Next-to-Leading-Order QCD Correction toe+e−→J/ψ+ηcats=

Abstract

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.

Relativistic corrections to the exclusive decays ofC-even bottomonia intoS-wave charmonium pairs

“…[8] based on the LC formula are greater than our final results Γ that include resummation of relativistic corrections to all orders in v 2n c . 11 For χ b0 → η 1 + η 2 , the LC results are greater than ours by factors ranging from 2 to 5. Especially, in the case of χ b2 → η 1 + η 2 , the LC results are greater than ours by factors ranging from 45 to 90.…”

“…[1,9]. 11 While we list only the central values of our predictions in Table. II, the authors of Ref. [8] have provided the results with uncertainties that are huge.…”

“…We know that the problem has been resolved within the NRQCD factorization formula in combination with the NLO corrections in α s [11] and the resummation of relativistic corrections [10] within errors.…”

The leading twist light-cone distribution amplitudes for the S-wave and P-wave quarkonia and their applications in single quarkonium exclusive productions

“…Especially, the attempts in [23,24] open a way to connect the predictions of hard quarkonium exclusive productions within the collinear factorization directly to those made within the NRQCD factorization (for examples, the many theoretical calculations based on NRQCD factorizations [25][26][27][28][29][30][31][32][33][34][35][36][37][38], triggered by the recent experimental measurements of charmonium exclusive productions at B-factories [39][40][41]). In particular, in [42,43], the authors have shown that the collinear factorization indeed can reproduce the exact asymptotic behavior of NRQCD predictions at the leading logarithms (LL) and next-toleading order (NLO) of the strong coupling α s , respectively, for a certain class of the quarkonium exclusive productions, if one employs the leading twist LCDAs calculated in [24]; and the ERBL equations can be used to resum the large logarithms appearing the NRQCD factorization calculations for the exclusive quarkonium productions, while such resummation cannot be done within the NRQCD factorization.…”

Which hadronic decay modes are good forηbsearching: DoubleJ/ψor something else?

“…Heavy b and c quark masses set hard scales so that we can confidently utilize pQCD to tackle this decay process, expecting those nonperturbative contributions plaguing the decay η c → V V play an insignificant role here. Since each involved particle is a heavy quarkonium, we work with the color-singlet model, in line with the calculation done for double charmonium production at e + e − colliders [25,26,27,28,29,30,31]. It is found that at the lowest order in α s , retaining the transverse momentum of c inside J/ψ is vital to obtain a non-vanishing result, and consequently, the correct asymptotic behavior of the hadronic decay branching ratio is α 2 s v 10 c (m c /m b ) 8 (v c stands for the typical velocity of c in J/ψ).…”