Search for the Exotic Meson $X(5568)$ with the Collider Detector at Fermilab

A search for the exotic meson $X(5568)$ decaying into the $B_s^0{\pi }^{\pm }$ final state is performed using data corresponding to $9.6{\mathrm{fb}}^{-1}$ from $p\overline{p}$ collisions at $\sqrt{s}=1960\mathrm{GeV}$ recorded by the Collider Detector at Fermilab. No evidence for this state is found and an upper limit of 6.7% at the 95% confidence level is set on the fraction of $B_s^0$ produced through the $X(5568)\to B_s^0{\pi }^{\pm }$ process.

Figure 1

Distribution of $J/\psi \varphi$ mass for $p_T>10\mathrm{GeV}/c$ with the fit overlaid on the histogram. The $B_s^0$ signal region is highlighted in gray. Areas used to define backgrounds based on the mass sidebands are indicated in black.

Figure 2

Distribution of $B_s^0{\pi }^{\pm }$ mass where the candidates within $21.6\mathrm{MeV}/c^2$ of the $X(5568)$ are omitted. The background model is overlaid in a solid line, where the line width indicates $\pm \sigma$ variations on the background model due to variations in the assumption for the $X(5568)$ signal amplitude. Dashed curves indicate the signal components used to obtain the background model and its variations.

Figure 3

Distribution of $B_s^0{\pi }^{\pm }$ mass for $p_T(B_s^0)>10\mathrm{GeV}/c$, for candidates in the $B_s^0$ mass range and for the mass sidebands, as indicated. The fit to the data with a freely floating (null) signal is overlaid in a solid (dashed) line.