Recent Results on Charm Hadrons from BaBar and Belle

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27/11/07

• Recent Results on Charm Hadrons from BaBar and
  Belle

Ruslan Chistov (ITEP)
? Introduction ? Evidence for D0-D0
mixing ? Measurement of Ds? ??? and fDs ?
Observation of new excited charm baryons
?c(3055/3123)
? Summary
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Recent Results on Charm Mesons
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D0-D0 mixing in the SM
Unlike mixing in K0, B0 and B0s systems, D0
system provides test for neutral meson mixing
with down type quarks in the box.
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• Dalitz plot analysis D0? KS ? -?
  t-dependent analysis
• interference of DCS and mixing
• e.g. D0? K?- CP final states e.g. D0? KS ?0
  (?)

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D0-D0 mixing Status 2006
Wrong sign (WS) hadronic decays K? -, K? -?
0, K? -? -? t-dependent analysis to
disentangle mixing and DCS
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D0-D0 mixingfrom BaBar
points data no-mixing fit curve mixing
fit no mixing fit Fit with mixing is better
match to data!
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D0-D0 mixing from BaBar Results

• x2 and y2 CL contours
• calculated from the change in log likelihood
• include systematic errors

x2 - (0.22?0.30?0.21)x10-3 y
(9.7?4.4?3.1)x10-3
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D0-D0 mixing at Belle ycp

• Measure relative lifetime difference D0? K-?
  and D0? KK- (? ?-)
• mixing parameter
• yCP y cos? - 1/2AMx sin
• CP conservation AM sin? 0 yCP y ??/ ?
• Search for CPV by measuring
• A? 1/2AMy cos? - x sin?

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D0-D0 mixing at Belle ycp results
Visual demonstration of non-zero y
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D0-D0 mixing at BelleDalitz analysis D0?
K0S ?-?
Study self-conjugate decay
D0? K0S ?-? t-dependence of Dalitz
plot distribution provide
direct access to x and y!!!
Strong phase difference between CF and DCS
amplitudes fixed by Dalitz fit!
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Belle results on Dalitz analysis D0? K0S
?-?
disfavor no-mixing xy0 point with significance
2.2 ?
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D0-D0 mixing measurements average
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Measurement of Ds? ??? and fDsat Belle
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Reconstruction of Ds? ???
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Measurement of Ds? ??? and fDsat Belle
(results)
!
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Recent Results on Charm Baryons
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Observation of new excited charm strange baryons
at Belle
?cK-p
?c(3080) NEW
hep-ex/0607042
?cK-p
?c(2980) NEW
?c(3080)
BaBar confirmed
?c(2980)
PRL97,162001
?cKsp-
?c(3080)0 NEW
New decay mechanism s-quark ? meson
Measurements of M and G are consistent
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Observation of ?c(3055) and Evidence for
?c(3123) at BaBar
?c(3080)
?c(3055) NEW
?c(2980)
Sc(2455)K-??cK-p
?c(3080)
Sc(2520)K-
For all new ?c ?
?c(3123) evidence
Mass ? D-wave excitations ? ?c(2980) 1/2,
3/2,.. ?c(3080) 5/2,..
hep-ex/... (preliminary)
More experimental studies to assign JP.
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Discussion of New ?cx States
Observed Properties Charm and
strange quarks in the final state (?c and
K-) These new charm baryons have
large masses (largest in grand family of
charm baryons), finite
widths Neutral partners also observed
not double charm baryons Most
natural interpretation excited charm strange
baryons which could be D-wave excitations.
Possible JP are 1/2(or 3/2) and 5/2
(H.-Y.Cheng, C.-K.Chua, hep-ph/0610283
J.L.Rosner, hep-ph/0612332) Note ? Not seen
in M(?cK-) and M(?cK-??-) spectra!
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Observation of ?cx(2980)/0 ? ?c0/?/- at
Belle
Search for another, natural channel for the new
states ?cx
M(?c(2645)0p)
M(?c(2645)p-)
?c(2815)0
?c(2815)
?cx(2970)0
Preliminary
?cx(2970)
No ?cx(3080)0
??
No ?cx(3080)
??
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Observation of ?c(2940) and ?c(2880)?D0p
BaBar
Belle
?c(2880)
?c(2880)
?c(2940)
?c(2940)
M(Sc(2455)0,p)
New decay mechanism of excited ?c !
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Study of B??c?c-K by BaBar(preliminary)
Originally, B??c?c-K decay has been observed
by Belle
PRL97,202003 (2006)
BaBar confirmation, resonant structure.
?cK-
?c ?c- K-
NEW
B meson signal
phase-space
sidebands
mbc (GeV/c2)
Excited ?c?
not seen in continuum
BaBar ? More data are needed before firm
conclusions can be drawn.
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Summary on New Charm Baryons
New charm baryons with new decay mechanism were
discovered by BaBar and Belle
?cK? threshold
D0p threshold
?c(2880) ? ?c? and D0p (!), ?c(2940) ? mostly
to D0p,
(?c?suppressed) ?cx(2980) ? ?c? and ?cK?
(?cK), ?cx(3080) ? only to ?cK? (?c()K),
(no signal for ?c?)
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Summary

• This year D0-D0 mixing results
• New D0?K?- study at BaBar 3.9? of (x,y)
  ?(0,0)
• (past
  year at Belle 2.1? of (x,y) ?(0,0)
• New Dalitz analysis D0? K0S ?-? at Belle 2.7?
  of (x,y) ?(0,0)
• New yCP measurement at Belle 3.2? of y ?0 (past
  year at BaBar 1.9? of y ?0)
• ? Combination of existing D0-D0 mixing results
  established at 5s
• ? New measurement of fDs fromBelle in good
  agreement with previous results and LQCD
• ? A lot of new charm baryons observed
• waiting interpretation from
  theory

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Back up slides
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KEKB asymmetric-energy ee- collider and Belle
detector
ee- Y(4S) ll, cc, qq Not only EWP and
CP!
gt 1 fb-1/day
gt 730 fb-1
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Angular analysis of Ds1(2536)?DK0s at Belle
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Angular analysis of Ds1(2536)?DK0s at Belle
(contd)
RESULT
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Observation of new excited charm strange baryon
at Belle and BaBar
PRL97,162001
?cK-p
?c(3080) NEW
?c(2980) NEW
New decay mechanisms-quark ? meson.
?cK-p
hep-ex/0607042
?c(3080)
BaBar confirmed
?cKsp-
?c(2980)
?c(3080)0 NEW
BaBar confirmed also ?c(3080)0
Measurements of M and G are consistent
Mass ? D-wave excitations ? ?c(2980) 1/2,
3/2,.. ?c(3080) 5/2,..
Rosner Chen, Chua, PRD75, 094017 Garcilazo,
Vijande, Valcarce, JPG34, 961 Chen, Chen, Liu,
Deng, Zhu, PRD75, 094017 Ebert
More experimental studies to assign JP.
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Observation of ?c(2980) and ?c(3080) by Belle
PRL97,162001
hep-ex/0607042
?cK-p
?cK-p
?c(3080) NEW
?c(3080)
BaBar confirmed
?c(2980) NEW
?c(2980)
New decay mechanisms-quark ? meson.
resonant structure
?cKsp-
?c(3080)0 NEW
BaBar confirmed also ?c(3080)0
Measurements of M and G are consistent
Mass ? D-wave excitations ? ?c(2980) 1/2,
3/2,.. ?c(3080) 5/2,..
Rosner Chen, Chua, PRD75, 094017 Garcilazo,
Vijande, Valcarce, JPG34, 961 Chen, Chen, Liu,
Deng, Zhu, PRD75, 094017 Ebert
More experimental studies to assign JP.
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