Charmonium results from BES

Using ～14×106ψ(2S) and ～58×106J/ψ data collected at BESⅡ/BEPC,the branching fraction of ψ(2S) →Ω+Ωˉ+ is measured with about 5σ statistical significance.The Λ electric dipole and Λ decay parameter are studied using the decay J/ψ→ΛΛ→ ppˉπ+π-.Using(106±3)×106 ψ(2S) decays collected at BESⅢ/BEPCⅡ,we have obtained some interesting physics results.The branching fractions of χcJ →π0π0,ηη are measured with precision improved.The mass and width of hc(11P1) state,together with the branching fractions of Br(ψ(2S) →π0hc) and Br(hc →γηc) are the first measurements.Surprisingly,the decays of χc1 →φφ,ωω,and ωφ are firstly observed in BESⅢ data.     

Charmonium results from BES

Using ～ 14 × 10^6 ψ（2S） and ～ 58 × 10^ J/ ψ data collected at BES Ⅱ/BEPC, the branching fraction of ψ（2S）→Ω-Ω^＋ is measured with about 5a statistical significance. The A electric dipole and ∧ decay parameter are studied using the decay J/ψ →∧∧→ ppπ^＋π^-. Using （106±3）× 10^6 ψ（2S） decays collected at BESⅢ/BEPC Ⅱ, we have obtained some interesting physics results. The branching fractions of XcJ→π^0π^0, ηη are measured with precision improved. The mass and width of he（l^1P1） state, together with the branching fractions of Br（ψ（2S） →π^0hc） and Br（hc →γηc） are the first measurements. Surprisingly, the decays of Xc1→φφ, ωω, and ωφ are firstly observed in BESⅢ data.     

New experimental results in proton radioactivity

A review of experimental data obtained recently on proton-radioactive nuclei is presented. The highlights include the observation of fine structure in proton emission, for the decays of ¹³¹Eu, ¹⁴⁵Tm and ¹⁴⁶Tm, and the studies of the excited states in proton-emitting nuclei. The observation limits are extended to few nanobarns cross-sections ( ¹⁴⁰Ho, ¹⁶⁴Ir and ¹³⁰Eu) and few microsecond half-lives (e.g., ¹⁴⁵Tm). Measured decay properties for thirty-nine proton-emitting ground and isomeric states contributed to the understanding of nuclear masses and evolution of single-particle states at and beyond the proton drip line. Experimental results have stimulated new theoretical approaches to proton emission and the structure of unbound narrow resonance states. Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002 RID="a" ID="a"e-mail: rykaczew@phy.ornl.gov     

Charmonium production inB-decays

We calculate partial widths for the decay of theB-meson into all possible charmonium states and estimate the corresponding branching ratios.     

New experimental results on emission and reaction barriers

The use of the method of experimental barrier distributions is now commonplace in the interpretation of heavy-ion fusion excitation functions. The application of a similar technique to the α emission from a hot compound nucleus will be briefly discussed. Less well known than the fusion-barrier distribution is the one obtained from quasi-elastic scattering. Some details of this method will be discussed with particular emphasis on possible advantages for its exploitation with radioactive beams.     

New experimental results for particle production from nuclei

Particle production from nuclei was studied for π, p, and $\text{p}$ interactions at 20 to 150 $\text{GeV}\text{c}$ at the CERN SPS. The detector distinguishes between fast and slow particles, mainly pions and recoil protons, respectively, with a cut at a velocity v = 0.7c. Angular distributions, multiplicity distributions, and correlations were analysed. The pseudorapidity distributions of fast particles, normalized to one collision, depend only very weakly on the incoming energy and scale well with $\text{〈ν〉 =}\text{Aσ}{}_{\mathrm{<mtext>h</mtext><mtext>N</mtext>}}\text{σ}{}_{\mathrm{<mtext>h</mtext><mtext>A</mtext>}}$. This novel result is in contradiction with most of the models proposed so far. Conclusions are drawn for those models which describe hadronnucleus collisions in terms of multiple soft quark interactions. As a function of the number of observed recoil protons, the multiplicity distributions of fast particles do not obey KNO scaling. We examine whether this result is consistent with the predictions of the coherent tube model. Finally, correlations in phase space of slow and fast particles are discussed and an outlook is given for future experiments.     

Gluonia and Charmonium Decays

We discuss the search for a 1^-- gluonium state, 0, in connection with a possible solution for the so-called ρπ, K^*K puzzle in the J/φ and φ' decays. Some issues are examined. In particular, we argue that the expected most favorable process φ → ππO can have an appreciable branching ratio (say 10^-3 ~ 10^-4) only if the O has a very narrow partial decay width to ρπ (say 1 ~ 10 MeV). For the 0^-+ system we deduce a relation that BR(η'_c → h) ≈ BR (η_c → h), where h denotes an exclusive light hadronic channel. This relation may be useful for the experimental search of the yet to be confirmed q: state, for which the branching ratios of φ' → η'_c → γKKπ, γηππ, γη'ππ are estimated to be about 1 × 10^-4 if the mass of η'_c is around 3600 MeV, and this relation may also serve as a criterion to determine whether there exist anomalous decays in the η_c and η'_c system, in particular in the VV decay channels, which might be related to the 0^-+ glueball-charmonium mixing. We emphasize that the bigluonium and the trigluonium may have very different effects on these decays.     

Charmonium cross-sections and the QGP

In this contribution we summarize experimental information and theoretical results for the dissociation cross-sections of charmonium by light hadrons, which are of great importance for the identification of a quark-gluon plasma (QGP). Recent theoretical predictions for these cross-sections differ by orders of magnitude over the physically relevant energy range. The methods discussed here include a color-dipole model, meson exchange models, a quark interchange model, and QCD sum rules.Received: 30 September 2002, Published online: 22 October 2003PACS: 25.75.-q Relativistic heavy-ion collisions - 25.75.Dw Particle and resonance production     

Charmonium production at high-energy colliders

I review inclusive charmonium production at the high-energy colliders Tevatron and HERA.     

Charmonium spectroscopy —A review

A review is presented of the latest developments in the spectroscopy of charmonium.     

Frictional cooling: Latest experimental results

Frictional cooling — that is cooling a beam of very low-energetic charged particles by moderation in matter and simultaneous acceleration in an electrostatic field — has been shown to be feasible during our experiments in 1994/1995 at PSI. In agreement with our previous closed-form and Monte Carlo calculations we found a significant increase in spectral density and a decrease in the angular spread in the case of a beam of negative muons.     

Charmonium and heavy quarks: status and future perspectives

The study of the production of heavy quarks and quarkonia in ultra-relativistic heavy-ion collisions is crucial for our understanding of high-temperature QCD. In particular, quarkonia states are sensitive to the presence of a deconfined state, and the study of heavy quark propagation in the medium created in the collision gives important information on the attained parton density. In this paper, I will shortly review the main questions that can be addressed by the study of these hard probes, summarize the SPS and RHIC results presented at this Conference and outline possible developments in the field.Arrival of the final proofs: 22 July 2005PACS: 25.75.Nq     

Charmonium states in quark-gluon plasma

We discuss how the spectral changes of quarkonia at T _c can reflect the ‘critical’ behaviour of QCD phase transition. Starting from the temperature dependencies of the energy density and pressure from lattice QCD calculation, we extract the temperature dependencies of the scalar and spin-2 gluon condensates near T _c. We also parametrize these changes into the electric and magnetic condensate near T _c. While the magnetic condensate hardly changes across T _c, we find that the electric condensate increases abruptly above T _c. Similar abrupt change is also seen in the scalar condensate. Using the QCD second-order Stark effect and QCD sum rules, we show that these sudden changes induce equally abrupt changes in the mass and width of J/ψ, both of which are larger than 100 MeV at slightly above T _c.      

Charmonium and bottomonium in heavy-ion collisions

We review the present status in the theoretical and phenomenological understanding of charmonium and bottomonium production in heavy-ion collisions. We start by recapitulating the basic notion of “anomalous quarkonium suppression” in heavy-ion collisions and its recent amendments involving regeneration reactions. We then survey in some detail concepts and ingredients needed for a comprehensive approach to utilize heavy quarkonia as a probe of hot and dense matter. The theoretical discussion encompasses recent lattice QCD computations of quarkonium properties in the Quark-Gluon Plasma, their interpretations using effective potential models, inelastic rate calculations and insights from analyses of electromagnetic plasmas. We illustrate the powerful techniques of thermodynamic Green functions (T-matrices) to provide a general framework for implementing microscopic properties of heavy quarkonia into a kinetic theory of suppression and regeneration reactions. The theoretical concepts are tested in applications to heavy-ion reactions at SPS, RHIC and LHC. We outline perspectives for future experiments on charmonium and bottomonium production in heavy-ion collisions over a large range of energies (FAIR, RHIC-II and LHC). These are expected to provide key insights into hadronic matter under extreme conditions using quarkonium observables.     

Charmonium spectroscopy and decay at CLEO-c

We report recent results on charmonium spectroscopy and decay from the CLEO-c experiment at the Cornell electrompositron storage ring accelerator, CESR. Most of the results are based on the analysis of 54 pb-1 of luminosity collected at the ψ（2S） resonance, corresponding to 27 M ψ（2S） decays. We concentrate on radiative decays of ψ（2S） and J/ψ, on two-body mesonic decay of XcJ, on hadronic decay of the he, and on higher multipoles in the two-photon cascade ψ（2S）→γχcJ, XcJ→γJ/ψ.