Charm Results from FOCUS

1

Charm Results from FOCUS

Kihyeon Cho Kyungpook National University

Daegu, Korea

(On behalf of FOCUS Collaborations)

Flavor Physics CP Violation 2004 October 4 -9, 2004

KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS2

ContentsContents

Why Charm Physics? FOCUS Experiment Recent Charm Results from FOCUS

1. Pseudoscalar semileptonic decays2. Vector semileptonic decays3. Charm hadronic mixing4. Search for new particles – pentaquarks, double charm baryons

Conclusions


Why charm physics?Why charm physics?

Window to new physics Standard model rates for rare decays, CP violation and mixing are very l

ow. With current experiments, observation of CP violation, rare decays or mi

xing new physics Provides information about QCD

Measurements of production characteristics, lifetimes, branching ratios and subresonant analyses provide insight into QCD.

Needed for b physics Many b particles decay to charm so branching ratios and lifetimes are ne

eded for accurate b results. Experimental techniques are developed in charm physics. (lifetime meas

urement, Dalitz plot analyses...) Heavy quark effective theory often needs charm to bootstrap to b physic

s.


Photoproduction of Charm with an Upgraded Spectrometer

~100 Physicists, 18 institutes from 5 countries

Univ. of California-Davis, CBPF-Rio de Janeiro, CINVESTAV-Mexico City, Univ. Colorado-Boulder, FERMILAB, Laboratori Nazionali di Frascati,

Univ. of Illinois-Urbana-Champaign, Indiana Univ.-Bloomington, Korea Univ.-Seoul, Kyungpook National Univ.-Daegu, INFN and Univ.-Milano,

Univ. of North Carolina-Asheville, INFN and Univ.-Pavia, Univ. of Puerto Rico-Mayaguez,Univ. of South Carolina-Columbia, Univ. of Tennessee-Knoxville,

Vanderbilt Univ.-Nashville, Univ. of Wisconsin-Madison

FOCUS ExperimentFOCUS Experiment


Vertexing is the KeyVertexing is the Key

Golden Modes:

D+ K- D0 K- D0 K- BeO

BeO

tarsiltarsil

| primary vtx | secondary vtx

Dec

ays

/ 200

m

BackgroundBackgroundSubtractedSubtracted

Golden ModeGolden ModeCharmCharm


1.1. Pseudoscalar Pseudoscalar semileptonic decay semileptonic decay

Using D0D0 (D0(D0 Pole masses f-(0)/f+(0)

f+(0)/f+

K(0)

Non-parametric q2 dependent


Why Pseudoscalar Why Pseudoscalar semileptonic decay?semileptonic decay?

The differential decay rate is

Measuring the q2 dependence and form factors in heavy quark transition is critical to our understanding of QCD.

Hadronic current contains information about strong contributions.


What do we measure What do we measure in Din D00PlPl

(D0(D0

Pole masses

f-(0)/f+(0)

f+(0)/f+

K(0) provides the test of SU(3)

symmetry breaking

Non-parametric q2 dependent A model independent

measurement would allow to discriminate between different models.

f+(q2) parameter

Pole form

Modified pole from


Fitting Technique on Fitting Technique on DD00

Fit D*-D0 mass difference plot to find the amount of combinatoric background.

Apply the mass difference cut (< 0.154 GeV/c2) to suppress combinatoric and peaking background


Results on Results on DD00

Fit to cos l and q2 to measure branching ratio, pole masses and the ratio f-(0)/f+(0).

28829

6574 92

30.015.091.1

M

007.0008.0074.0)(

)(0

0

KD

D

05.004.093.1

KM

6.14.17.1

)0(

)0(

K

K

f

fPreliminary

(GeV/c2),


Extracting fExtracting f++(0)/f(0)/f++

KK(0)(0)

Compute a numerical integration on Dalitz

Get efficiency as a function of q2

Get yield from the fit

Using PDG

|Vcd/Vcs|2 =0.051

Consistent with the predictions from SU(3) symmetry breaking and lattice QCD

Preliminary


Non-parametric qNon-parametric q22 dependentdependent

e

Ke

form factor f+(q²)

single-pole model

single-pole model

Based on 820 events

q² / GeV²

Kl

l

q² / GeV²

Using ~13,000 K events

3 brand new results from CLEO, Belle and FOCUS on form factor f+(q²) in DD00ll/ Kl/ Kl

f+(q²)

Excellent agreement with LQCD!

Preliminary


Summary for pseudoscalar semSummary for pseudoscalar semileptonic decayileptonic decay

The and branching ratio is consistent with recent results from CLEO.

The pole masses are lower than the predicted value at the D* or Ds* masses.

We presented a non-parametric analysis of the q2 dependence for D0K which shows excellent agreement with the results obtained with the parametric analysis and lattice QCD.

007.0008.0074.0)(

)(0

0

KD

D

30.015.091.1

M05.004.093.1

KM

6.14.17.1

)0(

)0(

K

K

f

f04.004.085.0

)0(

)0(

Kf

f

Preliminary

, (GeV/c2)


2. Vector Semileptonic decay2. Vector Semileptonic decay

D+ K*0 form factorBranching ratio D0 K*- form factorBranching ratio )(/)0( 00* KDKD

)(/)( 000* KDKD

KIHYEON CHOCENTER FOR HIGH ENERGY PHYSICS

(D(D++KK*0*0 / / DD++ K K00))

*0

00.594 0.043 0.033

D K

D K

Use upstream Ks (~10%) so that both the signal (K) and normalization (Ks ) leave 3 tracks in FOCUS microstrip

sK

*0 0D K l K l Theory

S-wave corrected

Old

qu

ark

mo

del

PLB 598 (2004) 33


Form Factors of DForm Factors of D00KK*-*-

++ K*- Ks -

After background subtraction, we fit D*-D0 mass difference and cosl X cos v X q2 distribution at the same time.

Results

RV= 1.706 0.677 0.342

R2 = 0.912 0.370 0.104 World’s first measurement

Preliminary


Summary of vector semilepotonSummary of vector semilepotonic decayic decay

Form Factor FOCUS D0K*-+ FOCUS D+K*0

Rv 1.706 0.677 0.342 1.504 0.057 0.039

R2 0.912 0.370 0.104 0.875 0.049 0.064

Reference Preliminary PLB 544 (2002) 89

013.0034.0337.0)(

)(00

*0

KD

KD

033.0043.0594.0)(

)(0

0*

KD

KDPLB 598 (2004) 33

Preliminary


3. D3. D00-D-D00 hadronic mixing hadronic mixing and DCS decaysand DCS decays

D0 goes to K+- in two ways (mixing + CF decay and DCS decay) Interference

Assuming CP conservation, D0 K+- wrong sign to right sign decay ratio is written by

Three terms from DCS decays, interference & mixing Soft pion charge in D*+ D0+ defines right sign(RS) and wrong sign

(WS). Fit for RDCS, x’2 and y’

Mixing parameters


Right Sign vs Wrong SignRight Sign vs Wrong Sign


Summary for Mixing Summary for Mixing ResultsResults

All results shown here assume CP conservation.

FOCUS results agree better with BaBar in location and shape than CLEO.


4. New particle searches4. New particle searches

S=-1 pentaquark (1540)+ with uuddsS=-2 pentaquark (1860)– – with uddssCharm pentaquark c(3100)0 with uuddc

Double charm baryons cc with ccu and ccd


Evidence for Evidence for ++(uudds)(uudds)


Evidence for Evidence for + + (cont’d) (cont’d)


(1540)(1540)++ p Ks search p Ks search

No evidence for (1540)+ pKs but reconstructs 8 million K*(892)+ Ks+ and 240,000 (1385)+ 0+


(1860)(1860)– –– – search search(1860)- - -- (S=-2 pentaquark)

NA49 shows evidence for (1860)- - and (1860)0 decaying -..

No evidence for (1860)- - -- but reconstructs 60,000 (1530)0 - +, approximately 1,000 times more than observing experiment.


Charm Pentaquark searchCharm Pentaquark search

No evidence for a charm pentaquark decaying to D*-p or D-p with a factor of 10 more D*+ decays than the observing experiment.


CCCC search search

No evidence


Summary for Search Summary for Search ResultsResults

No evidence for (1540)+ pKs but reconstructs 8 million K*(892)+ Ks+ and 240,000 (1385)+ 0

No evidence for (1860)- - -- but reconstructs 60,000 (1530)0 - +, approximately 1,000 times more than observing experiment

No evidence for a charm pentaquark decaying to D*-p or D-p with a factor of 10 more D*+ decays than the observing experiment.

No evidence for double charm baryons with 10 times more C decays than the observing experiment.


ConclusionsConclusions

Charm mode …Charm physics gives a rich source of new results.FOCUS is playing a major role in understanding the

charm decays.The recent charm results from FOCUS include

Charm pseudoscalar semileptonic decays Charm vector semileptonic decays Charm hadronic mixing Search for pentaquarks and double charm.

FOCUS is continuing studies of charm physics.


BackupsBackups


FOCUS SpectrometerFOCUS Spectrometer

At FermilabBeO charm

Segmented target

Silicon vertexing

MWPC tracking

~175 GeV

Cenenkov ID

EM/hadronic Calorimeter

Muon detectors


Fo

cus 04

MK

3

E691

Cleo

91

Cleo

93

E687 tag

E687 in

c

Cleo

041.4

1.6

1.8

2.0

2.2

2.4

2.6

po

le m

ass

Kl

1.910.04

qq22 dependent (cont’d) dependent (cont’d)Clearly the data does not favor the simple Ds* pole

We presented a non-parameteric analysis of the q2 dependence for D0K which shows excellent agreement with the results obtained with the parameteric analysis and lattice QCD.


DD++ K K*0 *0 channelchannel

Only external diagram involved.

Factorization is possible between hadronic and leptonic current.


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

right-handed +

left-handed +

Two amplitudes get summed over W polarization using D-matrices

22 2

(0)( )

1i

iA

AA q

q M

22 2

(0)( )

1 V

VV q

q M

Helicity FF are combinations of one vector and two axial form factors.

v 1(0) (0)r V A

2 2 1(0) (0)r A A

Two observables parameterize the decay

Four body decays requires five variables: 3 angles, Mk , q .

DD++ K K*0 *0 decaysdecays


2

20

2

2

2

5

)(sincos2

)()cos1(sin

)()cos1(sin

coscos

0*

0*

0*

qHB

qHBe

qHBe

ddddqdm

d

KV

Ki

V

Ki

V

Vk

0*KD

Yield 31,254

DataMC

Focus “K*” signal

matches model

-15% F-B asymmetry!

Interference in DInterference in D++ K K*0 *0

Huge Asymmetry in cosv below K* pole led to a discovery of s-wave interference.


KK** interference term (Ae interference term (Ae ii))

2

20

2

2

2

5

)()(cossin2

)(sin)cos1(

)(sin)cos1(

coscos

0*

0*

0*

qHAeB

qHBe

qHBe

ddddqdm

d

iKV

Ki

V

Ki

V

Vk

S-wave interference term

Signal events weightedby avg(cosV):

No added term

PLB535(2002) 43


S-Wave effects apparent only with high statistics

Lattice Gauge!

Experiment Models PLB544(2002) 89

Form Factors Form Factors DD++KK*0*0ll

A=0.3300.0220.015GeV-1

=0.68 0.07 0.05 rad

RV= 1.5040.0570.039

R2= 0.8750.0490.064


DD00KK*-*-++ channel channel


KK** interference term (Ae interference term (Ae ii))

A term which is non-symmetric vs. cosv appears due to the S-wave

Use a model that includes S-wave

= 0.68 rad fixed from

A=0.3470.2220.053 GeV-1

*0 KD

0** KD


Branching Ratio Branching Ratio

D*-D mass difference plot for normalization mode

Accounting for S-wave component in 00 KD

Normalization mode

Excellent agreement with semielectronic decay

)(

)(00

*0

KD

KD

013.0034.0337.0)(

)(00

*0

KD

KD


Summary of vector semilepotonSummary of vector semilepotonic decayic decay

FOCUS D0 FOCUS D+

Rv 1.706 0.677 0.342 1.504 0.057 0.039

R2 0.912 0.370 0.104 0.875 0.049 0.064

A(GeV-1) 0.347 0.222 0.053 0.330 0.022 0.015

(rad) 0.68 (fixed) 0.68 0.07 0.05

Reference Preliminary PLB 544 (2002) 89013.0034.0337.0

)(

)(00

*0

KD

KD

033.0043.0594.0)(

)(0

0*

KD

KD

PLB 598 (2004) 33

Preliminary


Fit Shape (Signal)Fit Shape (Signal)


Double charm baryon Double charm baryon production comparedproduction compared

If the C+K-+ (CK-++) signal is real, SELEX produces at

least 42 (111) times more cc baryons relative to C than FOCUS.

Documents

Charm Results from FOCUS