1. Charm Decays at B Factories
Brian Meadows
University of Cincinnati
Tau-Charm Workshop, IHEP, Beijing, China, Jun 5-7, 2006
Brian Meadows, U. Cincinnati.

2. Brian Meadows, U. Cincinnati
Outline
Charm Decays at B Factories:
(Semi-) Leptonic and rare decays – P. Jackson
D Mixing – A. Rahimi
Dalitz Plots – M. Papagallo
Charm Baryons – R. Chistov
Charmonium and other spectroscopy – S. Olsen, A. Palano, B. Yabsley, P. Pakhlov
Tau Physics – G. Lafferty
Here - Choice of some results (probably) not covered in above:
Charm Baryons (mostly from BaBar)
Charm Mesons – a few items
Summary
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

3. Brian Meadows, U. Cincinnati
BaBar and Belle
e+ (3.5 GeV/c)
e- (8 GeV/c)
Peak luminosity 1.081034 cm–2s–1
Integrated luminosity fb–1
Peak luminosity 1.621034 cm–2s–1
Integrated luminosity fb–1
Main purpose: Study CP violation in asymmetric e+e -  (4S)  BB
Both experiments have far exceeded their design goals
Approx. 1 ab-1 integrated flux combined
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

4. Charm Hadrons at “B” Factories?
Cross sections are large Can use “off peak” data
Very high statistics (~1.4 x 106 D’s / fb-1).
Also
Relatively small combinatorial backgrounds in e +e - interactions.
Good particle ID.
Detection of all possible final states including neutrals.
Good tracking and vertexing
Off On
ECM (GeV)
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

5. Brian Meadows, U. Cincinnati
Charm Baryons
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

6. Charm Baryon States BUT - No JP are yet measured ! |C| = 1:
JP=3/2+(L=0)
JP=1/2+ (L=0)
Strangeness
Charm
Isospin
BUT - No JP are yet measured !
|C| = 1:
L=0 Ground State – almost full:
JP=1/2+: {6}qq Sc(2455), Xc(2470), Wc(2698) All seen
JP=1/2+: {3}qq Lc(2285), X0c(2575) All seen
JP=3/2+: {6}qq Sc(2520), Xc(2645), ?? All but Wc*
L>1 – filling up ?
JP=1/2-: – Lc(2593), Xc(2790), …
JP=3/2-: – Lc(2625), Xc(2815), …
Several more new states from BaBar and Belle … and more
… from CLEO 2
(or )c(2880), (or )c (2765) ??
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

7. First Charm Baryon  Charm Meson Lc(2940)
Observed in cc continuum production in D 0p decay mode (D 0 K-p+, K-p+p-p+)
287 fb-1 hep-ex/
Λc(2940)+ :
M = (2939.8±1.3±1.0) MeV/c2
Γ = (17.5±5.2±5.9) MeV
Λc(2880)+
Λc(2940)+
New data on Λc(2880)+ :
New Decay Mode  D 0p
BaBar:
M = (2881.9±0.1±0.5) MeV/c2
Γ = (5.8±1.5±1.1) MeV
PDG: (“Could be Sc”)
M = (2880.9±2.3) MeV/c2 ; Γ < 8 MeV
Wrong sign D0p
D0 mass sidebands
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

8. Brian Meadows, U. Cincinnati
New Baryon Lc(2940)
Neither Lc(2940) nor Lc(2880) seen in D+p system
 Neither are Sc’s
287 fb-1 hep-ex/
Other observations:
Why not seen in Lcp+p- or Scp ?
Three states predicted near this mass 3/2-, ½+, ½-
Lc(2940) is 6 MeV/c2 below D*p threshold
Lc(2940) is p mass above Lc(2880)
c++’s ??
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

9. Brian Meadows, U. Cincinnati
Search for cc States
Predicted in mass range 3.5 – 3.8 GeV/c2
Predicted cross-sections from 10 GeV/c2 ~ fb
Double-charm cross-sections under-estimated by NRQCD
 expect to produce 102 – 104 from 232 fb-1
SELEX
Phys.Lett.B628:18-24,2005
SELEX reports state at 3.52 GeV/c2
- beam ~ 1,630 +c
Not confirmed by FOCUS
 beam ~ 19,500 +c
Nor BaBar, nor Belle
e+e- ~ 106 c+
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

10. Λc+K–π+π+ p*>2.3 GeV/c Λc+K–π+π+ p*> 0 GeV/c
Search for cc States
232 fb-1 hep-ex/
cc+(+)c+K-+(+)
Search made throughout ranges indicated
for both charge states,
with and without p*cuts
21 two-d fits: Gaussian signal on background in overlapping 10 MeV/c2 ranges.
Results normalized to cross-section for producing c+
95% C.L. limits:
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
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

11. Brian Meadows, U. Cincinnati
Search for cc States
232 fb-1 hep-ex/
95% C.L. limits:
c c+(+)Xc0+(+)
Search made throughout ranges indicated
50 fits: Double Gaussian signal on linear background in 10 MeV/c2 ranges.
Results compare with
Ξc0π+ p*> 0 GeV/c
Ξc0π+ p*> 2 GeV/c
Ξc0π+π+ p*> 0 GeV/c
Ξc0π+π+ p*> 2 GeV/c
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

12. Brian Meadows, U. Cincinnati
Search for Xcc States
Belle also found no evidence for the state seen by SELEX using an even larger sample.
462 fb-1 PRELIMINARY
M(Lc+K-p+) (GeV/c2)
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

13. Observation of Two New Xc(csu) States in cc Continuum Production
While searching for weak decay of
Xcc  Lc+K- p+
 p K-p+
Found strong decays of new Xc* ‘s instead:
Xcx  Lc+K- p+
462 fb-1
No structure in Lc+ sidebands
Nor in Lc+K+p- or Lc+K-p- wrong sign combinations.
462 fb-1 PRELIMINARY
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

14. Brian Meadows, U. Cincinnati
The Spin of The W-
The existence of large samples of charm baryons makes possible what was once incredibly difficult !
Xc0W-K+
Wc0W-p+
116 fb-1 Preliminary
230 fb-1 Preliminary
Earlier results from bubble chambers using small, unaligned samples of W- could only conclude that J>1/2.
Assume the spin of charmed parent is ½:
In the charm hyperon rest frame, the W- is produced with helicity § ½
independent of the W- spin J.
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

15. The Spin of The W-
The W- L K - decay distribution in its “helicity frame” is then
230 fb-1 Preliminary
116 fb-1 Preliminary
Xc0W-K+
Wc0W-p+
J = 5/2
J = 1/2
J = 3/2
 Conclude J = 3/2 (if charmed parents are J=1/2).
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

16. How About Charm Baryons?
Information on charm baryon spins could come from decays like
B+,0c0,-c+
 -+
So far (Belle 357 fb-1) only ~12 events where c0 -+
 Not promising for determination of J
357 fb-1 hep-ex/ (2005)
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

17. Maybe Three- (or more-) Body Decays ?
3-body BF’s about 10 x 2-body
B-c+ p p - (product of BF’s ~ 2 x 10-5)
have. significant # events:
B-  Sc0 p (Sc0  Lc+-)
Lots of other things going on
Good techniques for dealing with coherent backgrounds may be required.
c0(2455) c+-
140 fb-1 hep-ex/ (2005)
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

18. Brian Meadows, U. Cincinnati
Charm Mesons
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

19. Brian Meadows, U. Cincinnati
Heavy-Light Systems JP
2jq+1LJ 
jq = 3/2 2+
3P2
small
D-wave 1+
1P1
large
S-wave
L = 1 1+
3P1
small
D-wave
jq = 1/2 0+
1P0
large
S-wave
spin-orbit
tensor
jq = 1/2 1-
1S1
small
L = 0 0-
1S0
small
Expected by quark models
To be below D(*)K threshold
Narrow states are easy to find.
Two wide states are harder.
Since charm quark is not infinitely heavy, some jq=1/2, 3/2 mixing can occur between the two JP=1+ states.
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

20. Mixing in JP = 1+ DsJ(2460)/Ds1(2536) ?
Belle has analyzed Ds1(2536) decays to D*K to look for an S-wave component.
(In the limit the c quark has infinite mass, the narrow states would decay in pure D-wave)
Angular distribution of + in D*+ system leads to the limits:
0.277 < S/(S+D) < 0.955
Indicative of some S-wave
D+s1D*+K0 K0
DsJ   D* D
1 + A cos2  :
S-wave: A=0
D-wave: A=3
A = § 0.03
hep-ex/
281 fb-1
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

21. Brian Meadows, U. Cincinnati
DsJ’s - Overtly Exotic ?
No indication of overtly exotic charge states
Circles are Ds side-bands
For DsJ(2460) need to look in Ds(*)+0+,- if JP=1+
(See Antimo Palano’s talk for full details)
DsJ(2317) ?
DsJ(2460) ?
232 fb-1 hep-ex/
Ds+p-
Ds+p+
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

22. Decays of B0  Ds(DsJ )+ + h-
Exotic nature of DsJ states could show up in
B 0  Ds(J)K - is especially interesting none of the final state quarks (cuss) are in the initial B (bd) meson.
Expect Rh ~ 1 for cs and Rh ~ 0.1 for csuu
C.-H. Chen, H.-n Li, Phys. Rev. D 69, (2004)
hep-ex/
350 fb-1
 RK ~ RD ~ 1 (no clear evidence for csdd)
PRL 93,  fb-1
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

23. Doubly Cabbibo Suppressed Decays
First measurement of
(CLEO 1990 < 0.04%)
Measured rate relative to D+K-++
then used average of PDG and recent CLEO measurement for this rate.
Decays normalized to K-p+p+
D+p+p0
D+K+p0
Uncertainty in D+K-p+p+
124 fb-1 hep-ex/
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

24. Doubly Cabbibo Suppressed Decays
Naïve, exact SU(3):
BaBar: 2/(1.49 § 0.29)
Also:
BaBar: § 0.17 c d s u d
SU(3) predictions are over-simplified:
First ratio affected by Ks-KL interference
D+  K+0 can also proceed by W-exchange or annihilation diagrams.
 Measurements are challenging
Results still not well understood. c u s d
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

25. Wrong Sign D0 Decays Time-integrated rates can be compared with
Despite high backgrounds, measurements at few % level
(BaBar tags other side)
Time-integrated rates can be compared with
tan4 c = (0.281 § 0.006) x 10-2
Belle/BaBar agreement excellent
big improvement over PDG values
D* tagging allows measurement of CP asymmetries
Belle: K+2 ( § 0.053); K+3 ( § 0.044)
consistent with zero.
 any new physics at level much smaller than DCS for “wrong sign” decays.
Before After
229 fb-1 PRELIMINARY
K+ 2  M (MeV/c2)
hep-ex/
PRELIMINARY
281 fb-1
 M (MeV/c2)
K+ 2
K+ 3
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

26. (D(s)*D(s)0)/(D(s)*D(s))
BaBar has improved measurements of the 0/ ratios:
Agree with current results
Fresh input to PT
90.4 fb-1 hep-ex/
Ds*Ds
Ds*Ds0
M(K+K-+)-M(K+K-+)
M(K+K-+0)-M(K+K-+)
D0*D0
D0*D00
GeV/c2
Lost g
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

27. Brian Meadows, U. Cincinnati
Summary
B Factories provide a very clean environment for the production of all charm hadrons
new particle paradise !
BUT no doubly charmed baryons
Large (and growing) samples of charm mesons and baryons are likely to complement results from -charm facilities for some time to come
In several ways, we are learning how information on systems to which charm hadrons, or B mesons, decay can be extracted
There is a large and enthusiastic community anxious to work on all aspects of the physics available.
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

28. Brian Meadows, U. Cincinnati
Back up Slides
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

29. Precision Measurement of c Mass
hep-ex/ fb-1
Important measurement
most charm baryon masses measured relative to this
Method:
Choose decay modes with small Q-value/large BR:
c  K+Ks0 and 0K+Ks0
Estimate / adjust major systematic uncertainties in:
Material audit – determine  and K0 mass vs. decay path length
Magnetic field – determine  and K0 mass vs. momentum in lab.
Much larger control samples:
c+  pK-+ 1.5 x 106 evs.
c+  pK0 2.4 x 105 evs.
Q = MeV/c2
4627§ 84
events
Q = MeV/c2
264§ 20
events
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

30. Brian Meadows, U. Cincinnati
Results
c  K+Ks0
§ (stat.) § (syst.)
c  0K+Ks0
§ (stat.) § (syst.)
c  pK-+
§ (stat.) § (syst.)
c  pKs0
§ (stat.) § (syst.)
Large Q
m(Lc) =  0.14 MeV/c2
Combined measurement :
Most precise measurement of charm mass to date
Approximately 4 x more precise than
Current PDG value: § 0.6 MeV/c2
and about 2.5  higher
hep-ex/ fb-1
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

31. Brian Meadows, U. Cincinnati
Charm Baryon States
PDG 2005
L>1 – filling up ?
JP=1/2-: – Lc(2593), Xc(2790), …
JP=3/2-: – Lc(2625), Xc(2815), …
Most massive in PDG 2005 is c (2815)
CLEO 2 has added
c(2880) and c(2765)
D*p Dp
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

32. Brian Meadows, U. Cincinnati
New Sc (2800) Triplet
Lc  pK-p+ sidebands
281 fb-1 PRL94, (2005)
Could be JP = 3/2- Sc2 ??
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

33. Charmed Meson Spectroscopy pre 2003
D*0K+ threshold
D0K+ threshold
BABAR/CLEO may have found
these – but below threshold.
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

34. Charmed Meson Spectroscopy Now
John Bartelt, Sept, 2003
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

35. Brian Meadows, U. Cincinnati
DsJ*(2317)+Ds+0
BABAR: 232 fb-1
Submitted to PRD
N=3180±80
Preliminary
No indication of neutral or doubly-charged partner near 2317 MeV  I=0
Ds*(2112)
signal
Preliminary
Ds*(2112)
reflection
Dark shade:
DsJ(2460) reflection
Circles: Ds
sidebands
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

36. Update on Charmed-Strange Mesons DsJ*(2317)+ and DsJ(2460)+
New, comprehensive study of decays to Ds+ plus one or two ±, 0, or ’s
Decay pattern if JP=0+ and JP=1+, respectively
Ds+0 only decay
mode observed
for DsJ*(2317)+
NB: all “Seen” modes are also “Allowed”
232 fb-1 hep-ex/
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

37. Brian Meadows, U. Cincinnati
DsJ* Update:
From DsJ*(2317)+Ds+0 :
From DsJ*(2460)+Ds+ , Ds+0 :
New from Ds+ +- :
No indication of DsJ*(2317)+  Ds++-
New mode: DsJ*(2536)+  Ds++-
232 fb-1 hep-ex/
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

38. B Decays - Absolute Branching Fractions
BB sample with one B fully reconstructed decays of the other BD(*)+,0 X
Observe Ds+ and DsJ(2460) signals in the recoil mass, mX
 absolute BF’s for Ds+ ( +) and for DsJ*(2460)+ p e- D*
Breco e+
Bsignal D* X
211 fb-1 hep-ex/
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

39. DsJ(2460)+ Absolute BFs, cont.
PDG: (4.3 § 1.2) %
For the Ds+ signal:
Combine with previous measurements
to obtain absolute BFs:
Sum of known BFs: 0.76±0.20
113 fb-1 PRL 93, (2004)
(Ds*+ Ds+ )
211 fb-1 hep-ex/
Is there another mode ?
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

40. BD DsJ*(2317)+, DsJ*(2317)+Ds+0
Belle: 274M BB
BELLE-CONF-
0461 (2004)
DsJ*(2317) decay mode  natural spin-parity
DsJ*(2317) decay angular distribution  spin 0
Dotted line:
J = 1
2/d.o.f = 38/8 0
Natural
spin-
parity 
JP = 0+
Solid line:
J = 0
2/d.o.f = 3/8
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati

41. Brian Meadows, U. Cincinnati
DsJ(2460)+Ds+  / Ds*(2112)+0
Ds*+Ds+
DsJ(2460)+Ds+ 
Preliminary
Preliminary
Open points:
Ds sidebands
N=560±40
Light shade:
Ds*(2112)
reflection
Dark shade:
DsJ*(2317)
reflection
N=920±60
Open points:
Ds sidebands
BABAR: 232 fb-1
Submitted to PRD
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati
Preliminary

42. Brian Meadows, U. Cincinnati
Belle: 274M BB
BELLE-CONF-0461 (2004)
BD DsJ (2460)+
(b): DsJ(2460)+Ds+ 
(c): DsJ(2460)+Ds *(2112) +0
Ds*+
Ds+ 
Dashed line:
J = 2
2/d.o.f = 89/8
No Ds  decay for J=0
Ds*0
Solid line:
J = 1
S-wave
Solid line:
J = 1
2/d.o.f = 4/8
JP = 1+
IHEP, Beijing, China, June 5-7, 2006
Brian Meadows, U. Cincinnati
cos(Ds*0)