Abstract
Based on Monte Carlo techniques, we analyze the initial state radiation (ISR) effects in prompt $\jpsi$ inclusive production at B factories. ISR enhances cross section $\sigma(e^-e^+\to\jpsi+gg+X)$ by about $15-25\%$, which is almost the same size as the QCD and relativistic correction. Moreover, ISR slightly changes $\sigma(e^-e^+\to\jpsi+c\bar{c}+X)$. The $\jpsi$ momentum spectrum in $e^-e^+\to\jpsi+gg+X$ and in $e^-e^+\to\jpsi+c\bar{c}+X$ is softer after the photon showering from the initial $e^{\pm}$ beam radiation. After combining the QCD,relativistic, and ISR corrections,a more precise theoretical result is obtained. The new result provides a more stringent constraint of the color-octet contribution to $\sigma(e^-e^+\to\jpsi+X_{\rm{non-}c\bar{c}})$.
Highlights
JHEP04(2014)182 which has been confirmed by other authors [17]
Results indicate that the effect of initial state radiation (ISR) photon shower to e−e+ → J/ψ + cc + X is small but it is large to e−e+ → J/ψ + gg + X
ISR enhances the total cross section of e−e+ → J/ψ + gg + X by a factor of 15 − 25%, which depends on the input values of the parameters
Summary
J/ψ + gg + X increases as √sdecreases near 10.6 GeV, whereas that for e−e+ → J/ψ + cc + X changes minimally as sdecreases near 10.6 GeV. We will study the ISR effect in detail by including the QCD correction and relativistic correction. The color-singlet cross section with NLO QCD correction is 0.33(0.47) pb when mc = 1.5(1.4) GeV and μ = 2mc,|R(0)|2 = 1.01 GeV3. The QED and double photon contributions enhance the cross section by 8 + 29 fb [22]. The feed-down contribution from ψ(2S) increases the cross section by a factor of 1.355, whereas that from χcJ is 21 fb [22, 32]. The small color-octet contribution is 11 fb [32]. After these combinations are completed, the prompt cross section becomes 0.51(0.71) pb [22]. The relativistic correction was performed in ref. [55], but its effect was negligible
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