Triangle mechanism in the decay process $B_0\to J/\psi K^0{f}_0(980)(a_0(980))$

Abstract

The role of the triangle mechanism in the decay process $B_0\to J/\psi K^0{f}_0\to J/\psi K^0{\pi }^{+}{\pi }^{-}$ and $B_0\to J\psi K^0{a}_0\to J/\psi K^0{\pi }^0\eta$ is probed. In these process, the triangle singularity appears from the decay of $B^0$ into $J/\psi \varphi K^0$ then $\varphi$ decays into $K^0\overline{K^0}$ and $K^0\overline{K^0}$ merged into $f_0$ or $a_0$ which finally decay into ${\pi }^{+}{\pi }^{-}$ and ${\pi }^0\eta$ respectively. We find that this mechanism leads to a triangle singularity around $M_{\mathrm{inv}}(K^0{f}_0(a_0))\approx 1520\mathrm{MeV}$, and gives sizable branching fractions $\mathrm{Br}(B_0\to J/\psi K^0{f}_0\to J/\psi K^0{\pi }^{+}{\pi }^{-})=1.38\times 10^{-6}$ and $\mathrm{Br}(B_0\to J/\psi K^0{a}_0\to J/\psi K^0{\pi }^0\eta )=2.56\times 10^{-7}$. This potential investigation can help us obtain the information of the scalar meson $f_0(980)$ or $a_0(980)$.

Comments: 8 pages, 6 figures