Study of direct CP in charmed B decays and measurement of the CKM angle gamma at Belle

The Belle experiment, running at the KEKB e^+ e^- asymmetric energy collider during the first decade of the century, has recorded 770 fb^-1 of data at the Upsilon(4S) resonance. A combination of recent Belle results obtained with this sample is used to perform a measurement of the CKM angle gamma. We use B^+- -> DK^+- and B^+- -> D^*K^+- decays where the D meson decays into K_S^0pi+pi-, Kpi, KK, pipi, K_S^0 pi^0 and K_S^0 eta final states and D^* decays into Dpi^0 and Dgamma. Belle obtains the most precise gamma measurement to date, gamma = (68^{+15}_{-14}) degree.

KEKB Beam Collision Stability at the Picosecond Timing and Micron Position Resolution as observed with the Belle Detector

Using the Belle detector we study the characteristics of beam collisions at the KEKB 3.5 GeV $e^+$ on 8 GeV $e^-$ asymmetric energy collider. We investigate the collision timing {tip} and its $z$-coordinate along the beam axis {zip} as a function of the position of the colliding bunch in a beam train. The various {tip} and {zip} behaviors observed by Belle are attributed to beam loading effects in the radio frequency cavities that accelerate the beams with a beam abort gap. We report these results in detail and discuss the prospects for the SuperKEKB collider.