Sep. 29, 2006 Henry Band - U. of Wisconsin 1 Hadronic Charm Decays From B Factories Henry Band...
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Sep. 29, 2006 Henry Band - U. of Wisconsin 1
Hadronic Charm DecaysFrom B Factories
Henry BandUniversity of Wisconsin
11th International Conference on B Physics
at Hadron MachinesOxford, Sept. 25-29, 2006
Sep. 29, 2006 Henry Band - U. of Wisconsin 2
Talk Outline
Strange charmed mesons• DsJ(2860)+
• DsJ(2700)+
• Ds2(2573)+
• Ds1(2536)+
• Ds1(2460)+
• Ds0*(2317)+
• Ds*(2112)+
Abs. Branching Fractions • Ds
+→ K+ K- + • Ds
+→ +
Branching Fractions • D+→+0 • D+→K+0 • D0→ -+0
• D0→ K-K+0
Charm Baryons c(2940)
Λc(2880)+
c*
Ξc(2980)+
Ξc(3077)+
Sep. 29, 2006 Henry Band - U. of Wisconsin
BaBar and Belle
e+e-cc • continuum 1.3 nb • Off and on peak (4S)• 30% more cc than bb
bc• Cabbibo favored
Peak luminosity 1.211034 cm–
2s–1
Integrated luminosity 390 fb–1
Peak luminosity 1.651034 cm–
2s–1
Integrated luminosity 630 fb–1
Sep.
ab-1 integrated flux combined
B FactoriesC
Sep. 29, 2006 Henry Band - U. of Wisconsin 4
Ds family mesons
Observation by BaBar, Cleo, and Belle of Dsj(2317) and
Dsj(2460) at lower masses than expected by HQS theories
raised questions about cs meson spectroscopy
Ds mesons or exotics (4 quarks)?
Gather more info
• Masses
• Width
• Decay modes
• Branching fractions
• Other decay modes
• New states
DsJ*(2317)
DsJ(2460)
Ds
Ds*
Ds1(2536)
Ds2(2573)
Sep. 29, 2006 Henry Band - U. of Wisconsin 5
Spin Analysis
DsJ*(2317)
DsJ(2460)
Ds
Ds*
Ds1(2536)
Ds2(2573)
J = 0: 2/d.o.f = 3/8J = 1: 2/d.o.f = 38/8
JP = 0+
DsJ(2317)→Dsπ0
Belle-CONF-0461 (2004)
274M BB
J = 1: 2/d.o.f = 4/8J = 2: 2/d.o.f = 89/8
JP = 1+
DsJ(2460)→Ds γ
B decays
Sep. 29, 2006 Henry Band - U. of Wisconsin 6
Survey of Decays to DsFinal States
Select Ds→ K+K-+
Require K+K- or• K*(892) K-+
• p*> 2.2 GeV
Combine with , K, , 0
Tighter cuts on p* and kinematics to select intermediate states (Ds
(*), DsJ(2317))
Subtract DsX bkg using Ds mass sidebands
Fit mass spectrum • signal Breit-Wigner resolution
• Combinatorial background • include pdfs for possible reflections from othercs states
No cut
Cuts on intermediate
states
sid
eban
ds si
gnal
~4 105 Ds
+
Hep-ex 0604030
Sep. 29, 2006 Henry Band - U. of Wisconsin 7
DsDs*(2112), Ds1(2460)
Ds - Combine Ds with ‘s > 150 MeV/c
Raise E > 500 MeV/c Fit signal peak + sum
o Bkgdo Ds0
*(2317) Ds+)
o Ds1(2460) Ds*(2112)+)
232 fb-1
Ds1(2460)+Ds+
Ds sidebands
N=920±60
Bkgd. subtracted
Hep-ex 0604030
Ds+
invariant mass (GeV/c2)
Ds+
invariant mass (GeV/c2)
D s *
(2112)+N=
75,000
Sep. 29, 2006 Henry Band - U. of Wisconsin 8
Ds Ds0*(2317)
Ds+
0 invariant mass (GeV/c2)
Combine Ds with 2 ‘s
consistent with Fit Ds
+ 0 mass spectrum to Ds0
*(2317) Ds+
Ds1(2460) Ds+
Ds*(2112) Ds
+
Reflections from Ds
*(2112) Ds+(+)
Ds1(2460) Ds*(2112)+(-)
Combinatorial bkgd
232 fb-1
Ds0*(2317)+
Hep-ex 0604030
N= 26,500
Sep. 29, 2006 Henry Band - U. of Wisconsin 9
Ds DsDsDs1(2460)
Ds 0 Assume Ds1(2460) Ds*(2112)+0
Require 2092< m(Ds MeV/c Fit signal + reflections
Ds 0 0 no signal Ds no signal
232 fb-1
Ds sidebands
Light shade:
Ds*(2112)
reflection
Dark shade:
DsJ*(2317)
reflection
N=560±40
Preliminary
Hep-ex 0604030
Ds 0
Ds1(2460)+
038.0036.0337.0))2460((B
))2460((B0
±±=→→
++
++
ssJ
ssJ
DDDD
Ds+
0 invariant mass (GeV/c2)
Sep. 29, 2006 Henry Band - U. of Wisconsin 10
Ds±, DsDs1(2460)+ Ds1(2536)+
Look for isospin partners• Ds
+-: no signal
• Ds++: no signal
Ds +-: no DsJ
*(2317)
Strong signals Ds1(2460)+
Ds1(2536)+ Ds + -
232 fb-1
Ds1(2536)+
DsJ(2460)+
Hep-ex 0604030
Ds+ -
Ds+ +
008.0013.0077.0))2460((B
))2460((B0
±±=→→
++
−+++
ssJ
ssJ
DDDD
Ds+
+ invariant mass (GeV/c2)
Sep. 29, 2006 Henry Band - U. of Wisconsin 11
D0K+, D+K0s - Ds2(2573)+, DsJ(2860)+, X(2690)+
Look for new states in continuum above DK mass
Cuts on D0(+) and Ks reconstructed masses• a) D0 K-+ (950,000)• b) D0 K-+0 (790,000)• c) D+ K-++ (430,000)
Hep-ex 607082
D+
D0
D0
232 fb-1
Sep. 29, 2006 Henry Band - U. of Wisconsin 12
New States - DsJ(2860)+, X(2690)+ (?)
New resonance at 2.86 GeV/c2 Broad state at 2.69 GeV/c2
Hep-ex 0607082
Combined modes bkgd subtracted
DsJ(2860)+
Ds2(2573)+
invariant mass (GeV/c2)
D0 K-+ D0 K-+ 0 D+ K-++
Sep. 29, 2006 Henry Band - U. of Wisconsin 13
DDsj sj Production in B decaysProduction in B decays
BELLE has observed DDsj sj
production in several modesproduction in several modes BBDDDDsjsj(2317) or DD(2317) or DDsjsj(2460)(2460)
• Established spinsEstablished spins
BBKK--DDsjsj(2317) or K(2317) or K--DDsjsj(2460)(2460) BB++→→DD00DD00KK++
• S = 399 ± 40 S/B ~ 0.3• Dalitz plot and mass projections - different from 3-body phase space
Belle-CONF-0643 (2006)
447M BB
_ _
__
_
+
Sep. 29, 2006 Henry Band - U. of Wisconsin 14
BB++→→DD00DD00KK++
Contributions from several sources
Is DsJ(2700) = X(2690) ?
Belle-CONF-0643 (2006)
447M BB
■B+→D0DsJ(2700) ■B+→ψ(3770)K+ ■B+→ψ(4160)K+ ■B+→D0D0K+NR ■threshold comp
J=0 2/ndf = 185/5J=1 2/ndf = 7/5 J=2 2/ndf = 250/5
JP = 1-
■ ψ(4160) reflection
Spin Analysis
Sep. 29, 2006 Henry Band - U. of Wisconsin 15
D*+K0s - Ds1(2536)+
D*+D0+ • D0 K-+
• D0 K--++
Charged tracks = good mass resolution
Low Q – close to threshold
Hep-ex 0607084
First width measurement !
QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
Sep. 29, 2006 Henry Band - U. of Wisconsin 16
DsJ(2700) m= 2715 ±11 +11 -14 Mev/c2
= 115 ±20 +36 - 32 MeV /c2
Sep. 29, 2006 Henry Band - U. of Wisconsin 17
Branching Fraction Ds+ → K+K-+
Identify two body Ds1Ds* Reconstruct 1 side (Ds1
(2536) or Ds*) Recoil mass is Mrecoil = √((√s-E (Ds1 ))2- p2(Ds1 ))
Measure Ds* peak or Ds1
→ Ds → K+K-+
→ D*0 K+ →
D*+ Ks0
Sep. 29, 2006 Henry Band - U. of Wisconsin 18
Need further BKgd suppression so use cascade decays on both sides (not just tag)
Require additional with Ds1+
tag (Ds*+ → Ds+
Or K with D*s tag
recoil(Ds1) = Mrecoil(Ds1) - Mrecoil(Ds1)
B(Ds+ → K+K-+) = 4.1 ±0.4
±0.4% PDG 2006 5.2 ±0.9%
Branching Fraction Ds+ → K+K-+
D*s tag
Ds1 tag
Belle-CONF-0612 (2006)
Ds*+ → Ds+
Ds*+ → Ds+
recoil(Ds*K) GeV/c
recoil(Ds1) GeV/c
Sep. 29, 2006 Henry Band - U. of Wisconsin 19
BB sample with one B fully reconstructed
Other BD(*)+,0 X• Observe Ds
+ and DsJ(2460) signals in the recoil mass, mX
Abs. BF’s for Ds+ ( +) and
DsJ(2460)
ee--DD**
ee++
BBrecoreco
BBsignalsignal
D*D*
XX
Hep-ex 0605036
Fitting the different modes and combining with previously
measured branching ratios
PDG
Sep. 29, 2006 Henry Band - U. of Wisconsin 20
Branching Fractions - D+→+0, K+0
Improved BF measurements benefit D mixing analyses
Measure BF relative to D+→K-+ +
Reconstruct D+→h+0• Require D*+→D+0 • p*(D*) > 2.9 GeV/c• Use m sidebands to estimate peaking background
Efficiencies 5.9-8.5%
Sideband
region Signal
region
MC
Peaking bkg. from sideband
fit MC
Sep. 29, 2006 Henry Band - U. of Wisconsin 21
Fits
Yield from un-binned maximum likelihood fitsD+→+0 D+→K+0
D+→K-++
Using BF(D+K-++) = (9.4 0.3)x10-2 from CLEO-C & PDG
124 fb-1
First Observation
>6.5
D+→K+0
D+→+0ref: D+→K-++
BF(D++0)=( 1.25 0.10 0.09 0.04(ref) ) 10-3
BF(D+K+0)=( 2.52 0.47 0.25 0.08(ref) ) 10-4
Hep-ex 0605044
Sep. 29, 2006 Henry Band - U. of Wisconsin 22
Cabibbo suppressed 2 body decays of D0 show anomalous suppression of D0 -+ versus D0 K-K+ (~1/3)
Three body decays are poorly measured
Reconstruct D*+→D0+ m = m(D*+) - m(D0) • Fit K-+0 reflection in the -+0
and K-K+0 distributions
Recover non-uniform reconstruction efficiency weighting events with:
W = 1/efficiency no assumptions on Dalitz plot
structure
Branching Fractions - D0→ -+0, K-
K+0 D0→ K- +0
D0→ -+0
D0→ K- K+0
Belle±±Hep-ex
0608009
Belle-CONF-0608 (2006)
232 fb-1
Sep. 29, 2006 Henry Band - U. of Wisconsin 23
Charm Baryon States
JP=3/2+(L=0)JP=1/2+
(L=0)
JP=1/2+
(L=0)
Strangeness
Charm
Isospin
Most C = 1 baryon ground states have been observed (except *c)
L > 0 states now being seen C = 2 QQq candidates observed by SELEX
(ccd)+ c+ K- +
(ccu)++ c+ K-
cc+ p D+K-
C= 1
Sep. 29, 2006 Henry Band - U. of Wisconsin 24
c(2940)p D0
Search in continuum cc pD0 modes (D0K- K-)
Observe previously reported Λc(2880)+ (was observed in cby CLEO)
M = 2881.9±0.1±0.5 MeV/c2
Γ = 5.8±1.5±1.1 MeV
New state Λc(2940)+
• M = 2939.89±1.3±1.0 MeV/c2
• Γ = 17.5±5.2±5.9 MeV
• Confirmed by BELLE in Λc --> c
• First example of a charm baryon decay to a charm meson
No isospin partners seen in D+p so both Λc not c
Λc(2880)+ Λc(2940)+
Wrong sign D0p
Hep-ex 0603052
124 fb-1
Sep. 29, 2006 Henry Band - U. of Wisconsin 25
First Observation ofc*(css)
c
Reconstruct c0 →
• a) -+ (-→K-) 156 +/- 15 events
• b) -+0 (-→K-) 92 +/- 26
• c) -+-+ (-→K-) 23 +/- 10
• d) --++-→K-) 34 +/- 15
Combine with MeV) Plot M(c
– Mc+ Mc
PDG Combined yield 105 ± 21 ± 6
M = M(c–Mc
= 70.8 ± 1.0 ± 1.1 MeV
Theoretical predictions 50 – 73 MeV
Hep-ex 0608055
124 fb-1 M(c– Mc
+ McPDG GeV/c2
Sep. 29, 2006 Henry Band - U. of Wisconsin 26
Search for Doubly Charmed Baryons
SELEX reported evidence for cc
in c+K-+(+), D+pK-
Babar has looked for similar decays
cc+(+)c
+K-+(+) c c
+(+)c0+(+)
Belle searched cc
+(+)c+K-+
No evidence despite >106 c in B factories SELEX(1630 c )
Λc+K–π+ p*> 0
GeV/c
Λc+K–π+ p*>2.3
GeV/c
Λc+K–π+π+ p*>2.3
GeV/c
Λc+K–π+π+ p*> 0
GeV/c
Hep-ex 0605075
124 fb-1
Sep. 29, 2006 Henry Band - U. of Wisconsin 27
Observation of Ξc
(2980)+ and Ξc (3077)+
Look for decays to Λc+ K- π+
No peaks in the wrong sign distribution
No peaks in the side band
Also seen in the isospin partners
Λc+→pK-π+
Mass(Λc+ K- π+)
Λc+→pK+π-
Mass(Λc+ KS
π-)
hep-ex/0606051,
Ξc (2980) and Ξc (3077) excited charm strange baryons.
Belle
Hep-ex 0607042
Sep. 29, 2006 Henry Band - U. of Wisconsin 28
Summary
Large B factory charm samples still producing new charm meson and baryon discoveries
• DsJ(2860)+
• DsJ(2700)+
Plus refined masses, widths, BFs on previously discovered states
But no double charm Can expect much more in the coming years
c(2940)
Λc(2880)+
c*
Ξc(2980)+
Ξc(3077)+