cleo-c and ckm physics

October 7, 2003 CLEO-c and CKM Physics Karl Ecklund 1

CLEO-c and CKM Physics

Karl M. EcklundCornell University

WIN 2003October 7, 2003


CLEO-c and CESR-cWhat’s with the “-c”?

– CLEO detector– Symmetric e+e- collider

s=10.6 GeV– Add wigglers to improve

damping and run at s=3-6 GeV

• Access to charm threshold region

• Approved by National Science Board Feb 2003

• First Physics Run starts October 24, 2003

• 3+ year program


Context for CLEO-cFlavor physics:

• Overconstrain VCKM

• Inconsistency new physics

• Interpretation limited by strong interaction effects

• Measurements in Charm decays can validate QCD corrections needed to extract Weak physics from observables

• Sin 2 is clean• |Vub| is not• B mixing is notHadronic uncertainties confound theextraction of weak physics•Non-perturbative QCD•Perturbative QCD (on better ground)


UT Constraint from B mixing

• Lattice QCD predicts decay constants fD(s)/fB(s)

• If precise measurements of fD and fDs exist, then our confidence in non-perturbative QCD calculations needed to make constraints on the UT is increased.

• Even better if Bs mixing is observed!

2

3

2

1

108.820050.0

tdBB

d

V

MeV

fBpsM dd

d

d

BB

BB

d

d

td

td

Bf

Bf

M

M

V

V )()(5.0

||

|)(|

1.2% ~15% (LQCD)


UT Constraint from |Vub|

• Absolute rate and shape is a stringent test of theory• Heavy quark symmetry relates Dl to Bl• A precise measurement of Dl can calibrate LQCD

and allow a precise extraction of |Vub| from Bl

2232ub3

2F

2|)(qf|p|V|

24

G

q

d

d

|Vub| from B l

Form factor f(q2):• Not well known• Limits |Vub| precision• Predicted by LQCD


Status of CKM Matrix

Vub/Vub 17%lB

l

D

Vcd/Vcd 7%lD

Vcs/Vcs =11%l

B D

Vcb/Vcb 5%

Bd Bd

Vtd/Vtd =36%

Bs Bs

Vts/Vts 39%

Vus/Vus =1%

l Vud/Vud 0.1%

e

pn

Vtb/Vtb 29%

t

b

W

Current VCKM

From directMeasurements-no unitarity imposed

CLEO-c will redefine 2nd generation elementsAnd enable improvements in 3rd generation


CESR-c

6/12 WigglersInstalled Spring’036 more March-May’04

E=1.5-3 GeV


CESR-c

CESR: L((4S)) = 1.3.1033 cm-2 s-1

s L (1032 cm-2 s-1 )

3.1 GeV 2.0

3.77 GeV 3.0

4.1 GeV 3.6

CESR-c Design Luminosity:

One day scan of ’:

Machine performance: Ebeam ~ 1.6 MeV at ’ (6 wigglers)

L ~ 1.1030

(~BES)

1 wiggler

Ebeam

(n

b)

J/ J/


CLEO-c DetectorState of Art Detector:• Drift Chamber

Tracking (1 Tesla)• RICH Particle ID• Crystal EM

Calorimetry• 93% of solid angle• Only small changes

from CLEO III– B field 1.5 1 T– Silicon ZD


CsIElectromagnetic

Calorimeter(End Cap)

CsIElectromagnetic

Calorimeter

RICH

Drift ChamberOuter Endplate

Drift Chamber EndplateSmall Radius Section

cos = 0.93

Interaction Point

CESR

ZD Inner Drift Chamber

3560603-002


New Inner Detector• Replaced Silicon Vertex

Detector May 2003• 6 stereo layers:

– r=5.3 cm – 10.5 cm– 12-15o stereo angle– |cos < 0.93

• 300, 10 mm cells • 1% X0 inner Al

tube .8mm• Helium-Propane (60:40)• 20 m Au-W sense

wires• 110 m Au-Al field

wires• Outer Al-Mylar skin

• Continuous tracking volume• Low mass (p is MS limited)• Nothing to vertex at charm threshold!


CLEO IIIY(4S)

TypicalHadronic

Event

Average:• 10 tracks• 10

showers


CLEO-c(3770)Typical

HadronicEvent

Average:• 5 tracks• 5 showers

Event Recorded September 29, 2003


Charm Threshold Region• D+D-, D0D0 at

(3770)

• Ds+

Ds- at

s=4140 MeV

• Potential for c

+ c

-

• Will also run on J/ and possibly ’

CESR-c Energies

DD cross section at (3770) ~5 nb (Mark III)DsDs cross section ~0.5 nb


CLEO-c Run PlanPhase I: (3770) – 3 fb-1 ((3770) DD) 30 million DD events, 6 million tagged D decays (310 times MARK III)

Phase II: s=4140 MeV – 3 fb-1

1.5 million DsDs events, 0.3 million tagged Ds decays (480 times MARK III, 130 times BES)

Phase III: (3100) – 1 fb-1 1 Billion J/ decays (170 times MARK III, 20 times BES II)

Now: Dec’02 5 pb-1 at (3770)Oct’03-Jan’04 50 pb-1 on (3770)


Tagging Technique – Tag Purity(3770) D D s ~4140 Ds Ds

• Charm mesons have many large branching ratios (~1 - 15%)

• High reconstruction efficiency

High net tagging efficiency ~20%

Anticipate 6M D tags and 0.3M Ds tags

Monte Carlo

Monte Carlo

Log Scale!

Log Scale!

D K tag: S/B ~ 5000/1 Ds ( KK) tag: S/B ~

100/1


Absolute Charm Branching Ratios

Monte Carlo

D- tag

D+ K- + +

Double tag technique:Almost zero background in hadronic tag modes

Measure absolute B(D X) with double tags

B =

# of X

# of D tags

Decay s L (fb-1)Double

tags

B / B (%)

PDG CLEO-c

D0 K- + 3770 3 53,000 2.4 0.6

D+ K- + + 3770 3 60,000 7.2 0.7

Ds 4140 3 6,000 25 1.9CLEO-c: potential to set absolute scale for heavy quark measurements

50 pb-1 ~1,000 events x2 improvement (stat) on D+ K- ++

PDG dB/B


fDs from Absolute B(Ds +)Monte Carlo

DS tag

DS

|fD|2

|VCKM|2

• Measure absolute B(Ds )

• Fully reconstruct one D (tag)

• Require one additional charged track and no additional photons

• Compute MM2

• Peaks at zero for Ds

+ decay

• Expect resolution of ~O(Mo)Vcs (Vcd) known from unitarity to 0.1%

(1.1%)

Decay Constan

tReaction

Energy (MeV)

L (fb-1)

f / f (%)

PDG CLEO-c

fDs Ds+ 4140 3 17 1.9

fDs Ds+ 4140 3 33 1.6

fD+ D+ 3770 3 UL 2.3


Semileptonic Decays: |VCKM|2 |f(q2)|2

d/dpp

d/dpp

p

Measurement of complete set of charm P P l& P V l absolute form factor magnitudes and slopes to a few %:

• almost no background

• one experiment

CLEO-c

Monte Carlo

Lattice QCD

D0 l

D0 l

Emiss - Pmiss

Monte Carlo

D0 Kl

D0 l

Tagged Events & Low Bkg

p

Stringent test of theory!


CLEO-c Impact on Semileptonic B/B

0

10

20

30

40

50

60

70

80

90

100

1 2 3 4 5 6 7 8 9 10 11

Decay modes

Err

or (%

)

1: D0 K- e+

2: D0 K*- e+

3: D0 - e+

4: D0 - e+

5: D+ K0 e+

6: D+ K*0 e+

7: D+ 0 e+

8: D+ 0 e+

9: Ds K0 e+

10: Ds K*0 e+

11: Ds e+

CLEO-c will make significant improvements in precision for each absolute charm semileptonic branching ratio.

CLEO-c

PDG


Determining |Vcs| and |Vcd|Combine semileptonic and leptonic decays – eliminating VCKM

(D+ l )/(D+ l ) independent of |Vcd|

Test rate predictions at ~4% level

(Ds l ) / (Ds l ) independent of |Vcs|

Test rate predictions at ~4.5% level

Test amplitudes at 2% level

Stringent test of theory - If theory passes test …

D0 K- e+ Vcs/Vcs = 1.6% (now: 11%)

D0 - e+ Vcd/Vcd = 1.7% (now: 7%)

Use CLEO-c validated lattice to calculate B semileptonic form factor B factories can use B ///l for precise |Vub| determination.


Inclusive Semileptonic Decays

• Significantly improved D X e spectrum possible using tagged D’s

• Backgrounds in B X l analyses (bcl)

• Test of HQET: D0, D+, Ds+

same to few %– Ds and D+ weak annihilation

contribution – a concern for |Vub| from El endpoint

– Inclusive spectra + HQET used for |Vcb| from bc l

DELCO (3770) DD eX

Also can measure BSL to get SL

- currently no measurement for Ds


Strong Phases in Hadronic D• Methods to measure

in B± D0K±; D0 f • Aided by measurements

of strong phases in hadronic D decays:– Dmany Atwood & Soni

PRD 68, 033003– D0K*±K Rosner &

Suprun PRD 68, 054010

• CLEO-c: advantage of quantum coherence:(3770) DD ; JP=1-

( ) ( )

Interference of K*+ & K*- bands


CLEO-c & Unitarity Triangle• Potential Impact

– Top: current experimental and theoretical uncertainties

– Bottom: current experiment with 2% theory uncertainties – perhaps possible with LQCD calibrated with CLEO-c data


Potential Impact on VCKM

Vub/Vub 17%lB

l

D

Vcd/Vcd 7%

lD

Vcs/Vcs 11%l

B D

Vcb/Vcb 5%

Bd Bd

Vtd/Vtd 36%

Bs Bs

Vts/Vts 39%

Vus/Vus 1%

l Vud/Vud 0.1%

e

pn

Vtb/Vtb 29%

t

b

W

CLEO-c will redefine 2nd generation elementsAnd enable improvements in 3rd generation

Current VCKM

From directMeasurements-no unitarity imposed

2%

2%

5%

5%

5%

3%

Future VCKM


Summary• The CLEO detector is state of the art,

understood at a precision level, and collecting data in the cc resonance region.

• CLEO has a long history of weak decay and CKM physics interests that will carry over to the CLEO-c program– CKM physics

• semileptonic D decays: spectra, form factors, |Vcs| & |Vcd|• Leptonic decays: fD fDs informing B mixing interpretation

– Enabling measurements of Hadronic D decays• Strong Phases to inform determinations in BDK• Measurement of absolute branching fractions

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