Orsay, FranceMarch 19-22, 1999

“Precise measurement of the positive muon anomalous magnetic moment”(submitted to PRL February 23, 2001)

“Many people believethat the discovery ofsupersymmetry may be just around thecorner. We may haveopened the first tinywindow to that world.”

“We are now 99 percent sure that the present Standard Modelcalculations cannot describe our data.”

= (g2)/2 (SM)=11 659 159.6(6.7)10-10(0.57 ppm) (SM) (exp)= 43(16)10-10

Though just 5½ years ago...

Fig. 2 Rb and Rc data [2] and theSM predictions [5].

M

SUPERSYMMETRYNew symmetry unifying particles of different spin within multiplets -solves “fine-tuning” provided MSUSY < 1 TeV -allows unification of the gauge couplings

-includes quantum gravity

Particle Name Symbol Spartner Name Symbol gluon g gluino g charged Higgs Hchargino W1,2

charged weak boson light Higgs h neutralino Z1,2,3,4 heavy Higgs Hpseudoscalar Higgs Aneutral weak boson Z photon quark q squark qR,L

lepton l slepton lR,L

~

~

~~

~

Minimal Supersymmetric SM

Extension adding the fewest new particles

•2 Higgs doublet h0 H0 A0 H+

• and described by 4 parameters

M1 U(1) M2 U(2) gaugino mass parameter at EW scale

higgsino mass parametertan ratio of VEV of Higgs doublets

• scalar sector described by MANY mass parameters• different SUSY breaking different class of models

01

~ 1

~

MSSM Assumptions:

•SUSY particles are pair produced•Lightest SUSY particle (LSP) is stable

SLBparityR 23)1(

SUSY Symmetry BreakingSUGRA GeV)

•Lightest SUSY particle is

•5 free parametersmo common scalar massm1/2 common squark massAo trilinear couplingtansign(

01

~

pp e e X ~~

pp q g X ~ / ~

m mq g~ ~

m me eR L~ ~

Production has less dependence on SUSYparameters than decays

Squarks/gluinos dominant if kinematically accessible

Cross sections for scalarleptons are small

s 18. TeV

~q

~q

~*q

g

g

g

~q

~q

q

q

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay

Signal Cross SectionsSignal Cross Sections


If light, squarks and gluinos should be copiously produced at the Tevatron

g

g

q*

q

q

g

q

q

q

q

pp q g X ~ / ~

m mq g~ ~

s 18. TeV


q

g

0

1q

0

1q

q

Assuming R-partity is conserved, squarks and gluinos can decaydirectly into the LSP (0

1).

or cascade down to the LSP

q

g

q

So that the dominant signature for ppqq, qg, gg + X is jets+ET

q

q

q

q0

2

q

0

1

q

g q

qq

q

1

q

q

0

1

q


The 1992-1994 Tevatron RunThe 1992-1994 Tevatron Run

TeV 8.1s

Cross sections for new physics is smallcompared to Standard Model processes

But CDF and D0 both recorded over 100 pb-1 of data


The 1992-1994 Tevatron RunThe 1992-1994 Tevatron Run

DØ

Precision tracking: vertexing,b-tagging, lepton identification

Powerful calorimetry: e, , ET


D0 MET and Jets AnalysisD0 MET and Jets Analysis

pp q,g jets + ET

•large branching ratio, but suffers from enormous backgrounds•QCD multijet events w/faked ET

• W/Z+jets• t t

Used ET trigger, basic selection criteria:•ET

j1>115, ETj3>25 GeV

•ET>75 GeV •jets and ET not aligned Reduce QCD•HT( i >1Ei

T) > 100 GeV Reduce W/Z•veto isolated with PT > 15 GeV Reduce W/Z


Jet-EJet-ETT Correlations Correlations

Jet1

Jet2

Jet3

ET

3

1

3.0

2.5

2.0

1.5

1.0

0.5

0.00 0.5 1.0 1.5 2.0 2.5 3.0

MET, Jet1 vs MET, Jet2

Low Et JET MIN Trigger with offline Met > 10 GeV cut


Jet-EJet-ETT Correlations Correlations


D0 MET and Jets AnalysisD0 MET and Jets Analysis Final ET, HT cuts tuned to optimize S / B

across (m0, m1/2) plane79 pb-1 of data analyzed

Expected: 8.33.5 events Observed: 15

Mq > 250 GeV (95% C.L.)

Mg > 260 GeV (Mg=Mq)

Mg > 300 GeV (small mo)

~

~

~

~ ~

Phys.Rev.Lett. 83 4937 (1999); hep-ex/990213


D0 MET and Jets AnalysisD0 MET and Jets Analysis

Phys.Rev.Lett. 83 4937 (1999); hep-ex/990213

~

~

~

~ ~

Mq > 250 GeV (95% C.L.)

Mg > 260 GeV (Mg=Mq)

Mg > 300 GeV (small mo)


CDF MET and Jets AnalysisCDF MET and Jets Analysis

starting with basic cuts similar to DO

Missing ET trigger•cleanup jets projected to calorimeter gaps

Blind Box method defines signal region by:•ET>70 GeV

•HT( i >1EiT) > 150 GeV

•Ntrkiso (isolated tracks)=0

•indirect lepton veto


ET predominantly from mis-measured QCD events


QCD ET comparison:data(JET20+JET50) & predictions(Herwig)



Main backgroundsQCD, W/Z+jets, tt


CDF MET and Jets AnalysisCDF MET and Jets Analysis Expected: 76.02±12.8 events Observed 74



Expected: 76.02±12.8 events Observed 74

For mq mg mg > 300 GeV/c2

For mq << mg mg > 570 GeV/c2

For mq >> mg mg > 195 GeV/c2

~ ~

~ ~

~ ~

Daniel Claes, University of Nebraska Lincoln Higgs SUSY Conference 2001 Orsay, France

CDF Dilepton + Jets SearchCDF Dilepton + Jets Search

Squark & gluino cascade decays can also lead to dilepton final states

pp q, g 102+jj

jj + ET

Selection cuts on CDF’s dilepton trigger: 2 isolated leptons, PT > 11, 5 GeV 2 central jets ET > 15 GeV, | | < 2.4 ET > 15 GeV

q

q

~ ~ ~ ~~q

~q

02

1

q

~~

01

~

01

~

Z*W*

g


CDF Dilepton BackgroundsCDF Dilepton BackgroundsHeavy quark and di-boson production

Require LS leptons. Final M cut rejects Z-production.


CDF Dilepton + Jets SearchCDF Dilepton + Jets Search

Expect: 0.550.250.08 events

Observe: 0 events


Dilepton mSUGRA SearchDilepton mSUGRA SearchSquark and gluino search through dilepton final states

pp SUSY jj + ET

Selection, optimized for different regions of mSUGRA parameter space, made by (52 different) combinations ofET

jet 1,2 > 20 GeV or 45 GeV (optionally, also require ETjet3 > 20 GeV)

ee signatures: ETe1 > 17 GeV, ET

e2 > 15 GeVe signatures: ET

e > 17 GeV, ET > 4 GeV, 7 GeV or 10 GeV

signatures: ET1 > 20 GeV, ET

2 > 10 GeVET > 20, 30, or 40 GeV

q

q

~q

~q

02

1

q

~~

01

~

01

~

Z*W*

g


Dilepton mSUGRA SearchDilepton mSUGRA SearchBackground sources• QCD Multijet, W+jets

• estimated from data

• t t , Z + jets SPYTHIA-based Monte Carlo

(FMC0)

108 pb-1 of data analyzed

Mg = Mq > 255 GeV95% C.L. for tan = 2

~ ~


Charginos and NeutralinosCharginos and NeutralinosProduction of 1 0

2 will lead to trilepton final states with ET

perhaps the cleanest signature of supersymmetry.

pp q, g 102

+ ET

~ ~ ~ ~1

02

~

~

01

~

01

~

W*Z*

W*

q

q

q

q

1

02

~

~

1~ 0

2~

~0

1~

*

~

01

~

~ ~

q*~


Trilepton + Jets SearchTrilepton + Jets Search

Selection cuts : 3 (e,) with PT > 5 22 GeV require Opposite Sign Leptons (CDF) ET > 10 - 15 GeV mass and topological cuts

Both CDF and DO searched for trileptons (e,) in Run I PRL 80, 1591 (1998); PRL 80, 5275 (1998)

Very low background•Drell-Yan + fakes•heavy flavor production•ZZ, WZ


Trilepton + Jets SearchTrilepton + Jets Search

CDFExpected: 1.20.2Observed: 0

DOExpected: 1.30.4Observed: 0

mm

100<m0<2500 GeV/c2

a) m½=50 GeV/c2

b) m½=75 GeV/c2

c) m½=100 GeV/c2

d) m½=120 GeV/c2


Run II UpgradesRun II Upgrades

Main injector

Tevatron

DØCDF

Accelerator upgrade

Run I Run IItotal integrated luminosity

120 pb-1 2 fb-1 /2 years (20 fb-1 extended run)

instantaneous luminosity

4 - 20×1030/cm2sec 2×1032/cm2sec

bunch crossing intervals

3.8 sec 132 nsecbeam energy

1.8 TeV 2.0 TeV•complemented by major detector upgrades

Run II has begun with•Fermilab’s Main Injector(commissioned June 1999)•New anti-proton storage ring


The DO Detector UpgradeThe DO Detector Upgrade

•retain the uranium/liquid-argon calorimeter•retain most of its full-coverage muon system

But the entire tracking volume is being replaced•shorter bunch spacing, •higher radiation levels

New Detector Elements•inner silicon vertex detector•8 layers of scintillating fiber tracking•2 Tesla superconducting solenoid•scintillator-based preshower detecto


DO Upgraded TriggeringDO Upgraded Triggering •LEVEL 1 (trigger decisions within few sec)

•calorimeter trigger unchanged•new fiber tracker trigger•adds new preshower detector

•LEVEL 2 (trigger decisions within 100 sec)•global processors run algorithsm•correlating info from different subdetectors

•e.g., calorimeter-preshower-track matches•E/p and invariant mass cuts

•Event buffering between each trigger stage•deadtime due to pileup decreased•event transfer rates into LEVEL 3 1 kHz

•LEVEL 3 •rejection of 50 •average processing time < 100msec)

Run II machine goals:1) Run IIa to achieve a luminosity of 5x1031 cm-2s-1 and an integrated luminosity of 2 fb-1

2) Run IIb to achieve a luminosity of 2x1032 cm-2s-1 and an integrated luminosity of ~20 fb-1

The number of anti-protons in the ring hasbeen one of the major limiting factors in Tevatron luminosity. The anti-proton stacking rate will be increased to 2x1011/hr from 7x1010/hr

The machine will operate with 36x36 bunches (396 ns spacing) initially and (132 ns) eventually.

• a new massive silicon vertex detector – 7 layers extending to 28 cm in radius – deadtime-less SVX3 readout electronics

• a new central outer tracker (COT)• hermetic scintillator tile plug & forward calorimeter• large trigger bandwidth

Time-of-flight added

End Plugextendedto larger

COT replaces CTC

SVX replaced, Si layer added to beampipe, Intermed. Si Layers added

Shower max eddedForward calorimetereliminated

+ New Trigger, DAQ

• entirely new tracking

• improved muon spectrometer• new trigger and DAQ system

– 2T super conducting solenoid– disk/barrel silicon detector– 8 layers of scintillating fiber tracker– preshower detectors

Forward Mini-drift chambers

Shielding

New Solenoid & Tracking:Silicon, SciFi, Preshowers + New Electronics, Trigger, DAQ

Forward ScintillatorCentral Scintillator


RunII Squark and Gluino ProspectsRunII Squark and Gluino Prospects

•Multijets with ET remains the dominant signature of q’s & g’s

Critical •Understanding the tail of the ET distribution in multijet events• Methods to accurately estimate multijet backgrounds

•Large tan :enhanced g /i / 0i decays to 3rd generation

particles Critical -lepton and b-quark trigger and• identification capabilities.

~ ~

~ ~ ~

With 2 fb-1, DØ and CDF will probe m1/2 up to ~150 GeV

corresponding to Mgluino 400 GeV (for m0<200 GeV)

Run II improvements:1) improved ET resolution

– more hermetic calorimeter (CDF)– better vertexing (DØ)

2) Advanced analysis methods, improved tools


RunII Squark and Gluino ProspectsRunII Squark and Gluino Prospects


Chargino and Neutralino ProspectsChargino and Neutralino Prospects

At large , the lighter tau slepton is lighter than . Then, and

can dominantly decay into final states with via

tan~ ~ , ~ ~ ~

~

1 20

1 20

1

1

Trilepton signatures with

large content

Major backgrounds:W+jets, Z+jets, WZ,…

Critical: large acceptances and high efficiencies for high & low pT leptons including


Chargino and Neutralino ProspectsChargino and Neutralino Prospects

Run II improvements: 1) extended coverage improves lepton acceptances 2) lepton charge and better momentum measurements reducing backgrounds (DØ) 3) new preshower detectors 4) major effort on identification built upon Run I experiences

Mchargino reach >150 GeVfor most of parameter space

Mchargino reach ~200 GeVfor small to medium values of tan

sugra searches at the tevatron dan claes university of nebraska representing the cdf and d0...

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