Semi-analytical two-loop QCD corrections to e+e− → J/ψ + χcJ at B factories
- 1Southwest University
Abstract
A bstract : In this work, we compute the next-to-next-to-leading-order (NNLO) QCD corrections to the process e ⁺ e ⁻ → J / ψ + χ cJ at B factories within the NRQCD factorization framework. The helicity amplitudes are obtained via asymptotic expansions around r = 0 and r = 1, with r=16mc2/s . Our asymptotic expressions reproduce the exact numerical results with high accuracy across the kinematic range 0 ≤ r ≤ 1, achieving a relative error below 10 ⁻⁵ , which is sufficient for phenomenological applications. Notably, the large logarithmic terms are obtained analytically, and the explicit expressions established in this work provide a useful basis for further theoretical investigations.
We compute the unpolarized cross sections. The 𝒪(αs) correction is found to be large, while the 𝒪(αs2) correction for χ c 0 production amounts to 33% of the leading-order (LO) cross section, significantly reducing the scale uncertainties. For χ c 1 , the 𝒪(αs) and 𝒪(αs2) corrections correspond to 35% and − 15%, respectively. For χ c 2 , the corresponding corrections are 24% and − 38%. The large cancellation between the corrections for χ c 2 brings the NNLO cross section close to the LO prediction. Our prediction for χ c 0 is consistent with both the Belle and BaBar data within uncertainties.
We also predict the angular distribution parameters αθ J , which are independent of nonperturbative inputs. A sharp discrepancy between the theory and the Belle measurement is observed for αθ 0 , calling for further experimental and theoretical investigations. Moreover, future measurements of the angular distribution parameters for χ c 1 and χ c 2 will provide important tests of the theoretical framework.
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BibTeX
@article{liu2026semianalytical,
title = {{Semi-analytical two-loop QCD corrections to e+e− → J/ψ + χcJ at B factories}},
author = {Hao-Yang Liu and Cong Li and Wen-Long Sang},
journal = {Journal of High Energy Physics},
year = {2026},
month = oct,
doi = {10.1007/jhep10(2026)004},
url = {https://link.springer.com/10.1007/JHEP10(2026)004},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Semi-analytical two-loop QCD corrections to e+e− → J/ψ + χcJ at B factories
AU - Hao-Yang Liu
AU - Cong Li
AU - Wen-Long Sang
PY - 2026
DA - 2026/10/01
JO - Journal of High Energy Physics
DO - 10.1007/jhep10(2026)004
UR - https://link.springer.com/10.1007/JHEP10(2026)004
AB - A bstract : In this work, we compute the next-to-next-to-leading-order (NNLO) QCD corrections to the process e ⁺ e ⁻ → J / ψ + χ cJ at B factories within the NRQCD factorization framework. The helicity amplitudes are obtained via asymptotic expansions around r = 0 and r = 1, with r=16m_c^2/s . Our asymptotic expressions reproduce the exact numerical results with high accuracy across the kinematic range 0 ≤ r ≤ 1, achieving a relative error below 10 ⁻⁵ , which is sufficient for phenomenological applications. Notably, the large logarithmic terms are obtained analytically, and the explicit expressions established in this work provide a useful basis for further theoretical investigations. We compute the unpolarized cross sections. The 𝒪(α_s) correction is found to be large, while the 𝒪(α_s^2) correction for χ c 0 production amounts to 33% of the leading-order (LO) cross section, significantly reducing the scale uncertainties. For χ c 1 , the 𝒪(α_s) and 𝒪(α_s^2) corrections correspond to 35% and − 15%, respectively. For χ c 2 , the corresponding corrections are 24% and − 38%. The large cancellation between the corrections for χ c 2 brings the NNLO cross section close to the LO prediction. Our prediction for χ c 0 is consistent with both the Belle and BaBar data within uncertainties. We also predict the angular distribution parameters α_θ ^J , which are independent of nonperturbative inputs. A sharp discrepancy between the theory and the Belle measurement is observed for α_θ ^0 , calling for further experimental and theoretical investigations. Moreover, future measurements of the angular distribution parameters for χ c 1 and χ c 2 will provide important tests of the theoretical framework.
SN - 1029-8479
ER -