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Study of Charmed Mesons and New Observations at Belle: Insights from Charm07 Conference

This presentation by J. Brodzicka at the Charm07 conference discusses significant findings in the study of charmed mesons, particularly focusing on the observation of the Ds1(2536) meson decaying into D+π-K+ and the new DsJ(2700) state in B+ → D0D0K+. The analysis uses partial wave techniques and explores the implications of HQET predictions. Results suggest a dominance of S-wave states and provide insights into angular distributions and decay modes. The research enhances our understanding of multiplet structures in charmed mesons and contributes valuable data for future theoretical models.

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Study of Charmed Mesons and New Observations at Belle: Insights from Charm07 Conference

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  1. Charmed mesons J. Brodzicka (KEK) for Belle Charm07, Ithaca US

  2. Outline J. Brodzicka for Belle @ Charm07 • Introduction to cs multiplets • Observation of Ds1(2536)→D+π-K+ • Partial Wave Analysis of Ds1(2536)→D*+K0s • Observation of new DsJ(2700) →D0K+ in B+→D0D0K+ • Summary

  3. cs multiplets J. Brodzicka for Belle @ Charm07 jq = sq + L, J = jq+ sQ L = 2 JP ….. 2+ DsJ(2573) jq = 3/2 L = 1 1+ ? Ds1(2536) BaBar CLEO ‘03 Belle mix 1+ D*K jq = 1/2 ? 1+ 0+ Ds1(2460) D K 0+ D*s0(2317) spin-orbit tensor s-o spin-spin Ds* 1- jq = 1/2 L = 0 Ds 0- • HQS based potential model predictions • two doublets for orbitally excited L=1 cs states: (Godfrey-Isgur ‘85) • 0+, 1+ (jq=1/2) and 1+, 2+ (jq=3/2) • M(jq=1/2), M(jq=3/2) > MD+MK • Γ(jq=1/2) >> Γ(jq=3/2) Experiment: • jq=1/2 doublet 0+ : D*s0(2317)→Dsπ0 1+ : Ds1(2460)→D*sπ0 • jq=3/2 doublet 1+: Ds1(2536)→D*K(Argus ‘89) 2+: DsJ(2573)→DK(CLEO ‘94) jq=1/2 states:very narrow, masses below D(*)K →don’t match the potential model predictions

  4. Observation of Ds1(2536)→D+π-K+ J. Brodzicka for Belle @ Charm07 BELLE-CONF-0706 angular distribution studied for this Ds1(2536)→D*+Ks sample • Known decay modes of Ds1(2536) : D*+Ks, D*0K+, Dsπ+π- • Study of e+e-→Ds1(2536)X, Ds1(2536)→D+π-K+, D*+Ks • 462 fb-1 data sample used (normalization mode) • xP=pDs1/pmax >0.8 in e+e- cms • Two-body mass spectra consistent with Phase Space

  5. Mixing of jq=1/2 and jq=3/2 states J. Brodzicka for Belle @ Charm07 θ θ0 • HQET prediction for P-wave cs states: • 1+(jq=3/2)→D*K pure D-wave: Ds1(2536)→D*K • 1+(jq=1/2)→D*K pure S-wave: but Ds1(2460)→D*K forbidden • If HQET not exact: mixing of S-D waves possible (In Ds1(2536)→D*K D wave suppressed → small S-wave component can contribute much to the width) • Exp. knowledge on the mixing: • from BF’s ratio of Ds1(2460) radiative decays: D*sγ/Dsγ=0.31 ± 0.14 • switch from |jq>to |2S+1LJ >basis • tan2(θ+θ0)=0.8 ± 0.4 where tan2θ0=2 (no-mixing case)

  6. Partial Wave Analysis of Ds1(2536)→D*+K0s J. Brodzicka for Belle @ Charm07 BELLE-CONF-0706 • Angular distribution depends on α, β, γ angles defined as: • ρ: helicity density matrix; ρ00: probability of Ds1’s helicity=0 ρ11=ρ-1-1=(1-ρ00)/2 • √RΛ exp(iξ)=A10/A00A10 , A00: ampl. of D*‘s helicity= ±1, 0 ( A10 = (S+D/√2)/√3 A00 = (S-√2D)/√3 ) D/S =√ΓD/ΓS exp(iη)D, S: partial-wave ampl. in Ds1 decay • If no angle integrated → ξ-dependent term survives

  7. Fit to angular distribution of Ds1(2536)→D*+K0s J. Brodzicka for Belle @ Charm07 • 3D maximum-likelihood fit with PDF: • Background PDF: from M(D*+Ks) sidebands, normalized • fbck: background fraction in M(D*+Ks) signal region: ~9% • ε(α,β,γ)/<ε> → efficiency correction • Fit result projections (bckgd subtracted and efficiency corrected): • From χ2 of the fit: goodness-of-fit probability: 60%

  8. Results of Ds1(2536)→D*+K0sPWA J. Brodzicka for Belle @ Charm07 • Fit results (include systematic errors): • ΓS/ΓTOT = 0.72 ± 0.05 (η=43.9 ± 1.7°) S-wave dominates, contradicts HQET Ds1(2460) - Ds1(2536) mixing • Ds1’s helicity=0 preferred, agrees with HQET (aligned production of jq=3/2 states is predicted) • First full analysis for P-wave charmed mesons (CLEO integrated over βin PWA of D1(2420)→D*π)

  9. New DsJ meson in B+→D0D0K+ J. Brodzicka for Belle @ Charm07 hep-ex/0707.3491 (submitted to PRL) ΔE Mbc (4160) (3770) • b→ccs tree process; cs→D0K+ and cc→D0D0 states can contribute • B+→D0D0K+ signal identified using: ΔE=EB-Ebeam , Ebeam=√s/2 : cms energy difference Mbc= √E2beam-p2B : beam-constrained mass • S=399±40 for 449M BB pairs used • BF(B+→D0D0K+)=(22.2±2.2+2.6-2.4) x10-4 • Dalitz plot and mass projections different from 3-body Ph. Space new DsJ points: events from 1.5σ ΔE-Mbc signal box ■:background from sidebands

  10. Resonance contributions J. Brodzicka for Belle @ Charm07 fitted B signal yield ψ(4160) in ½ helicity distr. ψ(3770) • Non-coherent approach; possible interference effects included in syst. errors • 2D ΔE-Mbc fits in invariant mass bins → B signal extracted • Obtained background-free mass spectra used to estimate the resonance contributions: M(D0K+)for M(D0D0)>3.85 GeV fitted with: Breit-Wigner +ψ(4160) reflection + Ph. Space (shapes from MC) + exponential function (to describe the threshold enhancement (?) ) DsJ(2700)

  11. DsJ(2700) →D0K+ in B+→D0D0K+ J. Brodzicka for Belle @ Charm07 fitted B signal yield • Helicity angle distribution ofDsJ(2700): background free and efficiency corrected (reflections from threshold and ψ(4160) subtracted) • J=1 preferred; 1→0-0- decayimpliesP=-1 • Contributions to the observed mass spectra • Most observed features well described J=02/ndf=112/5 J=12/ndf= 11/5 J=22/ndf=146/5 ■DsJ(2700)■ψ(3770)■ψ(4160)■3body■threshold component (MC predicted shapes)

  12. DsJ(2700) interpretation J. Brodzicka for Belle @ Charm07 • DsJ(2700)→D0K+ 1- state can be: • radial excitation 23S1 (predicted by potential models at M~2720GeV) • chiral doubler state 1- to 1+ Ds1(2536)(predicted from chiral symmetry considerations at M=2721±10MeV) • BaBaR sees structure at M(DK)~2.69GeV produced in e+e- continuum. Is that due to DsJ(2700)? • DsJ(2860) observed by BaBar not seen in our data. Its production in B decays suppressed by its high spin? BaBar Coll. PRL 97, 222001 (2006) Godfrey, Isgur PRD 32, 189 (1985) Close, Swanson PLB 647, 159 (2007) Nowak, Rho, Zahed Acta Phys. Polon. B 35, 2377 (2004)

  13. Summary J. Brodzicka for Belle @ Charm07 • New info to cs multiplets: • new decay mode: Ds1(2536)→D+π-K+observed • from PWA of Ds1(2536)→D*+Ks (first full analysis for P-wave charmed mesons): • S-wave dominates: ΓS/ΓTOT = 0.72 ± 0.05 • Ds1(2536) and Ds1(2460) mix • longitudinal polarization: ρ00 = 0.490±0.013 → Falk-Peskin HQET parameter: w3/2 = 0.266 ± 0.019 • new DsJ(2700) meson observed: M=2708±9+11-10MeV Γ=108±26+36-31MeV JP=1- It opens a box of higher radial/orbital excitations of cs states

  14. J. Brodzicka for Belle @ Charm07 Backup

  15. Ds1 recoil mass study J. Brodzicka for Belle @ Charm07 • Ds1(2536) recoil mass: • Mrec spectrum indicates 2-body reactions: e+e-→Ds1(2536)X, where X=Ds ,D*s , higher D**s’s • Mrec resolution: ~70MeV at 2GeV, 1/Mrec dependence • 3D fits to angular distribution in bins of Mrec (RΛ and ξfixed) • Polarization at low Mrec: show structures expected for: e+e-→Ds1(2536)Ds ,Ds1(2536)D*s

  16. HQET Falk-Peskin parameter w3/2 (prob. of light quark’s helicities) • ρ00=2/3(1- w3/2) w3/2 = 0.266 ± 0.019 • (w3/2<0.24 @90%CL from D2*(2460)→Dπ by ARGUS) • Parameters: ρ00, RΛ, cosξ

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