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Outline• Detectors and Methods
– Spectrometer layout– Segmented target, OOT cut
effectiveness– CITADL
• Kaonicity• pion ID effect on K-pi
reflection– Target Silicon– Vertexing and skim strategy– Omega signal
• EM Calorimeters & Muon Upgrades– IE & OE
• pi0 reconstruction– D*-D mass– Semileptonic Physics
• Form Factor Measurement• D0-D0bar mixing
• FOCUS Physics– K K Ks Dalitz– DCSD : D+ -> KKK– Charm baryon signals
• CascadeC -> p k pi• LambdaC -> sigma pi pi
– Double-D Production– K K pi Dalitz– D lifetimes
• CP Violation and Mixing– D0 CP eigenstate lifetime diffs.
• CLEO plots• FOCUS Advantages• K-pi signal• Skim Strategy (candidate-
driven)
– CP asymmetry (Daniele)– CP asymetry (O’Reily)
Segmented TargetD
ecays/2
00
m Be
OBeO
tarsil
tarsil
black - primary vertex red - secondary vertex
• 62% of D decays occur in air• Out-of-Material cut virtually eliminates non-charm backgrounds
From background subtracted charm!
D+ Yield = 11528 S/N = 2.8
p( )M KK
DKK
p( )M KK
D+ Yield = 7157 S/N = 10
Out of Material
“Kaonicity” Golden Kaons & pions
Likelihood based Cerenkov algorithm
D+ +- without Cerenkov ID
K reflection
signal
D+ +- with loose pion IDp- >1.0KW W
Yield = 3317
D+ +- with tight pion ID
Yield = 2092
p- > 4.0KW W
0 reconstruction with the IE and OE
Y ield = 1 0 7 1 4S/N = 1 5
(with D* tag)
D0 K-+0
2 0( )M
2( )M K
*K
*0 0K
0K
D0 K-+0 has a rich substructure with lots of interference
Target Silicon Detector
20
25
30
35
40
45
50
5800 7800 9800 11800 13800run number
Proper time resolution vs run number
TS used
No TSTS inst
alle
d
ts ( )fs
Target Silicon detector improves proper time resolution by about 20%
D*-D Mass Difference Measurements• These measurements hilight our improved 0
reconstruction• Statistical errors should be about 3 times better than
present world average
*0 0( ) ( )M D M D
*0 0 0 0,D D D K
= 142.02 0.03 MeV
PDG = 142.12 0.07 MeV
M
* 0,D D D K
*( ) ( )M D M D
= 140.72 0.03 MeV
PDG = 140.64 0.10 MeV
M
c pK
Charm Baryon Signals
Cabibbo suppressed decay mode of the
(first observed by SELEX)
c
2GeV/c 2GeV/c
c c c
Expected resonance contributions to D0 KKKS
Class 1 BSW requires resonance coupling to u-dbar quarks and a dikaon. The only resonances are:
•a0 (980) (sub-threshold)
•a2 (1320)Class 2 BSW requires resonance coupling to u-ubar quarks and a dikaon:
f0 (980) (subthreshold)
•f2 (1270)
2( )SM K K
2( )M K K
lobes
0(980) ?a
0(980) ?f
2( ) (GeV/c )sM K KK
Dalitz Analyses SD K K K
FOCUS Semileptonic Physics
• Measure Form Factors for
– Check against recent LGT calculations
• Cabibbo suppressed decays:• Semileptonic mixing:• Rare or forbidden decays:
Expect roughly 50 times more semimuonic events than E687 with our rebuilt muon system!
*0
*0s
s
D K
D
D
De eK
0D l D lr n p n+ ® ®* 0 0 ( )D D D Kp mp p n+ + ++ + -® ® ®
0D mm+ -®
*0 ( )D K K
— Right Sign — Wrong Sign
RS-WS yield 56445
( )M K
D0 CP eigenstate Lifetime Differences
CLEOassuming CP
CLEO allowi
ng CP
violation
M
FOCUS can make competitive measurement
0 signal from FOCUSD K K
Y=16532 STN=2.3
Expect y =1.3%
(y (CLEO) = 1.73%)
M(KK)
• Extremely good proper time resolution : 8% (D0)
– No resolution systematics or error inflation
• A segmented target with ~62% of decays verticizing in air
– Grossly minimizes absorption corrections in matter
• Excellent (and flexible) Cerenkov identification
– Vary misidentification reflections to gauge systematics.
• Skims use a vertexing algorithm with nearly flat t’ acceptance
– Minimizes any reliance on MC and reduces systematic error
• We expect to measure y to within 1.3%
FOCUS ADVANTAGES
Skim Strategy with minimal time bias
K
KSeed track
Primary vtx track
Recoil charm track
Nearly uniform time acceptance --right up to the skim cut!
Nucleate about seed track to form a primary vertex.
Look for two tracks with a good intersection
A minimum bias skim for D0 KK
CP Violation Search in D+ and D0 Decays
0
0Where( ) ( ) ( )
( ) ( ) ( )
( )CP
D D N D K KA D
D D N D K
D KK D KK D
Asymmetry mechanism in PythiaNeed to correct for production asymmetry which occurs at ~3% level
*D *DExpecting 1-2% sensitivity
Doubly Cabibbo Suppressed Decays
D Peak DS PeakD = 8.5 MeV/c2
DS = 8.5 MeV/c2
D KKK
Double D Photoproduction Dynamics
Charm and anticharm acoplanarity distribution probes NLO QCD
The correlation between a charm particle and an anticharm particle in the same event
radians)
: kinematic tag
: Double D reconstruction ~