Search for the exotic states at Belle

Abstract

We review recent results on charmonium-like exotic states from the Belle experiment. The two-photon process $γγ\to ϕ\jpsi$ is measured to search for Y(4140). No signal for the $Y(4140) \to ϕ\jpsi$ is observed. But a narrow peak with a significance of 3.2$\sigma$ deviations including systematic uncertainty is observed at 4350.6 MeV/$c^2$ that we named X(4350). We also search for charmonium-like states, including X(3872), Y(4140), X(3915) and X(4350), in ${\rm Y}(1S)$ and ${\rm Y}(2S)$ radiative decays. No significant signal of any charmonium-like state is observed. The processes $\gamma \gamma \to VV$ ($V=\omega$ or $\varphi$) are also measured to search for the possible exotic states in low mass region. There are clear resonant structures in all the decay modes.

4 pages, 2 figures. Contribution to KMI Inauguration Conference "Quest for the Origin of Particles and the Universe" (KMIIN), 24-26 Nov. 2011, KMI, Nagoya University