Opportunities and Challenges in Hadronic D Decay Measurementsbes.ihep.ac.cn/conference/wksp04/reports/07.Hadronic D... · 2011. 11. 25. · Jim Alexander - Joint Workshop on Charm

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


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.


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%


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+


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


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


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


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-


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−−−+→→→


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


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


CLEO-c, 1fb-1, D0, D+ yields


D0→K-π+ Tag mass plots


Ds→φ π


Double TaggedBR

Singles yield

Doubles yield

Absolute Branching Ratio


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.


Reach of double tag technology

p105

KπKππφπ


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.”


BES III Particle ID


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


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%

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Opportunities and Challenges in Hadronic D Decay Measurementsbes.ihep.ac.cn/conference/wksp04/reports/07.Hadronic D... · 2011. 11. 25. · Jim Alexander - Joint Workshop on Charm