Belle II is an ongoing experiment operating the SuperKEKB electron-positron collider located in Tsukuba, Japan. Belle II is the successor of the previous Belle experiment. Belle was built as a B-factory experiment focusing on B-meson studies. Belle also experimentally confirmed the existence of three quark generations (Nobel Prize in 2008).

The physics at B-factories is not limited to B-mesons studies, Belle & Belle II have also collected a large D-meson and tau lepton sample. Thanks to the ideal environment at Belle II we can reconstruct the particle with very high precision, including the missing energy reconstruction.

Our group participates in various physics analyses at Belle & Belle II, data calibration and correction, as well as detector development and testing.

Physics topics within our group include CP violation studies, search for invisible particles in B decays and precision measurements in the tau sector.

We contribute to the Belle II software development and maintenance, data calibration and correction factors estimation.

Our team also develops silicon pixel and strip sensors for the Belle II detector, testing the sensors in lab and developing detector simulation and analysis software.

Contacts:

• Zdeněk Doležal
• Peter Kodyš

Publications:

[1] Belle II Collaboration, Evidence for 𝐵⁺→𝐾⁺⁢𝜈⁢𝜈 decays, Phys. Rev. D 109, 112006 (2024).

[2] Belle II Collaboration, Measurement of the 𝜏-lepton mass with the Belle II experiment, Phys. Rev. D 108, 032006 (2023).

[3] Belle II Collaboration, Test of light-lepton universality in τ decays with the Belle II experiment, J. High Energ. Phys. 2024, 205 (2024).