The CLEO-c Experiment and its Impact - Cornell University
Transcript of The CLEO-c Experiment and its Impact - Cornell University
A. Ryd, Cornell U. NSF Visit, Ithaca, October 24, 2006 Page: 1
Anders RydCornell University
Ithaca, Oct. 24, 2006
The CLEO-c Experiment and its Impact
Outline:The CLEO-c Physics ProgramTests of Lattice QCDSome Recent CLEO-c Results:• Hadronic D Decays• Leptonic D and Ds Decays• Semileptonic D DecaysConclusions
A. Ryd, Cornell U. NSF Visit, Ithaca, October 24, 2006 Page: 2
Heavy Quark PhysicsMany experiments study decays of b-quarks:
B-factories: BABAR and BelleTevatron: CDF and D0LHC: LHCb
The CLEO-c experiment is making unique contributions to these studies
fD
c d
l+W+
ν
u u _ _
Vcd
D0 -
Leptonic decays Semileptonic decays
Decay constant, fD, describesoverlap of c and d quark in the D+.
Form factors describe prob. toform final state: f(p)=<|H|D>
QCD (Quantum ChromoDynamics) is a strongly interacting theory
CLEO-c will allow crucial tests of Lattice QCD
A. Ryd, Cornell U. NSF Visit, Ithaca, October 24, 2006 Page: 3
Lattice QCDAt low energy QCD is strongly coupled
Calculations done on discrete latticeRecent revolutionary progress in algorithms have allowed simulation of full QCD.• Can handle QCD vacuum polarization
Understanding strongly coupled systems is important.• LHC might uncover new strongly interacting physics.
This dramatic improvement in Lattice QCD needs to be validated in calculations of form factors and decay constants
HPQCD+FERMILAB+MILCPRL 92:022001,2004
Before 2000 ~2004
Energy (GeV)
Couplin
g S
trength
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CLEO-c Experiment
New inner drift chamberTracking in 1.0 T field• p/p≈0.6% at 1 GeVExcellent E-M calorimeter• E/E≈2% at 1 GeVHadron PID from RICH• Very good below 1 GeV
CLEO-c detector is working very well.The detector capabilities are well matchedto the physics.
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Absolute D Branching Fractions
e+ e-
D-
D+
cc
K+
-
- Tag D – fully reconstructed
Unique to CLEO-c:Running near cc threshold
~80,000DK
Very littlebackground
Data (281 fb-1)D+K-++ Branching Fraction
_
_
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D++and fD+
e+ e-
D-
D+
cc
K+
-
-
+
50 SignalCandidates
D+K 0+
Data 281 pb-1
Br D++=4.40±0.660.12+0.09×104
fD+=222.6±16.73.4
+2.8 MeVPRL 95, 251801 (2005)
_
First significant measurement of D+
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Data vs. Lattice Calculations
Similar technique used also to measure fDs in Ds.CLEO results consistent with most (recent) predictions.For precision comparisons we need the complete CLEO-c program.• Will allow tests at the 2-4% level.
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Semileptonic Decays
An important goal of the CLEO-c program is to measure form factors to check lattice QCD calculations.
D0Ke
CLEO-c (Preliminary) CLEO-III (At bb threshold)
D0eD0Ke
c d
l+W+
ν
u u _ _
Vcd
D0 -
Semileptonic decay
The cc threshold operation of CLEO-c makes it unique _
_
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Exclusive Signals (281 pb-1)
U = Emiss– |Pmiss| (GeV)
295±20
699±28
2910±55
6796±84
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Form Factors and LQCD
DATA FIT
LQCD
DATA FIT
LQCD
CLEO-c measurements of semileptonic D decays world's best.
D0e+
D0e+
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ConclusionCLEO-c are producing unique results on charm decays• Very well understood detector and software• Small but dedicated and focused groupFor D decays we are rewriting the books• Absolute branching fractions for D and Ds decays• Leptonic D and Ds decays• Semileptonic D and Ds decaysThese measurements allow precise tests of Lattice calculations.• Important to interpret B-physics data from the B-factories and the Tevatron.
Many other important topics not discussed here, e.g., Dalitz studies for '' measurements, strong phase in D decays etc.
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Backup Slides
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Physics MotivationThe CLEO-c program impacts many of the CKM parametersIn particular, leptonic D and Ds decays allow measurements of the decay constantsThis will help the determination of VtdSemileptonic D decays will check form factor calculations and improve VubHadronic D decays are important for normalization of B decays
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Determining the CKM Matrix
δVub/Vub 10%lνBπ
l
νDπ
δVcd/Vcd 10%lνD
Κ
δVcs/Vcs =10%l
B νD
δVcb/Vcb 1.5%
Bd Bd
δVtd/Vtd =10%
Bs Bs
δVts/Vts 10% δVtb/Vtb 25%
δVus/Vus =1%
νπ
Κl
δVud/Vud 0.3%eνp
n
tb
W
CLEO-c willdirectly measure D-decays
Form factorsfrom D-decaysand LatticeQCD andprecision br. fr.From D decays will help improver
CLEO-c willmeasure D-decaysconstants
CLEO-c measurements of D-decays will have a significant impact on the determination of 6 of the CKM matrix elements.• Directly by studying De and DKe.• Or indirectly be measuring quantities that can be used to validated calculations of the strong dynamics that binds the quarks to hadrons.
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Testing Theories of Strong Interactions
B mixing is well measuredmd=(0.5020.007)10-12 s
But |Vtd| from md has large uncertainties from fBCLEO-c can measure fD
Bd Bd
md=GF
2
6MBMt
2∣V tdVtb* ∣2BS0xt f B
2BB
c d
l+W+
ν
u u _ _
Vcd
D0 -
b u
l-W-
ν
d d _ _
Vub
B0 _
Measure form factors in Dl and validate theoretical calculationsCan then use this to extract |Vub| from Bl
fD
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CLEO Collaboration
CLEO Collaboration Cornell
Syracuse
UIUC
Minnesota
Florida
Pittsburgh
Purdue
RPI
CMU
Rochester
NWU
SMU
Puerto Rico
Wayne State
SUNY Albany
U. Chicago
George Mason
Kansas
Luther
About 135 collaborators
CLEO Authors by year
New groups are still joining CLEO-c