Charmed Meson Spectroscopy Robert K. Kutschke Fermilab HQL04 June 4, 2004

R. K. KutschkeHeavy Quarks and Leptons Heavy-Light Mesons: Coupling Angular Mommenta SqSq Heavy Quark Symmetry (HQS): j l = total angular momentum of the light degrees of freedom. Spin of Q can be treated as a small perturbation. Main features understood by treating j l as a good Q#! q=u,d,s SQSQ L For L=1:

R. K. KutschkeHeavy Quarks and Leptons P-Wave Charmed Mesons For each of cd, cu, cs, expect two doublets: Narrow doublet: J P = ( 2 +, 1 + ) j light = 3/2 D (*)  decay: D wave.  O( 10 MeV ) All well established. Broad doublet: J P = ( 1 +, 0 + ) j light = ½ D (*)  decay: S wave.  O( 100 MeV ) First observations recently.

R. K. KutschkeHeavy Quarks and Leptons Cartoon of Dominant Decay Modes When permitted by conservation of Energy, J and P.

R. K. KutschkeHeavy Quarks and Leptons 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? D s1 right at threshold for D *  : Very narrow,  < 2.3 MeV/c 90% CL. Data suggests mostly S-wave!

R. K. KutschkeHeavy Quarks and Leptons Where Were We at HQL02? All data consistent with simple picture of HQS. Narrow doublet well established: D 0, D +, D S. Broad states not observed ( except for an unpublished CLEO result ).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 D J states. Observation of two new narrow D SJ states which decay to D S   and D S *  . –Are these the expected broad states ?

R. K. KutschkeHeavy Quarks and Leptons FOCUS’ Starting Point: D and D * Signals K-K- K-K- K-K- D *+  D 0  +

R. K. KutschkeHeavy Quarks and Leptons FOCUS Phys. Lett. B586, (2004) M(D 0  + ) Feeddown: Neutrals are unobserved BG Function: A,B,C,D Free parameters Horrible Fit! FOCUS

R. K. KutschkeHeavy Quarks and Leptons 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 FOCUS

R. K. KutschkeHeavy Quarks and Leptons 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. KutschkeHeavy Quarks and Leptons 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. KutschkeHeavy Quarks and Leptons 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 B  D (*)  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. KutschkeHeavy Quarks and Leptons Belle: hep-ex/ To Appear in PRD.hep-ex/ Good signal to background ratio. Delta E cut kills Feed-down.

R. K. KutschkeHeavy Quarks and Leptons Belle B  D +  Dalitz Plot Signal Region  E Sideband

R. K. KutschkeHeavy Quarks and Leptons Resonances Included: –Free M and  : D 2 * (2460) D 0 * –Virtual States: B* D* 0  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. KutschkeHeavy Quarks and Leptons Belle Signal Region  E Sideband Belle B  D* +  Dalitz Plot

R. K. KutschkeHeavy Quarks and Leptons Resonances included: –D 2 * (2460) –Free M and  D 1 (2420) D 1 (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. KutschkeHeavy Quarks and Leptons Summary of D 2 * Data

R. K. KutschkeHeavy Quarks and Leptons Summary of Data for D 1 (2420) 0

R. K. KutschkeHeavy Quarks and Leptons FOCUS measurements are of an unknown superposition of D 1 *0 and D 1 0. So it does not make sense to take an average of BELLE and FOCUS.

R. K. KutschkeHeavy Quarks and Leptons 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: –D 1 (2427): 1 + –D 0 * (2308): 0 + Mass ordering of the two 1 + states is not yet resolved. More statistics will help, especially the broad states.

R. K. KutschkeHeavy Quarks and Leptons A Surprise from BaBar: PRL 90, (2003) BABAR 91 fb -1 + Narrow peak in D S  . –J P = natural Width consistent with detector resolution, about 9 MeV. Mass near 2317 MeV. –About 40 MeV below DK threshold. Second state near 2456? M(D S   ) Could this be the D S *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. KutschkeHeavy Quarks and Leptons Where to Look if DK and D * K are Forbidden mixing Isospin violating! Cho and Wise, PRD 49, 6228 (1994)

R. K. KutschkeHeavy Quarks and Leptons CLEO Sees Two States D s * signal region D s * sideband region 55±10 events Confirms BaBar state at 2317 MeV. Establishes new state near 2460 MeV.

R. K. KutschkeHeavy Quarks and Leptons Belle Confirms Both States M(D s + π 0 )- M(D s + ) M(D s *+ π 0 )-M(D s *+ ) D s sidebands * Sidebands: D S solid,  0 dashed.

R. K. KutschkeHeavy Quarks and Leptons A Conspiracy ! Feed-down: –D S (2460)  D S *    (D S *  )   –Miss gamma and reconstruct as: D S   –Makes a narrow peak near 2317 MeV. Feed-up: –D S (2320)  D S  . –Add a random photon and require that D S  combination fall in D S * mass region. Plot mass of D S   combinations. –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. KutschkeHeavy Quarks and Leptons Example: BaBar’s Method Points: M(D S  ) in D S * region. Shaded: D S * sideband Subtract distributions on the right.

R. K. KutschkeHeavy Quarks and Leptons Belle: Two New Decay Modes of D S (2460) Forbids J=0 D S1 (2536) ! D S (2460) Histogram: D S sidebands. D S (2320)D S * (2112)

R. K. KutschkeHeavy Quarks and Leptons Belle: Sees the Decays B  DD sJ Histograms:  E sidebands D s (2317)  o D s D s (2460)  o D s * D s (2460)  D s D SJ Frame DSDS D S in B Frame

R. K. KutschkeHeavy Quarks and Leptons Focus Sees D S (2317) in Photoproduction Histograms: D S and  0 sidebands. First observation outside of e + e - at 10 GeV. M = 2323  2 MeV ( stat only; uses PDG D S mass). –About 2 sigma above average of other experiments. Width consistent with detector resolution. Energy calibration: D S *  D S  0 and D 0  K -    0.

R. K. KutschkeHeavy Quarks and Leptons Some Suggestions? HQS plus chiral symmetry explain low masses below DK threshold. –Bardeen, Eichten & Hill hep-ph/ –Nowak, Rho & Zahed hep-ph/ DK molecule – Barnes, Close & Lipkin hep-ph/ Mixture with 4-quark state above DK threshold –Browder et al. hep-ph/ Unitarized meson model –Van Beveran & Rupp hep-ph/ Masses using QCD Sum Rules –Dai, Huang & Zhu hep-ph/

R. K. KutschkeHeavy Quarks and Leptons Some Suggestions? Can the lattice explain these as csbar states? –No: Bali hep-ph/ , –Yes: Dougall et al hep-ph/ On the importance of radiative decays: –Colangelo & De Fazio hep-ph/ –Godfrey hep-ph/ Branching Fractions in B decay DD SJ are much smaller than for DD S. Factorization suggests that they should be similar. Is this a sign of non c-sbar nature? –Chen and Li hep-ph/ –Datta and O’donnel hep-ph/ –Cheng and Hou hep-ph/

R. K. KutschkeHeavy Quarks and Leptons Miscellany No signals seen in D S   ( CLEO and CDF ). –Excludes some molecule interpretations.

R. K. KutschkeHeavy Quarks and Leptons Summary of New D S States M=  0.8 MeV M=  1.1 MeV  < 4.6 MeV (90% CL)  < 5.5 MeV (90% CL) J P =0 + Favored J P =1 + Favored

R. K. KutschkeHeavy Quarks and Leptons 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 D S1 (2536). –Better measurements of D S1 (2536)  D S . –Measure: D S1 (2536)  D S (*)  –This can calibrate the models which can then be applied to the 0 + and 1 + states.

R. K. KutschkeHeavy Quarks and Leptons What’s Interesting to do Next Increase statistics on B  D (*)  Dalitz plot analyses. –Improve measurements of the broad states and find charged broad 1 + state. –Look for new states. Discover D S2  D * K. Dalitz plot analyses of B decays with D SJ 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. KutschkeHeavy Quarks and Leptons 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, D S *  0, D S  and D S . –Their J P are constrained but not fully determined. Lots still to do. Especially important to establish the widths of the narrow states.

R. K. KutschkeHeavy Quarks and Leptons Observation of the D s2 * at Focus Preliminary FOCUS First observation of the D + K S 0 mode! D0K+D0K+ D+KS0D+KS0 There are some real K S 0 in the sideband sample.

R. K. KutschkeHeavy Quarks and Leptons Simultaneous Fits to D 0 K + and D + K S 0 Spectra 1.D S2 Signal: D-wave Rel. BW 2.Smooth background shape 3.MC D S1 feeddown shape 4.MC D S2 feeddown shape. Significance is not stable with cut variations! Terms in the fit: Simultaneous: M and  same. Errors are statistical only PDG: M = ± 1.7 MeV/c 2  =  ± 5 MeV/c 2 Preliminary First observation of D + K S 0 mode

R. K. KutschkeHeavy Quarks and Leptons Observation of the D S1 at FOCUS Preliminary 1.D S1 Signal: Non Rel BW, convoluted with a gaussian. 2.Smooth background shape. 3.D S2 * Signal: D-wave Rel BW. Terms in the fit: Errors are statistical only PDG:  = ± 0.34 MeV/c 2  < 2.3 MeV/c 90 % CL. M(D *+ K s 0 )-M(D *+ )