Measurements of soft QCD and double parton scattering at LHCb

Soft QCD and double parton scattering are of great interest in high energy physics. They are both actively studied at the LHCb experiment. The measurement of the central exclusive production of $J\mathrm{/}\psi$ and $\psi (2S)$ mesons in $pp$ collisions at $\sqrt{s}=13\mathrm{T}\mathrm{e}\mathrm{V}$ is presented. The result shows good agreement with the theoretical predictions. The measurement of the $J\mathrm{/}\psi$ pair production cross-section in $pp$ collisions at $\sqrt{s} = 13 ,{$\mathrm{T}\mathrm{e}\mathrm{V}$}$ is reported. The differential cross-sections as functions of various kinematic variables are compared to the theoretical predictions, and show significant evidence of double parton scattering contribution.