8th December 2007 CLEO physics fest 1

Coherence factor analyses

Jim Libby, Andrew Powell and Guy Wilkinson (University of Oxford)

8th December 2007 CLEO physics fest 2

Outline

The ADS technique to measure γ Using D→Kπππ: introducing the coherence factor

Measuring the coherence factor at CLEOc Status of the D→Kπππ coherence factor

analysis 700 pb-1 results New CP tags

First steps with D→Kππ0 coherence analysis Conclusion and plans

8th December 2007 CLEO physics fest 3

B→DK decays involve b→c and b→u transitions

Access via interference if D0 and D0 decay to the same final state

These measurements are theoretically clean No penguin CKM standard candle largest correction is sub-degree from D-mixing

Number of strategies to study such decays

cbV

*usV

ubV

*csV

BAKDBA )( 0 )(0)( i

BB erAKDBA

Introduction B±→DK±

Ratio of absoluteamplitudes of

colour/CKM suppressed to favoured (~0.1)

Strong phasedifference

8th December 2007 CLEO physics fest 4

Look at DCS and CF decays of D to obtain rates that have enhanced interference terms

Unknowns : rB~0.1, B, DK, , NK, Nhh (rD=0.06 well measured)

With knowledge of the relevant efficiencies and BRs, the normalisation constants (NK, Nhh) can be related to one another

Important constraint from CLEOc σ(cos DK

Overconstrained: 6 observables and 5 unknowns

)cos(21))((

)cos(21))((

)cos(2)())((

),cos(2)(1))((

),cos(2)())((

),cos(2)(1))((

2

2

22

2

22

2

BBBD

BBBD

KDB

KDB

KDBD

KDB

KDB

KDBD

KDB

KDB

KDBD

KDB

KDB

KDBD

rrKhhB

rrKhhB

rrrrKKB

rrrrKKB

rrrrKKB

rrrrKKB

ADS method

h=π or K

8th December 2007 CLEO physics fest 5

Four-body ADS B→D(K πππ)K can also be used for ADS style analysis However, need to account for the resonant substructure in

D→Kπππ made up of D→K*ρ, K−a1(1260)+

,.,…

in principle each point in the phase space has a different strong phase associated with it - 3 and 4 body Dalitz plot analyses exploit this very fact to extract γ from amplitude fits

Atwood and Soni (hep-ph/0304085) show how to modify the usual ADS equations for this case Introduce coherence parameter RK3π which dilutes interference

term sensitive to γ

RK3π ranges from 1=coherent (dominated by a single mode) to 0=incoherent (several significant components)

Can slice and dice phase space to find most coherent regions

)cos(2)())(( 33

3232

KDBK

KDB

KDBD RrrrrKKB

ssss

sss s

dAdA

deAAeR

i

iK

KD

22

)(

3

)()(

)()(3

8th December 2007 CLEO physics fest 6

Measurements of the rate of K3π versus different tags at CLEO-c allows direct access to RK3π and δK3π

1. Normalisation from CF K−π+π+π− vs. K+π−π−π+ and K−π+π+π− vs. K+π−

2. CP eigenstates:

3. K−π+π+π− vs. K−π+π+π−:

4. K−π+π+π− vs. K−π+:

Determining the coherence factor

3

3323

3 cos21):3( KDK

KD

KDCP

CFK RrrCPK

233 3

1)3:3(

KRKK DCS

KCFK

32

33 cos21):3(3

33 KDr

r

r

rDCSK

CFK K

KD

KD

KD

KD RKK

0~ Assume KDδ

8th December 2007 CLEO physics fest 7

Jingoistic selection Analyzed data sets 31-33, 35-37 and 43-45

~700 pb-1

Standard selection based on ΔE and mbc

Ks veto to remove dominant sands peaking background

‘Flat’ background from sidebands Peaking from generic MC Efficiencies from dedicated signal

MC Details in Andrew’s Sept.

PTA talk

A

BD

D C

S

AllTruth-matched

8th December 2007 CLEO physics fest 8

Yields and efficienciesMode

Vs K-3

S Comb.Bkg

Peaking bkg

Yield Efficiency

(Opp Sign)

3340 75.9 ± 6.9 10.8 3253 ± 58 (20.4±0.1)%

(Same Sign)

28 1.8 ± 1.1 3.0 23.2 ± 5.2 (20.4±0.1)%

KK 441 6.8 ± 1.6 4.4 430 ± 21 (24.1±0.7)%

199 3.5 ± 1.4 1.7 194 ± 14 (32.1±1.3)%

Ks0 597 5.5 ± 1.8 4.2 587 ± 24(12.4±0.7)%

(includes π0 eff corr)

(Opp Sign)

4330 25.3 ± 3.9 13.0 4292 ± 66 (28.9±0.1)%

(Same Sign)

32 0 ± 0 1.7 30.3 ± 5.7 (28.9±0.1)%

8th December 2007 CLEO physics fest 9

Coherence factor extraction

To extract coherence factor and strong phase from these double-tag yields requires branching fractions All BF from PDG’07 except Ks0

Ks0 from recent CLEO-c pub arXiv:0711.1463v1 [hep-ex] efficiency systematic uncertainties cancels

Systematic uncertainties dominated by knowledge of branching fractions except for K+π− where the Kassumption dominates

8th December 2007 CLEO physics fest 10

Coherence factor: preliminary results

Tag mode RK3πcosK3π±σstat ±σsyst Weight in average

KK −1.01±0.51±0.45 0.15

−0.53±0.70±0.42 0.09

Ks0 −0.70±0.36±0.50 0.26

−0.06±0.16±0.31 0.50

Combination −0.41±0.14±0.20 χ2/ndf=1.1

3at 83.0 and 1at 41.0

likesign 3 from 09.025.010.0

33

23

KK

K

RR

KR

8th December 2007 CLEO physics fest 11

Coherence factor: preliminary results

K3π

RK3π

1σ bounds

Will benefit from more modes

First selection results today with additional KS

modes

For the future KL modes

RK3πcosK3πAllowed K3π

likesign

Preliminary

8th December 2007 CLEO physics fest 12

Additional CP tags Looked into 5 other CP tags:

KS(+-0) KS00

KS(K+K-) KS’()

KS() and KS(+-0)

Mass fit applied to →+−0 and ’ → Backgrounds as for earlier modes Signal efficiencies not calculated yet for all

modes

8th December 2007 CLEO physics fest 13

KS(+-0)DATA

DATA

MC

MC

8th December 2007 CLEO physics fest 14

KS()

DATA

DATA

MC

MC

8th December 2007 CLEO physics fest 15

New CP tagsMode

Vs K-3

S Comb.Bkg

Peaking bkg

Yield Efficiency

S 215 2.3 ± 1.3 7.1 206 ± 15 ?

S00 238 12.2 ± 3.1 3.8 222 ± 15?

KS 50 0 0.6 49 ± 7 6.1%

S 25 0 0.6 24 ± 5 ?

Sγγ) 114 3.4 ± 1.2 4.5 106 ±11 ?

S+−0) 35 1.0± 0.7 0 34 ± 6 ?

50% increase in the number of CP tags

8th December 2007 CLEO physics fest 16

Kππ0 selection Another ADS mode but multiple intermediate

states so need to calculate coherence factor Generated, reconstructed and D-skimmed

samples of 50k Kππ0 vs {Kππ0, Kπ,ππ,KK, KSπ0} Determine efficiencies for these channels:

ΔE selection 3σ with single tag resolutions taken from DTag CBX

Require π0 daughters satisfy standard ECAL shower shape cuts for single photons

8th December 2007 CLEO physics fest 17

Efficiencies and expected yieldsTag MC Efficiency Expected yields

from 800 pb-1

Kππ0 (13.1±0.2)% 4.4k

Kπ (23.2±0.2)% 7k

KK (20.6±0.2)% 800

ππ (25.4±0.2)% 300

KSπ0 (10.6±0.1)% 900

Efficiencies are a couple of % higher than in Dhad BF analysis – no corrections

8th December 2007 CLEO physics fest 18

Conclusion and plans Analyzed majority of the ψ data and evaluated coherence factor and

strong phase difference 50% more CP tags to be added KLX to be added

Kππ0 coherence started Predicted yields indicate slightly better sensitivity than K3π Add other modes already studied for K3π

Aim to publish first measurements of these parameters globally (no division of phase space to find the coherent regions) asap CBX and request committee early in ’08 Full data-set

Later longer paper with binned analysis and KSππ tags (Nov PTA) Binned analysis will be guided by full amplitude analysis (next talk)

Other modes of interest for γ measurements D→K0

SK+K− and D→K0SK+π−

D→K−K+π+π− and D→K0Sπ− π+ π0