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Conventional Charmonium States in Particle Physics Research

Explore the discovery, decay modes, measurements, and theoretical insights of conventional charmonium states observed in modern particle physics research. Discover the distinguishing features and production mechanisms of these states within the quark model framework.

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Conventional Charmonium States in Particle Physics Research

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  1. CONVENTIONAL CHARMONIA Section Editors BaBar: Riccardo Faccini Belle: Pavel Pakhlov Theory: Nora Brombilla

  2. Outline of the section. • 0. Introduction • Observation of new conventional charmonium states • 1.1 c(2S) • 1.2 c2 (2P) • 1.3 X(3940)/X(4160) • 1.4 X(4630) • 2. Observation of new decay modes of known charmonia • 2.1 c • 2.2 ψ(4415)  DD2 • 2.3 ψ(4040/4160)  DD, DD*, D*D* • 3. Measurements of parameters (mass, width, Br) • 3.1 c mass and width, transition FF • 3.2 J/ψ: Γee, Γtot from ISR • 3.3 c0 andc2 • 3.4 ψ(3770) mass and width • 4. Production • 4.1 in two body B-decays (interfere with B  charm) • 4.2 in ee annihilation (interfere with fragmentation) • 4.3 in gamma-gamma • 4.4 in ee annihilation at threshold (ISR) • 5. Theoretical insights From pedagogic point of view, it is better to start from “Production”

  3. Conventional charmonium • How to distinguish from exotic charmonium? • We live in the era, when any newly observed particle is by default an exotic. You need to prove that it can fit the quark model. • We are still disputing on inclusion of these states in our section: • c(2S) • c2 (2P) • X(3940) as c(3S) • X(4160) as c(4S) • X(4630) as ψ(5/6S) • do not contradict to quark model, at least qualitatively • “conventional” observation decay modes • some theorists agree that these can be conventional charmonium states

  4. Spin quarks Total momentum n2S+1LJ Radialexcitation Orbital momentum ...10 states were discovered before 1980, no one 1980-2002 J = S + L P = (–1)L+1parity C = (–1)L+Scharge conj. ...5 candidates to the standard charmonium have been observed since 2002 by BB hc have been observed by CLEO in 2003

  5. BaBar & Belle papers related to c(2S) + CLEO

  6. c(2S) M = 2654  6  8 MeV/c2  < 55 MeV M = 3630.8  3.4  1.0 MeV/c2  = 17.0  8.3  2.5 MeV • B  (KSK) K γγ (KSK) c(2S) M = 2630  12 MeV/c2 M = 3645  5.5  7.9 MeV/c2  = 22  14 MeV e+e– J/ X e+e– J/ X

  7. c(2S) parameters Mass Total width 6±12 MeV (CLEO) 17± 8 MeV (BaBar) PDG average: Γ = (14 ± 7) MeV γγ width Only CLEO result is used in PDG Absolute Br Br (c(2S)  KSKπ)= (1.9 ± 1.2) × 10− 2 Derived by PDG from BaBar measurements of Br(B+→ ηc(2S) K+) × Br(ηc(2S) → KKπ) and absolute Br( B+ → ηc(2S) K+ )

  8. c2’ in  χс2’ e+ e+ γ D γ D e– e–

  9. 2006, Belle M=393142MeV/c2 =2083MeV Helicity angle distribution consistent with J=2 J=0 disfavored 2010, BaBar M=3926.72.71.1MeV/c2 =21.36.83.6MeV Mass is 50-100 MeV lower than potential model predictions; width and Γγγare in agreement with theory

  10. X(3940) and X(4160) ine+e−→J/ D*D(*) M = 3942 ±6 MeV tot =37 ±12 MeV +7 −6 +26 −15 • decay to open charm final states like conventional charmonium • production mechanism fix C=+1 • known states produced in e+e− →J/ cc have J=0 • not seen in DD decay, exclude JPC=0++ • Plausible assignments are JPC=0–+ • X(3940) = 31S0 = ηc(3S) • X(4160) = 41S0 = ηc(4S) • For both X(3940) and X(4160) the masses predicted by the potential models are ~100250 MeV higher 6.0  X(3940) → DD* +25 −20 M= 4156 15 MeV tot = 139 21 MeV +111 − 61 5.5 X(4160) → D*D* ArXiv:0810.0358 PRL 98, 082001 X(3940) ≠ Y(3940)

  11. X(4630) ≡ Y(4660)? X(4630) in e+e–→Λc+Λc–γISR • JPC=1– – • dibaryon threshold effect or state? • the shape differs from those for light baryon-antibaryon production at threshold (ee→ΛΛ, ee→pp) • Plausible assignments are • X(4630) = ψ(5S) or ψ(6S) e+e–→Λc+Λc–γISR

  12. Observation of new decay modes DD e+e–→D(*)D(*)γISR DD* e+e–→DD2γISR B()K D*D* BR = (10.5 ± 2.4 ± 3.8)%

  13. Parameters (M, width, Br) of known charmonia Many papers: • do not need to describe the analyses (hopefully will be well described in other sections TWO-PHOTON, ) just review

  14. c parameters B(γγ)K B  K(cc) γγpp Mass Total width Absolute Br Br (c  γγ) and γγ-width Br (c KSKπ)= (8.5 ± 1.8 ) × 10− 2

  15. c transition FF tagged data tag 2< Q2<50 GeV2 Also γγ-width at Q2=0; to be included in PDG

  16. J/ψ in ISR Γtot = (93.7 ± 3.5) keV Γee = (5.57 ± 0.19) keV Similar accuracy to CLEO measurement and better than BES and χc0, χc2 in γγ

  17. ψ(3770)

  18. Production: two body B-decays Production: ee annihilation

  19. Contributors: principal authors of “observation” papers # of pages: rough estimate ~ 15 + 5 for the production

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