# The 2009 Europhysics Conference on High Energy Physics

Jul 16 – 22, 2009
Kraków, Poland
Europe/Warsaw timezone

## Light particle searches at Belle

Jul 16, 2009, 4:30 PM
20m
Exhibition room B (Kraków, Poland)

### Exhibition room B

#### Kraków, Poland

The Auditorium Maximum of the Jagiellonian University 33 Krupnicza Street 31-123 Kraków

Chao Liu (USTC)

### Description

We report on a search for the $X(1812)$ state in the decay $B^\pm \to K^\pm \omega \phi$ with a data sample of $657\times 10^6$ $B\bar{B}$ pairs collected with the Belle detector at the KEKB $e^+e^-$ collider. No significant signal is observed. An upper limit ${\cal B}(B^\pm \to K^\pm X(1812)$, $X(1812) \to \omega \phi) < 3.2\times 10^{-7}$ (90\% C.L.) is determined. We also constrain the three-body decay branching fraction to be ${\cal B}(B^\pm \to K^\pm \omega \phi) < 1.9 \times 10^{-6}$ (90\% C.L.). We also report on a search for a low mass particle with a mass of 214.3 MeV/$c^{2}$ reported by the HyperCP experiment at Fermilab. For this search we use the following decay modes: $B^{0}\to K^{-}\pi^{+}X^{0}$, $X^{0}\to \mu^{+}\mu^{-}$; $B^{0}\to \pi^{-}\pi^{+}X^{0}$, $X^{0}\to \mu^{+}\mu^{-}$; $B^{0}\to K^{*0} X^{0}$, $K^{*0}\to K^{+}\pi^{-}$, $X^{0}\to \mu^{+}\mu^{-}$; and $B^{0}\to \rho^{0} X^{0}$, $\rho^{0}\to \pi^{+}\pi^{-}$, $X^{0}\to \mu^{+}\mu^{-}$, where $X^{0}$ is a pseudo-scalar particle with mass of 214.3 MeV/$c^{2}$. We finally report a search for the $X(1835)$ state via $e^+ e^- \to J/\psi X(1835)$ process with a data sample of 673 fb$^{-1}$ collected on and off $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. As no significant signal is found for $e^+ e^- \to J/\psi X(1835)$ production, we measure an upper limit on its cross-section $\sigma_{Born}[e^+ e^- \to J/\psi X(1835)] \times [Br(X(1835) \to >2charged)]$.

Chao Liu (USTC)

 Slides