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Physical Review D

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$χ_{c J}$ production associated with a $c \bar{c}$ pair at hadron colliders

Dan Li¹, Yan-Qing Ma², and Kuang-Ta Chao^1,2

¹Department of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, China
²Center for High Energy Physics, Peking University, Beijing 100871, China

Phys. Rev. D 83, 114037 – Published 20 June, 2011

DOI: https://doi.org/10.1103/PhysRevD.83.114037

Abstract

$χ_{c J}$ ( $J = 0$ , 1, 2) production associated with a charm quark pair in hadron collisions is calculated in the framework of nonrelativistic QCD at the Tevatron and LHC. It is found that the color-singlet contribution is small and the color-octet contribution may be dominant in the large $p_{T}$ region. The differential cross section of $p \bar{p} \to χ_{c} + c \bar{c}$ is at least 1 order of magnitude smaller than the next-to-leading order result of $χ_{c J}$ inclusive production $p \bar{p} \to χ_{c} + X$ ; therefore $χ_{c J}$ production in $p \bar{p} \to χ_{c} + c \bar{c}$ may have negligible influence on the ratio $R_{χ_{c}} = \frac{σ_{χ_{c 2}}}{σ_{χ_{c 1}}}$ measured by CDF Collaboration at the Tevatron. The feed-down contribution from $χ_{c J} + c + \bar{c}$ to $J / ψ + c + \bar{c}$ is found to be large compared with $J / ψ$ direct production and may have important influence on the measurement of $J / ψ + c + \bar{c}$ . The validity of fragmentation approximation for the process is also discussed.

Article Text

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