FPCP-2002 Talk

1
CP Violation in D Meson Decays Mats
Selen, University of Illinois2002 FPCP Meeting,
University of Pennsylvania

• Expectation
• Experiments
• Rate Asymmetries
• Other Approaches
• Outlook

2
Indirect CPV
G( ) ? G( )
Very small in charm since mixing is
suppressed(i.e. good hunting ground for new
physics)
Direct CPV
G( ) ? G( )
3
Direct CPV
1) Consider D0 ? pp- (same for KK-, KK-p,
KK-p0, fp, pp-p, pp-p0, etc...)
u
c
d
4
Direct CPV
1) Consider D0 ? pp- (same for KK-, KK-p,
KK-p0, fp, pp-p, pp-p0, etc...)
we can modify itstopology in a simpleway to
get a penguin
5
We have the ingredients
differentweakphases
Expect ACP lt 10-3in most cases
6
2) Consider D ? KSp (also KSr, KSa1, K0p,
KSp0Kp, KSp0, DS?KSK-, KSp0KK-, etc...)
CabibboFavoredDecay
d
W
DoublyCabibboSuppressedDecay
c
u
7
CFD
DCSD
Lipkin Xing
8
CFD
DCSD
Lipkin Xing
From CPV in K0 system 3x10-3
1
hopefully big(measurablein principle)
10-3in SM(from data)
New physics couldmake this much bigger
9
3x10-3 new physics
So what?

• D ? KSp, KSr, KSa1
• D0 ? KSp0, KSpp-
• Should be able to see dK induced CPV with
  107-108 reconstructed D events.
• - This is in the ballpark for CLEO-c/Belle/BaBar
• New physics could make this asymmetry much
  bigger by increasing weak (and strong) phase
  differences.
• - If seen, this can be studied using a suite of
  decays involving KL and KS in final state.

not suppressed (big BR)
See Lipkin Xing, Phys. Lett B450 (1999)
Bigi Yamamoto, Phys. Lett B349 (1995)
10
The usual suspects
CLEO
11
Comments

• Since D and D- (and similarly D0 and D0) are not
  produced in equal numbers in FOCUS and E791,
  these experiments normalize all asymmetries to
  some known Cabibbo favored mode.
• ee- experiments need to worry about, A- , AFB

12
D Decays

• These modes are self-tagging (no D needed).
• E791
• D ? KK-p, fp ,K(892)0p, pp-p
• FOCUS
• D ? KK-p, KSK, KSp

13
D-?KK-p-
D?K-Kp
7355 112
6860 110
D-?Kp-p-
D?K-pp
73710 292
68607 282
14
D-?KSK-
D?KSK
D?KSp
D-?KSp-
454 42
495 38
5080 110
5518 110
15
D?K-pp
D-?Kp-p-
E791
23465 183
28014 201
D-?KK-p-
D-?fp-
D?K-Kp
D?fp
474 25
598 28
1265 48
1031 44
16
E791
D-?KK-p-
D?KKp
D-?pp-p-
D?p-pp
697 42
851 48
239 18
291 19
17
D ACPSummary
FOCUS
E791
fp
K-Kp
KSp
KSK(Kpp)
pp-p
KK
KSK(KSp)
K-Kp
K-Kp 0.6 1.1 0.5
KSp -1.6 1.5 0.9
KSK (K-pp) 6.9 6.0 1.5
KSK (KSp) 7.1 6.1 1.2
K-Kp -1.4 2.9
fp- -2.8 3.6
K(892)K- -1.0 5.0
pp-p -1.7 4.2
All analyses statistics limited. None are
background free.
18
D0 Decays

• Use D decays to tag D0 flavor
• E791
• D0 ? KK-, pp-, K-pp-p
• FOCUS
• D0 ? KK-, pp-
• CLEO
• D0 ? KK-, pp-, KSp0, KSKS, p0p0

19
607587
719895
E791
27620
33321
19418
14917
20
19633149
18501144
162347
170753
60631
57133
21
CLEO
246365
9099151
93037
22
CLEO
81089
6514
23
D0 ACPSummary
CLEO
FOCUS
E791
pp-
KK-
KSp0
KSKS
pp-
KK-
p0p0
pp-
KK-
KK- 0.0 2.2 0.8
pp- 1.9 3.2 0.8
KSp0 0.1 1.3
p0p0 0.1 4.8
KS KS -23 19
KK- -0.1 2.2 1.5
pp- 4.8 3.9 2.5
KK- -1.0 4.9 1.2
pp- -4.9 7.8 2.5
All analyses statistics limited. None are
background free.
24
Other Promising Approaches

• Look for CPV in Dalitz Plots
• Analyze D and D samples separately
• Any differences in amplitudes phases is an
  indication of CPV.
• Work under way by several groups.
• Examples from CLEO
• D0 ? K-pp0 (Published last year).
• D0 ? KS pp- (Preliminary results).
• D0 ? p-pp0 (soon)
• D0 ? KSp0p0 (soon).

25
CLEO
D0?K-pp0
26
CLEO
Resonance Fit Fraction Phase
1 r (770) 0.788 ? 0.023 0 (fixed)
2 K(892)- 0.161 ? 0.010 163 ? 4
3 K(892)0 0.127 ? 0.010 0 ? 4
4 r (1700) 0.057 ? 0.011 171 ? 7
5 K 0(1430)0 0.041 ? 0.009 166 ? 7
6 K 0(1430)- 0.033 ? 0.009 56 ? 7
7 K(1680)- 0.013 ? 0.004 103 ? 11
8 Non-res 0.075 ? 0.011 31 ? 7
(Show Movie)
We are sensitive to the amplitude and phase of
something with BR 10-3.
27
CLEO
Find ACP 0.031 ? 0.086
(Not an optimized ACP analysis)
28
CLEO
D0?KSpp-
Fit D0 and D0 samples separately
Almost nobackground
writing
with
PRELIMINARY
29
Outlook (is interesting)

• E791 and FOCUS
• Working on ACP analyses (for example Dalitz
  plots).
• CLEO-c
• Still working on analyses using CLEO-II, II.V and
  III data.
• CLEO-c will turn on in about a year.
• 30 million DD events (and new ACP search modes).
• 1.5 million DsDs events
• B Factories
• In the next 5 (?) years Belle and BaBar will
  accumulate 100 times the integrated luminosity
  that CLEO has at the ?(4S).
• Improve on present CLEO limits by at least a
  factor of 10.
• Hadron Machines
• CDF D0 are getting into the game.
• BTeV ( LHC-b ?) could have 109 reconstructed
  charm events.
• COMPASS ? Others ?
• BES

E791 K-pp
CLEO p-pp0
30
Extra Slides
31
CPV through quantum coherence at CLEO-c
ee- ? ? ? D0D0
JPC 1--
i.e. CP
Suppose both D0s decay to CP eigestates f1 and
f2 These can NOT have the same CP
Sensitivity to this will be at the 1 level
32
CLEO
D0?K-pp0 ACP Fits
33

• E791 references
• Phys. Lett. B403 (1997) 377
• Phys. Lett. B421 (1998) 405
• FOCUS references
• Phys. Lett. B491 (2000) 232
• Phys. Rev. Lett. 88 (2002) 041602
• CLEO references
• Phys. Rev. D63 (2001) 071101
• Phys. Rev. D65 (2002) 092001
• T. J. Bergfeld (Ph.D. Thesis, UIUC)
• Theory references
• Buchella et. al., Phys. Rev. D51 (1995)
• Burdman hep-ph/9407378
• Bigi Yamamoto, Phys. Lett B349 (1995)
• Lipkin Xing, Phys. Lett B450 (1999)