# The 2009 Europhysics Conference on High Energy Physics

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

## Charm decays at Belle

Jul 17, 2009, 11:15 AM
15m
Large (Kraków, Poland)

### Large

#### Kraków, Poland

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

### Speaker

Eunil Won (Korea University)

### Description

Dalitz plot analysis of the decay $D^0 \to \pi^+\pi^-\pi^0$ We report preliminary results of the Dalitz plot analysis of the decay $D^0 \to \pi^+\pi^-\pi^0$ using a 532 fb$^{-1}$ data sample collected with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. The fit model includes the intermediate vector resonances $\rho(770)$, $\omega$, $\rho(1450)$, and $\rho(1700)$, the scalar states $\sigma(600)$, $f_0(980)$, $f_0(1370)$, and $f_0(1500)$ as well as the tensor state $f_2(1270)$. The asymmetry between the two flavour samples - $D^0$ and $\bar D^0$ - has been also estimated. Search for $D^0$ leptonic decays with Belle We present a search for the rare $D^0$ leptonic decays, $D^0 \to e^+ e^-$, $\mu^+ \mu^-$, and the decays $D^0 \to e^+ \mu^-$ which are forbidden in the Standard Model. Limits on the branching fractions for these decays are obtained using the well measured $D^0 \to \pi^+ \pi^-$ decay channel for normalization. The search is performed using a large sample of $D^0$ decays recorded by the Belle experiment corresponding to an integrated luminosity of 660 fb$^{-1}$. Study of $D^+_{(s)}$ decays to $K_S \pi^+$ and $K_S K^+$ Using 605 fb$^{-1}$ of data collected by the Belle detector at the KEKB asymmetric energy $e^+ e^-$ collider, we study the decays of $D^+_{(s)}$ mesons to $K_S \pi^+$ and $K_S K^+$ final states. We report branching fractions normalized with respect to Cabibbo-favored modes, $\Gamma(D^+ \to K_S K^+)$/$\Gamma(D^+ \to K_S \pi^+)$ and $\Gamma(D^+_s \to K_S \pi^+)$/$\Gamma(D^+_s \to K_S K^+)$. Study of $\eta_c^{(')}$ properties in $B \to \eta_c^{(')}K$ decays Reconstructed $B$ decays to a charged kaon and an $\eta_c$-type charmonium from a data sample of 535 million $B \bar B$ meson pairs collected in the Belle experiment at the KEKB $e^+ e^-$ collider have been used to study properties of the $\eta_c$ and its first excitation, the $\eta_c(2S)$. We use the decay mode $K_S K \pi$ to study the effects of interference between charmonium signal and $B$ decays into the same final state without an intermediate charmonium. Taking this interference into account we obtain masses, widths, and decay branching fractions of the $\eta_c$ and $\eta_c(2S)$ mesons. The results agree with the world average values; for the first time, interference effects are taken into account. Measurement of the inclusive decay $D^0 \to \phi X$ and of exclusive decays of the $D^0$ particle involving a $K^+K^-$ pair Using data collected by the Belle detector at the KEKB storage ring and applying a novel method of completely reconstructing events up to a $D^0$, with a $K^+K^-$ pair "left over", the branching fraction of the inclusive decay of $D^0 \to \phi X$ has been measured with high precision. In addition, the exclusive branching fraction $D^0 \to K^+K^-$ has been determined with good precision. Furthermore various branching fractions of $D^0$ decays involving a $K^+K^-$ pair have been measured for consistency: $D^0 \to (K^+K^-K^0)_{nonres}, \phi K^0, K^+K^-\pi^0, \phi(K^+K^-)\pi^0, and$\phi(K^+K^-)\omega^0$. Results presented in the study are preliminary. Observation of the doubly Cabibbo-suppressed decay$D_s^+ \to K^+ K^+ \pi^-$We report the first observation of the doubly Cabibbo-suppressed decay$D^+_s\to K^+K^+\pi^-$using 605 fb$^{-1}$of data collected with the Belle detector at the KEKB asymmetric-energy$e^+e^-$collider. The branching ratio with respect to its Cabibbo-favored counterpart$\mathcal{B}(D^+_s\to K^+K^+\pi^-)$/$\mathcal{B}(D^+_s\to K^+K^-\pi^+)$is (0.229$\pm0.028\pm$0.012)%, where the first uncertainty is statistical and the second is systematic. We also report a new, more precise measurement of the doubly Cabibbo-suppressed decay$D^+\to K^+\pi^+\pi^-$, with a branching ratio$\mathcal{B}(D^+\to K^+\pi^+\pi^-)$/$\mathcal{B}(D^+\to K^-\pi^+\pi^+)$=(0.569$\pm0.018\pm\$0.014)%.

### Primary author

Eunil Won (Korea University)

 Slides