Search for the $X(4140)$ state in $B^+\to J/\psi\phi K^+$ decays
- Aaij, R et al
- arXiv:1202.5087CERN-PH-EP-2012-004LHCB-PAPER-2011-033
| \small Mass distribution for $\bujphik$ candidates in the data after the $\pm15$~MeV $\phi$ mass requirement. The fit of a Gaussian signal with a quadratic background (dashed line) is superimposed (solid red line). |
| \small Invariant $M(K^+K^-)$ mass distribution selecting $\bujkkk$ events in the $\pm2.5\,\sigma$ region around the $B^+$ mass peak. The dashed line shows the two-body phase-space contribution. The small blue dotted $\phi$ peak on top of it illustrates the amount of the background $\phi$ mesons estimated from the fit to the $B^+$ mass near-sidebands. |
| \small Distribution of the mass difference $M(\jpsi\phi)-M(\jpsi)$ for the $\bujphik$ in the $B^+$ ($\pm2.5\,\sigma$) and $\phi$ ($\pm15$~MeV) mass windows. Fit of $X(4140)$ signal on top of a smooth background is superimposed (solid red line). The dashed blue (dotted blue) line on top illustrates the expected $X(4140)$ ($X(4274)$) signal yield from the CDF measurement \cite{CDF}. The top and bottom plots differ by the background function (dashed black line) used in the fit: (a) an efficiency-corrected three-body phase-space ($\funone$); (b) a quadratic function multiplied by the efficiency-corrected three-body phase-space factor ($\funtwo$). The fit ranges are 1030--1400 and 1020--1400~MeV, respectively. |
| \small Efficiency dependence on $M(\jpsi\phi)-M(\jpsi)$ as determined from the simulation (points with error bars). The efficiency is normalized with respect to the efficiency of the $\phi$ signal fit to the $\bujphik$ events distributed according to the phase-space model. A cubic polynomial was fitted to the simulated data (superimposed). |