Hadronic Charm Decays

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Hadronic Charm Decays Do-Do Mixing

• Sheldon Stone,
• Syracuse University

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What We Hope to Learn

• Charm Mixing CP Violation
• Can we see new physics? SM mixing CP violation
  is small, so new effects dont have large SM
  background as in the K or B systems
• Hadronic Charm Decays
• Engineering numbers useful for other studies
• B?Charm is dominant, so knowing lots about charm
  is useful, e.g. absolute Bs, resonant
  substructure, phases on Dalitz plots, etc
• Learn about Strong Interactions, esp. final state
  interactions

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Absolute Charm Meson Branching Ratios Other
Hadronic Decays

• Do, D DS

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Experimental methods

• DD production at threshold used by Mark III,
  and more recently by CLEO-c and BES-II.
• Unique event properties
• Only DD not DDx produced
• Large cross sections
• s(DoDo) 3.72?0.09 nb s(DD-)
  2.82?0.09 nb
• s(DSDS) 1 nb
• Ease of B measurements using "double tags
• BA of A/ of D's

World Ave
Continuum 14.5 nb
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D?K-pp at the y (CLEO-c)

• Single tags
  Double tags

D?K-pp D-?Kp-p- 2002 events
D?K-pp or D-?Kp-p-, 80,865 events
281 pb-1 of data at y(3770)
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Absolute B Results for D Do 57 pb-1

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CLEO DS Results at 4170 MeV

• Since ee-?DSDS, the DS from the DS will be
  smeared in beam-constrained mass.
• ?cut on MBC plot invariant mass (equivalent to
  a p cut)

Signal MC
MBC
MBC from DS
Preliminary
KsK
h?p
697?35
271?21
Inv Mass (GeV)
Inv Mass (GeV)
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Ds ? K-Kp from CLEO-c (72 pb-1)

Ds ? f p
Ds ? K-Kp
20 MeV cut around f mass
1197?36
3057?78
Preliminary
Ds ? K K
Ds ? f0(980) p
1262?47
111?12
Inv Mass (GeV)
Inv Mass (GeV)
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Ds ? K-Kp from
From Sandra Malvezzi CIPANP 2000 AIP Conference
Proceedings -- December 12, 2000 -- Volume 549,
Issue 1, p. 569
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Single Double DS Tags in 76 pb-1

• Modes
• Different
• selection criteria
• than other analyses
• Clean double
• tag signal

Invariant mass2 (GeV)
Invariant mass1 (GeV)
Dmmass1-mass2
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Absolute B Results for DS 76 pb-1

• About 11 error
• Results are preliminary more modes are being
  added more data is being taken
• What about DS??? ?

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The Effective B(DS???)

• CLEO does not quote it. Because of the presence
  of f0p other interferences on the Dalitz plot,
  the B you get depends on your mass resolution
  your mass cut
• I, however, will make an estimate based on CLEOs
  mass resolution since many experiments have
  similar resolution. (Note that the observed f
  line shape is a convoluted BW Gaussian)
• Using a 10 MeV KK- mass cut about the f mass
  (91 efficient on the f), I find from the
  observed ratio of fp/KKp events
  Beff(DS???)(3.490.39). For 20 MeV cut (97
  efficient) (3.730.42), which gives a scale of
  the mass cut sensitivity

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Previous Measurements of Beff(DS???)

• Compare fully and partially reconstructed
  B?DDS(J) decays
• CLEO Beff(DS???)(3.60.80.5)
• BaBar Beff(DS???)(4.80.50.4)
• BaBar Beff(DS???)(4.80.40.5) (Marsiskes
  talk)
• BES Beff(DS???)
• Compare with my estimate
  Beff(DS???)(3.50.4).
• Upper limit based on counting all known modes
  lt4.8 _at_ 90 c.l ?5.2 based on current data
  (Muheim Stone Phys. Rev. D 49, 3767 (1994)).
  They also predicted B(DS???)(3.60.6)

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Inclusive ss Mesons from D decays

• Done using double tag events
• f h? rates are much higher for DS, useful for
  hadron collider b experiments

Preliminary
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Can be used to check Beff(DS???)
B(DS?fX)
B(DS?fp)
X fppo fpp- po f?n

fp
?(4.20.5) B(DS?fp)

• Procedure take all modes containing f, ?? ?
  all measured wrt to fp (bands are 1s). If new
  modes are found the slope of the bands would
  increase
• CLEOc measurements are horizontal lines, also at
  1s)
• Consistent with a 3.5 fp effective branching
  ratio
• If more modes are found slope would increase,
  implying a lower fp branching ratio

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The Real B(DS???)

• You can use a Dalitz plot fit (i.e. FOCUS) to get
  the fraction of fp. This is not the same
  procedure that was done in the past of merely
  cutting on the KK- invariant mass about the f.
• The FOCUS Dalitz plot analysis has the ??
  fraction of KK-p 0.450.01
• Dividing the CLEO number for B(DS? KK-p) by
  B(??KK-).491, gives B(DS???)(4.160.41)
• This is the branching ratio that is most
  appropriate to compare with theoretical
  calculations

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Cabibbo Suppressed Decays
CLEO-c Mode
Branching Ratio x 10-3
PDG

• BaBar
• D?Kp0
  0.2460.0460.0240.016
• D?pp0
  1.220.100.080.08 1.330.22

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Searches for New Physics in Charm Decays
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Do-Do Mixing

• Mixing could proceed via
• the presence of d-type quarks in the loop makes
  the SM expectations for Do- Do mixing small
  compared with systems involving u-type quarks in
  the box diagram because these loops include 1
  dominant super-heavy quark (t) Ko (50), Bo
  (20) Bs (50)
• New physics in loops implies x
  ?DM/Ggtgt y ?DG /2G but long range effects
  complicate predictions

Do
Do

• From H. Nelson, updated by
• A.A. Petrov hep-ph/0311371

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Do- Do mixing Wrong-sign K-p

• Complicated by interference between DCSD mixing
  strong phase d - will be measured by CLEOc
• Complicated by CP violation

Stolen from Ligeti
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Other Studies

• CDF WS/RS in Kp is (4.050.210.12)x10-3 (350
  pb-1)
• Direct measurements of C and C- D0 lifetime
  differences (yCP)
• WS rate in semileptonic decays measures (x2y2)/2
  directly

Average 0.920.43
PDG 2006 D. Asner
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Dalitz Plot Analyses D0? KSpp-

• CLEO D0? KSpp- full time dependent analysis,
• compared with Belle
• semileptonic analysis
• Essential feature distinct time-dependence of
  DCP, DCP- (CP?1, CP-?1)
• D1(t)exp(-i(m1iG1/2)t)
• D2(t)exp(-i(m2iG2/2)t)

PDG-2006 D. Asner

• Limits are (-4.5ltxlt9.3) (-6.4ltylt3.6) , _at_ 95
  C.L., without assumptions regarding CP-violating
  parameters.

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D0? Kp-po
Cabibbo favored
Wrong-sign

• BaBar Uses Dalitz plot to enhance Cabibbo
  favored rate since it proceeds largely via K-r,
  while wrong-sign rate goes to Kp- Kopo
• For CP conserving fit
• RMlt0.54x10-3 _at_ 95 cl
• RM is consistent with no mixing at 4.5 cl

RD ()
RM ()
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CP/T Violation

• Unexpectedly large CP violation asymmetries may
  be a better signature for new physics
  (0.01-0.001)
• CP violation can be studied in a variety of ways
• Direct CP violation
• CP violation in mixing
• T violation in 4-body decays of D0/D (assuming
  CPT) and studying triple product correlations
• Exploiting quantum coherence of DD produced in
  y(3770) decays (Dave Cinabros talk)

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CP/T Violation some recent data
9 -7
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Conclusions on Absolute Bs

• D meson absolute B scale now becoming well known
  
• B(D?K-pp) (9.43?0.31) CLEOcPDG
• error 3.3? 2.1 (in a few weeks)
• B(Do ?K-p) (3.85?0.07) CLEOcPDG
• error 1.9? 1.4 (in a few weeks)
• B(DS?K- Kp) CLEOc
• error 11 ? 4-6 (this summer)
• Beff(DS???)(3.490.39) SS
• Best to change base branching ratio for DS from
  fp to something else. Suggest KK-p, or KSK
• Already quite useful of charm particles/B
  decay 1.090.04 (includes Do, D, DS, Lc, Xc, 2x
  charmonium)

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Conclusions II

• Many more Cabibbo suppressed DCS modes found.
  Large phase shifts in D???
• No definitive evidence yet for charm mixing
• Best limits are y?lt2.5 x?2lt7.2x10-3 _at_ 95
  cl
• Hints from Belle in wrong sign K-p decays
• (only 3.9 cl for no mixing)
• Hints from BaBar in wrong sign Kp-po decays
  (only 4.5 cl for no mixing)
• No observations of CP Violation

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The End
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D?K-pp at the y (CLEO-c)

• Single tags
  Double Tags

D?K-pp D-?Kp-p- 377 events
D?K-pp or D-?Kp-p-, 15,120 events
57 pb-1 of data at y(3770), CLEO now has 281 pb-1