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04/18/23 1
Search of New Phenomena at the Tevatron
Carlos SánchezFor the DØ and CDF
experiments
IFAE - Barcelona
04/18/23 Carlos Sánchez - IFAE 2
The FNAL Tevatron p-pbar collisions at a
C.M energy of 2 TeV Two experiments around
the ring: CDF and DØ
Large amounts of data collected Analysis on 200 – 400 pb-1
Run 2 goal: 4.4 – 8.5 fb-1
Energy frontier until the LHC turns on
04/18/23 Carlos Sánchez - IFAE 3
CDF and DØ• Both detectors well understood and highly efficient• Extensive calorimeter, tracking and muon coverage
04/18/23 Carlos Sánchez - IFAE 4
Looking For SUSY
Introduces many new particles. Multiple signatures available. Pair produced. Decay into SM partners
plus MET. No knowledge of how
EWKSB occurs theorists choose models. Huge parameter space to
explore. Very small cross
sections.
Looking for new physics with the same old tools: jets, leptons, MET, …
04/18/23 Carlos Sánchez - IFAE 5
SUSY tri- and dilepton Searches
Classic tri-lepton SUSY signature:
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 masses.
2 like-sign leptons signatures available
04/18/23 Carlos Sánchez - IFAE 6
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
6 analyses:
-2l(l=e,,)+isolated track or
MET and topological cuts (Mll,,
MT)
Very clean signature
04/18/23 Carlos Sánchez - IFAE 7
Chargino Neutralino
LimitsmSUGRA: M(X±) ≈ M(X0
2) ≈ 2M(X0
1)
• “3l-max”
• M(slepton) ≥ M(X02)
• No slepton mixing
• M(X±1) > 116 GeV
• “Heavy squarks”
• M(X±) ≈ M(X02) ≠ 3M(qP)
• M(X±1) > 128 GeV
• “Large m0”
•M(slepton) >> (X02, X±)
• No sensitivity
Testing above LEP limit for mSUGRA
04/18/23 Carlos Sánchez - IFAE 8
Process
mSugra ee 0.5
Bkgnd Expected 0.16±0.07
OBSERVED 0
SELECTION:
-2 electrons + ( =e,)largeMET >15 GeV/c2
- 15<Mll<76, >106 GeV/c2
- ||< 160- Njets(20 GeV) <2
Chargino-neutralino in ee channel
(Work in progress)
04/18/23 Carlos Sánchez - IFAE 9
Gluino and Squark Search
(mSUGRA)
Jets + MET
#jets(PT (GeV))
∑Ptjet
(GeV)
MET(GeV
)
Bkg. Expected
OBS
2 jets(60,50) 250 175 12.8±5.4
12
3 jets(60,40,25) 325 100 6.1±3.1 5
4 jets(60,40,30,25)
175 75 9.3±0.5 10
• 4j(gPgP): M0 = 500 GeV M(gP) = 233
GeV
• 3j(gPqP): M(gP) = M(qP) M(qP) > 333 GeV
• 2j(qPqP): M0 = 25 GeV M(qP) > 318
GeV
Extended mSUGRA LEP limits
04/18/23 Carlos Sánchez - IFAE 10
Search for Gluinos and Squarks
• 254 pb-1 of data• Trigger: 2 jets + MET > 35 GeV • ≥ 3 jets (125, 75, 25 GeV)• MET > 165 GeV, HT > 350 GeV
• Expect 4.2 1.1 bkgnd events.• Expect 2.6 – 4.8 SUSY events.Observed 3 events in data
04/18/23 Carlos Sánchez - IFAE 12
Stop Search
Expected Observed
Pre-tag 105 ± 12 119
Tag (silicon) 8.3 ± 2.3 11
% 100)~ctBR( 011
~
GeV 40 )~M( 0
1 Selection: 2 jets + MET + lepton veto
04/18/23 Carlos Sánchez - IFAE 13
Chargino-Neutralino in
CDF and D0 combined
result:m(±)>209
GeV/c2
Bkgnd Expect
Obs Limit m+
D0 3.7±0.6 2 195 GeV
CDF 0.3±0.1 0 167 GeV
GMSB: GD is LSP, stable
2 photons ET > 20(13) GeV MET > 40(45) GeV
04/18/23 Carlos Sánchez - IFAE 14
Rp-Violation Searches
Have assumed Rp conservation 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 missing energy.
Production
and decay
133 122
04/18/23 Carlos Sánchez - IFAE 15
Rp-Violating Sleptons
• Resonant production
1.1±0.4 (Expected) 2 (Observed)
• Decay only
EXP OBS neutralin
o
chargino
0.6±1.
9
0.5±0.
4
1.0±1.
4
2
0
0
84
(GeV)
95
66
165
(GeV)
181
118
μμl
eel
eet
All improve the Run I results
04/18/23 Carlos Sánchez - IFAE 16
Stop in Rp-Violating SUSY(I)
1 1 had lep,qq gg t t b b
Assume
BR(t1b) ~ 100% Search for :
selection: 1 (=e,m)+ 1+ 2 jets
04/18/23 Carlos Sánchez - IFAE 17
Stop in Rp-Violating SUSY(II)
Limit: Stop > 129 GeV(same signature as 3rd gen. LQ)
e+ + SUM
Expect. BG
2.6±0.6 2.2±0.5 4.8±0.7
Observed 2 3 5
04/18/23 Carlos Sánchez - IFAE 18
Search in High Mass Dileptons
• Relatively ‘clean’ channel
• Z0 peak as a calibration point
• Many models to explore:
Z’, TC, RS graviton, LED
compositeness, etc…
∫Ldt = 200 pb-1
ee
Z’SM 600 GeV
ee
04/18/23 Carlos Sánchez - IFAE 19
Z´ Limits
ZI Zχ Zψ Zη
SM coupling SM Couplings ee ee+ CDF : 750 735 815 394 DØ: 780 680
E6 ZI Zχ Zψ Zη CDF: 610 670 690 715 (ee+) DØ: 575 640 650 680 (ee)
DØ: μμ
DØ: ee
CDF:
04/18/23 Carlos Sánchez - IFAE 20
W´ Search in e Channel W’: additional charged
heavy vector boson Appears in theories based
on extension of the gauge group
Left-right symmetric models: SU(2)R WR
Assume the neutrino from W’ decay is light and stable.
signature:
High PT lepton + high MET
MC only
04/18/23 Carlos Sánchez - IFAE 21
W´Search (cont.)MT Distribution of Data
highest MT event
MT = 524 GeV/c2
σ*B(W’ enu) limit: ~ 50 – 100 fb for M(W’) > 500 GeV/c2 at 95% CL.
Limit: M(W’SM )> 842 GeV/c2
04/18/23 Carlos Sánchez - IFAE 22
LeptoquarksGUTS, Technicolor, Compositeness, RPV-SUSY assume an additional symmetry between leptons and quarks.
Carry both lepton (L) and baryon (B) numbersCouple to quark and lepton of the same generation.
At the Tevatron they are pair produced.
Selection:
high PT isolated
lepton(s)and/or MET + 2 jets.
04/18/23 Carlos Sánchez - IFAE 23
1st, 2nd, and 3rd Generation LQ
channels: eejj, ejj, (jj)
channels: jj, jj, jj
D0: Run I, MLQ > 200
GeV/c2
CDF: Run II, MLQ > 224
GeV/c2
D0: Run I + II, MLQ > 256
GeV/c2
CDF: Run II, MLQ > 235 GeV/c2
04/18/23 Carlos Sánchez - IFAE 24
Extra Dimensions (ED)
exchange
ee
jet(s)+ET
+ ET
G
G
g,q
g,q
g,q
g,q
f
f
jet
emission
• Alternatives to SUSY for solving the hierarchy problem (MEW << MPlanck ???)
• Several different models:
• Large ED
• TeV-1 ED
• Warped ED
Arkani-Hamed, Dimopoulos, DvaliPhys Lett B429 (98)
Dienes, Dudas, GherghettaNucl Phys B537 (99)
Randall, Sundrum Phys Rev Lett 83 (99)
04/18/23 Carlos Sánchez - IFAE 25
Extra Dimensions (ED)
LED with ee &
Stadard Model
Signal predictio
nQCD
LED with
No deviation from SM predictions
04/18/23 Carlos Sánchez - IFAE 26
Randall-Sundrum Graviton (ee + + )
Dileptons have largest acceptance at low mass while has largest acceptance at high mass:
BR(G→) = 2 * BR(G→ee)
04/18/23 Carlos Sánchez - IFAE 27
Conclusions Delivered data at the Tevatron over 1 fb-1
CDF and DØ running efficiently Interesting regions of parameter space
(for many models) are now in reach Testing beyond LEP limits Improving Run I results
Many new exciting results from Tevatron experiments and more coming soon!
http://www-cdf.fnal.gov/physics/exotic/exotic.htmlhttp://www-d0.fnal.gov/Run2Physics/WWW/results/np.html
04/18/23 Carlos Sánchez - IFAE 31
“Mass Bump” Search Strategies
Perform general searches comparing data to expectation Determine spin dependent acceptance and .BR* Interpret the results according to many new models!
Spin-0: RPV sneutrinos Spin-1: Z’SM, E6 Z’, Little Higgs Z’, TC (rT, wT) Spin-2: RS graviton
l+
l-
l+
l-X? X?
04/18/23 Carlos Sánchez - IFAE 32
Spin Dependence Acceptance
spin-0 spin-1 spin-2
Angular distribution and therefore acceptance of decay product depends on the spin of the decaying particle.
central-central
central-forward
above combined
central: || < 1.1forward: 1.1 < || < 3.6
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