Search For New Physics at the TeVatron

1
Search For New Physics at the TeVatron
Jean-François Grivaz LAL-Orsay
http//www-cdf.fnal.gov/physics/exotic/exotic.html
http//www-d0.fnal.gov/Run2Physics/WWW/results.ht
m
2
The Tevatron at Run II

• New Main Injector
• Recycler
• Higher energy
• (1.96 TeV vs 1.8 TeV)
• gt Higher cross sections
• (30 for the top)
• Higher antiproton intensity
• 6x6 ? 36x36 bunches
• (3.5 ?s ? 396 ns)
• antiproton recycler
• gt Higher luminosity

3
Luminosity performance
In 2004

• Peak luminosity
• 4 - 8 1031 cm-2 s-1
• Weekly delivered
• 8 - 16 pb-1
• Data taking efficiency
• 80 - 90
• Physics quality data
• up to 350 pb-1
• analyzed as of ICHEP04

1032
4
Searches for New Phenomena
Supersymmetry (m)SUGRA, GMSB Extra Dimensions
large, warped Extended Gauge Theories Z Higgs
bosons SUSY, SM
In back-up slides RPV, leptoquarks, excited
leptons, doubly-charged Higgses Not covered
TeV1 ED, Technicolor, Little Higgs but same
signatures as e.g., LED, SM-Higgs,
RS-gravitons Real exotics (e.g. monopoles)
5
Supersymmetry
6
(m)SUGRA
m0 m1/2 tan(?) A0 sign(?)
Two main search streams at the Tevatron

• Squarks and gluinos ? multijets missing ET
• large production cross sections
• large experimental backgrounds

• Electroweak gauginos with leptonic decays
  (Trileptons)
• low production cross sections
• typically low leptonic branching ratios
• clean experimental signature

7
Trileptons (I)

• Arise from chargino-neutralino
• associated production
• Golden SUSY signature but
• - low cross sections (? BR)
• - soft leptons
• - taus (at large tan?)
• Needs large integrated luminosity
• Combine various final states

(Also decays via W/Z exchange)
DØ analysis based on 147 ? 249 pb?1 Combines eel,
e?l, ??l and same sign dimuon final
states Addresses just beyond LEP mSUGRA with
low mass sleptons
8
Trileptons (II)

• Two isolated (rather soft) e or ?
• Require some Missing ET
• ? channel-dependent cuts (e.g. anti Z)
• Two same sign muons, or
• An isolated third track (no e or ? ID)
• Main backgrounds WW, WZ, W?, a bit of bb
• Altogether 3 events observed vs 2.9 ? 0.8
  expected

9
Trileptons (III)
Substantial improvement wrt Run I m(??) ? 97
GeV for m(slepton) ? m(??) Should soon probe
virgin mSUGRA territory
10
Stop and sbottom

• CDF has searched for charged massive particles in
  53 pb?1
• appear as slow moving (TOF) high pT muons
• result interpreted for (meta)stable stop
• ? m(stop) ?108 GeV (isolated) or 95 GeV
  (non-isolated)

• CDF has searched for sbottoms
• in gluino decays (156 pb?1)
• assumes sb1 much lighter than
• all other squarks (large tan?)
• gluino ? sb1 b
• ? 4 b-jets Missing ET
• for gluino pairs
• the selection requires at least
• one b-tag, no isolated lepton
• With 2 b-tags 4 vs 2.6 ? 0.7 expected

11
Generic squarks (I)

• Strong production of
• sq-sqbar
• sq-sq
• sq-gl
• gl-gl

In 85 pb?1, DØ has searched along the minimum
sq-mass line of mSUGRA very low m0 (25
GeV), (tan? 3, A0 0, ? ? 0), scan over m1/2
? Mostly sq-sqbar with sq ? q ? ? Acoplanar jets
Missing ET
12
Generic squarks (II)

• Main selection cuts
• at least two high pT jets
• isolated lepton veto
• Missing ET should not be
• along or opposite to a jet
• Sum of jet pT ? 275 GeV
• Missing ET ? 175 GeV

• Main backgrounds left
• (Z ? ??) jets
• (W? ??) jets
• QCD negligible

4 events selected vs 2.7 2.3/?1.5 expected
13
Generic squarks (III)
Slight improvement over CDF-Run I along that
minimum sq-mass line (msq ? 292 GeV and mgl ?
333 GeV)
How relevant are the Tevatron results on squarks
and gluinos ? LEP slepton and chargino limits ?
much tighter constraints on m0 and m1/2 within
mSUGRA (or even MSSM with unification) The
Tevatron should consider models with smaller
M3/M2 ratios not unnatural in GUTs (e.g. M3/M2
1 if SUSY breaking by a 75) or in some string
inspired models
14
GMSB with ? NLSP (I)
Remember the CDF ee?? Missing ET event ?
? gravitino
? Inclusive search for ?? ? Missing ET by
both CDF / DØ

• Photon electron without track
• Photon ET ? 13 / 20 GeV
• Missing ET gt 45 / 40 GeV
• Mild topological cuts

• Main backgrounds
• EM-jets (or real QCD photons)
• fake Missing ET
• electron photon
• real Missing ET
• All determined from the data

CDF 0 vs 0.3 ? 0.1 expected DØ 2 vs 3.7 ?
0.6 expected
15
GMSB with ? NLSP (II)

• Interpretation within mGMSB
• with
• N 1
• Mmessenger 2?,
• ? ? 0,
• tan? 15 (aka Snowmass slope)
• Signal dominated by
• chargino-neutralino production

263 pb-1
World best limit m? ? 108 GeV (DØ)
(Also 93 GeV (CDF))
16
Superjets ?
CDF _at_ Run I observed an excess of W 2/3 jet
events with ? 1 jet double-tagged (Secondary
vertex Soft lepton) 13 vs 4.4 ? 0.6 expected
An interpretation in terms of light sbottom RPV
(??) has been suggested (not by CDF)
DØ has searched for such an anomaly in ?150 pb-1
of Run II data and did not find any. Lets wait
and see what CDF will find
17
Bs ? ??
In SM, tiny BR 3.5 10?9 (and 25 times smaller
for Bd) But in SUSY, a (tan?)6 factor could lead
to an enhancement by as much as three orders of
magnitude
Select dimuons originating from displaced
vertices, and look inside a mass window
BR limits (95 CL) 5.0 10-7 (DØ 240pb-1) and
7.5 10-7 (CDF 171 pb-1) Close to getting relevant
18
Extra Dimensions
19
Models of Extra Dimensions

• Two classes of models considered
• ADD
• 2 to 7 large (sub mm) EDs
• gravity propagates
• freely in the bulk
• KK excitations
• cannot be resolved
• RS
• one 5th (infinite) ED
• with warped geometry
• gravity is localized
• on a brane other than the SM
• KK excitations
• have spacings of order TeV

20
Large Extra Dimensions
Two main search streams at the TeVatron

• Real graviton emission
• Apparent energy-momentum
• non-conservation in 3D-space
• ? Monojets
• Direct sensitivity to the
• fundamental Planck scale MD

Virtual graviton exchange Modifies SM cross
sections Sensitivity to the theory cutoff MS (MS
expected to be ? MD)
21
Monojets
DØ search in 85 pb-1

• Main selection cuts
• one high pT jet (? 150 GeV)
• (soft jets from ISR are allowed)
• isolated lepton veto
• Missing ET away from all jets
• Missing ET ? 150 GeV

QCD
Main background (Z ???) jet QCD is negligible
63 events selected 100 51/-32 expected
Large error from Jet Energy Scale (Updated result
coming soon)
22
High pT dileptons diphotons
DØ search in 200 pb-1 combines ee and ?? to
maximize the sensitivity
Fit of Data to SMQCDLED(MS)
World tightest limits MS gt 1.36 TeV MS gt1.43 TeV
w/DØ_at_Run I in the GRW formalism
Also 1.1 TeV from CDF in dielectrons with 200
pb-1 from DØ in dimuons with 250 pb-1
23
Randall Sundrum gravitons
Here too, most of the sensitivity is in diphotons
(BR 2?ee)
DØ uses the same ee ?? data set as for the LED
search
300 GeV RS-graviton
DØ Run II Preliminary
Two model parameters Mass and coupling (?/MPl)
For ?/MPl 0.1 M ? 785 GeV
Also 690 GeV from CDF in diphotons with 345 pb-1
24
Z
25
Z in dielectrons
Now select only electron pairs (much reduced QCD
background)
For an SM-like Z M ? 780 GeV
Limits for SM-like Z and various E6 models
Also M gt 750 GeV from CDF (200 pb-1)
26
Z in dimuons
Dimuons vs. dielectrons lower background but
worse resolution
Z limits in various E6 models
For an SM-like Z M ? 735 GeV
Also M ? 680 GeV from DØ (250 pb1)
Combining ee and ?? M (SM-like Z) ? 815 GeV
(CDF)
27
Z in ??
CDF in 195 pb-1
4 events (eh,?h,hh) vs 2.8 ? 0.5 expected
28
Higgs bosons
29
SUSY-Higgs _at_ large tan?
Hbb coupling enhanced
DØ search for ? 3b jets (130 pb-1)
30
SM Higgs boson searches
LEP indirect MH lt 260 GeV LEP direct MH gt
114 GeV Hint at 115 GeV
MH lt 130 GeV H?bb gg ?H ?bb hopeless (H ???
maybe) H(W ? l?) and H(Z ? ll/??) best
processes Hbb OK for SUSY _at_ large tan? Htt maybe
MH gt150 GeV H ?WW gg ?H ?(W ? l?)(W ?l?) best
process Also (H ?WW)(W ?l? / Z ?ll)
31
High mass H?WW?
DØ search in the ee, e? and ?? Missing ET final
states
The WW background is reduced using the spin
correlations smaller ll angle in the Higgs
signal
2 ee events vs 2.7 ? 0.4 expected 2 e? events vs
3.1 ? 0.3 expected 5 ?? events vs 5.3 ? 0.6
expected
32
Low mass (W?l?)(H?bb)
CDF search in 162 pb1 e/? Missing ET 2jets
(? 1 b-tag)
Similar DØ search (174 pb1 - e only) with 2
b-tags
Still a long way to go
33
Are we going there ?
Updated signal and background cross
sections Full detector simulation established
analysis techniques reasonable
extrapolations Signal shape (vs. mass
window) (but no systematics)
If we are lucky 3s evidence If not 95 CL
exclusion of the MSSM range
34
Final remarks
The Higgs is not the whole story
With a data sample at least 20 to 40 times larger
than at Run I, collected at higher energy with
improved detectors, there is a lot of beautiful
(but difficult) physics to be done

• W and top masses, top properties, single top
  production
• B physics Bs mixing, rare Bs decays, Bs and Lb
  lifetimes
• Exploration of new territory (SUSY, LED) we
  may be lucky
• already well underway
• interaction with theorists welcome !

With a steadily improving collider performance
there are still a number of years and fb1 ahead
of us for frontier physics at the Tevatron.
35
Back-up Slides
36
The CDF and DØ upgrades

• New tracking silicon and
• fibers in 2T magnetic field
• Upgraded muon system
• New DAQ and new trigger
• (commissioning displaced track)

• New silicon and drift chamber
• Upgraded calorimeter (plug)
• and muon system
• New DAQ and new trigger,
• (displaced track trigger)

and new software (C, OO)
37
The Run II Menu
With 2 fb-1

• Top mass to ? 3 GeV
• W mass to ? 30 MeV
• Bs mixing to 20 ps-1
• Exclude mH 115 GeV

• And much more
• High pT jets
• LED to 2 TeV
• SUSY

And beyond
38
RPV with ?ijkLiLjLk coupling (I)
DØ has searched for multilpeton final states
arising from SUSY particle pair production with
R-parity violating decays of two neutralino
LSPs in the regime where ? is small enough so
that only the LSP has an RPV decay, and large
enough for its lifetime to be negligible.
The couplings considered were ?121 ? eeee, eee?
or ee?? ?? ?122 ? ????, ???e or ??ee ??
Three isolated (rather soft) e or ? Require some
Missing ET ? channel-dependent cuts (e.g. anti Z)
39
RPV with ?ijkLiLjLk coupling (II)
?121 0 vs 0.5 ? 0.4 expected (238 pb-1)
?122 2 vs 0.6 ? 1.9 expected (163 pb-1)
eee/?
A search has also been performed for the ?133
coupling, in the ee?X final state, with ? ?
hadrons ? (199 pb-1)
Resonant single slepton or sneutrino production
via a ??211 RPV coupling has also been
investigated (154 pb-1)
m?? ? 200 GeV
40
Leptoquarks
LQ ? l?q (BR ?) or LQ ? ?q (BR 1 ?)
Pair produced ? llqq, l?qq or ??qq final states
2nd generation LQ in ??qq (CDF 200 pb-1)
2 muons, 2 jets, Z-veto
2 events vs 3.2 ? 1.2 expected
41
1st generation Leptoquarks (I)
DØ analysis performed in the eeqq and e?qq
channels (175 pb-1)
2 electrons, 2 jets and Z-veto
1 electron, missing ET and W-veto
ST ET(e1)METET(j1)ET(j2)
ST ET(e1)ET(e2)ET(j1)ET(j2)
(Before W-veto)
(After all other cuts)
0 events vs 0.4 ? 0.1 expected
2 events vs 4.7 ? 0.9 expected
42
1st generation Leptoquarks (II)
M ? 238 GeV (? 1) M ? 213 GeV (? 0.5)
(DØ 175 pb-1)
Also CDF with 200 pb-1 M ? 230 GeV (? 1) M ?
176 GeV (? 0.5 not combined)
43
Leptoquarks in the ??qq channel
Topology Acoplanar jets Missing ET Large
backgrounds from QCD multijets and from SM
processes (Z ?????? jets)
Also DØ with 85 pb-1 M ? 109 GeV
124 events vs 118.5 ?14.5 expected
44
Excited electrons
CDF search in the ee? final state (200 pb-1)
Z - veto
3 events vs 3.0 ? 0.4 expected
(main background Z?)
45
Doubly-charged Higgs Bosons
Doubly charged Higgs (from Higgs triplets) are
predicted in, e.g., LR-symmetric models
CDF has searched for H???? pair production in
240 pb-1
The signature is a pair of same sign ee, e? or
?? 0 ee events vs 1.5 0.9?0.6 expected 0 e?
events vs 0.4 ?0.2 expected 0 ?? events vs 0.8
0.5?0.4 expected
Also DØ in ?? (113 pb-1) M(H??L) gt 118
GeV M(H??R) gt 98 GeV