Exotic Searches at the Tevatron

1
Recontres Des Moriond
Exotic Searches at the Tevatron Amitabh Lath For
the D0 and CDF Collaborations
2
CDF Detector

• Extended spatial e, µ coverage
• New plug calorimeter improves also MET measurement

• New displaced vertex trigger (SVT)
• New silicon and gas tracker
• Upgrade of muon system

3
Squark-gluino Search

• ET gt 175 GeV,
• ? jet ET gt 250 GeV

• ET gt 75 GeV,
• ? jet ET gt 250 GeV

4
Squark-gluino Search

• ET gt 100 GeV,
• ? jet ET gt 325 GeV

5
Search for Gluino ? Sbottom

• b1 can be very light for large tan?
• Expect large branching fraction
• of gluinos to sbottoms.

? Distinctive signature 4 b-jets and ET
/
Exp 2.6 - 0.7 Obs 4
6
DiphotonsMissing Energy

Typical GMSB signature from ? decay Gaugino pair
production ? lightest neutralino
0 1
/
Signature 2 energetic photons ET
263 pb-1
(? 80 TeV)
7

/
D0 ET (?) gt20 GeV, ET gt40 GeV Expect 3.60.6
events Obs 2
Phys. Rev. Letters 94, 041801 (2005).
Current results CDF m(?) gt 167 GeV
D0 m(?) gt 195 GeV


1
1
/
CDF ET (?) gt13 GeV, ET gt45 GeV Expect 0.30.1
events Obs 0
Accepted by Phys Rev. D.
8
SUSY tri- di-lepton searches

• Trilepton signature is one of cleanest SUSY
  signatures
• Chargino-Neutralino production
• Decay to WZ (or sleptons) 2 LSP
• Low SM background
• But also Small x-section
• Leptonic Br are enhanced if slepton masses are
  close to gaugino (i.e. c-1 in mSUGRA) masses.
• Classic tri-lepton SUSY signature
• 2 like-sign leptons signatures available
• Strategy
• Combine eel, mµl, eµl, µ-µ-, t(t,l)l

9
SUSY Trileptons

• eel
• pT 1,2,3 gt 12, 8, 4 GeV
• ET x pT3 gt 220 GeV2

3rd track pt
Expected BG 0.21- 0.12 Observed 0
2) mml pT 1,2,3 gt 11, 5, 3 GeV
ET x pT3 gt 150 GeV2
Expected BG 1.75 - 0.57 Observed 2
10
SUSY Trileptons
3) eml pT 1,2,3 gt 12, 8, 7 GeV
Expected BG 0.31 0.150.12 Observed 0
4) like-sign mm pT 1,2 gt 11, 5 GeV
ET x pT2 gt 300 GeV2
Expected BG 0.66 - 0.37 Observed 1
11
SUSY Trileptons, with t
5a) etl t ? hadronic decay pT 1,2,3 gt 8,
8, 5 GeV ET x pT(track) gt 350 GeV2
Expected BG 0.582 0.112 -0.105 Observed
0
5a) mtl t ? hadronic decay pT 1,2,3 gt 14,
7, 4 GeV ET x pT(track) gt 250 GeV2
Expected BG 0.36 - 0.12 Observed 1
12
SUSY Trileptons, Combined Result
t helps!
W. Beenakker et al., Phys. Rev. Lett. 83, 3780
(1999)
Huge improvement on Run 1 (1.5 pb limit)
13
Charged Massive Particles
L390 pb-1

• O data
• 60 GeV
• stau

CHAMPS look like muons. - inv mass, speed
inconsistent with beam-production. - speed
significance 1-speed
s (speed) - significance gt 0 for both muons
Gaugino-like chargino gt 174 GeV/c2 Higgsino-like
charginogt 140 GeV/c2
CDF Champs search (85 pb-1) M_stop gt
108 GeV/c2
14
SuperSymmetry (RPV)
No large ET requirement possible!


pp? t t ? bt bt
control
Z?tt visible
Signal
Biggest background Real t from Z?tt
15
SuperSymmetry (RPV)
Expect 4.8 ? 0.7 events Obs 5

m(t1)gt 129 GeV/c2
3rd Gen. LQ also ruled out at mgt129 GeV/c2

16
Large Extra Dimension (LED)

• Dilepton and diphoton channels
• Monojet channel where a jet recoils
• against the graviton which leaves
• the usual 3D dimension.

• ?G F/MS4
• F is a model dependent dimensionless parameter
  1
• GRW F 1
• HLZ
• F log(Ms2/M2), n 2
• F 2/(n-2), n gt 2
• Hewett
• F 2 ?/p, ? 1
• Ms is UV cutoff
• MPL(3n dim)

g,q
G
jet
g,q
G. Giudice, R. Rattazzi, and J. Wells, Nucl.
Phys. B544, 3 (1999)
T. Han, J. Lykken, and R. Zhang, Phys. Rev. D 59,
105006 (1999)
J. Hewett, Phys. Rev. Lett. 82, 4765 (1999).
17
LED with ee gg
SM prediction
Signal prediction
QCD

• Fit Mee,M?? and cos?, extract hG95

Limits on Fundamental Planck Scale, in TeV
DØ RunII
DØ RunI Run II
18
ED with di-photons
pp? G ?gg
L. Randall and R. Sundrum, Phys. Rev. Lett. 83,
3370 (1999).
19
W search in en channel

• W additional charged heavy vector boson
• appears in theories based on the extension of the
  gauge group
• e.g. Left-right symmetric models SU(2)R WR
• assume the neutrino from W decay is light and
  stable.
• signature

high pT electron high ET
MC only
20
W search (cont.)

• No events above SM expectation, set limits on W
  production rate
• use binned likelihood fitting method
• two types of systematics are examined as a
  function of MT
• affect event rate
• (dominant PDF, 14)
• affect the shape
• (dominant electron energy scale, 16)
• sB(W en) limit 50 100 fb for M(W) gt
  500 GeV/c2 at 95 CL.

WSM
Limit
Limit M(WSM )gt 842 GeV/c2
Run I results (with the same assumptions) M(WSM
)gt 754 GeV/c2
21
Searches in high mass dileptons (cont.)
ee
mm
both-central or central-forward
ee both-forward
tt
22
sBR Limits (X? ee or mm)
spin-0 spin-1
spin-2
spin-0 spin-1 spin-2

• sBr limit 25 fb for all spins for the high
  mass region (Mll gt 600 GeV)
• These limit curves can be compared with many
  models
• Individual channel limits are still very
  important - lepton universality ?

23
Spin-1, Z limits
?Ldt 250 pb-1
CDF tt
D0 mm


?Ldt 200 pb-1
D0 ee
z mass limits (in GeV/c2)
SM Couplings ee mm eemm tt
CDF 750 735 815 394
DØ 780 680 E6
ZI Z? Z? Z? CDF
610 670 690 715 (eemm) DØ
575 640 650 680 (ee)
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Leptoquarks (direct searches)
Carry both lepton (L) and baryon (B)
numbers Couple to quark and lepton of the same
generation
3 generations
At the TeVatron they are pair produced
Their decay is controlled by ? BR (LQ?lq )
Experimental signature high PT isolated
lepton(s) (b1) or ET 2 jets (b0)
25
1st, 2nd and 3rd Generation LQ
channels mmjj, enjj, nnjj
channels eejj, enjj, (nnjj)
1st Gen
2nd Gen
for b1, D0 Run I II, MLQ gt 256 GeV/c2 CDF
Run II, MLQ gt 235 GeV/c2
for b1, D0 Run I, MLQ gt 200 GeV/c2 CDF Run II,
MLQ gt 224 GeV/c2
3rd Gen. LQ ruled out by CDF at mgt129 GeV/c2
(b1) See the RPV stop search
26
Bs ???
Complementary to other SUSY searches, indirect
BR could be enhanced from new physics loop
decays (MSSM, mSugra) or direct (RP)
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
27
hep-ph/0411216
Bs ???
Now
8fb-1
SM expectation
CDF (171pb-1) Expect 1.05 0.30 Obs
1 D0(240pb-1) Expect 3.7 1.1 Obs
4
Combined BR(Bs???) lt 2.7 x 10-7 BR(Bd ???) lt 1.5
x 10-7 (CDF)
90 CL
28
Summary and Conclusions

• Presented some of the more recent preliminary
  results
• Surpassed the sensitivity and results of Run I
• Limits shown either exceed any published results
  of direct searches or are the first limits ever!
• Limits shown with 200 300 pb-1 of data
• We have about 600 pb-1 of data on tape (per
  detector)
• We will eventually get 2 to 4 fb-1
• Interesting regions of parameter space
• (for many models) are now in reach.

?.BR upper and mass lower limits on various new
physics models _at_ 95 using 200 pb-1 of CDF II
high mass ee???? data
Many new exciting results from Tevatron
experiments and more coming soon!
29
Backup
30
Run II Tevatron Performance
Highest Energy Collider in Operation!
Int. Lum.
place to search for new physics
FY2004

• Operating extremely well with recycler.
• highest Lum 1.052 e32 cm-2sec-1,Jan,2005
• single store high 5.05 pb-1, Jan,2005
• Analyses presented here are using up to
• 345 pb-1 of data

FY2003
FY2005
FY2002
Peak Lum.
vs ? 1.96 TeV
FY2004
CDF
D0
FY2003
P
P
FY2002
FY2005
31
Supersymmetry at the Tevatron
Looking for supersymmetric partners of SM
particles
Excesses in SM-like channels and SUSY-only
signatures

• Frameworks used
• Minimal Supersymmetric extention of the SM
  (MSSM)
• minimal Supergravity (mSugra)
• Gauge mediated Supersymmetry Breaking (GMSB)

Expected cross sections SMALL!
New quantum number
32
Lepton Signatures
/
Also plentiful in SUSY both RP and RP -
cascade decays from charginos, neutralinos,
sleptons Most models predict low pT,
non-central leptons High tan? SUSY models predict
?-signatures






? ??l? , ? ?l l, l?l ?
1
0 2
0 1
0 1

• Standard Trileptons (D0)
• RPV Stops (CDF)
• RPV Smuons (D0)
• Bs ? ?? (both)

33
Extra Dimensions (ED)

• Alternatives to SUSY for solving the hierarchy
  problem (MEW ltlt MPlank ?)
• Focus on
• Models with n extra spatial dimensions
• Large ED (ADD)
• ngt0 (ngt2) compactified
• M2PLRnMsn2, Ms string scale
• TeV-1 ED (DDG)
• ngt1 (n1)
• Mc compactification scale
• Warped ED (RS)
• n1, highly curved
• k/MPl, k curvature scale

exchange
G
ee mm gg
g,q
Arkani-Hamed, Dimopoulos, Dvali Phys Lett B429
(98)
f
f
g,q
G
g,q
Dienes, Dudas, Gherghetta Nucl Phys B537 (99)
jet
g,q
jet(s)ET g ET
emission
Randall, Sundrum Phys Rev Lett 83 (99)
34
LED with mm
DØ ?Ldt 250 pb-1

• Event selection
• pT gt 15 GeV for both muon objects
• Isolated tracks
• M(mumu) gt 50 GeV
• Cosmics removed
• Weighted average PT correction

Observed events 17,000 events
No deviation from SM in data
Lower limits on the fundamental Plank scale, MS
in TeV
35
Randall-Sundrum Graviton (ee mm gg)
Dilepton Channel
??
gg initiated process
Clean experimental signature. Low backgrounds
K/Mpl 0.1 620 0.05 470 0.02 310 0.01 200
ll has largest acceptance at low mass ?? has
largest acceptance at high mass BR(G???) 2
BR(G?ee)
for k/M_Pl0.05 masses less than 500 GeV are
ruled out at 95 C.L..
Randall-Sundrum gravitons are excluded by these
data in the plane of coupling (k/MPl) versus
effective graviton mass. E.g. for k/M_Pl0.05
masses less than 500 GeV are ruled out at 95
C.L..
Add Run I limits?!
Scale of physical phenomena on the TeV-brane is
specified by the exponential warp factor
?? Mple-kRc? ?? TeV if kRc 11-12.
Scale of physical phenomena on the TeV-brane is
specified by the exponential warp factor
?? Mple-kRc?
?? TeV if kRc 11-12.
36
mSUGRA
Masses and mixing angles can be determined
solving RGE with SM constraints

• Many results below are interpreted in mSUGRA
  framework
• Simplest SUSY model good benchmark
• Requires only 5 parameters
• (Very) restricted by LEP

• Squarks and gluinos generally not expected to be
  lighter than others
• However, large parameter space can accommodate
  various mass spectra

Typical mass spectrum in mSUGRA
37
Highest MET event
38
Leptoquarks

• LQ are coupled to both quarks and fermions
• Predicted in many Grand Unification extensions
  of SM
• Carry both lepton and color quantum numbers
• Family diagonal coupling to avoid FCNC beyond
  CKM mixing

Searched first generation LQ in channels eejj
and enjj
39
First generation LQ eejj channel

• Background

• Drell-Yan/Z jets,
• QCD (with 2 fakes EM)
• tt

ee invariant mass

• Selections
• Electrons Et gt 25 GeV
• Jets Et gt 20 GeV, etalt2.4
• Z veto
• ST gt 450 GeV
• Signal Eff 12 33

L ? 175 pb-1
40
eejj candidate event

• Invariant mass 475 GeV/c2, cos ? 0.01

41
Jet Energy Scale Corrections
Offset electronic noise, uranium noise,
underlying event zero bias and minimum bias
events (data)

• Correct the measured energy

out of cone Showering energy density in ring
around the jet axis (data)
Response Emeas/Edeposit ? 1 imbalance energy in
? jet events (data)
42
Jet Resolution

• Jet PT resolution

• using energy asymmetry in dijet events

parametrized as
N 0.0 ? 2.2, S 0.902 ? 0.045, C 0.052 ?
0.008
43
Resonant Smuon Production
?-
d

-
/
? produced via RP ? decay Result
2 muons, 2 jets, and no ET i.e. possible to
reconstruct mass chain
d


?
0 1
0 1
?211

?
/
?211

u
?-
-
?-
u

0 1

• Assume prompt ? decay
• Soft leptons and jets
• pT (?2) ? 10 GeV
• pT (leading jet) ? 25 GeV

Mass 102 GeV


0 1
Can reconstruct ? and ? masses Use this to
suppress backgrounds
44
In 154 pb-1 See 2 events Expect 1.2 0.3
from backgrounds
Limit on ?211 coupling
Limit on cross section
45
More data is on the way, almost 500 pb-1 for
2005 Lots of room to make discoveries before LHC
46
Diphoton Smuon backup
47
Run II Bs ? mm
CDF (171 pb-1) c? gt 200 ?m ??(Bs
,vertex) lt 0.1 rad mass window 3?
D0 (240 pb-1) Lxy/?Lxy gt 18.47 ??(Bs
,vertex) lt 0.2 rad mass window 2?
Bs CDF lt 5.8 10-7
1.5 10-7 (90 CL) D0 (240
pb-1) lt 3.8 10-7 Combined
lt 2.7 10-7 _at_ 90 CL
48
Stop to tau b backup