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Recent Results of SUSY Searches at the Tevatron Collider. Tibor Kurča IPN Lyon. On behalf of CDF & D0 collaborations. DIS 2004 Štrbské Pleso, Slovakia 14.-18. 4. 2004. Outline. Tevatron and CDF & D0 detectors upgrades Supersymmetry searches Direct: * in mSUGRA: - PowerPoint PPT Presentation
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14.-18.4.2004 1
Tibor KurčaIPN Lyon
DIS 2004Štrbské Pleso, Slovakia
14.-18. 4. 2004
Recent Results of SUSY Searches at the Tevatron Collider
On behalf of CDF & D0 collaborations
14.-18.4.2004 DIS 2004 Tibor Kurca 2
Tevatron and CDF & D0 detectors upgrades Supersymmetry searches Direct:
* in mSUGRA: 3-leptons + mET (charginos, neutralinos)
jets + mET (squarks, gluinos) * in mGMSB:
2-photons + mET (charginos, neutralinos)
Indirect: Rare B-meson decays (lightest Higgs)
Summary
Outline
14.-18.4.2004 DIS 2004 Tibor Kurca 3
Tevatron Upgrade - RUN II
Higher energy:√s = 1.8 TeV 1.96 TeV
Higher cross sections (30-40 % for SUSY)
More(anti)protons/bunch
(New Main Injector & Recycler)
More bunches: 6x6 36x36 bunches (3.5 s 396 ns)
Higher luminosity Run I : 2x1031 cm-
2s-1
Run II : 2.9x1032 cm-2s-1
Chicago
Tevatron
Main Injector & Recycler
DØCDF
p source
14.-18.4.2004 DIS 2004 Tibor Kurca 4
D0 Detector – Run II
Muon forward chamber 2
Calorimeter electronics
Trigger system
DAQ system
Solenoid (2 T)
Central tracker (SciFi) 1.7 L1
Silicon vertex detector 3 L1
Preshower – Central & Forward
14.-18.4.2004 DIS 2004 Tibor Kurca 5
CDF Detector – Run II New Si Tracker:
• ||< 2; 7-8 layers Central Drift
Chamber: 1.0; 96 layers
Solenoid/ Time of Flight
150 ps /150 cm Muon Drift
Chambers Muon Scintil.
Counters
extended coverage
||= 1 Forward
Calorimeter
1.1 3.5
Trigger :• COT tracks at L1• Silicon tracks at L2
DAQ
14.-18.4.2004 DIS 2004 Tibor Kurca 6
Run II Data Taking Presented analyses are based on data taken before Sept 2003
All results are preliminary !
Sept 2003
Physics Analysis Sample ∫ℒ dt 200pb-1
14.-18.4.2004 DIS 2004 Tibor Kurca 7
SUSY Particles Spectrum
)1(R )23(
P
SLB Rp-conservation produced in pairs
existence of stable LSP
14.-18.4.2004 DIS 2004 Tibor Kurca 8
Trileptons in mSUGRA 3-leptons (isolated) final state – « gold plated channel »
Challenges: - low x-section (EW-production) - rather soft leptons !
Background: W+Z ℓ ℓ ℓmSUGRA mass assumptions:
Search in 3 channels:• 2e + lepton• e + (+lepton) combined results higher sensitivity• 2 LS
mmm 2 01
021
mmm 02
, ~ 1
14.-18.4.2004 DIS 2004 Tibor Kurca 9
mSUGRA Trileptons: 2e + ℓ (1) Background rejection
Z: 15<Mee<60 GeV
(ee) <2.8
We(+): 1 hit in silicon or
tighter e-likelihood
jets: veto jets ET>80 GeV
scaled mET > 20 GeV
Drell-Yan: mET>20 GeV
(e,mET)>0.4
‘Wannabe’ signal
ℒ dt = 17511/pb
14.-18.4.2004 DIS 2004 Tibor Kurca 10
mSUGRA Trileptons: 2e + ℓ (2)
2 electrons, track matched: pT > 12 (8) GeV, 1.1 (3.0)
• mET > 20 GeV• 3rd lepton isolated high-quality track
• Final cut: mET pT(track) > 250 GeV
(signal) = 2 – 3 %
14.-18.4.2004 DIS 2004 Tibor Kurca 11
mSUGRA Trileptons: 2e + ℓ (3)
expected signal events 0.8 – 1.6 ; tan =3, m =(100-115)GeV expected bgr 0.3 + 0.4 – 0.3 (Zee, WWe e; limited MC statistics) 1 event observed : pT1=33.3, pT2=25.7, pTtrack=8.6
mET=52.1 GeV
14.-18.4.2004 DIS 2004 Tibor Kurca 12
mSUGRA Trileptons: e + (+ ℓ) (1)
Selection cuts:
good e , with isolated, matching tracks: pTe>12, pT>8 GeV; - also calorimeter isolation
mET > 15 GeV
minimal transversal mass: 15<minMT(e, )<80 GeV (Z/*, WW cut)
no dileptons with masses around MZ veto 70-110 GeV, (, ) < 2.5; (,e) > 0.3
jet veto : pT> 60 GeV (1-jet events) (anti tt) pT1 > 40 , pT2 >30 GeV (2 jets)
anti -conversion cut: silicon (SMT) hits 3 for e-track (W)
ℒ dt =
15810/pb
14.-18.4.2004 DIS 2004 Tibor Kurca 13
mSUGRA Trileptons: e + (+ ℓ) (2)
2 subselections: (a) imbalance between pTe, pT and MET: ( for e + , 3rd ℓ missing ! anti WW cut)
(b) 3rd lepton isolated high-quality track pT>3 GeV ( hollow cone, track from the same vtx as other 2, CFT hits..)
most of the remaining bgr ↘… but also signal ↘ Results:
expected signal events 0 – 0.9 ; tan =3, m =(97-114), m° =(57-67) expected bgr : (a) 2.87 0.36 1 event observed (Z/*->, WW,W+jets/ ) (b) 0.54 0.24 no event observed
GeV 6Empp TTeT
±
14.-18.4.2004 DIS 2004 Tibor Kurca 14
Like-Sign Dimuon Channel (1)
Idea: 3ℓ 2LS-leptons…. profit from increased acceptance, while reducing bgr
Challenge: modelling bgr
tt, W+jets, WZ, ZZ Monte Carlo - taken from data
Selection Cuts: 2 track-matched, isolated like-sign , (, )<2.7 pT1 > 11 , pT2 > 5 GeV, mET > 15 GeV topology to kill bb: if pT2 < 11 GeV (jet,mET) < 2.4; min(mET, )>0.5, max(mET, )<2.4, mass cuts to kill Z: OS - M(, )<70 or M(, )>110 GeV LS - M(, )<80 GeV (avoid sign flip)
c/cbb
ℒ dt = 14710/pb
14.-18.4.2004 DIS 2004 Tibor Kurca 15
mSUGRA LS Dimuon Channel (2)
Data points: M(,) – isolated LS
Shaded histogram: remaining bgr estimated from nearly-isolated LS data
Results - events: expected signal : 0 – 0.4; (tan =3, m =(97-114), m°=(57,67) )
expected bgr: 0.13 0.04 (bb, WZ, ZZ, Z)
observed: 1 event pT1=29.1, pT2=13.8, LSmass=37.8, mET=33.5GeV, =1.55
±
14.-18.4.2004 DIS 2004 Tibor Kurca 16
SUSY Trileptons – Combined Result (1)
mSUGRA : tan =3, >0, A0=0, m0=(72,88), m½=(165,185)
m m° 2m° 2e + ℓ e + (+ ℓ ) combined using Likelihood Ratio Method
2 LS signal overlap 15 % (5%) between e++ℓ (e+) e+e+ℓ ,
negligible for LS-dimuon analysis
overlap event assigned to channel with the highest S/B
correlated errors taken into account (main ℒ uncertainty)
±1 12
14.-18.4.2004 DIS 2004 Tibor Kurca 17
SUSY Trileptons – Combined Result (2)
significant improvement of Run I limit
not reaching mSUGRA prediction yet … constrain more generic SUSY models with compatible mass hierarchies
14.-18.4.2004 DIS 2004 Tibor Kurca 18
Squarks & Gluinos Search in mSUGRA
Squarks, gluinos pair production dominates (if light enough…)
- consider only 1st & 2nd families with degenerate masses
- decay chains depend on mass relations
- general event signature: n-jets + MET +m-leptons
Have a look at :
production & 2-body decays dominate
Background: QCD, W/Z+jets
g~q~,g~q~ ,q~q~ ,g~g~ ,q~q~ pp
mm g~ q~
0q q~
qq g~ ... 0
q~q~
Signature: 2 acoplanar jets + mET
14.-18.4.2004 DIS 2004 Tibor Kurca 19
• Jets + Missing ET Trigger (L2, L3) from April 2003
2 jets (cone 0.5) in acoplanar topology
pT1 60, pT2 50 GeV, det1 0.8 - SM, QCD bgr
not EM-object –jet1,jet2 (emf<0.95)
no EM-object with pT>10 GeV W/Z+jets
no isolated with pT>10 GeV
• anti -wrong vertex, -cosmics (cpf>0.05)
mET 60 GeV QCD (moderate MET/correlated with jets) 30 (mET,jet) 165
Final cuts: mET 175 GeV, HT(=Etjets) 275 GeV (optimized for m½=130 GeV )
Squarks & Gluinos – Event Selection
Data : ℒ dt = 85 pb-1
14.-18.4.2004 DIS 2004 Tibor Kurca 20
Squarks & Gluinos Search : Results (2)
mET > 175 GeVHT > 275 GeVObserved 4 events
Expected 2.7 ± 0.95
14.-18.4.2004 DIS 2004 Tibor Kurca 21
Squarks & Gluinos Search: Results (1)
observed 4 events expected 2.7 0.95 Systematics• luminosity: 6.5 %• cross-sections: 8% SM bgr; 10% signal (from Prospino)• jet energy scales (data & MC): +77% -43% SM background +20% -15% signal efficiency
14.-18.4.2004 DIS 2004 Tibor Kurca 22
Signal x-section: PYTHIA (LO) + k-factors PROSPINO (NLO)
mSUGRA parameters: m0 = 25 GeV, A0 = 0, tan =3, <0 m½ = 100 - 140 GeV scan in 5 GeV steps
Mass limits: Msquark > 292 GeV, Mgluino > 333 GeV
Squarks & Gluinos Mass Limits
14.-18.4.2004 DIS 2004 Tibor Kurca 23
Pairs production - large tan 3rd generation sparticles could be light due to large mixing
Gluino production
Sbottom Quarks Production @Tevatron
ggpp ~~
b~bg~mm 1
g~b~
bbpp ~~11
mm q~b~
1
14.-18.4.2004 DIS 2004 Tibor Kurca 24
4 bjets + MET
Background: -QCD, Top, W/Z+jets
Preselection cuts: Signal cuts: 3 jets 15 GeV, < 2 mET > 50 GeV mET > 35 GeV 1 b-tag svx lepton veto (EW bgr) 2 b-tags svx (mET,jets) (QCD bgr)
Assuming:
Btag Observed evts Expected Bgr Expected Signal=================================================Single 4 5.6 1.4 10.6 1.7 Double 1 0.5 0.1 4.4 0.9
Sbottom Quarks from Gluinos
) )( ( ) )( ( ~~ ~~~~ 0
1
0
111 bbbbbbbbgg
bb
GeV60mGeV160mGeV 220m , , ~b~g~
0
11
ℒ dt = 38.4/pb
14.-18.4.2004 DIS 2004 Tibor Kurca 25
Sbottom & Gluino Limits
GeV60mGeV60mm , ~b~g~
0
11
GeV500mq~
14.-18.4.2004 DIS 2004 Tibor Kurca 26
Gauge Mediated SUSY Breaking
SUSY breaking at a scale ~10-100 TeV (<< GUT)
mediated by new gauge fields – « messengers »
LSP is gravitino
- very light M( ) < 1 keV
if NLSP is neutralino:
( also possible)
Exp. Signature: 2 photons + mET
- Assume prompt NLSP decay photons pointing to interaction vtx
G~~0
1
gauginosmostlypp
CDF Run 1
GZ ~~0
1
G~
XGGX ~~ ~~ 0
1
0
1
14.-18.4.2004 DIS 2004 Tibor Kurca 27
mGMSB 2 +mET search : Analysis
Background: 1. fake mET - mismeasured jets, vtx
2. real mET - lost e-track, fake
W e (dominant), Wj e j, Z, WW, WZ, top
Event selection: 2 isolated photons ET> 20 GeV, det,
no matching tracks, no tracks in hollow cone (0.05, 0.4) pT < 2 GeV
- topology : (mET,jet1) < 2.5
(mET, ) > 0.5
- optimized mET > 40 GeV
Signal: looking for excess in tails
of mET distribution
mET (GeV)
14.-18.4.2004 DIS 2004 Tibor Kurca 28
mGMSB 2 +mET search : Results
Observed rates consistent with SM
New limits:
Errors: reco eff. 5%
MC-accept. 6%, 6.5%ℒ
• mGMSB parameters
- scale of SUSY breaking
Mm=2 - messenger mass scale
tan = 5 - vev’s ratio
> 0 – sign of higgsino mass term
GeV 180 )m( GeV, 105 )m( TeV, 7.78 1
0
1
(TeV)
ℒ dt = 18512/pb
95% CL
World’s best !
14.-18.4.2004 DIS 2004 Tibor Kurca 29
mGMSB 2 +mET : CDF Results
Event selection: 2 isolated photons ET> 13 GeV, det, mET > 25 GeV Expected events: bgr 2 ± 1 ± 1; signal 6.6 2 events found Mass limit : tan =15, >0, M=2, N5 =1
GeV 113 )m( 1
(TeV)
ℒ dt = 84/pb
14.-18.4.2004 DIS 2004 Tibor Kurca 30
Rare B-meson Decays – Indirect SUSY Search
• SM prediction:
• FCNC decay - very sensitive probe beyond SM • not observed yet , best limit is CDF-I
• Can be very strongly enhanced for high tan() SUSY complements 3-lepton search
SUSY predicts enhancement by 10-1000 ! … in mSUGRA correlation with a
• search in M=±80 MeV centered on world average Bs(Bd) value
6-E 0.2)B((Br 0
S
)(B B
0
d
0
S
9-E )5.05.3()B((Br 0
S
14.-18.4.2004 DIS 2004 Tibor Kurca 31
Rare B-meson Decays: Results
• expected events: 1.05 ± 0.30 … Bs
1.07 ± 0.31 … Bd
1.75 ± 0.34 … combined• found 1 event : M() = 5.295 GeV … in both windows
Limits @ 90% CL :
•
… 3x better than Run I
• … BELLE@LP03 1.6E-7
ℒ dt =
171/pb
7-E 8.5)B((Br 0
S
7-E 5.1)B((Br 0
d
14.-18.4.2004 DIS 2004 Tibor Kurca 32
Summary Presented results based on ≤ 185ℒ /pb Tevatron experiments are exploring « Terra Incognita » limits extended beyond Run I : - 3ℓ + mET - jets, b-jets + mET - GMSB 2 + mET Many analyses in progress, first Run II papers coming soon Tevatron performance improving end of 2004 on tape ~ 0.5 /fb Better optimized analyses higher sensitivity to signal Excellent opportunity for exciting physics at the highest energy frontier
Hic Sunt Gluinos
14.-18.4.2004 DIS 2004 Tibor Kurca 33
Luminosity Prospects
36×36 bunches396 ns bunch crossing
design: challengingbase: conservative
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