1. Jim Linnemann, Michigan State
Recent Tevatron Searches: Large Extra Dimensions, SUSY, and other New Phenomena
Jim Linnemann, Michigan State
For DØ and CDF
Moriond EW
La Thuile, Italy, March 23, 2004

2. Overview Tevatron LED, Z, miscellany and SUSY
Emphasize updates since LP 03
We are starting to see a flood of new results!
Shortchanging older analyses
Will also skip some interesting new analyses—time
Showing limits (alas) at 95% CL
In a mixture of prescriptions

3. Large Extra Dimensions: Strategies
ee, and EM = e+γ
Central + central-end
end-end has big QCD bkg
2-D M, Cos θ* fit
Fit C-C and C-E separately
to background + model
Model: specific processes
CDF ee
Central + central-end
mostly
Likelihood fit to M
Cos θ* is a cross-check
Spin-dependent σ·B limits beyond SM
Interpret in many models

4. Large Extra Dimension Searches
DØ 2-D model-specific fit
CDF σ ·BSpin limits
Spin = 2 (example)

5. LED signal limits New limits from both DØ & CDF L= 200 events/pb
ηG95 = F/M4S
parameterizes ED effects
Limits using GRW: F= = HLZ n=4, F = 2/(n-2) =1
CDF II Ms > TeV
DØ II Ms > 1.36 TeV
DØ I + II Ms > 1.43 TeV most restrictive to date
LED signal MC
“bump” looks like statistics, not signal
fakes
L = 200 / pb
Bkg

6. Dedicated ee Search for TeV-1 Dimensions
Model:
fermions on 3d
SM gauge bosons in bulk of branes
M2n= Mo^2 + n2/M2c KK towers extra virtual effects
Negative Interference effects
unlike LED
Find: Mc > 1.12 TeV (95% CL)
First direct search
Indirect searches:
LEP: > 6.6 TeV; all: > 6.8 TeV
Jet mis-ID
Mc signal
SM + mis-ID

7. Z Limits from ee: SM, E6 CDF: use spin 1 acceptance DØ: Pythia Z
Optimize window vs. MZ
Limits in Aσ/σZ
SM Couplings Run I SM Run II
CDF :
DØ:
E ZI Zχ Zψ Zη
CDF II:
DØ:
Some difference from σZ’ calculations
Caveat: DØ: K(MZ), K=
actually, using NNLO + M-dependent K factor. Mass dependence increases limit by perhaps 5 GeV
CDF: K = 1.30, but wrt different LO X section

8. CDF Forward ee?
DØ sees 1 event > 450, ± .2 SM expected

9. LED with jets + MET: DØ update (L= 85/pb)
Consider G radiation
Monojet-like
J1 > 150, J2 < 50, MET > 150
ΔΦJ,MET > 30o
Observe 63; expect 100 ±6±7
-37 “signal”
Signal Limit = 84 events
expected 128 ± 28—a bit lucky?
Includes large energy scale uncertainty
Both MC and Data scales!
Efficiency: 20%
Background: +50% and –30%
K=1
Better than Run I,
but need better Jet Energy Scale

10. Other CDF limits from ee
Reinterpret Spin 0, 1, 2
σ·B limits in various models
.05 to .2 pb (mass, spin dependent)
Examples:
little higgs
RPV sneutrino
R-S graviton
techni rho: more data needed
Non-optimal is still useful !
From TOF (not ee):
Mstop > 95
“Champ” Analysis

11. DØ Jets + MET SUSY interest: LSP escapes as MET
Light squarks decay to q LSP
Light gluinos:
decay to qqbar LSP (more jets)
acoplanar, but not monojets
Require acoplanar topology:
j1 > 60
j2 > opposite of LED
ΔΦj,MET > 30o
ΔΦjj < 165o
Optimize MET, Ht: σLimit / σs
σs is typical mSUGRA signal
use: M0 = 25, M½ = 130
Choose:
MET > 175, HT > 275

12. Squark Gluino Limit Status
Expect 2.7 ± 1.0 SM
efficiency ~ 5%
See 4 events with L=85/pb
Analysis better optimized for light squarks than light gluinos
Results of M½ scan with
Mo = 25, Ao = 0, tan β = 3, μ < 0
For Msquark ~ 290, Mgluino > 333
Already better limit than Run I
better QCD rejection
data, MC)
+25%, -15% efficiency; +77%, -43% background

13. SUSY trilepton search: DØ
Chargino + N2; masses ~ 2 MLSP
Decay to WZ or sleptons +2 LSP
Low mass sleptons: good BR
Gold plated: trileptons
2 like-sign available
BUT:
Signal a bit thin on the ground
σ·B < 1pb
low chargino mass: soft leptons
LEP II cleared a good bit of
mSUGRA space
Strategy: Combine ee, μμ, eμ:
tune cuts for low background

14. Like Sign μμ with 147/pb μ1 > 11, μ2 > 5 isolated MET > 15
Kinematics to kill Z
M < 80 sign flip avoided
exclude Z if have μ+μ- pair
And QCD b and c+ν decays
ΔΦμμ < 2.7
If μ2 < 11, tighten further:
.5 < ΔΦ μ,MET < 2.4
ΔΦμj < 2.4
not fully optimized, but blind
Expect .13 events; observe 1
σ·B SUSY ~ .2 to .4/pb: ε ~1%
.2 to .4 SUSY events expected
B/c background in LS checked by using same method to estimate background in OS low-mass data
b background scaled from like-sign data non-isolated μ’s

15. SUSY eμ L = 158/pb e >12 μ > 8 isolated WW, Wj prevention:
15 < MET < 80
tighter ID near MT (W)
10 < Meμ < 100
|e, μ, MET| > 6 ~ pT(l3)
Expect 2.9 ± See 1 event
can also require:
Iso Track > 3 weak 3rd lepton
Expect 0.5 ± See 0 events
SUSY: .6 to .9 events for either
(little loss due to isolated track)
Before pT(l3) cuts

16. SUSY ee with L = 174/pb e > 12, 8 one central MET > 20
track >3; ΔRe,tr > rd lepton
Kill Z, top by kinematics
irritating SM backgrounds already!
jets < 80
Mee < 60, ΔΦee < 2.8
Mt >15; ΔRe,MET > .4
tr  MET > 250
Expect SM .3 ±.4; observe 1
Signal: to 1.6 events

17. η φ Et e Friday the 13th Event track 33.2 -.97 3.37 25.7 -2.19 2.97
8.6
.67
5.87
MET
52.1
.12

18. DØ combined lepton limits
SUSY Scan
M0 M½ A0 = 0, tan β = 3, μ < 0
72 165
180
88 185
.4 to 2 pb σ·B SUSY
typically 2-3 events .
CLs combination of 3 channels
including correlations
Channel Data SM  stat  syst. L/pb
eel  .42 
eμl  .24 
eμ  
μ+μ+ μ-μ  .06 

19. SUSY Limit Results Better than Run I σ·B < .5pb
Not quite excluding predictions

20. Summary Nature declined to flood us with new phenomena so far
Clear improvements over Run I are visible
L ~ 200/pb x 2 and counting
apparatus understood well enough to use it
Not fully optimized but already have
σ·B <.5 pb –or better- limits
e.g. sensitive to 10 ε~10%
Publications in our near future
buon appetito!