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One of the most challenging open problems in heavy quarkonium physics is the double charm production in e + e − annihilation at B factories. The measured cross section of e + e − → J/ψ + ηc is much larger than leading order (LO) theoretical predictions. With the nonrelativistic QCD factorization formalism, we calculate the next-to-leading order (NLO) QCD correction to this process. Taking all one-loop self-energy, triangle, box, and pentagon diagrams into account, and factoring the Coulomb-singular term into the cc bound state wave function, we get an ultraviolet and infrared finite correction to the cross section of e + e − → J/ψ + ηc at √ s = 10.6 GeV. We find that the NLO QCD correction can substantially enhance the cross section with a K factor (the ratio of NLO to LO ) of about 1.8-2.1; hence it greatly reduces the large discrepancy between theory and experiment.With mc = 1.4GeV and µ = 2mc, the NLO cross section is estimated to be 18.9 fb, which reaches to the lower bound of experiment.

With nonrelativistic QCD factorization, we present a full next-to-leading order computation of the polarization observable for J/ψ production at hadron colliders including all important Fock states, i.e., 3S(1)([1,8]), 1S(0)([8]), and 3P(J)([8]). We find the 3P(J)([8]) channel contributes a positive longitudinal component and a negative transverse component, so the J/ψ polarization puzzle may be understood as the transverse components canceling between the 3S(1)([8]) and 3P(J)([8]) channels, which results in mainly the unpolarized (even slightly longitudinally polarized) J/ψ. This may give a possible solution to the long-standing J/ψ polarization puzzle. Predictions for J/ψ polarization at the LHC are also presented.

In order to clarify the puzzling problems in double charm production, relativistic corrections at order v 2 to the processes e + e − → J/ψ + η c and e + e − → J/ψ + cc at B factories are studied in non-relativistic quantum chromodynamics. The short-distance parts of production cross sections are calculated perturbatively, while the long-distance matrix elements are estimated from J/ψ and η c decays up to errors of order v 4 . Our results show that the relativistic correction to the exclusive process e + e − → J/ψ + η c is significant, which, when combined together with the next-toleading order α s corrections, could resolve the large discrepancy between theory and experiment; whereas for the inclusive process e + e − → J/ψ + cc the relativistic correction is tiny and negligible.The physical reason for the above difference between exclusive and inclusive processes largely lies in the fact that in the exclusive process the relative momentum between quarks in charmonium substantially reduces the virtuality of the gluon that converts into a charm quark pair, but this is not the case for the inclusive process, in which the charm quark fragmentation c → J/ψ + c is significant, and QCD radiative corrections can be more essential.

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To clarify the outstanding problem in charmonium production that existing theories cannot explain the observed cross sections of cJ ðJ ¼ 0; 1; 2Þ and ratio R c ¼ c2 = c1 % 0:75 (in contrast to the spin counting value 5=3) at the Tevatron, we study the complete next-to-leading order radiative corrections in nonrelativistic QCD, and find next-to-leading order contributions of 3 P ½1 J are more important than leading order at high p T , and 3 P ½1 1 decreases slower than 3 P ½1 2 , implying a natural explanation for the R c puzzle. By fitting R c , the predicted cross sections of cJ are found to agree with data. The result indicates coloroctet contribution is crucially needed, thus providing a unique test for heavy quarkonium production mechanisms. Feed-down contributions of cJ to prompt J=c production are estimated to be substantial, about 30%-40% at p T ¼ 20 GeV. Production of cJ ðJ ¼ 0; 1; 2Þ at the LHC is also predicted.

We employ a quark model with ingredients suggested by quantum chromodynamics to study strangeness -2 and -3 resonances. Predictions of the spectrum and decay couplings of such states are made based on previous studies of the nonstrange and strangeness -1 sectors.

The inclusive J/psi production in e;{+}e;{-}-->J/psicc at B factories is one of the most challenging open problems in heavy quarkonium physics. The observed cross section of this double-charm production process is larger than existing leading order (LO) QCD predictions by a factor of 5. In the nonrelativistic QCD (NRQCD) factorization formalism, we calculate the next-to-leading order (NLO) QCD virtual and real corrections to this process, and find that these corrections can substantially enhance the cross section with a K factor of about 1.8. We further take into account the feeddown contributions from higher charmonium states [mainly the psi(2S) as well as chi_{cJ}] and the two-photon contributions, and find that the discrepancy between theory and experiment can be largely removed.