1. Recent (Charm) Electroweak Results from CLEO
Content
I: The CESR-c and the CLEO-c Experiment.
II: Leptonic D decays.
III: Semileptonic D decays: Exclusive
IV: Semileptonic D decays: Inclusive
V: Inclusive BF of D Xln and ln
VI: CPV from CLEO II.V
VII: Summary & Future.
Moriond EW session March 5-12, 2005 La Thuile, Italy
Doris Y. Kim University of Illinois Urbana-Champaign
3/11/2005
CLEO / Doris Kim

2. I. The Cornell Electron Storage Ring (CESR)
The size of CESR 768m long. Wigglers increase the synchrotron radiation -> damping the beam -> increase luminosity,
Added 12 superconducting wigglers to CESR for low energy running.
Ebeam = 1.5 – 5.6 GeV
3/11/2005
CLEO / Doris Kim

3. The CLEO-c Detector Run plan: ´, (3770) and Ds, J/  thresholds.
CLEO-c  CLEO III det.
New inner drift chamber replaced old silicon vertex
1T B field (old 1.5 T)
Track (93% of 4p): s = 1 GeV
PID: Rich (80% of 4p), dE/dx, EM calorimeter, muon (> 1GeV)
E: s = 1 GeV, 100 MeV.
Don’t stay too long here. Just mention the new inner draft chamber.
1) inner drift = six-layer stereo wire 2) Drift = 47 layers 3) 7800 CsI Cal. 95% of 4pi
3/11/2005
CLEO / Doris Kim

4. Impact of CLEO-c Measurements W+
Electroweak
Physics: Vcq
An example of semileptonic decay
QCD: form factors D
Leptonic decays give fD and fDs
validate Lattice QCD and improve fB
Semileptonic decays give Vcs, Vcd and form factors
test theoretical form factor models
enhance LQCD calculations, which will improve B decay form factors.
test CKM unitarity.
Improved (already) BF measurements of many important normalization modes and more coming.
Hadronic decays measure strong phases, needed for CPV.
Initial state is coherent: Ideal for charm mixing and CPV.
3/11/2005
CLEO / Doris Kim

5. The Future of Precision Flavor Physics
The Goal: Measure all CKM matrix elements and associated phases in order to over-constrain the unitary triangles.
CLEO-c + Lattice QCD +B factories
Vub/Vub 5% l n B p D
Vcb/Vcb 3%
Vud/Vud 0.1%
Vus/Vus 1%
Vub/Vub 15% n  K l e n p l n B p
CLEO-c
Vcd/Vcd 1.7%
Vcs/Vcs 1.6% l n D p K
Vcd/Vcd 7%
Vcs/Vcs 16%
Vcb/Vcb 5% l n D p l n D K l B n D
CLEO-c + Lattice QCD +B factories + ppbar Bd
Vtd/Vtd 5% Bs
Vts/Vts 5%
Vtd/Vtd 36%
Vts/Vts 39%
Vtb/Vtb 29% t b W Bd Bs
3/11/2005
CLEO / Doris Kim

6. (3770) Analysis Techniques K-
Fully reconstruct 1st D “the tag”, then analyze decay of 2nd D to extract exclusive or inclusive properties. K+ - e+
(3770) ~ DDbar threshold
No extra fragmentation = simpler geometry / combination
Clean neutrino reconstruction
High tagging efficiency at 25% of all D’s produced.
This method is quite effective for absolute branching fraction studies.
3/11/2005
CLEO / Doris Kim

7. Examples of CLEO-c Tagged D samples
~60,000 tagged D0 decays
From Dec 03 to Mar 04, we collected the first 3770 MeV with 6 wigglers, corresponding to 360,000 DDbar pairs.
Basic selection / fit variables are …
If there are multiple candidates, choose the smallest delta E one.
Delta E cut between 25 ~ 30 MeV.
Ddbar pairs: Neutral 200,000 charged 160,000
Selected 32,000 charged D tags
Signal: Gaussian + bifurcated Gaussian Background: ARGUS function
Preliminary MBC plots from semileptonic BF study
3/11/2005
CLEO / Doris Kim

8. II. Leptonic Decays: D+m+n
A “D hadronic tag” is required.
An additional charged track as m+ and no extra shower > 250 MeV as a signal.
Fit “missing-mass”2
Tag D n m+
Signal D
~60 pb–1
Yellow Book
Phys. Rev. D, 70, (2004)
8 signal
candidates
We don’t need muon ID detector.
1fb-1
3/11/2005
CLEO / Doris Kim

9. fD from Absolute Br(D+  m+n)
|VCKM|2
Vcd (1.1%) from 3 generation unitarity
tD+ (0.3%) well-measured
The first CLEO-c paper published. Phys. Rev. D, 70, (2004)
Based on 60 pb–1, tags and 8 signal events.
Background is ~ one event.
BES
Lattice 2004
CLEO-c
Isospin Mass Splittings
Potential Model
Rel. Quark Model
QCD Sum Rules
QCD Spectral Sum Rules
MILC
UKQCD
LQCD error 10% / CLEO-c error 22%. BES f(D) = – MeV
Mark III <290 MeV
BES I: 1 event (1998)
BES II: 3 events (2004) fD ~ 371 MeV
ICHEP 2004
3/11/2005
CLEO / Doris Kim

10. III. Exclusive Semileptonic BF. W+
Vcq
Analysis Techniques c MC
Fit to U q D
P, V
Fit to MBC
Reconstruct one hadronic D tag.
Reconstruct a semileptonic signal candidate from the remaining tracks/showers.
Fit kinematic variable U ( = Emiss – |Pmiss| ) for the missing neutrino of the signal.
Decay rate for D  P
Analysis going on in two steps: First, BF study. Second, FF study.
EID efficiency: 50% at 200 MeV, 95% above 300 MeV. mis-ID rate of Kaons and pions into e =0.1%
Kaon/Pion : efficiecy 95%, a few percent mis-ID, Since the kinematic constraint given by the threshold geometry and the detector resolution
gives a good filter performance, we don’t need a tight selection cut set.
Pi0 ID: +-3 sigma mass
Ks ID: +-12 MeV within Ks mass
Latest LQCD, PRL 94, (2005)
3/11/2005
CLEO / Doris Kim

11. Signal Candidates of Neutral Semileptonic Modes.
Cabibbo favored modes
Cabibbo suppressed modes
The first 60pb-1
(~1400 events)
(~110 events)
(~90 events)
First Observation
Signal function = Gaussian + Crystal Ball function (asymmetry due to ISR/FSR).
Background function = multinomial
(~30 events)
Preliminary U ( = Emiss – |Pmiss| ) plots
3/11/2005
CLEO / Doris Kim

12. Signal Candidates of Charged Semileptonic Modes.
Cabibbo favored modes
Cabibbo suppressed modes
(~60 events)
(~500 events)
Events / ( 10 MeV )
Events / ( 10 MeV )
This is the brand new preliminary result.
(~400 events)
Events / ( 10 MeV )
Events / ( 10 MeV )
(~30 events)
Preliminary U ( = Emiss – |Pmiss| ) plots
The first 60pb-1
3/11/2005
CLEO / Doris Kim

13. The Preliminary Exclusive BF.
(8 events)
World First Observation
Events / ( 10 MeV )
The first 60pb-1
Preliminary
Preliminary U ( = Emiss – |Pmiss| )
Omega decaying into pi+ pi- pi0
Note the 30% increase of BF in the D+ -> Ks e nu channel. It is a 2-sigma effect.
Ref) D+ -> K mu nu mode: FOCUS: vs PDG 2004: – 2.0 %
3/11/2005
CLEO / Doris Kim

14. Or We Can Do Without D Tagging!
With D Tag, we have cleaner signal sample, but we loose statistics. What if we do not use D Tagging? Let’s try for D  K/p e n decays.
Require a signal: one e± and one K or p
Assume the other tracks/showeres are coming from the other D, ID them using dE/dx, RICH and EM calorimeter information.  Calculate Pmiss
Fit on E, MBC
Check number again! Plots for D+ tagging modes needed!
Signal MC
Background MC
3/11/2005
CLEO / Doris Kim

15. Semileptonic Events without D Tagging
D+D- Bkgd
t MC
Cont MC
Fakes
K  e n
p e n
p0 e n
KS(p+p-) e n
K0other e n
Bkgd
Data
D+D- Bkgd
t MC
Cont MC
Fakes
p  e n
K e n
p0 e n
KS(p+p-) e n
K0other e n
Bkgd
Data
Preliminary
D+D- Bkgd
t MC
Cont MC
Fakes
KS(p+p-) e n
p0 e n
p e n
K e n
K0other e n
Bkgd
Data
D+D- Bkgd
t MC
Cont MC
Fakes
p 0 e n
KS(p+p-) e n
p e n
K± e n
K0other e n
Bkgd
Data
Left column cabibbo suppressed.
Should mention why we fit all four modes together ... I.e. backgrounds.
3/11/2005
CLEO / Doris Kim

16. IV. Inclusive Semileptonic BF.
Preliminary P(e+) spectra
PDG(2004) B(D0  X e+ n) = 6.87 ± 0.28 %
PDG(2004) B(D+  X e+ n) = 17.2 ± 1.9 %
Analysis Techniques
Reconstruct one hadronic D tag.
Signal e+ : ID’d by dE/dx, RICH and E/p calorimeter
Right/Wrong sign defined by K charge for D0, signal side charge for D+  background subtraction by wrong sign events.
Both charm and beauty physics needs precise decay spectrum of charm particles in their MC. Inclusive BF is an excellent
channel to test MC.
HQET predicts slightly different endpoint behavior between D0 and D+.
Cut off at 200 MeV: low efficiency, high background due to gamma conversion, pi0 Dalitz decay, etc.
These plots have all the background subtractions and efficiency correction except the final state radiation correction.
CLEO-c
(in D rest frame)
Cut-off
3/11/2005
CLEO / Doris Kim

17. Expected Uncertainty from the First 60 pb-1
tag mode
tag mode
Preliminary
No BR yet
3/11/2005
CLEO / Doris Kim

18. V: Inclusive BF of D Xln, ln
Electron and Neutrino Spectra are Different!
Conservation of angular momentum  n get boost from W+ in the lab frame. s e+
W+*
Low Q2
Analysis Techniques
Reconstruct one hadronic D tag.
Signal side: ID’d by dE/dx, RICH and E/p calorimeter, than add all.
Get Pmiss and Mmiss^2.
KL suppression is important.
This analysis is lepton flavor blind.
We study spin correlations to determine favorable and suppressed directions for neutrino. The top diagram is favored, the neutrino will get a boost from the W+* compared to the electron in the lab frame.
3/11/2005
CLEO / Doris Kim

19. MC Example of Emiss Spectra
Red = signal
Blue = background
Black = Red + Blue D0 MC D± MC
D±  ln
Zero supressed due to minP cut, and V cut
Point out D -> munu
Emiss(GeV)
Emiss(GeV)
3/11/2005
CLEO / Doris Kim

20. The Inclusive D  Xln, ln CandidatesMC
Data
60 pb-1
Missing Energy (GeV)
KL Background
KL Background
Signal
This is the N-1 cut plot, to show you the reliability of our selection. Missing energy = neutrino energy.
Missing mass^2 = cut variable (GeV)^2 means Klong
Signal
3/11/2005
CLEO / Doris Kim

21. VI. CPV search in D0  Ks p+ p- from CLEO II.V
D0 + D0bar
D0 - D0bar
PRL 92, (2004)
D0 / D0bar tagged by D*  D0 p+(slow).
Standard Model prediction at 10–6 for this channel from K mixing.  sensitive to new physics
Dalitz technique studies decay amplitude, not decay rate.  sensitivity increase.
M(Ks p-)
M((p+ p-)
Get mixing numbers from David Asner. The plots are not fits, but the projections of the actual fits.
M(Ks p+)
3/11/2005
CLEO / Doris Kim

22. VII: Summary and Future
New results on BF D+  mn and fD
(2) Exclusive BF of semileptonic decays coming (pretty) soon.
With just 60 pb-1, stastistical power of many decay modes already at the world best.
The world first events of and
We have two analysis options available: With and wo DTag
(3) Inclusive BF of D Xen and D Xln, ln coming.
(4) Currently we are running at (3770) with 12 “8-pole” wigglers. More data is coming on (3770), Ds threshold, etc.
Vub : Currently, both exclusive and inclusive analyses are going on based on CLEO II, II.V, III data (9 + 6 fb-1).
fDs
3/11/2005
CLEO / Doris Kim

23. Question slides
3/11/2005
CLEO / Doris Kim

24. CLEO-c Impacts on the Unitarity Triangle
Now: Theory Uncertainties Dominate
Future: With CLEO-c, improved LQCD and 500 fb-1 each from the B factories
3/11/2005
CLEO / Doris Kim

25. Electron Spectrum of Inclusive Events
time
Very Preliminary
CLEO-c
(in D rest frame)
3/11/2005
CLEO / Doris Kim

26. Charged D Meson Tags – Distributions of Mbc
~30,000 tagged D± decays
Examples only .... Other modes similar
Preliminary MBC plots from semileptonic BF study
3/11/2005
CLEO / Doris Kim