outline detectors and methods –spectrometer layout –segmented target, oot cut effectiveness...

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 ~