Production of $\psi (2\mathrm{S})$ mesons in $p\overline{p}$ collisions at 1.96 TeV

We have measured the differential cross section for the inclusive production of $\psi (2\mathrm{S})$ mesons decaying to ${\mu }^{+}{\mu }^{-}$ that were produced in prompt or $B$-decay processes from $p\overline{p}$ collisions at 1.96 TeV. These measurements have been made using a data set from an integrated luminosity of $1.1{\mathrm{fb}}^{-1}$ collected by the CDF II detector at Fermilab. For events with transverse momentum $p_T(\psi (2\mathrm{S}))>2\mathrm{GeV}/c$ and rapidity $|y(\psi (2\mathrm{S}))|<0.6$ we measure the integrated inclusive cross section $\sigma (p\overline{p}\to \psi (2\mathrm{S})X)·\mathrm{Br}(\psi (2\mathrm{S})\to {\mu }^{+}{\mu }^{-})$ to be $3.29\pm 0.04(\mathrm{stat})\pm 0.32(\mathrm{syst})\mathrm{nb}$.

Figure 1

The projections on the invariant mass (a) and the proper decay length (b) for $5.5<p_T<6.0\mathrm{GeV}/c$. The fitted curve for total signal plus background is overlaid on the data points. The prompt (solid lines) and long-lived (dashed lines) proper time signal curves are shown separately.

Figure 2

(a) Prompt and $B$-decay production cross section distributions versus $p_T$ for these data. (b) The same data with the run I points included. We ignore differences between rapidity and pseudorapidity for this comparison. The $B$-decay points have been scaled down by a factor of 10 for clarity of display.

Figure 3

(a) The differential cross section ratio of $\psi (2\mathrm{S})$ to $J/\psi$ as a function of vector meson $p_T$ for prompt events ($R_p$) and $B$-decay events ($R_b$). The main error bar on each point is the quadrature sum of the statistical and uncorrelated systematic uncertainties for that $p_T$ bin. The extensions to the error bars show the correlated uncertainty from the luminosity. The dashed line is calculated using the prompt ratio predicted from Ref. [4] normalized to data for the $p_T$ bin covering $8–9\mathrm{GeV}/c$. (b) The ratio of $B$ decay to prompt ratios $R_b/R_p$ as a function of vector meson $p_T$. The fit to a constant gives a ${\chi }^2$ of 13 for 14 degrees of freedom.