Amplitude Analysis of Singly Cabibbo-Suppressed Decay $Λ^{+}_{c}\to p K^{+} K^{-}$

Abstract

Using a sample of $e^{+}e^{-}$ annihilation data corresponding to an integrated luminosity of 4.4 $\rm{fb}^{-1}$ collected with the BESIII detector at the BEPCII collider and produced at center-of-mass energies from $4600$ to $4698~\rm{MeV}$, an amplitude analysis is performed of the singly Cabibbo-suppressed decay $Λ^{+}_{c}\to pK^{+}K^{-}$. The branching fractions of $Λ^{+}_{c}\to pφ(1020)$, $pf_{0}(980)$, $Λ(1405)K^{+}$, and $Λ(1670)K^{+}$ are measured, where the latter two modes are decays that are observed for the first time. At the same time, with the detection efficiency based on the results of the amplitude analysis, the branching fraction of $Λ^{+}_{c}\to pK^{+}K^{-}$ is updated to be $(9.94\pm0.65_{\text{stat.}}\pm0.50_{\text{syst.}})\times10^{-4}$, which is consistent with the current world average value within one standard deviation. The result supersedes the previous BESIII measurement with precision improved by approximately a factor of 1.5.

Figures (4)

• Figure 1: Feynman diagrams of $\Lambda^{+}_{c}\to pK^{+}K^{-}$ via internal W-emission (a), $\Lambda^{+}_{c}\to pK^{+}K^{-}$ via W-exchange (b), and $\Lambda^{+}_{c}\to p\phi(1020)$ via internal W-emission (c).
• Figure 2: Fit to the $M_{\text{BC}}$ distribution of the accepted candidates for $\Lambda^+_c\to pK^+K^-$ at $4600\,{\rm MeV}$. The black dots with error bars represent the data, and the blue-shaded region indicates the combinatorial background. $|\Delta E| < 0.02~\rm{GeV}$ is applied in this figure.
• Figure 3: Definition of the helicity frame for $e^{+}e^{-}\to\Lambda^{+}_{c}\bar{\Lambda}^{-}_{c}, \Lambda^{+}_{c}\to \Lambda^{*}K^{+}$.
• Figure 4: Projections of the amplitude fit results on the $M_{K^{+}K^{-}}$, $M_{pK^{-}}$, and $M_{pK^{+}}$ spectra. The points with error bars are weighted data at all energy points. Different colored curves represent different components, as shown in the legend.