Measurement ofJ/ψProduction in Continuume+e−

Abstract

The production of J/ψ mesons in continuum e + e − annihilations has been studied with the BABAR detector at energies near the Υ (4S) resonance. The mesons are distinguished from J/ψ production in B decays through their center-of-mass momentum and energy. We measure the cross section

Next-to-next-to-leading-order radiative corrections to e+e− → χcJ + γ at B factory

“…Substituting these values into (4.1), one immediately obtains the corresponding NRQCD LDME O( 3 P J ) = 0.107 GeV 5 from BT potential model, and O( 3 P J ) = 0.186 GeV 5 from Cornell model. 4 By setting the renormalization scale µ R = √ s/2 and the NRQCD factorization scale µ Λ = m, we can express the cross sections of e + e − → χ cJ + γ as the following power series:…”

Power expansion for heavy quarkonium production at next-to-leading order in e+e− annihilation

“…The LO color octet cross section begins at order O(α 2 α s ), where it would appear with an end-point enhancement [30] at x H ∼ 1. This, however, has not been observed in the data [24][25][26][27][28][29]. We focus our study in the region x H away from 1 and thus only calculate the real contributions of the NLO short-distance coefficients.…”

“…In this work, we study the energy fraction, x H = 2E H /Q, distributions of heavy quarkonium H produced in gluon-associated processes, which only contributes at NLP up to O(α 2 α 2 s ). Note that the Belle experiment is able to separate heavy quarkonium production associated with and without cc, σ(e + e − → J/ψ + cc) and σ(e + e − → J/ψ + X cc ) [23], and that the contributions without cc are mainly gluon-associated production at Belle's energy within the NRQCD formalism [24][25][26][27][28][29]. The LO color octet cross section begins at order O(α 2 α s ), where it would appear with an end-point enhancement [30] at x H ∼ 1.…”

“…for producing a heavy quarkonium at large transverse momentum at collider energies can be expanded as a power series of 1/p 2 T , and that the leading power term and the first subleading power terms can be perturbatively factorized into infrared safe short-distance hard parts in convolution with nonperturbative but universal long-distance fragmentation functions [25,26].…”

Prompt $$J/\psi $$ photoproduction within the non-relativistic QCD framework at the CEPC

“…There are two modes of heavy quarkonium production, i.e., e + e − annihilation and γ γ collision. The J/ψ production through these two modes had been measured at B factories [12,13] and CERN LEP-II [14,15] respectively. As for the results of e + e − annihilation, NRQCD can not give congruous explanation.…”