Figure 1

Examples of fit to the OS dimuon invariant mass distribution in the mass region $2 < m_{\mu^{+}\mu^{-}} < 5$ GeV/$c^{2}$ for $\pt < 20$ GeV/$c$ (left), and $7< m_{\mu^{+}\mu^{-}} < 13$ GeV/$c^{2}$ for $\pt < 15$ GeV/$c$ (right). The J/$\psi$, $\psi$(2S) and $\Upsilon$(nS) signals are modelled with extended Crystal Ball functions, while the background is described by a pseudo Gaussian with a width increasing linearly with the invariant mass. The fit is performed on the full data sample. The widths of the $\psi$(2S) , $\Upsilon$(2S) and $\Upsilon$(3S), for these examples, are fixed to 73 MeV/$c^2$, 156 MeV/$c^2$ and 161 MeV/$c^2$, respectively.