absolute d hadronic branching fractionshadron.physics.fsu.edu/~crede/files/ddbar.pdf · 2007. 7....
TRANSCRIPT
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
D Hadronic Branching Fractions andDD Cross Section at ψ′′(3770) from CLEO–c
V. Credé 1 2
1Cornell University, Ithaca, NY
2now at Florida State UniversityTallahassee, FL
Hadron 05
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
Outline
1 IntroductionCESR-cCLEO-c Detector
2 Absolute D-Hadronic Branching FractionsWhy are Hadronic D Decays interesting ?D TaggingFitting the Branching Fractions
3 Results: Branching Fractions and Cross Sections
4 Summary and Outlook
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
CESR-cCLEO-c Detector
Outline
1 IntroductionCESR-cCLEO-c Detector
2 Absolute D-Hadronic Branching FractionsWhy are Hadronic D Decays interesting ?D TaggingFitting the Branching Fractions
3 Results: Branching Fractions and Cross Sections
4 Summary and Outlook
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
CESR-cCLEO-c Detector
e+e− → ψ′′(3770) at Cornell
Ü
CESR–c at CornellE beam = (1.5− 5.6) GeV
⇒ √s = (3.0− 11.2) GeV
CESR–c collides e+ e− in order toproduce the ψ
′′(3770)
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
CESR-cCLEO-c Detector
Outline
1 IntroductionCESR-cCLEO-c Detector
2 Absolute D-Hadronic Branching FractionsWhy are Hadronic D Decays interesting ?D TaggingFitting the Branching Fractions
3 Results: Branching Fractions and Cross Sections
4 Summary and Outlook
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
CESR-cCLEO-c Detector
Solenoid Coil Barrel Calorimeter
Drift Chamber
Inner Drift Chamber /Beampipe
EndcapCalorimeter
IronPolepiece
Barrel MuonChambers
MagnetIron
Rare EarthQuadrupole
SC Quadrupoles
SC QuadrupolePylon
2230104-002
CLEO-c
Ring Imaging CherenkovDetector
Excellent Calorimeter
Excellent Tracking
RICH and dE/dx for PID
Muon Chambers+ A Great Accelerator Team
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
Why are Hadronic D Decays interesting?D TaggingFitting the Branching Fractions
Outline
1 IntroductionCESR-cCLEO-c Detector
2 Absolute D-Hadronic Branching FractionsWhy are Hadronic D Decays interesting ?D TaggingFitting the Branching Fractions
3 Results: Branching Fractions and Cross Sections
4 Summary and Outlook
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
Why are Hadronic D Decays interesting?D TaggingFitting the Branching Fractions
Hadronic D Decays
Measurements of hadronic charm meson branching fractions playcentral role in study of weak interaction
Serve to normalize many D and B meson branching fractions(normalizing modes: D0 → K−π+ and D+ → K−π+π+)Used to determine Cabibbo–Kobayashi–Maskawa (CKM) matrixelements (e.g. |Vcb | from B→ D∗ l ν requires D meson BF)
CLEO–c will provide most precise measurements of D hadronicbranching fractions
Also, determination of DD production cross sectionsFirst step towards improved constraints on D mixing parameters
First results: 55.8 pb−1 (0.36 M DD pairs)CLEO Collaboration (Q. He et al.), hep–ex/0504003, accepted by PRL
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
Why are Hadronic D Decays interesting?D TaggingFitting the Branching Fractions
Outline
1 IntroductionCESR-cCLEO-c Detector
2 Absolute D-Hadronic Branching FractionsWhy are Hadronic D Decays interesting ?D TaggingFitting the Branching Fractions
3 Results: Branching Fractions and Cross Sections
4 Summary and Outlook
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
Why are Hadronic D Decays interesting?D TaggingFitting the Branching Fractions
D Tagging and the Mark III Method
Basic strategy(for most CLEO–c analyses)
Full reconstruction of oneD meson (the tag)Search for 2nd D meson inthe remainder of the event
Identification of D meson candidatesusing beam–constrained mass:
∆E = ED − E beam
M bc =√
E2beam − |pD|2
Reconstruction
Charged tracks: Track fit quality andoriginate from interaction point
π / K separation by dE/dx and RICH
KS → π+π− and π0 reconstruction
3σ cut on ∆E ≡ ED − E0
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
Why are Hadronic D Decays interesting?D TaggingFitting the Branching Fractions
Single Tags and Double Tags
Measurement of single tags and double tags
Ü Ü
⇓ Wanted
Ni = NDD Bi εi
Nij = NDD BiBj εijÜÜ
Measured
Known
Bi =Nij εjNj εij
NDD =Ni Nj εijNij εi εj
Determination of Branching FractionsDetermine yields Ni and Nij
Simultaneously fit forND+D− , ND0D0 , and all Bi
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
Why are Hadronic D Decays interesting?D TaggingFitting the Branching Fractions
Outline
1 IntroductionCESR-cCLEO-c Detector
2 Absolute D-Hadronic Branching FractionsWhy are Hadronic D Decays interesting ?D TaggingFitting the Branching Fractions
3 Results: Branching Fractions and Cross Sections
4 Summary and Outlook
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
Why are Hadronic D Decays interesting?D TaggingFitting the Branching Fractions
Fitting Technique (I)
Simultaneous fit for all BR & cross sections is performed⇒ All correlations and errors properly taken into account
Charged and neutral modesfit simultaneouslyD and D yields measuredseparately
D0 → K−π+ D0 → K+π−
D0 → K−π+π0 D0 → K+π−π0
D0 → K−π+π+π− D0 → K+π−π−π+
D+ → K−π+π+ D− → K+π−π−
D+ → K−π+π+π0 D− → K+π−π−π0
D+ → KSπ+ D− → KSπ
−
D+ → KSπ+π0 D− → KSπ
−π0
D+ → KSπ+π+π− D− → KSπ
−π−π+
D+ → K−K+π+ D− → K+K−π−
W.M. SunarXiv:physics/0503050accepted by NIM A
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
Why are Hadronic D Decays interesting?D TaggingFitting the Branching Fractions
Fitting Technique (II)
Background sources:D modes not in the fite+e− → continuumMost Cabibbo-suppressed modes small
Errors on signals and background:Tracking, π0, KS systematics(correlates all elements)Resonant substructureCorrelations between D0 and D+
Analysis technique validated by studying simulated DD events
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
Why are Hadronic D Decays interesting?D TaggingFitting the Branching Fractions
Single–Tag Event Yields
3970305-001
104
103
102
10
104
103
102
104
103
102
1.84 1.86 1.88 1.84 1.86 1.88 1.84 1.86 1.88M (GeV/c2)
Eve
nts
/ (0.
002
GeV
/c2 )
+D0 K + ++D K
+ +D K0S
+D0 K 0 ++ +D K 0 + +D K0S
0
++D K 0 ++ +D K0S
+ + +D K K
Yields vary between 0.6 kand ≈10 k events
Signal shape:ψ(3770) lineshape + ISR+ beam–energy smearing,+ reconstruction resolutionBackground shape:ARGUS function
Note: log scale for single tags !
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
Why are Hadronic D Decays interesting?D TaggingFitting the Branching Fractions
Double–Tag Event Yields
3970305-002800
600
400
200
0
600
400
200
0 1.84 1.86 1.881.84 1.86 1.88M (GeV/c2)
Eve
nts
/ (0.
0012
GeV
/c2 )
D+DD0D0 Mass of D for allmodes combinedDT Yields
2484± 51 for D0
1650± 42 for D+
Double–tag modes clean⇒ Statistical yield uncertainties close to
√N ij
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
Why are Hadronic D Decays interesting?D TaggingFitting the Branching Fractions
Example: Tracking Systematics
250
200
150
100
50
00.1 0 0.1 0.2 0.3 0.4 0.5
MM2 (GeV/c2)2
Eve
nts
/ 0.0
1 (G
eV/c
2 )2
0140704-014
( a ) Data: K Detected
2000
1600
1200
800
400
00.1 0 0.1 0.2 0.3 0.4 0.5
MM2 (GeV/c2)2
Eve
nts
/ 0.0
1 (G
eV/c
2 )2 ( b ) MC: K Detected
0140704-015
( c ) Data: K Not Detected
0140704-016
807060
5040
30
20
1000.1 0 0.1 0.2 0.3 0.4 0.5
MM2 (GeV/c2)2E
vent
s / 0
.01
(GeV
/c2 )
2
600
500
400
300
200
100
0
( d ) MC: K Not Detected
0140704-017
0.1 0 0.1 0.2 0.3 0.4 0.5
Eve
nts
/ 0.0
1 (G
eV/c
2 )2
MM2 (GeV/c2)2
ProcedureExample:Reaction D0 → K−π+
Leaving out K⇒ MM peaks
at mass ofomitted K
Efficiency:Ratio of(a) and (c)
Comparisonbetween Dataand MC
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
Why are Hadronic D Decays interesting?D TaggingFitting the Branching Fractions
Systematics
Tracking Systematicsψ(2S)→ J/ψ π+π−
also:ψ(2S)→ J/ψ π0π0
KS from D→ KS ππ(double–tag events)
Source Value (%)Tracking / KS /π0 0.7 / 3.0 / 2.0Particle ID 0.3/π± 1.3/K±
∆E 1.0 – 2.5ΓΨ(3770) 0.6Final State Radiation 0.5 ST / 1.0 DTResonant Substructure 0.4 / 1.5DCSD Interference 0.8Fit Functions 0.5Online/Offline Filtering 0.4MultiplicityDetector Noise
0.2 – 1.3
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
Why are Hadronic D Decays interesting?D TaggingFitting the Branching Fractions
Comparison with PDG
0.4 0.6 0.8 1.0 1.2 1.4 1.6
PDGCLEO-c
0.4 0.6 0.8 1.0 1.2 1.4 1.6
PDGCLEO-c
CLEO−cPDG
CLEO−cPDG
CLEO efficiencies include Final State Radiation (FSR)In some channels, systematics is already the limiting factor
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
Why are Hadronic D Decays interesting?D TaggingFitting the Branching Fractions
Comparison with other direct measurements in PDG
0.010 0.020 0.030 0.040 0.050 0.060
PDG
0.045 0.065 0.085 0.105
PDG
B(D0 → K−π+) B(D+ → K−π+π+)
PDG band corresponds to the average of all direct measurements⇒ Not a global fit !
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
Cross Sections and Absolute Branching Fractions
Determination of cross sections(scaling N DD by the luminosity)
σ (e+e− → DD) = (6.23± 0.09± 0.21) nb
σ (e+e− → D0D0) = (3.51± 0.07± 0.14) nb
σ (e+e− → D+D−) = (2.72± 0.07± 0.09) nb
Comparison with BES(PLB 603, 130 (2004))
(6.14 ± 0.12 ± 0.50) nb
(3.58 ± 0.09 ± 0.31) nb
(2.56 ± 0.08 ± 0.26) nb
⇒ much larger
Ü
Values higher thanthose of MARK III
Currently, most precise dataDetermination of charged to neutral ratio(→ next slide)
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
Charged to Neutral Ratio
0.9
1.0
1.1
1.2
0.5
0.6
0.7
0.8
10.572 10.580 10.588 3750 3760 3770 3780 3790E [ GeV ] E [ MeV ]
•
•
This analysis
Predictions: M. Voloshin(hep-ph/0402170)
Ü
Rchargedneutral = σ(e+e−→D+D−)
σ(e+e−→D0D0)= 0.78± 0.02± 0.02
Discrepancies ⇒ Speculation of 4–quark component of ψ(3770)(M.V., hep-ph/0504197)
DB
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
CLEO–c Absolute Hadronic BF: Summary
First results based on (arXiv:hep–ex/0504003)
55.8 pb−1 of e+e− colllisions9 decay modes⇒ Including reference branching fractionsB(D0 → K− π+) = (3.91± 0.08± 0.09) %B(D+ → K− π+π+) = (9.5± 0.2± 0.3) %
Comparison with PDG: Branching fractions a little bit higher⇒ CLEO measurements corrected for FSRAlready systematics limited in some modes⇒ New data will reduce statistical errors even moreCross sections:σ(ψ
′′ → DD), σ(ψ′′ → D0D0), σ(ψ
′′ → D+D−), and Rchargedneutral
V. Credé Absolute D Hadronic Branching Fractions
IntroductionAbsolute D-Hadronic Branching Fractions
Results: Branching Fractions and Cross SectionsSummary and Outlook
Hadronic D Decays: Outlook
There will be more data available for this analysis281 pb−1 as of this summerStatistical error will be reduced by a factor of 2
Addition of Cabibbo–suppressed hadronic D decays⇒ including π0
D mixing constraints(hep–ph/0507238, submitted to PRD)
V. Credé Absolute D Hadronic Branching Fractions