Charmed Meson Spectroscopy

Charmed Meson Spectroscopy

Robert K. KutschkeFermilab

HQL04 June 4, 2004

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:

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.

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.

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!

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• Broad states not observed ( except for an unpublished CLEO result ).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 ?

R. K. Kutschke Heavy Quarks and Leptons. 2004 7

FOCUS’ Starting Point: D and D* Signals

K-K-

K-D*+ D0+

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

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

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.

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

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.

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

R. K. Kutschke Heavy Quarks and Leptons. 2004 14

Belle BD+ Dalitz Plot

Signal Region E Sideband

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

R. K. Kutschke Heavy Quarks and Leptons. 2004 16

Belle

Belle

Signal Region E Sideband

Belle BD*+ Dalitz Plot

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

R. K. Kutschke Heavy Quarks and Leptons. 2004 18

Summary of D2* Data

R. K. Kutschke Heavy Quarks and Leptons. 2004 19

Summary of Data for D1(2420)0

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.

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.

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).

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)

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.

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.

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.

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.

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)

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

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.

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

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

R. K. Kutschke Heavy Quarks and Leptons. 2004 33

Miscellany

• No signals seen in DS ( CLEO and CDF ).

– Excludes some molecule interpretations.

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

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.

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.

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.

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.

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

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*+)