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Charmonium and Exotics

This presentation by Klaus Peters at Ruhr-University Bochum delves into the characteristics of charmonium and exotic mesons, highlighting their interactions and implications in the context of Quantum Chromodynamics (QCD). Key topics include the spectrum of light mesons and baryons, the phenomena of hybrid states, glueballs, and the complexities arising from the QCD vacuum. The emergence of exotic states and the role of quark-antiquark dynamics will be explored, along with implications for current theoretical models and experimental observations.

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Charmonium and Exotics

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  1. Charmonium and Exotics Klaus Peters Ruhr-University Bochum Krakow, June 5, 2004

  2. Mesons/Baryons Molecules/Multiquarks Hybrids Glueballs + Effects due to the complicated QCD vacuum Objects of Interest Quark AntiQuark K. Peters - Charmonium and Exotics

  3. Light Meson Spectrum qq Mesons Each box corresponds to 4 nonets (2 for L=0) Radial excitations 2–+ 2.5 0–+ Hybrids 2+– 2++ 2–+ 1–– 2.0 exotic nonets 1–+ Glueballs 1+– 1++ 1.5 Lattice 1-+ 1.9 GeV 0+– 0–+ 0++ 1.0 0++ 1.6 GeV L = 0 1 2 3 4 (L = qq angular momentum) K. Peters - Charmonium and Exotics

  4. strong interaction C undefined K1A-K1B Kaon mixing strong interaction IG, JPC identical η-η‘ Isoscalar mixing elm interaction ΔI=1 ρ-ω Isospin mixing a1 f1 f1’ K1B JPC=JP+ b1 h1 h1’ K1A JPC=JP- I=1 I=0nn I=0ss I=½ Glueball mixing Hybrid mixing Level Mixing • Light quark problem • the mixing • Mixing • broad states • high level density K. Peters - Charmonium and Exotics

  5. Level Mixing • Light quark problem • the mixing • Mixing • broad states • high level density • Better: • narrow states • and/or • lower level density • charmed systems ! K. Peters - Charmonium and Exotics

  6. P S Charmed Hybrids • Gluonic excitations of the quark-antiquark-potential may lead to bound states • LQCD: • P-potential of excited gluon fluxin addition to S-potential for one-gluon exchange • mHc ~ 4.2-4.5 GeV/c2 • Light charmed hybridscould be narrow if open charm decays are inaccessible or suppressed important <r2> and rBreakup K. Peters - Charmonium and Exotics

  7. q q gMIX gFSI Simplest Hybrids • S-Wave+Gluon (qq)8g with ()8=coloured • 1S0­¯3S1­­ • combined with a 1+ or 1- gluon Meson – Hybrid Mixing Exotic JPCcannot! be formedby qq K. Peters - Charmonium and Exotics

  8. LQCD ccg 1-+ vs. cc 1-- (J/y) K. Peters - Charmonium and Exotics

  9. 1-- (0,1,2)-+ < 1++ (0,1,2)+- JKM00, NPB83Suppl83(2000)304 and Manke, PRD57(1998)3829 L-Splitting Dm ~ 100-250 MeV/c2 for 1-+ to 0+- S-Splittings Page thesis,1995 and PRD35(1987)1668 4.14 (0-+ ) to 4.52 GeV/c2 (2-+) consistent w/LQCD JKM, NPB86suppl(2000)397, PLB478(2000) 151 2+- 4.85 1++ 4.81 1+- 4.70 2-+ 4.52 1-- 4.48 0+- 4.47 1-+ 4.37 4.3 4.5 4.1 4.4 4.7 4.6 4.8 4.2 0-+ 4.14 Charmed Hybrid Level Scheme DD** K. Peters - Charmonium and Exotics

  10. Meson Hybrid Fluxtube ~ Simplified Lattice Approach Flux (excited Gluon) carries angular momentum Bali, priv. comm., 1991 K. Peters - Charmonium and Exotics

  11. Proposed Decays K. Peters - Charmonium and Exotics

  12. 8.0 4.0 7.1 3.9 3.8 6.3 3.7 3.6 5.5 3.5 3.4 3.3 4.8 3.2 3.1 4.1 3.0 3.4 2.9 JP=0- 1- 1+ (0,1,2)+ 2- (1,2,3)- Charmonium Physics Open questions … ψ(33S1) D*D* χc2(23P2) ψ(13D3) pp [GeV/c] Mcc [GeV/c2] ηc(31S0) χc1(23P1) Peculiar ψ(4040) ψ(13D2) DD* h1c(21P1) χc0(23P0) ψ(11D2) ψ(13D1) DD Terra incognita for 2P and 1D-States ψ(23S1) ηc(21S0) χc2(13P2) h1c(11P1) χc1(13P1) ηc’- ψ(2S) splitting χc0(13P0) h1c– unconfirmed … Exclusive Channels Helicity violation G-Parity violation Higher Fock state contributions J/ψ(13S1) ηc – inconsistencies ηc(11S0) K. Peters - Charmonium and Exotics

  13. The c(11S0) T. Skwarnicki – Lepton Photon 2003 M(c) = 2979.9  1.0 MeV (c) = 25.5  3.3 MeV K. Peters - Charmonium and Exotics

  14. The Belle collaboration has recently presented a 6 signal for BKKSK which they interpret as evidence for c production and decay via the process: with: in disagreement with the Crystal Ball result, but reasonably consistent with potential model expectations. (DPF 2002). The c(21S0) discovery by BELLE K. Peters - Charmonium and Exotics

  15.   c(21S0) T. Skwarnicki – Lepton Photon 2003 Log-scale BaBar 88 fb-1 Preliminary M(c) = 3637.7  4.4 MeV (c) = 19  10 MeV K. Peters - Charmonium and Exotics

  16. Quantum numbers JPC=1+- The mass is predicted to be within a few MeV of the center of gravity of the c(3P0,1,2) states Mcog=1/9 {M(cc0)+3M(cc1)+5M(cc2)} The width is expected to be small (hc)  1 MeV The dominant decay mode c ( 50 %) It can also decay to J/: J/0 violates isospin J/+- suppressed by phase space and angular momentum barrier Analysis of E835 data (also in other channels) underway Expected properties of the h1c(1P1) pp®h1c®J/yp0 E760 M(h1c) = 3526.2  0.15  0.2 MeV (h1c) < 1.1 MeV K. Peters - Charmonium and Exotics

  17. The hc(1P1) 1P1 vs 3Pcog mass – distinguish models • In QM triplet-singlet splittings test • the Lorentz nature of the confining potential • Relativistic effects • important validation of • lattice QCD calculations • NRQCD calculations • Observation and precision measurementof 1P1 states is an important test of theory S. Godfrey – QWG03 K. Peters - Charmonium and Exotics

  18. The X(3872) New state discovered by Belle in BK (J/+-), J/µ+µ- or e+e- X(3872) seen also by CDF M = 3872.0  0.6  0.5 MeV  2.3 MeV (90 % C.L.) M = 3871.4  0.7  0.4 MeV K. Peters - Charmonium and Exotics

  19. DD Possible interpretations • y(13D2) • D-states have negative parity, spin-2 states cannot decay to DD • They are narrow as long as below the DD* threshold • y(11D2) • preferentially decays to h1c • decays to p+p-J/y would be of magnetic type and suppressed • Width • Some models predict large widths for y(13D2) → p+p-J/y • All models predict even larger widths for y(13D2) → gcc2 • D0D*0 Molecule ? • No model can accomodate (3770) and X(3872) in the same 13DJ triplet. • Can coupled channel effects and (13D1)- (23S1) mixing change this ? y(13D3) y(11D2) y(13D2) y(13D1) 14% g g g 65% g g 7% 20% 32% p+p- g Based on: E.J.Eichten, K.Lane C.Quigg PRL 89,162002(2002) J/y K. Peters - Charmonium and Exotics

  20. Charmonium States above the DD threshold • It is extremely important • to identify as many missing states above the open charm threshold as possible • and to confirm the ones for which we only have a weak evidence. • This will require • high-statistics • small-step scans of the • entire energy region accessible at GSI. K. Peters - Charmonium and Exotics

  21. CBall E835 100 cc1 1000 CBall ev./2 MeV E 835 ev./pb ECM 3500 3510 3520 MeV Charmonium Physics • e+e- interactions: • Only 1-- states are formed • Other states only bysecondary decays (moderate mass resolution) • pp reactions: • All states directly formed(very good mass resolution) K. Peters - Charmonium and Exotics

  22. Exotics in Proton-Antiproton • Exotics are heavily produced in pp reactions • High production yields for exotic mesons (or with a large fraction of it) • f0(1500)p® ~25 % in 3p0 • f0(1500)p® ~25 % in 2hp0 • p1(1400)p® >10 % in p±p0h Crystal Barrel Interference with other well known (conventional) states is mandatory for the phase analysis K. Peters - Charmonium and Exotics

  23. p p p p G G p p H H H H _ _ _ _ _ _ p p p p M p p M M Proton-Antiproton @ Rest/Flight nng ssg/ccg • Gluon rich process creates gluonic excitation in a direct way • cc requires the quarks to annihilate (no rearrangement) • yield comparable to charmonium production • even at low momenta large exotic content has been proven • Momentum range for a survey pp® ~15 GeV • But also Glueball Formation Production all JPC available Formation only selected JPC K. Peters - Charmonium and Exotics

  24. Summary and Outlook • It’s an amazing time in charm spectroscopy • many new states – but a lot is missing for a coherent picture • What are the new DsJ states • what are their properties like width and decay channels • How do the new cc findings fit into one model • like the new X(3872) state • understand the large width of the cc groundstate hC • and the hC-y(2S) splitting • Where are gluonic excited charmonia (hybrids) • spectrum, widths and decay channels • Only high precision experiments can finallyhelp to solve the puzzle like Panda @ HESR @ GSI K. Peters - Charmonium and Exotics

  25. Accessible cc-Hadrons at PANDA • Other exotics with identical decay channels ® same region mass and phase space of recoil meson for exotic JPC included conventional charmonium K. Peters - Charmonium and Exotics

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