Results on ${\varphi }_2$ from Belle

Abstract

We present a summary of measurements sensitive to the CKM angle ${\varphi }_2$, performed by the Belle experiment using the final data sample of $772\times 10^6$ $B\bar{B}$ pairs produced at the ${\rm Y}(4S)$ resonance at the KEK asymmetric $e^{+}{e}^{-}$ collider. We discuss $CP$ asymmetries from the decay $B^0\to {\pi }^{+}{\pi }^{-}$ and briefly mention a preliminary measurement of the branching fraction of $B\to {\pi }^0{\pi }^0$ decays. Furthermore the measurement of the branching fraction of $B^0\to {\rho }^0{\rho }^0$ decays and fraction of longitudinal polarization in this decay is presented. We use the results to constrain ${\varphi }_2$ with isospin analyses in the $B\to \pi \pi$ and $B\to \rho \rho$ systems.

Proceedings of the 8th International Workshop on the CKM Unitarity Triangle (CKM 2014), Vienna, Austria, September 8-12, 2014