Opportunities and Challenges in Hadronic D Decay...
Transcript of Opportunities and Challenges in Hadronic D Decay...
Jim Alexander - Joint Workshop on Charm Physics 北京市 1/2004
Opportunities and Challenges inHadronic D Decay Measurements
Rich set of phenomena in hadronic D decays
Significant theoretical challenges
Cornucopia of measurements to come
Powerful detectors with good kinematic resolutions, PID
Related talks in this Workshop:
Theoretical Challenges in Charm Physics Ikaros Bigi - ThPrecision Charm Experiment and Precision LQCD Shoji Hashimoto - ThCharm Effects in phi_3 Measurements Alex BondarCharm Baryons John YeltonDDbar mixing CPV and Rare D Decays Theory Ikaros Bigi - ThDDbar mixing CPV and Rare D Decays Experiment David Asner
This Talk: Overview - Absolute BR Measurements
Jim Alexander - Joint Workshop on Charm Physics 北京市 1/2004
Why measure the D hadronicdecay modes?
1. It is useful engineering:- Fix absolute scale of heavy quark decay rates.
• Affects CKM measurements• Resolve charm counting issues in B decay• Understand two-body B decays
- Measure strong phases. Useful for CPV work in B decays• Identify targets for Acp measurements in D
- Part of understanding what is SM behaviour
2. It is interesting science:- QCD dynamics is rich and vibrant in D system.
- Measurements will drive theory… maybe future theory
3. We can do it.
Jim Alexander - Joint Workshop on Charm Physics 北京市 1/2004
Hadronic D0 Br Measurements k+k-k-pi+
pi0pi0 ksksks pi+pi- kseta k+k- k0barf2(1270) phiks k0barpi+pi+pi-pi- rho0ks k*0(1430)0pi0 ksetapr k0bark+k- omegaks pi+pi-pi0 k1(1270)-pi+ kspi0 k*0(1430)-pi+ k*(1680)-pi+ k*0barrho0 k*bar0pi_pi-pi0 k*0bareta k*0barpi+pi- k*0barpi0 k-pi+omega k-pi+ k-pi+pi+pi0 k0barpi+pi- k*-pi+ k*-rho+ k-a1(1260)+ k-pi+pi-pi+ rho+k- k0barpi+pi-pi0 k-pi+pi0
0 2 4 6 8 10 12 14
PDG 2003
Branching Ratio (%)
Normalizingmode
Jim Alexander - Joint Workshop on Charm Physics 北京市 1/20040 10% 20% 30% 40% 50%
Relative Precision: δBr/Br (D0)
PDG 2003
0 10% 20% 30% 40% 50% k-pi+
k+k- k-pi+pi-pi+ pi+pi- k0barpi+pi- k-pi+pi0 rho+k- k*-pi+ kspi0 k0bark+k- k-pi+pi+pi0 k0barpi+pi-pi0 phiks kseta k*0barpi0 ksetapr k-a1(1260)+ ksksks omegaks k-pi+omega rho0ks k*0(1430)-pi+ k*0barrho0 k*0barpi+pi- pi0pi0 k1(1270)-pi+ k0barpi+pi+pi-pi- k+k-k-pi+ pi+pi-pi0 k*(1680)-pi+ k*-rho+ k*0(1430)0pi0 k*bar0pi_pi-pi0 k*0bareta k0barf2(1270)
0 10% 20% 30% 40% 50%
Jim Alexander - Joint Workshop on Charm Physics 北京市 1/2004
Absolute BranchingRatio: D0→K-π+
Method: Detect D*+→π+Do,when
Do →K-π+ and Do → anything.
Problem: Systematic errordue to backgroundextrapolation
PDG 2.3 3.83±0.09
ALEPH 3.83.82±0.09±0.12
CLEO 3.63.82±0.07±0.12
SourceError(%) B (%)
α is angle between thrustaxis & slow π+
Jim Alexander - Joint Workshop on Charm Physics 北京市 1/2004
Hadronic D+ Br Measurements
k-pi+pi+pi+pi- kspi+ k*(1680)0pi+ kbar0kbar0k+ K*0barpi+ k*0rho+ phipi+pi0 k*+k*0 k0barpi+ k-rho+pi+ k*+k0 rho+ks k*0bar(1430)0pi+ kbar0rho0pi+ k1bar(1400)0pi+ k-pi+pi-pi0 k*bar0pi+pi0 k0barpi+pi+pi- k0bara1(1260)+ k-pi+pi+ k0barpi+pi0
0 2 4 6 8 10 12 14%Branching Ratio (%)
PDG 2003
Normalizingmode
Jim Alexander - Joint Workshop on Charm Physics 北京市 1/2004
Hadronic D+ δBr/Br
kspi+ k0barpi+ k-pi+pi+ K*0barpi+ k*0bar(1430)0pi+ k0barpi+pi+pi- k-pi+pi+pi+pi- k-pi+pi-pi0 k*bar0pi+pi0 k0bara1(1260)+ k*(1680)0pi+ kbar0rho0pi+ k1bar(1400)0pi+ k0barpi+pi0 k-rho+pi+ rho+ks k*+k*0 phipi+pi0 kbar0kbar0k+ k*+k0 k*0rho+
0 10% 20% 30% 40% 50%
PDG 2003
Jim Alexander - Joint Workshop on Charm Physics 北京市 1/2004
Hadronic Ds Br Measurements
0 2 4 6 8 10 12 14%
Branching Ratio (%)
PDG 2003 omegapi+ k+k-pi+pi+pi- k+pi+pi- pi+pi+pi- pi+eta k+ks k*+ks k+k0barpi+pi- k*0bark+ phipi+ pi+etapr k0k-pi+pi+ k+k-pi+ phirho+ rho+etapr rho+eta
Normalizingmode
Jim Alexander - Joint Workshop on Charm Physics 北京市 1/2004
Hadronic Ds δBr/Br
PDG 2003
0 10% 20% 30% 40% 50%
phipi+ pi+etapr k+k-pi+ k*0bark+ pi+pi+pi- rho+eta rho+etapr pi+eta k+ks k*+ks phirho+ k0k-pi+pi+ k+k0barpi+pi- omegapi+ k+k-pi+pi+pi- k+pi+pi-
Jim Alexander - Joint Workshop on Charm Physics 北京市 1/2004
Method: Reconstruct B-> Ds* D* bypartial reconstruction twice -once for Ds, once for D0
Observe signal both with & withoutexplicit Ds or Do reconstruction
Ratio measures B(Ds→φπ+)/B(Do→K-π+)
Large backgrounds associated withpartial reconstruction methods
Absolute BranchingRatio: Ds→φ π+
PDG25.0 3.6±0.9CLEO25.33.59±0.77±0.48SourceErr (%) B (%)
*+**sss*+oBDD,DãDorDDπ−−−+→→→
Jim Alexander - Joint Workshop on Charm Physics 北京市 1/2004
Experiments Psi(3770) MARK III BES II CLEO-c BES III
(Large)
High
(excellent)
tagging; coherence
Fixed Target FOCUS E791 E691
Large
Moderate
Excellent
displ vtx
Y(4S) Babar Belle CLEO II CLEO III
Large
Moderate
Excellent
displ vtx
Collider CDF D0 BTeV LHCb
Huge
Low
()
displ vtx vtx trigg
DATA SAMPLE
SIGNAL/BKG
PARTICLE ID?
FEATURES?
PastPresentFuture
Jim Alexander - Joint Workshop on Charm Physics 北京市 1/2004
Unique features available withcharmonium initial state1. Cleanliness
Charged multiplicity ~ 2.5/D mesonNeutral multiplicity ~ 1.3/D mesonNo other particles in event
2. TaggingDDbar state produced with no extra particles
Exploit large branching ratios, Abundant kinematic constraints.
Reduce combinatoricsObtain absolute BR via double/single tagCP tagging for CPV studies
3. Quantum CoherenceD mixing studies: Doubly Cabibbo Suppressed mode = 0CP Violation searches
Jim Alexander - Joint Workshop on Charm Physics 北京市 1/2004
CLEO-c, 1fb-1, D0, D+ yields
Jim Alexander - Joint Workshop on Charm Physics 北京市 1/2004
D0→K-π+ Tag mass plots
Jim Alexander - Joint Workshop on Charm Physics 北京市 1/2004
Ds→φ π
Jim Alexander - Joint Workshop on Charm Physics 北京市 1/2004
Double TaggedBR
Singles yield
Doubles yield
Absolute Branching Ratio
Jim Alexander - Joint Workshop on Charm Physics 北京市 1/2004
Systematics of Absolute BRMeasurements
For CLEO-c projections we have estimated thesystematic uncertainty of the efficiency, due totrack finding.
CLEO II: 0.7% achieved in clean events.
CLEO-c: evaluate systematic error by partialreconstruction: (tag event), observe K-… requireMissing Mass consistent with Pion. Compare with caseof reconstructed Pion. --> MC study indicated 0.2%achievable by this method.
Jim Alexander - Joint Workshop on Charm Physics 北京市 1/2004
Reach of double tag technology
p105
KπKππφπ
Jim Alexander - Joint Workshop on Charm Physics 北京市 1/2004
温故知新Original MARK III doubletagged BR measurements werewrong by 21-24% due to unsubtracted backgrounds:
Feed-across: D->KK, D->pipi ---misID--> D->KpiFeed-down: D->Kpipi0 ---pi0Loss--> D->Kpi
dE/dx resolution ~10% TOF resolution 189ps
Translation: “Study MARKIII experience beforeplunging ahead with CLEo-cand BES III.”
Jim Alexander - Joint Workshop on Charm Physics 北京市 1/2004
BES III Particle ID
Jim Alexander - Joint Workshop on Charm Physics 北京市 1/2004
MARK III CLEO-c BES IIIMomentumResolution 1.7% 0.5% 0.5%@500 MeV/c
dE/dxResolution 10% 5-6% 6-7%@min-I
RICH K/piSeparation - ~20σ −@ 1GeV
TOF res 190ps - 100ps
PID solid 75% 90% 90%Angle
Photon E res 17% 2.1% 2.5%@1GEV
Jim Alexander - Joint Workshop on Charm Physics 北京市 1/2004
SummaryCharm physics at threshold returns to center stage
Powerful, modern detectors (PID! Pi0! Hermetic!)
High luminosity accelerators: 10-100M D decayspossible
Absolute charm branching ratios will be measured withunprecedented precision: 1-2%