charmed meson spectroscopy
DESCRIPTION
Charmed Meson Spectroscopy. Robert K. Kutschke Fermilab HQL04 June 4, 2004. For L=1:. Heavy-Light Mesons: Coupling Angular Mommenta. L. Spin of Q can be treated as a small perturbation. S q. q=u,d,s. Heavy Quark Symmetry (HQS):. S Q. - PowerPoint PPT PresentationTRANSCRIPT
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Charmed Meson Spectroscopy
Robert K. KutschkeFermilab
HQL04 June 4, 2004
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R. K. Kutschke Heavy Quarks and Leptons. 2004 2
Heavy-Light Mesons: Coupling Angular Mommenta
Sq
jSLSSJ QqQ )(
Heavy Quark Symmetry (HQS):
jl = total angular momentum of the light degrees of freedom.
QQ m
1
Spin of Q can be treated as a small perturbation.
Main features understood by treating jl as a good Q#!
q=u,d,s
SQ
L
0,1,1,2PJFor L=1:
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R. K. Kutschke Heavy Quarks and Leptons. 2004 3
P-Wave Charmed Mesons
• For each of cd, cu, cs, expect two doublets:
Narrow doublet:
•JP = ( 2+, 1+)
• jlight = 3/2
• D(*)decay: D wave.
• O( 10 MeV )
• All well established.
Broad doublet:
•JP = ( 1+, 0+)
• jlight = ½
• D(*)decay: S wave.
• O( 100 MeV )
• First observations recently.
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R. K. Kutschke Heavy Quarks and Leptons. 2004 4
Cartoon of Dominant Decay Modes
Q
Q
q
q
q
q
ssdduu ,,
*** ,DDD
SS DKDDKD ,, *** When permitted by conservation of Energy, J and P.
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R. K. Kutschke Heavy Quarks and Leptons. 2004 5
What’s Overly Simplified in the Ideal Picture?
• Doublets may overlap ( which 1+ is more massive?)
• Are all states above D and DK thresholds?
•Is suppression of S wave widths complete?
• Ds1 right at threshold for D*:
• Very narrow, < 2.3 MeV/c2 @ 90% CL.
• Data suggests mostly S-wave!
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R. K. Kutschke Heavy Quarks and Leptons. 2004 6
Where Were We at HQL02?
• All data consistent with simple picture of HQS.
• Narrow doublet well established: D0, D+, DS.
• Broad states not observed ( except for an unpublished CLEO result ).
• Delphi D’ still not confirmed by anyone.
What’s New Since HQ&L 2002?
• Observation of the expected broad DJ states.
• Observation of two new narrow DSJ states which decay to DS and DS
*.
– Are these the expected broad states ?
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R. K. Kutschke Heavy Quarks and Leptons. 2004 7
FOCUS’ Starting Point: D and D* Signals
K-K-
K-D*+ D0+
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R. K. Kutschke Heavy Quarks and Leptons. 2004 8
FOCUS Phys. Lett. B586, 11-20 (2004)
M(D0+)
Feeddown: ),( 000* DDDJ
Neutrals are unobserved
BG Function:DBmA Cme )()(
A,B,C,D Free parameters
Horrible Fit!
FOCUS
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R. K. Kutschke Heavy Quarks and Leptons. 2004 9
Same problem for M(D+-): Horrible Fit
M(D+-)
FOCUS explored many BG models but all failed.
Idea: We expect a broad state so add one to the fit.
Caveat: 2 broad states DD 0*
0
),( 0*01 DDD
FOCUS
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R. K. Kutschke Heavy Quarks and Leptons. 2004 10
FOCUS
• Add a single S-wave resonance to the fit.
• Get excellent fit quality.
• Fit is robust against many variations in background.
• Yield of broad resonance:– 18754 2200– 8.5 stnd. dev.
• Relative yields of signals and feed-downs consistent with expectations.
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R. K. Kutschke Heavy Quarks and Leptons. 2004 11
• Add a single S-wave resonance to the fit.
• Get excellent fit quality.
• Fit is robust against many variations in background.
• Yield of broad resonance:– 9810 2700– 3.6 stnd. dev.
• Relative yields of signals and feed-downs consistent with expectations.
FOCUS
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R. K. Kutschke Heavy Quarks and Leptons. 2004 12
Changing of the Guard
• To date all published measurements of D** come from inclusive measurements.
• A more powerful way of doing charm spectroscopy is to look at the Dalitz plots in BD(*) Dalitz decays.– The penalty is small product branching ratios.– We have been waiting a long time for this.– Remember the power of D Dalitz plots for light
quark spectroscopy.• CLEO CONF-99-6, unpublished, uses this technique
but with partial reconstruction of the final state.• Last year Belle submitted the first use of this
technique with full reconstruction.
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R. K. Kutschke Heavy Quarks and Leptons. 2004 13
Belle: hep-ex/0307021 To Appear in PRD.
DB *DB
Good signal to background ratio. Delta E cut kills Feed-down.
KD 0* DD KD0
KD0
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R. K. Kutschke Heavy Quarks and Leptons. 2004 14
Belle BD+ Dalitz Plot
Signal Region E Sideband
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R. K. Kutschke Heavy Quarks and Leptons. 2004 15
• Resonances Included:– Free M and :
• D2*(2460)
• D0*
– Virtual States:• B*• D*0D+
• All have significant fit fractions.
• Most new features established by interference effects.
• No constant term in final fit. It does not improve the likelihood.
Belle
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R. K. Kutschke Heavy Quarks and Leptons. 2004 16
Belle
Belle
Signal Region E Sideband
Belle BD*+ Dalitz Plot
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R. K. Kutschke Heavy Quarks and Leptons. 2004 17
• Resonances included:
– D2*(2460)
– Free M and
• D1(2420)
• D1(broad)
– Virtual States:• B*• D*
• All have significant fit fractions.
• Most new features established by interference effects.
• No constant term in final fit. It does not improve the likelihood.
Belle
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R. K. Kutschke Heavy Quarks and Leptons. 2004 18
Summary of D2* Data
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R. K. Kutschke Heavy Quarks and Leptons. 2004 19
Summary of Data for D1(2420)0
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R. K. Kutschke Heavy Quarks and Leptons. 2004 20
FOCUS measurements are of an unknown superposition of D1
*0 and D1
0. So it does not make sense to take an average of BELLE and FOCUS.
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R. K. Kutschke Heavy Quarks and Leptons. 2004 21
Summary of Charm Non-Strange Spectroscopy
• Broad states have now been seen.• Above threshold for decay to D(*)• Masses and widths approximately
as expected.• Angular distributions in the B Dalitz
plots supports the conventional spin parity assignments:
– D1(2427): 1+
– D0*(2308): 0+
• Mass ordering of the two 1+ states is not yet resolved.
• More statistics will help, especially the broad states.
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R. K. Kutschke Heavy Quarks and Leptons. 2004 22
A Surprise from BaBar: PRL 90, 242001 (2003)
BABAR91 fb-1
+
• Narrow peak in DS.
– JP = natural• Width consistent with
detector resolution, about 9 MeV.
• Mass near 2317 MeV.– About 40 MeV below
DK threshold.• Second state near 2456?M(DS)
• Could this be the DS*0?
• Mass is below most, but not all predictions, – Nowak, Rho and Zahed, PRD 49, 4370 (1993).– Bardeen and Hill, PRD 49, 409 (1994).
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R. K. Kutschke Heavy Quarks and Leptons. 2004 23
Where to Look if DK and D*K are Forbidden
c
c
s
s
s
s
0(*)SD
mixing
0
c c
s s
(*)
SD
c c
s s
(*)SD
Isospin violating! Cho and Wise, PRD 49, 6228
(1994)
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R. K. Kutschke Heavy Quarks and Leptons. 2004 24
CLEO Sees Two States
Ds* signal region
Ds* sideband region
55±10 events
• Confirms BaBar state at 2317 MeV.
• Establishes new state near 2460 MeV.
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R. K. Kutschke Heavy Quarks and Leptons. 2004 25
Belle Confirms Both States
M(Ds+
π0 )-M(Ds+) M(Ds
*+ π0 )-M(Ds
*+)
Ds sidebands*
Sidebands: DS solid, 0 dashed.
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R. K. Kutschke Heavy Quarks and Leptons. 2004 26
A Conspiracy !• Feed-down:
– DS(2460) DS* (DS
*)
– Miss gamma and reconstruct as: DS
– Makes a narrow peak near 2317 MeV.• Feed-up:
– DS(2320) DS.– Add a random photon and require that
DScombination fall in DS* mass region. Plot
mass of DScombinations.– Makes a narrow peak near 2460 MeV.
• Most signal are about 75% pure and 25% feed up/down.
• CLEO, BaBar, Belle: different methods to deconvolve.
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R. K. Kutschke Heavy Quarks and Leptons. 2004 27
Example: BaBar’s Method)()( 0
0 SS DmDmm
Points: M(DS) in DS*
region.
Shaded: DS* sideband
Subtract distributions on the right.
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R. K. Kutschke Heavy Quarks and Leptons. 2004 28
Belle: Two New Decay Modes of DS(2460)
Forbids J=0
DS1(2536) !DS(2460)
Histogram: DS sidebands.
DS(2320) DS*(2112)
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R. K. Kutschke Heavy Quarks and Leptons. 2004 29
Belle: Sees the Decays BDDsJ
Histograms: E sidebands
Ds(2317)oDs
Ds(2460)oDs*
Ds(2460)Ds
2+
1+
DSJ Frame
DS
DS in B Frame
sJD
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R. K. Kutschke Heavy Quarks and Leptons. 2004 30
Focus Sees DS(2317) in Photoproduction
• Histograms: DS and 0 sidebands.
• First observation outside of e+e- at 10 GeV.
• M = 2323 2 MeV ( stat only; uses PDG DS mass).
– About 2 sigma above average of other experiments.• Width consistent with detector resolution.
• Energy calibration: DS* DS0 and D0 K-0.
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R. K. Kutschke Heavy Quarks and Leptons. 2004 31
Some Suggestions?
• HQS plus chiral symmetry explain low masses below DK threshold.– Bardeen, Eichten & Hill hep-ph/0305049. – Nowak, Rho & Zahed hep-ph/0307102.
• DK molecule– Barnes, Close & Lipkin hep-ph/0305025
• Mixture with 4-quark state above DK threshold – Browder et al. hep-ph/0307054
• Unitarized meson model – Van Beveran & Rupp hep-ph/0305049
• Masses using QCD Sum Rules– Dai, Huang & Zhu hep-ph/0306274
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R. K. Kutschke Heavy Quarks and Leptons. 2004 32
Some Suggestions?
• Can the lattice explain these as csbar states?– No: Bali hep-ph/0305049,– Yes: Dougall et al hep-ph/0307001
• On the importance of radiative decays:– Colangelo & De Fazio hep-ph/0305140– Godfrey hep-ph/0305122
• Branching Fractions in B decay DDSJ are much smaller than for DDS. Factorization suggests that they should be similar. Is this a sign of non c-sbar nature?– Chen and Li hep-ph/0307075 – Datta and O’donnel hep-ph/0307106 – Cheng and Hou hep-ph/0305038
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R. K. Kutschke Heavy Quarks and Leptons. 2004 33
Miscellany
• No signals seen in DS ( CLEO and CDF ).
– Excludes some molecule interpretations.
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R. K. Kutschke Heavy Quarks and Leptons. 2004 34
Summary of New DS States
M=2317.6 0.8 MeV M=2459.2 1.1 MeV < 4.6 MeV (90% CL) < 5.5 MeV (90% CL)
JP=0+ Favored JP=1+ Favored
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R. K. Kutschke Heavy Quarks and Leptons. 2004 35
An Important Measurement to Do
• Set the scale of the partial widths. This will help sort out competing models.– Hard to impossible with and 0 final states.
• An idea:
– Measure the width of the DS1(2536).
– Better measurements of DS1(2536) DS.
– Measure: DS1(2536) DS(*)
– This can calibrate the models which can then be applied to the 0+ and 1+ states.
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R. K. Kutschke Heavy Quarks and Leptons. 2004 36
What’s Interesting to do Next
• Increase statistics on BD(*)Dalitz plot analyses.– Improve measurements of the broad states and
find charged broad 1+ state.– Look for new states.
• Discover DS2 D*K.
• Dalitz plot analyses of B decays with DSJ in final state.– This will be hard and require lots of data but
Belle has shown that it is not out of the question.• CDF, D0, LHC-b and BTeV.
– Combinatoric BG kills inclusive measurements.– Should do well with analysis of B Dalitz plots.
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R. K. Kutschke Heavy Quarks and Leptons. 2004 37
Summary and Conclusions
• The charmed-non-strange P-wave broad states are established with their expected properties.– Waiting for BaBar’s results.– Can CDF and D0 compete here?.
• The charmed-strange “broad” states are really strange. They are narrow!– Below threshold for decay to D*K so they
appear in unexpected decay modes, DS*0,
DS and DS.
– Their JP are constrained but not fully determined.
• Lots still to do. Especially important to establish the widths of the narrow states.
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R. K. Kutschke Heavy Quarks and Leptons. 2004 38
Observation of the Ds2* at Focus
Prelim
inar
y
FOCUS
First observation of the D+KS
0 mode!
D0K+ D+KS0
There are some real KS0 in
the sideband sample.
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R. K. Kutschke Heavy Quarks and Leptons. 2004 39
Simultaneous Fits to D0K+ and D+KS0
Spectra
1. DS2 Signal: D-wave Rel. BW
2. Smooth background shape
3. MC DS1 feeddown shape
4. MC DS2 feeddown shape. Significance is not stable with cut variations!
Terms in the fit:
• Simultaneous: M and same.• Errors are statistical only PDG:
M = 2573.5 ± 1.7 MeV/c2
= ± 5 MeV/c2
Prelim
inar
y
First observation of D+KS0
mode
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R. K. Kutschke Heavy Quarks and Leptons. 2004 40
Observation of the DS1 at FOCUS
Prelim
inar
y
1. DS1 Signal: Non Rel BW, convoluted with a gaussian.
2. Smooth background shape.
3. DS2* Signal: D-wave Rel
BW.
Terms in the fit:
• Errors are statistical only
PDG:
= 525.35 ± 0.34 MeV/c2
< 2.3 MeV/c2 @ 90 % CL.
M(D*+Ks0)-
M(D*+)