Measurement of the production cross-section of $\psi (2S)\to J\mathrm{/}\psi (\to {\mu }^{+}{\mu }^{-}){\pi }^{+}{\pi }^{-}$ in $pp$ collisions at $\sqrt{s}=7$ TeV at ATLAS

The prompt and non-prompt production cross-sections for $\psi (2S)$ mesons are measured using 2.1 fb${}^{-1}$ of $pp$ collision data at a centre-of-mass energy of 7 TeV recorded by the ATLAS experiment at the LHC. The measurement exploits the $\psi (2S)\to J\mathrm{/}\psi (\to {\mu }^{+}{\mu }^{-}){\pi }^{+}{\pi }^{-}$ decay mode, and probes $\psi (2S)$ mesons with transverse momenta in the range $10\le p_T<100$ GeV and rapidity $\mathrm{\mid }y\mathrm{\mid }<2.0$. The results are compared to other measurements of $\psi (2S)$ production at the LHC and to various theoretical models for prompt and non-prompt quarkonium production.