Tuesday, February 19, 2013

1302.4282 (Zhan Sun et al.)

Heavy Quarkonium Production through the Semi-Exclusive $e^+ e^-$
Annihilation Channels around the $Z^0$ Peak
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Zhan Sun, Xing-Gang Wu, Gu Chen, Jun Jiang, Zhi Yang
Within the non-relativistic QCD framework, we make a detailed discussion on the heavy quarkonium production at a high luminosity $e^+ e^-$ collider around the $Z^0$ peak, which are produced through the semi-exclusive channels $e^{+}e^{-} \rightarrow |H_{Q\bar{Q}}> +X$ with $X=Q\bar{Q}$ or $gg$ and $Q=b$ or $c$, respectively. In addition to the color-singlet 1S-level quarkonium states, the color-singlet quarkonium states at the 2S-level and the 1P-level, and the color-octet quarkonium state $|(Q\bar{Q})[(1^3S_1^{\bf (8)})]g>$ can also provide sizable contributions. The heavy quarkonium transverse momentum and rapidity distributions for the $e^+ e^-$ collision energy $E_{cm}=m_Z$ are presented. For the charmonium or bottomonium production channels via the $Z^0$ propagator, there is approximate "spin degeneracy" for the spin-triplet and spin-singlet quarkonium states. Uncertainties for the total cross sections are predicted by taking $m_c=1.50\pm0.15$ GeV and $m_b=4.90\pm0.15$ GeV. Around $E_{cm}=m_{Z}$, due to the $Z^0$-boson resonance effect, total cross sections become much larger for the production processes via the $Z^0$ propagator. Then, in addition to the $B$ factories as BABAR and Belle and the hadronic colliders as Tevatron and LHC, such a super $Z$-factory shall provide an excellent platform for studying the heavy quarkonium properties.
View original: http://arxiv.org/abs/1302.4282

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