recent (charm) electroweak results from cleo

3/11/2005 CLEO / Doris Kim 1

Doris Y. KimUniversity of IllinoisUrbana-Champaign

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 Xland l

• VI: CPV from CLEO II.V

• VII: Summary & Future.

Recent (Charm) Electroweak Results from CLEO

Moriond EW sessionMarch 5-12, 2005

La Thuile, Italy


I. The Cornell Electron Storage Ring (CESR)

Ebeam = 1.5 – 5.6 GeVAdded 12 superconducting wigglers to CESR for low

energy running.


The CLEO-c Detector

• New inner drift chamber replaced old silicon vertex

• 1T B field (old 1.5 T)

• Track (93% of 4): = 0.6% @ 1 GeV

• PID: Rich (80% of 4, dE/dx, EM calorimeter, muon (> 1GeV)

• E: = 2.2% @ 1 GeV, 5% @ 100 MeV.

Run plan: ´, (3770) and Ds, J/ thresholds.

CLEO-c CLEO III det.


Impact of CLEO-c Measurements

• 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.

e+

W+

ElectroweakPhysics: Vcq

QCD: form factors

D

An example of semileptonic decay


The Future of Precision Flavor Physics

Vub/Vub 15%lB

l

D

Vcd/Vcd 7%lD

Vcs/Vcs 16%l

B D

Vcb/Vcb 5%

Bd Bd

Vtd/Vtd 36%

Bs Bs

Vts/Vts 39% Vtb/Vtb 29%

Vus/Vus 1%

l Vud/Vud 0.1%

e

pn

t

b

W

The Goal: Measure all CKM matrix elements and associated phases in order to over-constrain the unitary triangles.

CLEO-c

Vcd/Vcd 1.7% Vcs/Vcs 1.6%l

D

lD

CLEO-c + Lattice QCD +B factories + ppbar

Bd Bd

Vtd/Vtd 5%

Bs Bs

Vts/Vts 5%

CLEO-c + Lattice QCD +B factories

Vub/Vub 5%lB

l

B D

Vcb/Vcb 3%


(3770) Analysis Techniques

Fully reconstruct 1st D “the tag”, then analyze decay of 2nd D to extract exclusive or inclusive properties.

(3770) ~ DDbar threshold No extra fragmentation = simpler geometry / combination Clean neutrino reconstruction High tagging efficiency at 25% of all D’s produced.

e

De

DK-

-

e+

K+

0

0

0

0

(3770)

,

D

D

D

D K eK


Examples of CLEO-c Tagged D samples

~60,000 tagged D0 decaysFrom Dec 03 to Mar 04, we

collected the first 60pb-1 @ 3770 MeV with 6 wigglers, corresponding to 360,000 DDbar pairs.

Preliminary MBC plots from semileptonic BF study

Basic selection / fit variables are …

beam

22beamBC

E E D E

M E p D

Signal: Gaussian + bifurcated GaussianBackground: ARGUS function


II. Leptonic Decays: D++• A “D hadronic tag” is required.• An additional charged track as +

and no extra shower > 250 MeV as a signal.

• Fit “missing-mass”2

Tag D

Signal D+

2 22

beam DMM E E p p

0D K

8 signal candidates

~60 pb–1

Yellow Book

1fb-1

Ph

ys. R

ev. D

, 70,

112

004

(200

4)


fD from Absolute Br(D+ +)

150 180 210 240 270 300 330 360 390 420 450 480 510

Charged D Decay Constant (MeV)

• BES• Lattice 2004• CLEO-c• Isospin Mass Splittings• Potential Model• Rel. Quark Model• QCD Sum Rules• QCD Spectral Sum Rules• MILC• UKQCD

|fD|2

|VCKM|2

2222 2

21

8( ) / ( )F

cdD D DD

mGB D f m M V

M

Vcd (1.1%) from 3 generation unitarity

D+ (0.3%) well-measured

The first CLEO-c paper published.Phys. Rev. D, 70, 112004 (2004)• Based on 60 pb–1, 28651 tags and 8 signal events.• Background is ~ one event.

Mark III <290 MeV

BES I: 1 event (1998)

BES II: 3 events (2004) fD ~ 371 MeV

MeV 1741202

106.04.15.3 4

Df

DB

ICHEP 2004


III. Exclusive Semileptonic BF.

Analysis Techniquese+

W+

Vcq

D

22

23 2

2 324F cqP

P p

G Vdp f q

dq

c qP, V

Decay rate for D P

Latest LQCD, PRL 94, 011601 (2005)

/ /

/

signal signal signal Xe

tag tag tag

N NB

N N

• 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.

MC

Fit to MBC

Fit to U


Signal Candidates of Neutral Semileptonic Modes.

Cabibbo favored modes Cabibbo suppressed modes

eKD0 eD0

0*

*0

KK

eKD0

0

D e

Preliminary U ( = Emiss – |Pmiss| ) plots

(~1400 events) (~110 events)

(~90 events) (~30 events) First Observation

The first 60pb-1


Signal Candidates of Charged Semileptonic Modes.

Events

/ (

10

MeV

)Events

/ (

10

MeV

)

Events

/ (

10

MeV

)Events

/ (

10

MeV

)

eD 0

0D e

eKD 0

KK

eKD*0

*0 ,

(~60 events)

(~30 events)

(~500 events)

(~400 events)

Cabibbo suppressed modesCabibbo favored modes

Preliminary U ( = Emiss – |Pmiss| ) plots The first 60pb-1


The Preliminary Exclusive BF.

Events

/ (

10

MeV

) 0

D e

(8 events)

Preliminary U( = Emiss – |Pmiss| )

World First Observation

The first 60pb-1

Preliminary


Or We Can Do Without D Tagging!

• Require a signal: one e± and one

K or • 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

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/ e decays.

Signal MC

Background MC


Semileptonic Events without D Tagging

D+D- Bkgd MCCont MCFakes

e e

e KS(+-) e

other e

Bkgd0 0D D

Data


e S(+-) e

e K± e

other e

Bkgd0 0D D

Data


e e

e KS(+-) e

other e

Bkgd0 0D D

Data


KS(+-) e e

e K e

other e

Bkgd0 0D D

Data

eKD0 eD0

eKD 0 eD 0

Pre

limin

ary


IV. Inclusive Semileptonic BF.

Analysis Techniques


• 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.

PDG(2004) B(D0 X e+ ) = 6.87 ± 0.28 %

PDG(2004) B(D+ X e+ ) = 17.2 ± 1.9 %

Preliminary P(e+) spectra

CLEO-c (in D rest frame)

Cut-off


Expected Uncertainty from the First 60 pb-1

%3.0~sysstat:PDG

%2.0~stat:c-CLEO : 0

BR

BRXeD

%9.1~sysstat:PDG

%3.0~stat:c-CLEO :

BR

BRXeD

tag m

ode

tag m

ode

PreliminaryNo BR yet


V: Inclusive BF of D Xll

Electron and Neutrino Spectra are Different!

s

e+

se+

W+*

W+*

Low Q2

Low Q2

High , Low eE E

High , LoweE E

Conservation of angular

momentum get boost from W+ in the lab frame.

Analysis Techniques


• Signal side: ID’d by dE/dx, RICH and E/p calorimeter, than add all.

• Get Pmiss and Mmiss^2.

• KL suppression is important.


Emiss(GeV)

D0 D±

Red = signal

Blue = background

Black = Red + Blue

MCMC

MC Example of Emiss Spectra

Emiss(GeV)

D± l


MC Data

Mis

sin

g E

ner

gy

(GeV

)

2 2 2( )miss missE P GeV

The Inclusive D XllCandidates

60 pb-1

2 2 2( )miss missE P GeV

KL Background

KL BackgroundSignal

Signal


VI. CPV search in D0 Ks + - from CLEO II.V

• PRL 92, 142001 (2004)

• D0 / D0bar tagged by D* D0 +

(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.

0 010 0 0130 043 0 0370 009 0 021 . .

. .. .CPA

M(Ks -)

M(Ks +)

M(+ -)

D0 + D0bar D0 - D0bar


(1) New results on BF D+ 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 Xeand D Xllcoming.

(4) Currently we are running at (3770) with 12 “8-pole” wigglers.

More data is coming on (3770), Ds threshold, etc.

VII: Summary and Future

MeV 1741202

106.04.15.3 4

Df

DB

0D e D e

fDs


Question slides


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


Electron Spectrum of Inclusive Events

Very Preliminary

CLEO-c (in D rest frame)

time


Charged D Meson Tags – Distributions of Mbc

SD K D K

0D K

0SD K

SD K D K K

~30,000 tagged D±

decays

Preliminary MBC plots from semileptonic BF study

recent (charm) electroweak results from cleo

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