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'Also See:
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.
The Belle II B-factory, an upgraded facility with two orders of magnitude more luminosity, has been approved in June 2010. The design and construction work is ongoing.