English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

The exclusive production of double excited quarkonium is comprehensivestudied, i.e., the production of double excitedcharmonium, double excitedbottomonium, and double excited $Bc$-mesons via $e^+e^-\to \gamma^*/Z^0\to|(Q\bar{Q'})[n]\rangle +|(Q'\bar{Q})[n']\rangle$ ($Q/Q'=c$- or $b$-quarks)at a future $Z$ factory under the nonrelativistic quantum chromodynamicsframework, where the $[n]$~/$[n']$ represents the color-singlet heavyquarkonium states $[^1S_0]\rangle, ~[^3S_1]\rangle, ~[^1P_1]\rangle$, and$[^3P_J]\rangle$ ($J=0,1,2$). The "improved trace technology" is adopted forcalculating the complicated $P$-wave channels for derive the analyticexpressions at the amplitude level. According to our study, the productionrates of double heavy quarkonium are considerable at the future $Z$ factory. Weobtain the cross sections for the production of double excited charmonium for$\sigma{(|(c\bar{c})[n]\rangle+|(c\bar{c})[n']\rangle)_{total}}=1.167^{+0.113}_{-0.164}\times10^{-2}~fb$, the cross sections of double excited bottomonium for$\sigma{(|(b\bar{b})[n]\rangle+|(b\bar{b})[n']\rangle)_{total}}=0.1132^{+0.0139}_{-0.0130}~fb$,and the cross sections of double excited $Bc$-mesons for$\sigma{(|(c\bar{b})[n]\rangle+|(b\bar{c})[n']\rangle)_{total}}=3.692^{+0.124}_{-0.097}~fb$.The main uncertainties come from the mass of the heavy quarkonium and theradial wave functions at the origin and their derivatives at the origin underdifferent potential models. The numerical results show that such the super $Z$factory should be a good platform to study the properties of the double excitedcharmonium, the double excited bottomonium , especially the double excited$Bc$-mesons.

Production double heavy quarkonium via $e^+e^-\to \gamma^*/Z^0 \to|(Q\bar{Q'})[n]\rangle +|(Q'\bar{Q})[n']\rangle$ at Z mass pole