the physics of generations don lincoln f. four fermion general ‘theory’ theory consists of all...
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The Physicsof
Generations
Don Lincolnf
Four Fermion General ‘Theory’
Theory consists of all terms of any chiral combinations
)}(
))(())((
))((
))(())((
)2
)(2
())(({ 12
2
HCLedq
eeddeeuu
eeqq
LLddLLuu
LLqqLLqqg
LRRLSC
RRRRdRRRRRR
uRR
RRLLeLR
LLRRdRLLLRR
uRL
La
LLa
LLLLLLLoLL
oDY
L
L
LL
L
LL l
Ld
uq
l
lq
q
Drell-Yan Only
Tevatron R
un I L
imits
Model Λ+ Λ- Λ+ Λ- Λ+ Λ- Λ+ Λ-
LL 3.3 4.2 2.5 3.7 2.9 4.2 3.1 4.2LR 3.4 3.6 2.8 3.3 3.1 6.7 3.3 3.7RL 3.3 3.7 2.9 3.2 3.2 3.5 3.3 3.9RR 3.3 4.0 2.6 3.6 2.9 4.0 3.0 4.3LL+RR 4.2 5.1LR+RL 3.9 4.4LL-LR 3.9 4.5RL-RR 4.0 4.3VV 4.9 6.1 3.5 5.2 4.2 6.0 5.0 6.3AA 4.7 5.5 3.8 4.8 4.2 5.4 4.5 5.6
e+e-
DØ CDF
e+e- +- combineD
rell
-Yan
QC
D
Model Λ+ Λ- Λ+ Λ- Λ+ Λ- Λ+ Λ-
Limit 2.7 2.4 2.1 2.2 1.6 1.4
DØ CDFds/dM ds/d(cos q*)ds/dM ds/d(cos q*)
Units:TeV
Topics Currently Covered
• All pp two particles– pp (p resolution limited)
– pp eevisa problems)
– pp e(MET questions)
– pp bb (two tagging approaches)
– pp jet-jet (most robust)
– ds/dM & ds/d(cos q*)
Run II Projected: Dijet Mass Spectrum
Dramatic increase in high pT cross sectionsLarge gains in statistics
Run II: Drell-Yan
ConstructiveInterference
DestructiveInterference
mass bin Run I Run II Run II
(GeV) 100 pb-1 2 fb-1 30 fb-1
120-160 136 2329 34414160-200 38 610 8970200-240 7 234 3584240-290 2 119 1939290-340 4 65 884340-400 0 35 468400-500 0 24 273500-600 0 6.5 98
600-1000 0 1.4 431000-1500 0 0 2.2
NkDY
Channel -lim
+lim
-lim
+lim
LL 10.1 8.0 18.9 17.8RR 9.3 6.0 17.0 15.1RL 7.8 5.7 13.5 9.1LR 7.3 6.0 12.1 9.2
L = 2 fb-1 L = 30 fb-1
Projected Limits (Bayesian)
PRL 82 4769 (1999)
2VTX Tagging High P b Jets
Don Lincoln
f
Isn’t that two there?
Bee) (Two ! || Bee) Two(
Kapow!
Motivation
Fit to CDFqQCD calculation
CDF: PRL 82 (1999) 2038
• High mass bb pairs can be sign of new physics (compositeness ?)
• Problem– ~100:1 QCD:bb
• Solutions tagging
– 2nd VTX tagging
– Impact parameter
Current Work
DCA
DecayLength
Key
Calorimeter Jet
b hadron
Secondary vertex
Primary vertex
Particles of Interest
Question: Is failure to reconstructsecondary vertex due to tracking efficiency or vertex algorithm?
•Many variables have been tried for 2 VTX tag•Decay length & significance (2D & 3D)•Vertex MassR•etc.
•Only decay length and related quantities works.
•Consider other tags eventually.
R
ImpactParameter
What if ?We know that one can findsecondary vertices by accidentin light quark initiated events
Estimate Eff(right) ~ Eff(found) - Eff(light)
No light statistics at high ptReality could be worse
Eyeball trends and guess.
Eff(found) = Eff(luck) + Eff(right)
Efficiency only that of finding a ‘good’ secondary vertex
Decay Length (found and 2VTX)
Found = found track2VTX = used in secondary vertex
Ptmin(track) = 500 MeV
Efficiency = 2VTX/found
Efficiency ~ Pt and flavor-initiator independent
R (real and found) Found = correct + fake
Ptmin(track) = 500 MeV
Efficiency = found/real
Light quark jets has better tracking efficiency in core.
Pt Eff (b) Eff (light)100-150 ~52% ~58%250-300 ~34% ~42%
Tracking ‘Efficiency’ vs Pt.
Summary• Several different high mass di-object searches
underway
• In bb– Need to understand tracking efficiency in core of jets– Need to look more at muon tagging (but low mass
reach)– Need to better understand b quark content from parton
showers.
• Active effort
• Need more people thinking about it.