The Belle B Factory experiment, which began in 1999 with the aim of elucidating the origin of particle-anti-particle symmetry breaking (CP violation), has contributed to the Nobel Prize in Physics in 2008 awarded to Drs. Kobayashi and Maskawa. Moreover, data obtained from electron–positron collisions with the world’s highest luminosity achieved at the KEKB accelerator have resulted in a series of unexpected discoveries of exotic hadrons, opening a new research frontier in particle physics. Data taking at the Belle Experiment has already been completed, but a vast amount of data is still awaiting detailed analysis. Moreover, an upgraded version of the KEKB/Belle Experiment, called SuperKEKB/Belle II is currently being prepared. Belle II aims to collect 50 times more data than the earlier experiment……… See: Belle Discovers New Heavy ‘Exotic Hadrons’
The Belle experiment is a particle physics experiment conducted by the Belle Collaboration, an international collaboration of more than 400 physicists and engineers investigating CP-violation effects at the High Energy Accelerator Research Organisation (KEK) in Tsukuba, Ibaraki Prefecture, Japan
The Belle detector, located at the collision point of the e−e+ asymmetric-energy collider (KEKB), is a multilayer particle detector. Its large solid angle coverage, vertex location with precision on the order of tens of micrometres (provided by a silicon vertex detector), good pion–kaon separation at the momenta range from 100 MeV/c till few GeV/c (provided by a novel Cherenkov detector), and few-percent precision electromagnetic calorimetry (CsI(Tl) scintillating crystals) allow for many other scientific searches apart from CP-violation. Extensive studies of rare decays, searches for exotic particles and precision measurements of B mesons, D mesons, and tau particles have been carried out and have resulted in almost 300 publications in physics journals.
Highlights of the Belle experiment so far include
- the first observation of CP-violation outside of the kaon system (2001)
- observation of: and
- measurement of ϕ3 using the Dalitz plot
- measurement of the CKM quark mixing matrix elements | Vub | and | Vcb |
- observation of direct CP-violation in and
- observation of transitions
- evidence for
- observations of a number of new particles including the X(3872)
The Belle experiment operated at the KEKB accelerator, the world’s highest luminosity machine. The instantaneous luminosity exceeded 2.11×1034 cm−2·s−1. The integrated luminosity collected at the ?(4S) resonance mass is ~710 fb−1 (corresponds to 771 million BB meson pairs). Most data is recorded on the ?(4S) resonance, which decays to pairs of B mesons. About 10% of the data is recorded below the ?(4S) resonance in order to study backgrounds. In addition, Belle has carried out special short runs at the ?(5S) resonance to study B
s mesons as well as on the ?(3S) resonance to search for evidence of Dark Matter and the Higgs Boson.