Belle experiment

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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 pionkaon 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 using the Dalitz plot
  • measurement of the CKM quark mixing matrix elements and
  • 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
ϒ
(4S)
resonance mass is ~710 fb−1 (corresponds to 771 million
B

B
meson pairs). Most data is recorded on the
ϒ
(4S) resonance, which decays to pairs of B mesons. About 10% of the data is recorded below the
ϒ
(4S) resonance in order to study backgrounds. In addition, Belle has carried out special runs at the
ϒ
(5S)
resonance to study
B
s
mesons
as well as on the
ϒ
(1S)
,
ϒ
(2S)
and
ϒ
(3S)
resonances to search for evidence of Dark Matter and the Higgs Boson. The samples of
ϒ
(1S)
,
ϒ
(2S)
and
ϒ
(5S)
collected by Belle are the world largest samples available.

The Belle II B-factory, an upgraded facility with two orders of magnitude more luminosity, has been approved in June 2010.[1] The design and construction work is ongoing.

See also[edit]

References[edit]

  1. ^ KEK press release

External links[edit]

Coordinates: 36°09′28″N 140°04′31″E / 36.15778°N 140.07528°E / 36.15778; 140.07528