Supersymmetry @ Tevatron

Supersymmetry @ TevatronPeter WittichUniversity of PennsylvaniaFor the DØ and CDF CollaborationsApril 19 APS 2005

April 19 Peter Wittich - U Penn 2

Supersymmetry Based on fundamental symmetries String theories are supersymmetric Solves some technical problems of

Standard Model How: double particle spectrum!

Worked before: postulate positron for quantum electro dynamics

Introduce “super-partners” with different spin Makes theory self-consistent Also provides dark matter candidate

But: where are they? m(positron)=m(electron) But not so for selectron SUSY is broken!

Should be visible in near future, at Tevatron collider or at next generation (LHC)

e e

04

01

21

~...~,~,~

Particle Super-partner

e,,u,d

,W,Z,h

due ~,~,~,~

Dark Matter Candidate

2

2 201 1

2

GeVc

GeV GeVc c

GeV/ c

100

43 , 104

195(300)

l

g q

m

m m

m


Experimental SUSY signatures Rp (R-parity) conserving

Lightest Supersymmetric Particle (LSP) is stable, escapes detector (undetected)

Results in large ETMiss

striking exp. Signature (Rp violating signatures)

Often include lepton flavor violating decaysBreaking Models: mSugra: supergravity-inspired

Best-studied model, 5 parameters

GMSB-motivated signatures LSP: Gravitino, various next-LSP (NLSP)

Experimentally: photons! Run 1 CDF eET

Miss

AMSB-motivated signatures Long-lived particles, soft pions Very hard at hadron colliders

G~~01

120 , , , tan ,sign( )m m A

0 0 122 1 1

122 0.8gm m m m m

sLBPR

2)(3)1(


Tevatron at Fermi National Accelerator Lab Tevatron circulates protons

(p’s) and anti-protons (pbar’s)

Particle beams collide at experiment sites (CDF, DØ) Energy in C.O.M.: ~2 TeV

Now have >600/pb of data on tape

Current analyses 200-390/pb

Run 2 goal: 4.4-8.5/fb Take data until 2009

Tevatron is Energy Frontier until LHC turn-on


Tevatron Experiments: DØ & CDF Well-understood, mature detectors

Excellent particle ID, coverage, tracking and triggering

=1.0

=1.0=0

=2.0

=3.0=3.8


Gauginos

Squarks & Gluinos

Rp violating decays

Other and indirect searches


Chargino-Neutralino Searches Recall:

@ Tev: Look for lightest chargino, 2nd neutralino

Final state with many leptons, large ET

Miss from LSP

One of the SUSY “golden modes” Small SM backgrounds but

small (EW) cross sections Striking signature

Xlll 01

011

02

~~~~

21~,~~,~ HW

04

03

02

01

0000 ~,~,~,~~,~,~,~ ud HHBW

Gaugino, Higgsino content, m(slepton) determines BR’s, coupling strengths

“Charginos”

“Neutralinos”


Chargino and Neutralino in 3+ETMiss

In models with Rp:3 leptons+ETMiss

6 analyses: -2l(l=e,,)+isolated track or

ETMiss

and topological cuts (Mll,, MT)

Selection Bkgnd expected OBSERVED

ee+l 0.21±0.12 0

el 0.31±0.13 0

l 1.75±0.57 2

±± 0.64±0.38 1

e+l 0.58±0.14 0

+l 0.36±0.13 1

SUM 3.85±0.75 4

M( (GeV/c2)

xBR~0.2 pbVery clean signature SM background very

small


Chargino Neutralino Limits

“3l-max”•

Limits : M(±

1)>116 GeV/c2

“Heavy Squarks”•

M(±1)>128 GeV/c2

“Large m0”• M(~)>>M(0

2 ,±) No sensitivity due to smaller

leptonic BR’s

Start testing above LEP limit for mSugra—but

LEP Model Independent !

A0=0

02lm m

adding ’s improves sensitivity (low tan )

Limit: xBR ~ 0.2 pb

02

q lm m m


CDF is also in the game…Chargino-neutralino in ee channel

SELECTION: -2 electrons+ (

=e,)largeET

Miss>15 GeV/c2

- 15<Mll<76, >106 GeV/c2

- ||< 160- Njets(20 GeV) <2

Process

mSugra ee 0.5

Bkgnd Expected 0.16±0.07

OBSERVED 0

VERY FIRST LOOK AT THE DATA!!Still a lot to do:Still a lot to do:

- improve acceptance: forward e’s- add the other channels

ETMiss>15


Chargino-Neutralino in +ETMiss

D0(CDF) Event selection:-2 photons ET > 20(13) GeV

-ETMiss>40(45) GeV

In GMSB: 2 photons+ET

Miss

Bkgnd Expect Obs Limit m+

D0 3.7±0.6 2 195 GeV

CDF 0.3±0.1 0 167 GeV

CDF and D0 combined

result:m(±)>209

GeV/c2

CDF-I eeET event

ET (GeV)

hep-ex/0504004


Gauginos

Squarks & Gluinos

Rp violating decays



Squark-gluino searches

2222~

2~

2~

2~

2~ )cot(4)(

21

2,1 ttttttt Ammmmmm

RLRL

Lightest squark:

)tanhigh(~ ),tanlow(~11 bt

tancot masses, replace:~b

Target w/special searches

btscdu

qqqgggpp~,~,~,~,~,~

~~,~~,~~

generic specific

Large strong-interaction cross sections Another “golden mode” at Tevatron

Typical searches, generic: search for jets + ET

Miss

Use to suppress bkgnds Signal-specific:3rd family can look

quite different! Large mixing

Stop: due to large mt. Sbottom: due to large tan.


Squarks and Gluinos in jets+ETMiss

• In mSUGRA: Njets+ ET

Miss

selection •3 analyses#jets(PT (GeV)) ∑Pt

jet ETMiss Bkgd Expected OBS

2 jets(60,50) 250 GeV 175 GeV 12.8±5.4 12

3 jets(60,40,25) 325 GeV 100 GeV 6.1±3.1 5

4 jets(60,40,30,25) 175 GeV 75 GeV 9.3±0.5 10

L=310 pb-1

Limits (tan=3, A0=0,<0, q=u,d,c,s,b):2j :M0=25 GeV -> M(q) > 318 GeV/c2 3j :M(g)=M(q) -> M(q) > 333 GeV/c2

4j :M0=500 GeV-> M(g)> 233 GeV/c2

~ ~~~~

~~~~~

Extended LEP mSUGRA reach for M(~q)<M(~g)

4 jet


Gluino-Squark in jets + ETMiss

New CDF result! 254/pb of data Trigger: 2 jets + ET

Miss>35 ≥3 jets (125, 75, 25 GeV) ET

Miss>165 GeV, HT>350 Expect 4.2 1.1 bkgnd

events (SUSY: 0.7-4.8) Observe 3 events in data Scan parameter space, set

limit soon

Require ETMiss>165

Require HT>350


Light Stop in mSugraIn mSugra with stop NLSP, assume

Expected Observed

Pre-tag 105 ± 12 119

Tag (silicon) 8.3 ± 2.3 11

Limit on Limit on xBRxBR

2011 /GeV40%,100~)~~( 0

1cmctBR

selection: 2 jets, large ETMiss, no l,

charm tag


Gauginos

Squarks & Gluinos

Rp violating decays



R-parity Global symmetry of MSSM All analyses presented so far

assume Rp is conserved Kills (B-L) violating terms of

Lagrangian No proton decay no flavor-violating decays

LSP is stable: good dark matter candidate

What if RP is not conserved? Global symmetries are theoretically

shaky Introduce new terms in MSSM Can produce single sparticles No stable LSP: no dark matter

candidate, no ETMiss.

But no one says SUSY has to solve all our problems…

sLBPR

2)(3)1(

ijkijkijk ,,Lepton-number violating terms

Baryon-number violating terms


133 122

RPV Sleptons RPV tested in Production and Decay of SUSY particles

´211

u-

d

-~

-

d-´211

u

-

+~01

~

Resonant sparticle production ’ijk coupling

Selection: 2jets+2 isolated ’s ’211

RPV decay of LSP(0

1) ijk coupling

Selection: 3+ET

Miss+channel-dependent cuts121 -> e.122 -> e 133 -> e


RPV Slepton limits

(L=154 pb-1)’211

(L=160 pb-1)122 M(0(+)1)>84(165)

GeV/c2 (L=238 pb-1)121 M(0(+)

1)>95(181) GeV/c2

(L=200 pb-1)133 M(0(+)1)>66(118)

GeV/c2

EXP OBS

1.1±0.4 2

EXP OBS

0.6±1.9

0.5±0.4

1.0±1.4

2

0

0

Resonant production:

Minimal Rp violation in decay only:


Stop in RP–violating SUSY (I)AssumeBR(t1b) ~

100% Search for :

~

selection: 1 (=e,m)+ 1+ 2 jets

’3331 1 had lep,qq gg t t b b

Z visible

Biggest background: Real from Z Check in 0 jet bin control region


Stop in RP–violating SUSY (II) Control region looks

good Search in signal

region

e+ + SUM

Expect. BG 2.6±0.6 2.2±0.5 4.8±0.7

Observed 2 3 5

•Limit: m(stop)>129 GeV/c2


Gauginos

Squarks & Gluinos

Rp violating decays



BR(Bs ) (I) Indirect search for SUSY

Process greatly enhanced by SUSY

Complimentary to direct searches

Complimentary Can restrict generic high tan

models Challenging:

SM prediction is 3.4×10-9

Use sidebands, same-sign data to understand backgrounds in Bs mass region

b

s

W+t

W-

b

s

H+ H0

t

4

64

0

)(tan)()(H

b

mmSMBRSUSYBR

Standard Model:

SUSY enhancement prop to (tan 6


BR(Bs ) (II)

New CDF result with many improvements

Use B+J/ K+ normal. Mode (lower B pT)

Include 0.6 < ||<1.0 ’s, also in trigger

Multivariate discriminant for more rejection power

n(Expected BG) = 1.47 ± 0.18 for ±60 MeV/c2 and LH > 0.99

n(Observed) = 0

8

7

( ) 4.9 10 at 95% CL

( ) 2.0 10 at 95% CLd

s

BR B

BR B

2x improvement wrt prev. best published result


Charged massive stable particle search

~

~

Look for particle that is charged Massive: v<<c Lifetime long enough to

decay outside detector (c>10 m)

Massively ionizing (Not used)

Event Selection: 2 muons pT> 15 GeV,

isolated Speed significantly

slower than c

cutL=390 pb-1

1 21 0, , cutv v vv

vs s s m


Limits:In GMSB: champ = (NLSP)In AMSB: champ = ±

M(±1)>174 GeV/c2

Champs (II)

Not sensitive yet

Expected bgknd OBSERVED

0.66±0.06 0

~

~

Estimate backgrounds from data sv<0, Z boson data

SUSY interpretation: Set limits for (quasi)-stable staus, charginos Stau: GMSB-like models Charginos: AMSB-like models


In Conclusion… SUSY promising venues for new physics

DØ and CDF both mounting extensive program – this is just a small taste!

Gluino-squark Chargino-neutralino R-parity violating modes Stop, sbottom, sneutrino, rare b decays, …

Starting to exclude new regions in parameter space

Stay tuned for more data, more channels, …

http://www-cdf.fnal.gov/physics/exotic/exotic.htmlhttp://www-d0.fnal.gov/Run2Physics/WWW/results/np.html


Backup Slides


Delivered Luminosity

Current record initial luminosity >12×1032/cm2/s Frequent records before shutdown Goal: 300/pb delivered in FY04 was reached

Run analyses currently using ~240/pb-390/pb Run 2 goals: “Base:” 4.4 fb-1. “Design:” 8.5 fb-1


BR(Bsmumu) in SUSY

Dashed blue lines are are contours of constant BR( Bs → μμ )

dashed black lines are are contours of constant higgs mass

green areas are regions of parameter space consistent with the observed relic density of dark matter

pink areas are excluded.


CDF Acquired Luminosity

CDF had 430/pb on tape at start of 2004 shut-down

CDFRun II

Time(hr)

Init Lum(E30)

Efficiency(%)

Average 17.2 33.2 72.5

Record 62.4 118.8 98.5


SUSY searches with Rp conservationLook for classes of particles Sleptons: … Gaugino searches

“Chargino-Neutralino” (small) EWK cross sections Typically search via decays into leptons

Squark, gluino Searches (large) strong-interaction cross sections Typical searches, generic: search for jets + ET

Miss

Signal-specific:3rd family can look quite different! Large mixing

Stop: due to large mt. Sbottom: due to large tan.

2222~

2~

2~

2~

2~ )cot(4)(

21

2,1 ttttttt Ammmmmm

RLRL

Lightest squark:

)tanhigh(~ ),tanlow(~11 bt

tancot masses, replace:~b

Xlll 01

011

02

~~~~

Target w/special searches


Bs (I)Complementary to other SUSY searches, indirect BR could be enhanced from new physics: loop decays (MSSM, mSugra) or direct (RP viol.)

Challenging: SM prediction is 3.4 x 10-9 ...

Sidebands and same-sign data used to optimize cuts and check background estimates

SM signal x 10 5

Use lifetime information to reduce backgrounds

Supersymmetry @ Tevatron

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