Doris Yangsoo Kim

11 July 2024
IDM 2024

Abstract: The Belle and Belle II experiment have collected samples of e+ e- collision data at centre-of-mass energies near the Upsilon(nS) resonances. These data have constrained kinematics and low multiplicity, which allow searches for dark sector particles in the mass range from a few MeV to 10 GeV. Using a 426/fb sample collected by Belle II, we search for a light dark photon that could explain the ATOMKI anomaly and a Z' boson that decays invisibly. Using a 711/fb sample collected by Belle, we search for B to h + invisible decays, where h is a pi, K, D, D_s, or p, and B to K a, where a is an axion-like particle.

Keyword(s): dark sector ; Belle ; Belle II
Note: 16 min + 4 min Q & A