Belle experiment

The retired central drift tracking chamber from Belle, now exhibited at the National Museum of Nature and Science.

The experiment was motivated by the search for CP-violation.[6] However the experiment also performed extensive studies of rare decays, searches for exotic particles and precision measurements of the properties of D mesons, and tau particles.[1] The experiment has resulted in almost 300 publications in physics journals.

Highlights of the Belle experiment include

• an observation of large CP-violation in the neutral B meson system[7]
• measurement of the branching fraction of inclusive ${\displaystyle B\to X_{s}\gamma }$ decays[8]
• observation of the ${\displaystyle b\to sl^{+}l^{-}}$ transition with ${\displaystyle B\to Kl^{+}l^{-}}$[9] and ${\displaystyle B\to K^{*}l^{+}l^{-}}$[10]
• measurement of ${\displaystyle \phi _{3}}$ using the ${\displaystyle B\to DK,D\to K_{S}\pi ^{+}\pi ^{-}}$ Dalitz plot[1]
• measurement of the CKM quark mixing matrix elements ${\displaystyle |V_{ub}|}$ and ${\displaystyle |V_{cb}|}$[1]
• observation of direct CP-violation in ${\displaystyle B^{0}\to \pi ^{+}\pi ^{-}}$[11] and ${\displaystyle B^{0}\to K^{-}\pi ^{+}}$[12]
• observation of ${\displaystyle b\to d}$ transitions[13]
• evidence for ${\displaystyle B\to \tau \nu }$[14]
• observations of a number of new particles including the X(3872)[15]

The KEKB accelerator was the world's highest luminosity machine at the time. A large fraction of the data was collected at the
ϒ
(4S). The instantaneous luminosity exceeded 2.11×10³⁴ cm⁻²·s⁻¹. The integrated luminosity collected at the
ϒ
(4S) mass was about 710 fb⁻¹ (corresponding to 771 million
B

B
meson pairs). About 10% of the data was recorded below the
ϒ
(4S) resonance in order to study backgrounds. In addition, KEKB 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.

• B-factory
• 
  B
  –
  B
  oscillation

Wikimedia Commons has media related to Belle experiment.

• Official Belle Website
• Belle II Collaboration Website
• Belle II Public Website
• Record for KEK-BF-BELLE Experiment on INSPIRE-HEP

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