xliid rencontres de moriond electroweak interactions and unified theories cleo-c results basit athar...

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XLIId RENCONTRES DE MORIONDXLIId RENCONTRES DE MORIONDELECTROWEAK INTERACTIONS AND UNIFIED THEORIESELECTROWEAK INTERACTIONS AND UNIFIED THEORIES

CLEO-c ResultsCLEO-c ResultsCLEO-c ResultsCLEO-c Results

Basit AtharBasit Athar

March 10 - 17, 2007March 10 - 17, 2007University of FloridaUniversity of FloridaCLEO CollaborationCLEO Collaboration



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La Thuile Mar. 10-17

B. Athar - Moriond EW'07 2

OutlineOutline Program OverviewProgram Overview Physics MotivationPhysics Motivation Pure leptonic decaysPure leptonic decays

D & DD & Dss Decay constants Decay constants

Semi Leptonic decaysSemi Leptonic decays Exclusive decay - CKM & FFExclusive decay - CKM & FF Rare DecaysRare Decays



CLEO-c Program

4170 MeV: Ds decay Leptonic decays.Leptonic decays. Hadronic branching fractions. Semi-Leptonic decays.

3770 MeV: D decay (Semi) Leptonic decays.(Semi) Leptonic decays. Hadronic branching fractions. Dalitz Analysis. D-mixing. Quantum Correlation in D system.

3686 MeV: (2S), c,J/,hc, c

3970-4260 MeV: Ds scan & Y(4260).

4170 MeV: Ds decay Leptonic decays.Leptonic decays. Hadronic branching fractions. Semi-Leptonic decays.

3770 MeV: D decay (Semi) Leptonic decays.(Semi) Leptonic decays. Hadronic branching fractions. Dalitz Analysis. D-mixing. Quantum Correlation in D system.

3686 MeV: (2S), c,J/,hc, c

3970-4260 MeV: Ds scan & Y(4260).

Charm threshold at various energies~28 106 (2S) 60pb-1 3.97-4.26 GeV

195+130 pb-1 4170 GeV

281 pb-1 (3770)





Motivation

CLEO-c provides a unique environment for studying Leptonic & Semi-Leptonic charmdecays. Modern detector at charm threshold.

Good tracking & particle identification & EM calorimetry Low track multiplicity - 5 to 6 tracks/event

Pure Leptonic decays: Determine fD and fDs use them to test LQCD

models. Help calibrate LQCD for fB and fBs predictions.

Semi Leptonic decays: Form factors and QCD checks.

Assuming Vcs & Vcd known. Precision measurements Vcd & Vcs.

Trusting LQCD predictions.

€

VCKM =

Vub Vus Vub

Vcd Vcs Vcb

Vtd Vts Vtb

⎛

⎝

⎜ ⎜ ⎜

⎞

⎠

⎟ ⎟ ⎟



Leptonic decays

c and q annihilation is proportional to overlap function.

DD →ll = 2.35x10= 2.35x10-5-5:1:2.64 (e:1:2.64 (e))DDss

→ll = 2.5x10= 2.5x10-5-5:1:9.7 (e:1:9.7 (e))

_

€

D S( )+ → l+ν( ) =

GF2

8πfD S( )

2 ml2M

D( S )+ 1−

ml2

MD S( )

2

⎛

⎝

⎜ ⎜ ⎜

⎞

⎠

⎟ ⎟ ⎟

2

Vc d ,s( )| |2

(s)

(s)

SM



Ds-

Ds*+

4170

e+

e-

-

K+

Ds+

K-

D & Ds tag Method

DD Tag: MarkIII pioneered Dtag method of

DD production at threshold and used by CLEO and BESII

Ds*Ds Tag:

Tag one in a Ds hadronic mode Add a photon Signal may be from Ds or Ds

*

Form a 2 with both hypothesis and keep the best.

Look for signal in missing mass.

”

D-

D+ e+

e-

-

-

K+

Ds*-

4170

e+

e-

Ds+

Ds-

-

K+

K-

_

_

_

D TAG

Ds TAG



D- Invariant mass

D+ → + → Two s and pion in the final state.

Look for pion opposite to D tag and calculate Missing mass squared.

MM2 for will not peak at 0 but rather be spread out.

€

mbc = Ebeam − pDtag| |2 ⎛

⎝ ⎜

⎞

⎠ ⎟≈ MD

CLEO-cL= 281 pb-1

160K Single Tags”

D-

D+ e+

e-

-

-

K+

€

MM 2 = Ebeam − E trk( )2

− pD + ptrk( )2

MM2



D+ → +

12 signal

8 signal

ECC

< 300 MeV

ECC

> 300 MeV

D+ → KL

D+ → KL

PRD

73,

112

005

(200

6)

Select tracks (from +) in two MM2 regions based on calorimeter (CC) info: Interactions in calorimeter● E

CC < 300 MeV minimum interacting & +

● ECC

> 300 MeV interacting +

B(D+ → ) < 2.110-3 (90% CL)

Using CLEO-c B(D+ → ) = (3.5±1.4±0.6)x10-4

SM: B(D+ → ) = (1.1 ± 0.2)10-3

[B(D+ → )/B(D+ → )]meas

[B(D+ → )/B(D+ → )]SM

< 1.8 (90% CL)< 1.8 (90% CL)

D+ →

”

D-

D+ e+

e-

-

-

K+



Ds Invariant massesK-K++ KsK+

+

K*K* from KsK

Detect all particles except A kinematic fit is used

Improve resolution 2 cut on “tagged Ds“ mass

Total # of Ds Tags:

19185±325(stat.) Combine with the selected Ds tags.

Ds*-

4170 e+

e-

Ds+

Ds-

-

K+K-

Ds-

Ds*+

4170

e+

e-

-

K+

Ds+

K-

195 pb-1



MC: DS → + MC: D

S → +

Ds Missing Mass2

Look at the recoiling mass against the ”8 Ds” tag modes & the .

Total # of Ds tags after MM*2 selection: 11880±399(stat.) tags

Look for + and + signal at the same time.

Look at the recoiling or 2

€

MM*2 = ECM − EDS− Eγ( )

2

− pDS+ pγ( )

2

€

MM 2 = ECM − EDS− Eγ − Eμ( )

2

− pDS+ pγ + pμ( )

2

All 8 Tag modes



Electron Sample

DATA 200/pb

<0.3GeV in CC

DATA 200/pb

>0.3GeV in CC

64 events

24 events

12 events

Case (i)

Case (ii)

CL

EO

preliminary

ECC

< 300 MeV

ECC

> 300 MeV

DS → + +

Three casesI. Track Ecc < 300 MeV (,)

accepts ~99% & ~60% +

II. Track Ecc > 300 MeV ()accepts ~1% & ~40% +

§ Track Ecc consistent with e.

Cases 1&2 allow simultaneous study of D

S → +

24 events in case (i) 12 events in case (ii)

I. No DS → e+ seen in case (iii)



100 events

Sum of case (i) & case (ii) signal line shape

CL

EO

preliminary

K

L

DS → &

DS → [Case (i) + Case (ii)]

Total of 36 signal, 5 bkgd events B(D

S → ) = (7.1±1.4±0.3)%

[B(DS → ) = (6.4 ± 1.5)% PDG06]

+

+

DS → [Case (i)]

64 signal, 2 + 5 bkgd events, B(D

S → ) = (0.66±0.09±0.03)%

+

+

Sum signal MM2 < 0.2, Beff(D

S → ) = (0.66±0.08±0.03)%

B(DS → ) = (0.61±0.19)% PDG06

DS → e [Case (iii)]

No events in signal region B(D

S → e) <1.310-4 (90% CL)

+

+

+Use SM to for bkg near MM2=0

Use SM for bkg near MM2=05



Measuring DS+→+ +→e+

Three s in the final state B(DS

+→+B+→e+1.3% is “significant” compared with expected B(DS

+→Xe+ Analysis Technique

Find Ds tag and e+ - no need to find from Ds

*

No extra track Ecc < 400 MeV

Summary

B(DB(DSS → → ) = (6.3 ) = (6.3 ± 0.8 ± 0.5± 0.8 ± 0.5)% from )% from →→ ee++ analysisanalysis

B(DS → ) = (8.0 ± 1.3 ± 0.4)% from → analysis

extra

Complimentary Analysis



fDs

Summary

Weighted CLEO-c Results:f

Ds = (280 ± 12 ± 6) MeV,

Using the CLEO-c fD result,

fD = (223 ± 17 ± 3) MeV,

Ratio: f

Ds/f

D = 1.26 ± 0.11 ± 0.03

LQCD: fDs

/fD = 1.24 ± 0.07

Ds :f

Ds = (281 ± 19 ± 7) MeV

Ds and : f

Ds = (296 ± 29 ± 12) MeV

Ds and e: f

Ds = (278 ± 17 ± 12) MeV

280±12±6 1.26±0.11±0.03



Semi Leptonic Decays: CKM elements & Form Factor

For any pseudoscalars (P)

€

q2 = (pDμ − pK (π )

μ )2 = mD2 − mK (π )

2 − 2mD EK (π )

Propagator (W+) q transfer is defined as

€

dΓ(D+ → Peυ )

dq2=

GF2

24π 3Vc q| |

2pP

3 f+ q2( )| |

2

q V = K* (ρ)

+l

D

W +

€

υ l

s(d)c V

c s(d)

P = K (π)h

Brown Muck

lBest way to determine CKM elements is to study

semileptonic decays



D - Exclusive Semileptonic Decays

29520

69928

291055

679684

14397132

134749

58468845029

€

Umiss = Emiss − pmiss| |

€

Mbc = Ebeam2 − pK π( ) + pe +ξpmiss( )

2 ⎛ ⎝ ⎜ ⎞

⎠ ⎟

Standard D-Tag MethodUntagged reconstruction

281pb-1

-

Two Two methods methods

have 40% have 40% overlapoverlap

K-

-e+

K+

Missing 4-Mom Pvisible =Pcharge + PneutralPmiss = Pevent - Pvisible



Exclusive Branching Ratio ComparisonDo → K- e+ ν Do → π- e+ ν

(2006)(2006)

Good consistency between two methods.LQCD precision lags experiment.



Form Factor Fit Comparison(Tag)

+−→ eKD0 ( )( )2

2 2 2 2

(0)( )

1 1pole pole

ff q

q m q mα+

+ =− −

Modified Pole Model

f + (q2 )=f + (0)

1−q2 mpole2( )

Simple Pole ModelHill series expansion

(Phys. Lett. B 633, 61 (2006)))

3 popular FF parameterizations methods

D+→Kse+ν

D0→K-e+νD0→π-e+ν

D+→π0e+ν

--- Simple pole

--- Modified Pole

--- Series with 2 par Series with 3 par Data

Data and Fit results are normalized to the fit results for the series parameterization with 3 parameters.



Form Factor Fit Comparison(Untagged)

All these models describe the data pretty wellAll these models describe the data pretty well



DATA FIT

LQCD

€

D0 → π −e+ν

DATA FIT

€

D0 → K−e+ν

CL

EO

preliminary

LQCD

Data-LQCD Comparison

LQCD [PRL 94, 011601 (2005)]f+(0) pole

Assume Vcd = 0.2238

Assume Vcs = 0.9745



Vcd & Vcs Summary

Tagged and untagged consistent. Tagged and untagged consistent. 40% of events are common to both analyses: 40% of events are common to both analyses: DO NOT AVERAGE!DO NOT AVERAGE!Uncertainties: Experiment VUncertainties: Experiment Vcscs~2%, V~2%, Vcdcd~4% - LQCD f~4% - LQCD f++(0) prediction: (0) prediction: 10%10%

Combine |Vcx|f+(0) values from fits with unquenched LQCD f+(0) results |Vcs| and |Vcd|

Decay ModeDecay Mode ||VVcxcx|| ± (± (statstat) ± () ± (systsyst) ± () ± (theorytheory)) PDG/HF ValuePDG/HF Value

D D ee (tagged)(tagged) 0.234 ± 0.010 ± 0.004 ± 0.0240.234 ± 0.010 ± 0.004 ± 0.024

D D ee (untagged) (untagged) 0.229 ± 0.007 ± 0.005 ± 0.0240.229 ± 0.007 ± 0.005 ± 0.024 0.224 ± 0.0120.224 ± 0.012

D D Ke Ke (tagged)(tagged) 1.014 ± 0.013 ± 0.009 ± 0.1061.014 ± 0.013 ± 0.009 ± 0.106

D D Ke Ke (untagged)(untagged) 0.996 ± 0.008 ± 0.015 ± 0.1040.996 ± 0.008 ± 0.015 ± 0.104 0.976 ± 0.0140.976 ± 0.014

PRL 94, 011601 (2005)

Unitarity constraint on the second row along with |VUnitarity constraint on the second row along with |Vcbcb| =(41.0±0.6)x10| =(41.0±0.6)x10-3-3(PDG)(PDG)

∆ ∆ = 1 - (|V= 1 - (|Vcdcd||22+|V+|Vcscs||22+|V+|Vcbcb||22) = 0.012 ± 0.18) = 0.012 ± 0.18

Untagged



Rare Semi Leptonic Decays

Umiss

= Emiss - Pmiss (GeV)

Mode BR (10-4)

e+ 12.91.90.7

K-e+K1(1270)e+

2.9+1.5-1.00.5

2.2+1.4-1.0 0.2

e+ 14.92.70.5

8.5 +4.5-3.2D0K-e+ 32.7

6.7

D+e+ 37.3 6.7

Umiss = Emiss- Pmiss (GeV2)

13.3 4.0

* First observation



Summary

By March 2008 double our data sets Improve precision on Leptonic decay

constants Improve precision on Vcd and Vcs. Understand the form factor shape better. Improve signal significance in RARE D

decays. CLEO-c at Charm threshold

Great place to do charm physics.

3770 & 4170 MeV



Inclusive Semileptonic Results

Consistent with the known exclusive modes saturating the inclusive branching fractions.

mode Branching Fraction

D0Xe+ (6.46 ± 0.17 ± 0.13)%

i i (D0 Xe+ (6.1 ± 0.2 ± 0.2)%

D+ Xe+ (16.13 ± 0.20 ± 0.33)%

i i (D+ Xe+ (15.1 ± 0.5 ± 0.5)%

Consistent with isospin symmetry

Extrapolated below 0.2

0

0 0

0.985 0.028 0.015SL SL

D D DSL SL

D D D

B

B

+ +

+

= × = ± ±

CLEO-c 281pb-1, DTaggedhep-ex/0604044, subm to PRL

•Measure Br(D0Xe+) & compare with the known hadronic modes.•Precision lepton momentum spectrum measurement.

•Help in bcse cascade decay modeling. •Compare sl(D0)/sl(D+)



DVector l Decay

H0(q2), H+(q2), H-(q2) are helicity-basis form factors computable by LQCD

A new factor h0 (q2) is needed to describe s-wave interference piece in K* l .

( )

( )

( )( ) { }δθ θ

θ θ

θ θ

θ θ

+

−

−

⎧ ⎫+⎪ ⎪⎪ ⎪+ −⎪ ⎪

⎪ ⎪⎪ ⎪= +⎨ ⎬⎪ ⎪⎪ ⎪⎪ ⎪⎪ ⎪⎪ ⎪⎩ ⎭+

+

∫

2 22 2

2 22 2

22 222 20

2 2 20

2

(1 cos )sin ( )

(1 cos )sin ( )

1A 2sin cos ( )

8 sin cos ( ) ( ) e8

R

( )

l V

l V

l V

V

o

l

iH q h q

H q BW

H q BW

d q H q B

O

W

A

Ae BW Present in K* l

Spectroscopic pole dominance

2V 2

1 1

A (0)V(0)R = R =

A (0) A (0)

2.1 2.5V A1 A2M GeV M M GeV= = =

H±(q2), H0(q2) can be expressed in terms of vector and axial vector form factors.

Helicity amplitudes



D+ K*(K+)e+ Form Factors

Data fits spectroscopic poles well.

MV=2.1 MA=2.5

2 2 2( )q H q

2 2 2( )q H q

2 2 20 ( )q H q

PRD 74, 052001 (2006)

• data (281 pb-1)

– overlay (not fit)



D → e+

Simultaneous fit to D+ 0e , D0 -eRv = 1.40 0.25 0.03, R2 = 0.57 0.18

0.06

Line is projection for fitted RV, R2

Fix

ed b

ack

gro

und sh

ape a

nd sig

nal ta

ils from

M

C

B(D0 -e+)= (1.560.160.09)10-3

B(D+ 0e+)= (2.320.200.12)10-3

Isospin average:(D0 -e+) = (0.410.030.02)10-2 ps-1

this analysis

(D0 -e+) = (0.440.060.02)10-2 ps-1 FOCUS PLB 637,32 (2006)

Dtagged, 281/pb

1st measurement of FF in Cabibbo-suppressed charm PS V decay

q2

cos θ

cos θe

No-interference MC describes data

Umiss

(GeV)

D+ → 0 e

Umiss

(GeV)

D0 → e



Form-factor Parameterization

General dispersion relation:

Modified Pole:

Series Expansion:

( )( )2

2 2 2 2

(0)( )

1 1pole pole

ff q

q m q mα+

+ =− −

Simple pole model

Popular: LQCD extrapolations & Experimental extraction of SL FF

( )2

2 02( ) 0 2

0

, ( , )D K

t q t tt M m z q t

t q t tπ

+ +±

+ +

− − −≡ ± =

− + −

Hill & Becher, Phys. Lett. B 633, 61 (2006)

2 20 02 2

00

1( ) ( )[ ( , )]

( ) ( , )k

kk

f q a t z q tP q q tφ

∞

+=

= ∑

xliid rencontres de moriond electroweak interactions and unified theories cleo-c results basit athar...

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