Triangular singularity and a possible ϕp\phi p resonance in the Λc+→π0ϕp\Lambda^+_c \to \pi^0 \phi p decay

We study the $\Lambda^+_c \to \pi^0 \phi p$ decay by considering a triangle singularity mechanism. In this mechanism, the $\Lambda^+_c$ decays into the $K^* \Sigma^*(1385)$, the $\Sigma^*(1385)$ decays into the $\pi^0 \Sigma$ (or $\Lambda$), and then the $K^* \Sigma$ (or $\Lambda$) interact to produce the $\phi p$ in the final state. This mechanism produces a peak structure around $2020$ MeV. In addition, the possibility that there is a hidden-strange pentaquark-like state is also considered by taking into account the final state interactions of $K^* \Lambda$, $K^* \Sigma$, and $\phi p$. We conclude that it is difficult to search for the hidden-strange analogue of the $P_c$ states in this decay. However, we do expect nontrivial behavior in the $\phi p$ invariant mass distribution. The predictions can be tested by experiments such as BESIII, LHCb and Belle-II.Comment: 7 pages, 3 figure

Role of the possible Σ∗(12−)\Sigma^*(\frac{1}{2}^-) state in the Λp→Λpπ0\Lambda p \to \Lambda p \pi^0 reaction

The $\Lambda p \to \Lambda p \pi^0$ reaction near threshold is studied within an effective Lagrangian method. The production process is described by single-pion and single-kaon exchange. In addition to the role played by the $\Sigma^*(1385)$ resonance of spin-parity $J^P = 3/2^+$, the effects of a newly proposed $\Sigma^*$ ($J^P = 1/2^-$) state with mass and width around $1380$ MeV and $120$ MeV are investigated. We show that our model leads to a good description of the experimental data on the total cross section of the $\Lambda p \to \Lambda p \pi^0$ reaction by including the contributions from the possible $\Sigma^*(\frac{1}{2}^-)$ state. However, the theoretical calculations by considering only the $\Sigma^*(1385)$ resonance fail to reproduce the experimental data, especially for the enhancement close to the reaction threshold. On the other hand, it is found that the single-pion exchange is dominant. Furthermore, we also demonstrate that the angular distributions provide direct information of this reaction, hence could be useful for the investigation of the existence of the $\Sigma^*(\frac{1}{2}^-)$ state and may be tested by future experiments.Comment: 8 pages, 5 figure

Implication the observed ψ(3770)→ppˉπ0\psi(3770)\to p\bar{p}\pi^0 for studying the ppˉ→ψ(3770)π0p\bar{p}\to \psi(3770)\pi^0 process

We study the charmonium $p \bar{p} \to \psi(3770) \pi^0$ reaction using effective lagrangian approach where the contributions from well established $N^*$ states are considered, and all parameters are fixed in the process of $e^+e^- \to p \bar{p}\pi^0$ at center of mass energy $\sqrt{s} = 3.773$ GeV. The experimental data on the line shape of the mass distribution of the $e^+e^- \to p\bar{p}\pi^0$ can be well reproduced. Based on the studying of $e^+e^- \to p \bar{p}\pi^0$, the total and differential cross sections of the $p \bar{p} \to \psi(3770) \pi^0$ reaction are predicted. At the same time we evaluated also the cross sections of the $p \bar{p} \to \psi(3686) \pi^0$ reaction. It is shown that the contribution of nucleon pole to this reaction is largest close to the reaction threshold. However, the interference between nucleon pole and the other nucleon resonance can still change the angle distributions significantly. Those theoretical results may be test by the future experiments at \overline{\mbox{P}}ANDA.Comment: 8 pages, 10 figures, and 4 tables. More discussions added and typos corrected. Accepted by Eur. Phys. J.