Belle II

The SuperKEKB collider, situated in Tsukuba, Japan, is currently the largest e+e− collider in the world. The Belle II detector surrounds the SuperKEKB interaction point, and has been designed to make precise measurements of weak interaction parameters, study exotic hadrons, and search for new phenomena beyond the Standard Model of particle physics.

We currently hold the world record for the highest instantaneous luminosity ever achieved at a particle accelerator: 5.24434cm−2s−1 achieved on March 19, 2026. Since our last run period finished, we have accumulated a total of 763 fb-1 of data rich in beauty and charm hadrons as well as tau leptons. To see our current data-taking status, click on some links below!

Our Next Events

Here for the complete list of events

 

Documents

Recent physics publications

  • Search for the decay \(B^+\to K^+\tau^+\tau^-\) using data from the Belle and Belle II experiments [2603.24437]
  • Search for charged lepton flavor violation in \(\chi_{bJ}(1P)\) meson decays [2603.10818]
  • Study of \(e^+e^- \to \pi^+\pi^-\Upsilon(1D)\) at Belle II [2602.19807]
  • Study of \(e^{+}e^{-}\to h^{+}h^{-}J/\psi~(h=\pi,~K,~p)\) via initial-state radiation at Belle II [2602.13569]
  • Study of \( B^+\to \mu^+\nu_\mu \) decays at Belle and Belle II [2602.09800]
Here for the complete list of physics publications