Speaker
Description
$\eta_c$ production at the LHC and indications on the understanding of $J/\psi$
Summary
We present a complete evaluation for the prompt $\eta_c$ production at the LHC at NLO in $\alpha_s$ within the framework of NRQCD factorization formula. By assuming heavy quark spin symmetry, the recently observed $\eta_c$ production data by LHCb results in a very strong constraint on the upper bound of the color-octet long distance matrix element $\langle\mathcal{O}^{J/\psi}(\bigl.^1\hspace{-1mm}S_0^{[8]})\rangle$ of $J/\psi$. We find this upper bound is consistent with our previous study of the $J/\psi$ yield and polarization and can give good descriptions for the measurements. This may provide important information for understanding the nonrelativistic QCD factorization formulism.
