04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

1

SUSY Searches at theTevatronPeter Ratoff

Lancaster University

CDF, DØ and Tevatron Status New Run I SUSY Results First Glimpse of Run II Data

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

2

Main Injector & Recycler

Tevatron

Chicago

p source

BoosterCDF

DØ

p

p

p p

1.96 TeV

CDFDØ

The Fermilab Tevatron Collider

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

3

4.82.32.5interactions/xing

1323963500bunch xing (ns)

10517.33.2 Ldt (pb-1/week)

5.2x10328.6x10311.6x1030typ L (cm-2s-1)

1.961.961.8s (TeV)

140x10336x366x6#bunches

Run 2bRun 2aRun 1b

The Tevatron Run 2

Tevatron upgrade: Increased energy

1.8 TeV 1.96 TeV Increased luminosity

0.1 fb-1 2 fb-1 15 fb-1

Detector upgrades: Higher event rates and

backgrounds (electronics, DAQ, trigger)

Considerable expansion of the physics capabilities(Run 1) (Run 2a) (Run 2b)

Physics opportunities: Top Higgs New Phenomena Electroweak Beauty QCD

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

4date

Inte

gra

ted

Lu

min

osi

ty (

pb

-1)

2002 Projected Integrated Luminosity

Considerable fraction (~25%) of collected luminosity devoted to detector commissioning.

Significant progress in identification of “physics objects”: e, , jets, electromagnetic and jet energy scales, etc.

Run 2 in 2001/2002

Currently: Finishing detector commissioning Completing triggers and improve DAQ Debugging, calibration, alignment Refining reconstruction algorithms … Also looking forward to more

integrated luminosity!!!

DØ roll-in

Run II start

First Collisions

Detector Commissioning;Timing in; Improve electronics, DAQ and offline

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

5

The Upgraded DØ Detector

Builds on the strengths of DØ: Excellent calorimetry with faster readout Upgraded muon system for better -ID

Augments its tracker and trigger capabilities: Inner tracking (silicon tracker, fiber tracker)

with 2T superconducting solenoid Preshowers Pipelined 3-level trigger

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

6

SUSY models

SUSY is the best motivated scenario today for physics beyond the Standard Modeldoesn’t contradict precise Electroweak datapredicts light Higgsunification of gauge couplings at GUT scaleessential element of String Theories… provides explanation of Cold Dark Matter in the Universe!

SUSY must be broken symmetry (otherwise MSUSY = MSM)variety of models proposed - differ mainly in the nature of the “messenger interactions”most experimental results obtained in the context of the SUGRA and GMSB models

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

7

SUSY Phenomenology at Hadron Colliders

Physics environment and expected SUSY phenomenology are quite different at e+e- and Hadron collider machines

production expected to dominatesquarks and gluinos are quite heavy decay via multi-step

cascades 0

1

0

2

~~

Zqqqqqqg

~~~~~~

,, gggqqq

many high PT jets and leptons plus large missing transverse energy

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

8

SUGRA models

SUSY breaking is communicated to the physical sector by gravitational interactions

GUT scale parameters + RGE’s low-scale phenomenologyM0 = common scalar massM1/2 = common gaugino massA0 = common trilinear coupling valuetanratio of the V.E.V. of the two Higgs doubletssign of = Higgsino mass parameter

LSP is lightest neutralino - a neutral WIMP excellent CDM candidate

Highly constrained

minimal SUGRA

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

9

Single Electron Channel

qq

g~

g~

q

q

g

q'q

q

01

~

01

~ee

1~

02

~

q

Sensitive to moderate m0

Complements dilepton and Jets+MET channels

Bckg: W+jets, qcd multijet, ttCuts: Et

e >20 GeV,Etj >14 GeV

( 4), no isolated muons, MET > 25 GeVL = 92.7 pb-1

Observed events = 72Expected background = 80 ± 10DØ

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

10

Single Electron Channel

DØ

A0 = 0, < 0 , tan = 3

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

11

Stop Search

Final state: 2 leptons+jets+MET

Drell-Yan, heavy quark pair prod.,QCD fakes, diboson production

Assume sneutrino is LSP...

Mixing between SUSY partners of tL and tR is

proportional to mtop large mixing lighter SUSY

state experimentally accessible

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

12

Stop Search (II)

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

13

R-parity and its violation

Discrete quantum number R = (-1)3B+2S+L ; is 1 for SM particle,-1 for

sparticles

R-parity violation can be introduced by WL=1 = (1/2)ijkLiLjēk+' ijkLiQjđk+' iLiHu

WB=1 = (1/2)'' ijkūiđjđk

Decay of the LSPSignatures maybe very differentSingle sparticle production possibleWhither dark matter candidate

mSUGRA with RPVOne RPV coupling dominatesIf coupling large enough, resonant prod.Otherwise pair production

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

14

Decays of Stop Pair

Assuming RPV only in 3rd gen.tt+X = l + b + h + b + XFinal state: lepton + hadronic + 2 jets

Bckg: W/Z + jets, multijet, dibosonCuts: pT

lepton >10 GeV,h cluster>15, MT

(lepton,Met)<35GeV/c2,HT>70, 2jets (ET >15 GeV)L = 106 pb-1

Bilinear RPV (“BRPV”) stop + b

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

15

Decays of Stop Pair

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

16

Pair Production: di-muon channel

01

~~

c

s

'222

Final state: 2 + 4jets

•Bckg: Drell-Yan, tt, Z+jets, Z•Cuts: pt

>15(10) GeV,ptjets >15 GeV,

•St > 150 GeV,M >5 GeV,Acoplanarity>0.03•Run1 L = 77.5 ± 4 pb-1

Events observed = 0Expected bckg. = 0.18 ± 0.03 ±0.02

DØ

No missing ET

LSP

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

17

Pair Production: di-muon channel

DØ

Run IIa projection

2 fb-1

< 0 , A0 = 0 , tan = 2

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

18

Resonant Production:di-muon channel

u 1o~

L

~

d_

u d

'211

u d

d 1-~

+

~

d_

l -

l

W -

1o~

_

_

Resonant prod. and decayof LSP via RPVFinal state: 2+ 2jets

Bckg: tt, Z+2jets, WW+jetsCuts: pT

>20 GeV, pTjets >20 GeV,

ST >50 GeV, R(-jet) > 0.5L = 94 ± 5 pb-1

Observed events = 5Expected bckg = 5.34 ± 0.07

D

Large RPV coupling

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

19

Resonant Production:di-muon channel

Run IIa projection

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

20

GMSB models

‘Messenger’ sector couples to source of SUSY-breaking and physical sector of MSSM (through gauge interactions)

The identity of the NLSP and its lifetime determine the phenomenology

~ ~ GSMT CFT CAL

Tracks as we know Kinks Large dE/dx

Hot cell c

Photons as we know Impact

parameter

~ ~ 10 G

slepton

llG

c

NLSP

neutralino

G

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

21

Light Gravitino Search

Final state: MET+jet

Bckg: mismeasured multi-jets W/Z + jets, tt, dibosonCuts: MET >50 GeV, removalof events w/ isolated tracks, (MET,jet) >90o, Et

lead-jet >80GeV, 0.1 < EMFlead-jet < 0.95L = 87 pb-1

CDF

qq GGg

qg GGq

gg GGg

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

22

Light Gravitino Search (II)

For MET >175 GeV:Events observed = 19Expected bckg = 21.6

(PTĞĞ >100GeV) < 3.1pb

F > 217 GeVmĞ > 1.1 x 10-5 eV/c2

CDF

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

23

Di-photon Channel

Final state: 2 photons + MET

Bckg: multijet, direct photons,W, W+jets, ZeeCuts: ET

>20 GeV,ET >12 GeV,

recon. Vertex, MET>25 GeVL = 106.3 ± 5.6 pb-1

Events observed = 2Expected bckg = 2.3 ± 0.9

D

Neutralino pair production

G 0

1

Publ. 1998

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

24

Di-photon Channel (II)

D

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

25

Di-photon Channel (III)

Run II

MET

D Run IIpreliminary

~ 10 pb-1

04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff

26

Summary

Comprehensive searches for SUSY have been carried out at the Tevatron exploiting the Run I data to the fullest.

A new era is beginning ...First preliminary Run II Results …