Cabibbo-Allowed and Doubly-Cabibbo Suppressed D?Kp Decays

1
Cabibbo-Allowed and Doubly-Cabibbo Suppressed
D?Kp Decays

• Steven BluskSyracuse Universityon behalf of the
  CLEO Collaboration
• XXXIII International Conference on High Energy
  PhysicsJuly 26 August 2, 2006, Moscow, Russia

Other CLEO-c charm talks Leptonic Charm decays
Sheldon Stone, 10-2 Semileptonic Charm decays
Yongsheng Gao, Session 10-3 Charm Hadronic
Decays S. Blusk, Session 10-2 Y(4260) at
CLEO Ian Shipsey, Session 9-3 Charmonium
decays at CLEO Tomasz Skwarnicki, Session 9-4
2
Introduction

• D?Kp decay plays a special role in CLEO
• Large BF, high efficiency, lt1 background
• Many reasons to study this mode
• D0?K-p normalization for most D0 BFs and hence
  many B decays
• ADS method for extracting g needs strong phase
  shift between CF D0?K-p and DCSD D0?Kp-
• Can be measured using quantum coherence of
  y(3770)?DD decay
• Limits on mixing
• But other Kp modes are also of interest, such as
• KLp0 , KSp0
• KLp , KSp
• Kp0 (DCSD)

Understand/test strong dynamics of D decays,
phases
3
Cleo-c Overview

• Pure DD final state, no additional particles (ED
  Ebeam).
• Low particle multiplicity
• 5-6 charged particles/event
• Excellent coverage ? infer reconstruct n in
  (semi)leptonic decays
• Pure JPC 1- - initial state
• Quantum correlations

CLEO Analysis - 101
Untagged Analysis
Tagged Analysis

• Reconstruct one D (tag) Single tags
• In D-tagged events, count yield of events
  in a particular signal decay mode Double tags
• Absolute BFs can be computed, independent of s,
  L
• Neednt fully reconstruct Dsig. If 1 particle is
  missing from decay, missing mass (MM) is the
  signal.
• Used extensively for analyses involving ns !

e.g. For Dsig?pX
Neglect mixing ?10-3
4
Quantum Coherence in y(3770)?D0D0
K-p Kp-
Kp- K-p
K-p K-p
K-p Kl -n
CP Kl -n
CP- Kl -n
K-l n Kl -n
CP CP-
CP CP
CP- CP-
Interference btw CF DCSD

• Diagonalization gives the masses (M1 M2) and
  widths (G1 G2) of the weakly decaying
  eigenstates.
• Convenient to define normalized differences

forbidden by Bose symmetry
unchanged
Mixing
No Mixing
maximal constructive interference
CF/DCSD Interfere
forbidden by CP conservation
5
Expected and Some Observed rates (C -1)
Double Tag Rates in units of BiBj
f l CP CP-
f Rm
f 1r2(2-(2cos?)2)
l - 1 1
CP 1r (2cos?) 1 0
CP- 1-r (2cos?) 1 2 0
X 1 ry (2cos?) 1 1-y 1y
States (non-CP) accessible to both D0 and D0.
-
Fit for BFs, Rm, y, r2 and 2rcos(d)
Leptonic
No QC Data K-K ?-? Ks?0?0 Ks?0
K-K 5.20.4 -2.21.9 4.50.3 0.10.9 5.70.4 1.61.3 16.00.6 39.66.3
?-? 1.10.2 0.21.4 2.20.2 1.61.3 5.80.4 14.03.7
Ks?0?0 1.20.2 1.01.0 7.30.4 19.04.4
Ks?0 9.70.5 3.01.7
CP
CP-
MaximalInterference
C P
CP-
6
Results, based on 281 pb-1
Parameter CLEO-c TQCA PDG or CLEO-c
y -0.0570.066 0.0080.005
r2 -0.0280.069 (3.740.18)X10-3
r (2cos?D?K? ) 0.1300.082
RM (1.741.47)x10-3 lt 1x10-3
B(D?K?) (3.800.029) (3.910.12)
B(D?KK-) (0.3570.029) (0.3890.012)
B(D???-) (0.1250.011) (0.1380.005)
B(D?Ks?0?0) (0.9320.087) (0.890.41)
B(D?Ks?0) (1.270.09) (1.550.12)
B(D0?Xe?) (6.210.42) (6.460.21)
TQCAerrorsare stat.only.

• Fitted r2 unphysical. If constrained to WA,
  cos?Kp 1.08 0.66(stat)
• With 3-4X more data 4170 MeV data, expect
  s(cos?Kp) 0.15

See talk by David Asner, CHARM 2006, also D.
Asner, W. Sun, Phys. Rev. D73, 034024 (2006)
7
D ?Kp
Isospin Decomposition
3 observables, 3 unknowns..
Find A3/2 (¼)A1/2 , dI 900
What can we learn from this ?
8
Analysis Overview
Measure the asymmetry
Plug in
Then
tan2qC

• rKp , dKp , R(D0), R(D) are each functions of
  the Isospin amplitudes and phase

• After some algebra

But, need to measure BF(D?KLp) BF(D0?KLp0) !!
9
D?KLp Analysis Technique
Tagged analysis
Peak at MK02 for D?(Ks,KL)p

• Isolate KL contribution by
• Vetoing extra tracks and p0s
• Correct for Ks leak-through (small) loss
  of KL signal from veto (small)

D?KLp
D0?KLp0

• Because of D0-D0 mixing DCSD, what we
  measure in D0 decays are
• ST BF(D0?KL,Sp0) (1y)
• DT BF(D0?KL,Sp0) (12rf cosdrf2)
• Measure B(D0?KS,p0) in both ST and DT
• Since ylt1, compute 1-2rf cosdr 2 by
  comparing ST and DT BFs
• Correct DT BF(D0?KLp0) using 12rf cosdrf 2
  from Ks analysis and PDG values for rf
• ? Compute R(D0)

• Measure D?KLp using MM method.
• Use CLEO-c BF measurementof D ?KSp (57
  pb-1, to be updated to 281 pb-1 soon )
• ? Compute R(D)

KL KS -
10
D?KLp
K-ppp0
K-pp
Extra trk/p0 Veto(removes most Ks)
No Veto
KSp
KSpp0
KSpp-p
K-Kp
Missing Mass Squared
Missing Mass Squared
Summing over all modes
Single Tags 165,000 after selection on Mbc
Yield Efficency BF ()
KS,Lp 442879 85.20.1 3.0950.056
KLp 202354 81.80.1 1.4560.040
Dominant systematics Signal fit and D?pp-p BG
(KS,Lp only)
11
D0?KS,Lp0

• Single Tag B(D0 ? KS p0)
• Inclusive search, reconstruct Ks?pp- and p0.
• Yield7487, determined from Mbc by DE and
  M(pp-) sideband subtraction
• N(D0) 2.02x106, e29

B(D0 ? KSp0) (1.2120.0160.039)
DD cross-section dominant uncertainty (2.75)
Mbc

• Double Tag B(D0 ? KS p0)
• 3 tag modes, K-p, K-pp0 Kpp-p.
• Reconstruct D0 ? KS p0 - DE and M(pp-)
  sideband subtraction
• Ntag 182,000, Yield 614, e32

K-p tag
K-pp0 tag
K-pp-p tag
Mbc
B(D0 ? KSp0)(1-2rcosdr2) (1.0320.0470.016)

• Double Tag B(D0 ? KLp0)
• Follows KSp0 DT analysis, except use MM2.
• Veto candidates with extra tracks/p0s
• Ntag 182,000, Yield 1115, e55

MM2
B(D0 ? KLp0)(12rcosdr2) (1.0770.0360.023)
12
Corrections to D0?KLp0 for Interference
Strategy Determine 2rcosd from KSp0 ? apply
correction to KLp0
Ksp0 corr. factor
KLp0 corr. factor
B(D0 ? KLp0) (0.9400.0460.032)
Significanteffect here !
B(D0 ? KSp0) (1.2120.0160.039)
13
D?KL,Sp Results
Preliminary
rKp 0.003630.00038 (PDG04)
R(D)
dKp ( 3 6 7)o
Strong phase between CF andDCS D0?Kp is close to
0

• Assumptions
• Zero phase between B1/2 and C1/2
• Zero phase between A1/2 and B1/2

? (R(D0),R(D)) measurement
Systematics associated with these assumptions
are being studied
R(D0)
14
D ?Kp0

• Very few DCSD measurement in D decays
• Provide a useful handle on understanding strong
  dynamics and tests of SU(3) symmetry
• Recent BaBar measurement
• 124 fb-1 at/just below Y(4S)
• 124M cc events, e6
• B(D?Kp0) (2.460.460.240.16)x10-4
• CLEO-c excels in reconstructing decayssuch as
  these.
• 0.8 M DD- events, e45

BaBar
15
D ?Kp0

• Reconstruct K using RICH (some dE/dx), p0?gg.
• Require -40ltEcand-Ebeamlt35 MeV ? Fit Mbc spectrum

Yield 14823 e 44.5
B(D ? Kp0) (2.25 0.36 0.15 0.07) x 10-4
16
More on Isospin Amplitudes
Using Isospin Amplitudes
(Small)
Taking a2 small
Using measured B(D?Kp0), R(D),R(D0)
b 0 or b 1
So, either
C1/2 ltlt B1/2
C1/2 gtgt B1/2
Need additional information to distinguish
between the two possibilities
17
Acknowledgements

• Thanks to CLEO collaborators who have made this
  talk possible..
• Ed Thorndike, Dave Asner, Anders Ryd, Werner Sun,
  Steve Stroiney, Qing He, Fan Yang
• Hanna Mahlke-Krueger for coordinating CLEO_at_ICHEP

18
Summary

• Probing mixing and DCSD through time-integrated
  ST and DT BFs. By the end of the CLEO-c program,
  expect
• s(y) 0.012, s(x2)0.0006, s(cos?K?) 0.15, RMlt
  O(10-4)
• s(xsin?K?) 0.024 (Needs C1 initial state from
  DD? DD??0 from 4170 MeV)
• The Kp system is a very nice laboratory to study
  and extract important hadronic parameters.
• Isospin decomposition relating observed rates to
  amplitudes phases
• CLEOs ability to measure D?KLp germaine to
  carrying out these measurements.
• D?KL,Sp asymmetries consistent with rKp from
  BF(D0?K-p)/ BF(D0?Kp)
• Preliminary results indicate ?K? near zero,
  systematic errors from assumptions still being
  investigated.
• Full fit for amplitudes and strong phases in
  progress, expect results soon

Lots of beautiful results still pouring out of
CLEO ! Stay tuned for more