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
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