Studies of Charm Meson Decays at BaBar Kalanand Mishra University of Cincinnati University of Cincinnati On behalf of the BaBar Collaboration DPF 06, Honolulu,

Studies of Charm Meson Decays at BaBar

Kalanand MishraKalanand Mishra University of CincinnatiUniversity of CincinnatiOn behalf of the BaBar CollaborationOn behalf of the BaBar Collaboration

DPF 06, Honolulu, October 31, 2006DPF 06, Honolulu, October 31, 2006

DPF 06, Honolulu, October 31, 2006DPF 06, Honolulu, October 31, 2006 Kalanand Mishra,Kalanand Mishra, University of CincinnatiUniversity of Cincinnati

22/22/22

OutlineOutline

• Measurements of the ratio of branching fractions for the Measurements of the ratio of branching fractions for the decaysdecays

• DD++++00, , KK++00 • DD00--++00, , KK--KK++00

• Amplitude (Dalitz plot) analysis of the decaysAmplitude (Dalitz plot) analysis of the decays

• DD00KK--KK++00 • DDss

++KK++KK--++

hep-ex / 0608009, 2006, submitted to PRD hep-ex / 0608009, 2006, submitted to PRD

BaBar PreliminaryBaBar Preliminary


Phys.Rev.D74:011107,2006Phys.Rev.D74:011107,2006


33/22/22

- Use the decay D+K-++ as reference for normalization.

- Reconstruct the decay chain: [ D*+D+0s, D+h+0,K-++, 0 ].

- Reject the events with D+ NOT coming from D*+ decay (for cleaner signal).

• PCM (D*) > 2.9 GeV/c• |mD* - m D+ | < 155 MeV/c2

D*+

D+

0soft

0

K+ / +

Data Sample = 124 fb-1

B.R. of the Decays DB.R. of the Decays D++++00, K, K++00

1.1. Measurement of the Cabibbo-Measurement of the Cabibbo-suppressed branching ratio Dsuppressed branching ratio D++++00..

2.2. The first measurement of DThe first measurement of D++KK++00 branching ratio.branching ratio.

MotivationMotivation Event ReconstructionEvent Reconstruction

Signal Reconstruction Efficiency

●D*+ D+ 0soft

, D+ + 0 7.8%

●D*+ D+ 0soft

, D+ K+ 0 5.9%

●D*+ D+ 0soft

, D+ K- + + 8.5%

The description of charge conjugate decay is implied throughout this presentation unless explicitly stated otherwise.


44/22/22

Signal band

Side ban

d

m-++ [GeV/c2]

m-++ [GeV/c2]

m [GeV/c2]

Signal YieldSignal Yield

● Divide M into 2 signal band and >5 side band● Fit D+ mass distribution separately(with the same signal pdf)● Subtract side band yield from signal band yield (adjusted by scale factor)

Even

ts /

(0.5

MeV

/cEv

ents

/ (0

.5 M

eV/c

22 ))

D+ K-++

signal yield 101380 ± 415

Even

ts /

(15

MeV

/cEv

ents

/ (1

5 M

eV/c

22 ))Ev

ents

/ (5

Ev

ents

/ (5

M

eV/c

MeV

/c22 ))

m distribution These are These are DD++ events events NOT NOT coming coming from D*from D*++ decay.decay.

[ 1.78 < m[ 1.78 < mKK--++++ < < 1.95 GeV/c1.95 GeV/c22 ] ]


55/22/22


m+0 [GeV/c2]

Signal Yield Signal Yield continuedcontinued …. ….

m+0 [GeV/c2]

First observation of D+ +0

Background from Ds+K+Ks , Ks00

events, when we miss one 0.

D+ +0 D+ +0 signal yield 189 ± 35

Even

ts /

(10

MeV

/cEv

ents

/ (1

0 M

eV/c

22 ))

Even

ts /

(10

Even

ts /

(10

MeV

/cM

eV/c

22 ))

Background from a missing Background from a missing 00 in the in the event, parameterized by an event, parameterized by an exponential function.exponential function.

• Signal events are modeled by bifurcated Gaussian functions. • Combinatorial backgrounds are modeled by linear functions.


66/22/22

B(D+ +0) / B (D+ K-++) = ( 1.33 ± 0.11 (stat) ± 0.09 (sys) ) x 10-2 B(D+ K+0) / B(D+ K-++) = ( 2.68 ± 0.50 (stat) ± 0.26 (sys) ) x 10-3

B(D+ +0) = ( 1.25 ± 0.10 (stat) ± 0.09 (sys) ± 0.04 (ref) ) x 10-3

using B(D+ K-++) = ( 9.4 ± 0.3 ) x 10-2,

B(D+ K+0) = ( 2.52 ± 0.47 (stat) ± 0.25 (sys) ± 0.08 (ref) ) x 10-4

Comparison to the current PDG values : ●D+ +0 world average (2006) B(D++0) = (1.28 ± 0.09 ) x 10-3

●D+ K+0 world average (2006) B(D+ K+0) < 4.2 x 10-4 at 90% CL

Results and ConclusionResults and Conclusion

This is the first measurement of the doubly Cabibbo-This is the first measurement of the doubly Cabibbo-suppressed decay Dsuppressed decay D++KK++0 0 [ [ The CLEO-c collaboration recently made The CLEO-c collaboration recently made a new measurement which is consistent with our result:a new measurement which is consistent with our result: B(D+K+0) = ( 2.25 ± 0.36 (stat) ± 0.15 (sys) ± 0.07 (ref) ) x 10-4 ]. ]. hep-ex/0607075hep-ex/0607075

Phys.Rev.D74:011107,2006Phys.Rev.D74:011107,2006

Excellent kaon ID has contributed significantly to the sensitivity of this Excellent kaon ID has contributed significantly to the sensitivity of this measurement. measurement.

Preliminary Preliminary resultresult


77/22/22

B.R. of the Decays DB.R. of the Decays D00--++00, K, K--KK++00

Event ReconstructionEvent Reconstruction PCM ( D0 ) > 2.77 GeV/c |mD* - m D0 - 145.5| < 0.6 MeV/c2

Background Sources Combinatorial K0 reflection in 0 and KK0 modes Data Sample = 232 fb-1

Use the the Cabibbo-favored decay D0K-+0 as reference for normalization. Reconstruct the decay chain: [ D*+D0s

+, D0h-h+0, 0 ] and c.c.

D*+

D0

+soft

0

K- / -K+ / +

1.1. Precision measurement of the Precision measurement of the branching ratios of 3-body branching ratios of 3-body Cabibbo-suppressed decays of Cabibbo-suppressed decays of DD00..

2.2. To investigate the anomaly in the To investigate the anomaly in the BR of 2- & 3-body CS decays of BR of 2- & 3-body CS decays of DD00..

Motivation

The charge of the soft determines the charm content of the D0 meson (i.e., whether it is D0 or D0).

__


88/22/22

Fit for Signal YieldFit for Signal Yield

• Signal events are modeled by the sum of 3 Gaussian functions. The means and ’s of the Gaussians are allowed to vary. • Combinatorial backgrounds are modeled by linear functions. • The shape of K-+0 reflection events in the sidebands of -+0 and K-K+0 is obtained from MC as described on the next slide.

KK--++00

--++00 KK--KK++00Maximum Likelihood fit for signal yield




Even

ts /

(2.5

MeV

/cEv

ents

/ (2

.5 M

eV/c

22 ))

Even

ts /

(625

keV

/cEv

ents

/ (6

25 k

eV/c

22 ))

Even

ts /

(5 M

eV/c

Even

ts /

(5 M

eV/c

22 ))Removed Removed DD00KKss

00[[--

++]]00 events events (~0.5 % of (~0.5 % of the the observed observed number).number).

BABARBABAR prelim.prelim.




99/22/22

Background Events in Monte CarloBackground Events in Monte Carlo--++00

signal

Combinatorial Background

K-+0 reflection

K-+0 reflection

KK--KK++00

signal

±3 RMS±3 RMS

• Above: three-body invariant mass distributions of DD00--++00 and D D00KK--KK++00 events in generic cc Monte Carlo (MC).• K- +0 reflection events peak in the sidebands of -+0, K-K+0. • We take the shape of the reflection from MC and obtain the number of reflection events by fitting their distribution in data.

±3 RMS±3 RMS

Combinatorial Background

__

Note Log y-scale.Note Log y-scale.

BABARBABAR prelim.prelim. BABARBABAR

prelim.prelim.


1010/22/22

ReconstructionReconstruction Efficiency Efficiency

--++00

~ 0.5 % bkg

~ 2 % bkg

~ 5 % bkg

KK--++00

KK--KK++00

Reco. Efficiency (%) from Monte Carlo Dalitz plot of events in datamm

22 (h (h

++ 00 )

[GeV

/c) [

GeV/

c22]]22

mm22(h(h--00) [GeV/c) [GeV/c22]]22

Avg EffAvg Eff~10%~10%

Avg EffAvg Eff~11%~11%

Avg EffAvg Eff ~9%~9%

BABAR

BABAR

prelim

inary

prelim

inary


1111/22/22

Results and ConclusionResults and ConclusionD0 decay mode Our Results(%)B(πππ0 )/B(K π0) 10.59 0.06

0.13B(K π0 )/B(K π0) 2.37 0.03 0.04

PDG-2006 (%) 8.40 3.11 0.95 0.26

The decay rate for each mode = < |M|2 > . where M = decay matrix element = phase space factor

Roughly consistent Roughly consistent with naïve with naïve expectations,expectations,i.e., sini.e., sin22cc = 0.05 = 0.05

Very different from naïve Very different from naïve expectationsexpectations(see the orange box below).(see the orange box below).

( Naïve expectation = ( Naïve expectation = 1.0 )1.0 )

For 3-body decays:For 3-body decays: area of the Dalitz plotarea of the Dalitz plotFor 2-body decays:For 2-body decays: momentum of either momentum of either daughter in Ddaughter in D00 rest frame. rest frame.

==

|M|2(πππ0)/ |M|2(Kππ0) = 0.0668 0.0004 0.0008|M|2(π0)/ |M|2(Kππ0) = 0.0453 0.0006 0.0008 |M|2(π0)/ |M|2(πππ0) = 0.678 0.014 0.021

|M|2(ππ )/ |M|2(Kπ ) = 0.034 0.001|M|2( )/ |M|2(Kπ ) = 0.111 0.002 |M|2()/ |M|2(ππ ) = 3.53 0.12

Using branching ratio values from above Using branching ratio values from above table:table:

Using 2-body B.R. values from Using 2-body B.R. values from PDG:PDG:

hep-ex / 0608009, 2006, submitted to PRD hep-ex / 0608009, 2006, submitted to PRD

> 5> 5 difference with difference with PDG value. Excellent PDG value. Excellent PID performance has PID performance has greatly improved the greatly improved the the sensitivity of this the sensitivity of this measurement. measurement.


1212/22/22

Amplitude Analysis of D and DAmplitude Analysis of D and Dss decaysdecays


1313/22/22

K*(892)K*(892)--

K*(892)K*(892)++

(1020)(1020)

ff 00(98

0)(9

80)

K*(1410)K*(1410)++

K*(1410)K*(1410)--

KK++00 (s) (s)

KK--00 (s) (s) ff22’’(1525)(1525)

- Extract information useful for determination of Extract information useful for determination of angle angle of the CKM matrix: strong phase difference of the CKM matrix: strong phase difference & relative phase for D& relative phase for D00K*(892)K*(892)- - KK++, K*(892), K*(892)+ + KK--..- Is there a charged Is there a charged state ? state ?- Nature of Kπ S-wave below 1.4 GeV/cNature of Kπ S-wave below 1.4 GeV/c22 ? ?

Amplitude Analysis of the Decay DAmplitude Analysis of the Decay D00KK--

KK++00


MotivationMotivation

Events used to obtain bkg shape

±1 region: ≈ 7000 events, purity ≈ 97 %



1414/22/22

⎪⎪⎩

⎪⎪⎨

⎧

−−

−−=

)(1

)(1

)(

222

211

2

2

ggiMsM

siMsMsBW

rr

rrrJr

ρρ

Isobar Model FormalismIsobar Model Formalism three-body decay Dthree-body decay DABC decaying through an r=[AB] ABC decaying through an r=[AB] resonanceresonance

D decay three-body amplitudeD decay three-body amplitude ),(),( 1312013120 sseaeass r

ri

rr

iD AA δδ ∑=

Jr

Jr

Jr

JDr BWMFFss ××=),( 1312A Relativistic Breit-WignerRelativistic Breit-Wigner

Angular distributionAngular distributionD D and and r r Blatt-WeisskopfBlatt-Weisskopf form form factorsfactors

NR termNR term(direct 3 body (direct 3 body decay)decay)aa00, , δδ00, a, arr, , δδrr : Free parameters of fit : Free parameters of fit

ff00(980)(980)

1 1

12

2

3 3 3

{12} {13} {23}12

32

NRNR

((


1515/22/22

– K S-wave in mass range 0.6–1.4 GeV/c2 is not well-understood. A possible state ~ 800 MeV/c2 has been conjectured, but this has only been reported in the neutral state.

– For the K+0 and K-0 S-wave amplitudes, we try three models:

I=1/2 KI=1/2 K S-wave ParameterizationS-wave Parameterization

- Amplitude obtained from LASS K-+ K-+ scattering.

- K-+ amplitude extracted from a model-independent partial-wave analysis of D+K-++ decay by the E791 collaboration.

- [ coherent sum of (800) + uniform NR + K*0(1430) ].

Normalized to Normalized to arbitrary scale arbitrary scale for m(Kfor m(K)>1.1 )>1.1 Gev/cGev/c2 2 forforeasy easy comparison.comparison.

- - 808000

Nucl. Phys. B296, 493 (1988); W. Dunwoodie, web notes.Nucl. Phys. B296, 493 (1988); W. Dunwoodie, web notes.

{ No evidence in K{ No evidence in K elastic elastic scattering. scattering. }}

Phys. Rev. D73, 032004 (2006)Phys. Rev. D73, 032004 (2006)


1616/22/22

LASS parameterization for Kπ S-wave Fit ResultsFit Results

m2(K+π0)m2(K-π0) m2(K+K-)

- The best fit is LASS - The best fit is LASS parameterization. parameterization. - E791 fit worse at low mass.E791 fit worse at low mass.- model yields model yields mass 870 ± 30 MeV/cmass 870 ± 30 MeV/c22 width 150 ± 20 MeV/cwidth 150 ± 20 MeV/c22

significantly different from significantly different from the values reported the values reported previously for previously for 00..

Use the Use the fit model fit model with Kwith K S- S-wave wave from from E791 for E791 for model model systematisystematic c uncertainuncertainty. ty. For KFor K S-wave S-wave

These results are preliminary. We are investigating the KThese results are preliminary. We are investigating the K S-wave at lower mass, and contribution of S-wave at lower mass, and contribution of K*(1410).K*(1410).


1717/22/22

Each event was weighted by the Each event was weighted by the spherical harmonicspherical harmonic YY00LL(cos (cos HH) ) ((LL=0,1,2,…..).=0,1,2,…..).

Excellent agreement between data & model.

⎪⎪⎪

⎩

⎪⎪⎪

⎨

⎧

=

=

=

202

01

2200

524

cos24

4

PY

PSY

PSY

SP

π

φπ

π

For S- and P- waves in absence of cross-feeds from other channels (also, assuming

negligible contributions from D- and higher waves):

Analysis of Angular MomentsAnalysis of Angular Moments

Y01

Y00

Y02

Y04

Y06

Y03

Y05

Y07


Significantly large Significantly large interference between S and interference between S and P waves. P waves.Higher moments above 1 GeV Higher moments above 1 GeV are coming from cross are coming from cross channels.channels.


1818/22/22

Strong Phase Difference & Amplitude Strong Phase Difference & Amplitude Ratio Ratio

The strong phase difference δD and relative amplitude rD between the decays D0K*-K+ and D0K*+K- are defined, neglecting direct CP violation in D0 decays, by the equation:

rD eiδD = [aK*-K+/ aK*+K-] exp[ i(δK*-K+ - δK*-K+) ]

We find δD = -37.9o ± 2.2o (stat) ± 0.7o (exp sys) ± 4.2o (model sys) rD = 0.64 ± 0.01 (stat) ± 0.01 (exp sys) ± 0.01 (model sys).

These measurements are consistent with the previous measurement These measurements are consistent with the previous measurement by CLEO:by CLEO: δD = -28o ± 8o (stat) ± 2.9o (exp sys) ± 10.6o (model sys) rD = 0.52 ± 0.05 (stat) ± 0.02 (exp sys) ± 0.04 (model sys).

These results are preliminary.These results are preliminary.


hep-ex/ 0606045hep-ex/ 0606045


1919/22/22

Amplitude Analysis of DAmplitude Analysis of Dss++KK++KK--++

DecayDecay


- Clean signal obtained Clean signal obtained with a likelihood with a likelihood selection using vertex selection using vertex separation and p*. separation and p*. - Average reconstruction Average reconstruction efficiency ~30 %.efficiency ~30 %.

Precise measurement of the branching Precise measurement of the branching fractions of Dfractions of Dss

++++ and and DDss

++K*(892)K*(892)00 K K++. .

MotivationMotivation



±2 sig. region: ≈100850 events, purity ≈ 95 %



(1020)(1020)

ff00(980)(980)

K*(892)K*(892)00mm

22 (K(K--

++ ) / [

GeV

) / [

GeV22

/c/c44 ]]

even

ts /

0.02

GeV

even

ts /

0.02

GeV

22 /c/c44

__

__


2020/22/22

Fit ResultsFit ResultsLarge systematic Large systematic uncertainty in funcertainty in f00(980) (980) amplitude and phase amplitude and phase because several because several different different parameterizations parameterizations were tried.were tried. Decay is dominated

by Ds+K*0K+, +,

and f0(980)+

f0(980) contribution is large but has large systematic error as well.

Higher mass f0’s and D-wave resonances have small contributions.

Angular moments : Excellent agreement with data

__

Large fLarge f00(980) (980) contribution contribution


Very small interference Very small interference between S-wave (between S-wave ((800) ?) (800) ?) and P-wave (K*(892)) => and P-wave (K*(892)) => no no (800) contribution (800) contribution found. found.


2121/22/22

The decay Ds++ is frequently used as the Ds

+ reference decay mode for measurement of branching ratios.

The previous analysis (E687) of this Dalitz plot was performed with ~ 700 events (vs. 105 events in our case).

Using Dalitz plot results, we make a precise measurement of the branching ratios of the decays Ds

++ and Ds+K*(892)0 K+

integrated over the whole phase space.

Branching Ratios Branching Ratios


B(Ds++) / B(Ds

+K+K-+) = 0.379 ± 0.002 (stat) ± 0.018 (sys)

B(Ds+K*(892)0 K+ ) / B(Ds

+K+K-+) = 0.487 ± 0.002 (stat) ± 0.016 (sys)

where where KK++KK-- and K*(892) and K*(892)00 KK--++. .

__

____

These results are preliminary.These results are preliminary.


2222/22/22

Precise measurements of singly Cabibbo-suppressed branching ratios: D++0 and D0-+0, K-K+0.

First measurement of doubly Cabibbo-suppressed branching ratio : D+K+0.

Amplitude analysis of D0K-K+0 : measure δD & rD for the charge-conjugate dominant decays.

Amplitude analysis Ds+K+K-+ : measure precise branching

ratios of Ds++ and Ds

+K*0(892)K+ with with KK++KK-- and and K*(892)K*(892)00 KK--++.

Summary Summary

____

Back up slides


2424/22/22

Event Reconstruction• 0 reconstruction: have two of them, one from D*+, other from D+ :

•0 from D*+ is soft , 150 < p0 < 450 MeV/c

•0 from D+ has higher mom., p0 > 200 MeV/c

• D+h+0 reconstruction: 1.7 < m(h+0) < 2.0 GeV/c2, -0.9 < cos h < 0.8 (0.7 in case of K+0).• K-, + and + tracks are fit to a vertex to reconstruct D+ candidate for reference mode.• PCM (D*) > 2.9 GeV/c, |mD* - m D+ | < 155 MeV/c2

• In case of multiple candidates in an event, select the one with higher D* momentum.

DD++++00, K, K++00

pq

cos = p. q

D+

+

0

Helicity angle for Helicity angle for ++00 modemode


2525/22/22

DD00--++00, K, K--KK++00

DD00hh--hh++00 Reconstruction Reconstruction h- and h+ tracks are fit to a vertex Mass of 0 candidate is constrained to m0 at h-h+ vertex PCM ( D0 ) > 2.77 GeV/c

D* Reconstruction D*+ candidate is made by fitting the D0 and the s

+ to a vertex constrained in x and y to the measured beam-spot for the run. |mD* - m D0 - 145.5| < 0.6 MeV/c2

Vertex 2 probability > 0.01 Choose a single best candidate with smallest 2 for the whole decay chain ( multiplicity = 1.03 ).

Background Sources Charged track combinatoric Mis-reconstructed 0

Real D0, fake s

K0 reflection in 0 and KK0 modes


2626/22/22

KK--KK++0 0 branching ratio: CLEO resultbranching ratio: CLEO result CLEOCLEO collaborationcollaboration

KK--KK++00

signal

K-+0 reflection

Phys. Rev. D54, 4211 (1996)B(D0KK0)/ B(D0KK0) =0.95 ± 0.26 %

Signal yield 151 ± 42Efficiency 9.2 ± 0.3 %

A new cross-check done by the CLEO A new cross-check done by the CLEO collaboration shows B(Dcollaboration shows B(D00KKKK00)/ )/ B(DB(D00KK00) = 2.21 ± 0.14 (stat) %, ) = 2.21 ± 0.14 (stat) %, which is consistent with our which is consistent with our measurement. measurement.

Phys. Rev. D74, 031108 (2006)Phys. Rev. D74, 031108 (2006)

High pion-to-kaon misidentification rate contamination from D0K-

+0 events very high. Had to apply various

vetoes and the corresponding efficiency corrections.

Combinatorial background not fully understood.


2727/22/22

Kπ S-wave amplitude is described by the coherent sum of an effective range term and the K*0(1430) resonance:

S(s) = (√s/ p). sin . ei

= cot-1 [ 1/ap + rp/2 ] + cot -1 [ (m2R-s)/(mR R ) ]

Effective Range (NR) term K*0(1430) resonance term

a = scat. length, r = eff. range, mR = mass of K*0(1430), R= width p = momentum of either daughter in the Kπ rest frame.

For Kπ scattering, S-wave is elastic up to K' threshold (1.45 GeV).

Phase space factor

LASSLASS KK S-wave ParameterizationS-wave Parameterization


2828/22/22

Divide m2(K-+) into slices

Find s–wave amplitude in each slice (two parameters) Use remainder of Dalitz plot as an interferometer

For s-wave:

- Interpolate between (ck,k).

Model P and D waves.

[ E791 Collaboration, slide from Brian Meadow’s Moriond 2005 talk ]

S (“partial wave”)

KK S-wave from S-wave from DD00KK--++++ DP DP


2929/22/22

Each event was weighted by the Each event was weighted by the spherical harmonicspherical harmonic YY00LL(cos (cos HH) ) ((LL=0,1,2).=0,1,2).

Excellent agreement between data & model.

Y01Y0

0

Y02

Y04

Y06

Y03

Y05

Y07

⎪⎪⎪

⎩

⎪⎪⎪

⎨

⎧

=

=

=

202

01

2200

524

cos24

4

PY

PSY

PSY

SP

π

φπ

π

With cross-feeds or in the presence of D-waves, higher

moments ≠ 0 . Wrong fit models tend to give rise to higher moments

in the region, creating disagreement with data.

For S- and P- waves in absence of cross-feeds from

other channels:

Moments Analysis in KMoments Analysis in K--KK++ channel channel



3030/22/22

±2 sig. region: ≈ 100850 events, purity ≈ 95 %

DDss++KK++KK--++

m = 1969.0± 0.1 MeV/c2

= 5.8 MeV/c2

Data Sample = 240 fb-1 Signal events Signal events reconstructed from two reconstructed from two kaon and a pion charged kaon and a pion charged tracks fitted to a common tracks fitted to a common vertex, with vertex, with 22>0.1 %.>0.1 %.

Background from D*Background from D*++ DD00[K[K++KK--] ] ++ removed by removed by requiring m(Krequiring m(K++KK--)<1.85 )<1.85 GeV/cGeV/c22..

Removed KRemoved K--++mismis++

reflection by requiring m(Kreflection by requiring m(K--

++mismis++) - m(K) - m(K--++

mismis) > 0.15 ) > 0.15 GeV/cGeV/c22..

Average event Average event reconstruction efficiency ~ reconstruction efficiency ~ 30 %.30 %.

Events used to obtain Bkg shape: (-10, -6) and (6, 10).


Documents

Studies of Charm Meson Decays at BaBar Kalanand Mishra University of Cincinnati University of Cincinnati On behalf of the BaBar Collaboration DPF 06, Honolulu,