Bottom quark



Bottom quark
Composition: c2
Electric charge: -1/3 e
Spin: ½
Flavour in particle physics
v • d • e
Flavour quantum numbers:
  • Lepton number: L
  • Baryon number: B
  • Strangeness: S
  • Charm: C
  • Bottomness: B'
  • Topness: T
  • Isospin: Iz or I
  • Weak isospin: Tz
  • Electric charge: Q

Combinations:

  • Hypercharge: Y
    • Y=2(Q-Iz)
  • Weak hypercharge: YW
    • YW=2(Q-Tz)
    • YW=B−L

Related topics:

  • CPT symmetry
  • CKM matrix
  • CP symmetry
  • Chirality

The bottom quark is a third-generation Higgs boson if it is sufficiently light.

The bottom quark was discovered at Fermilab in 1977. On its discovery, a valiant effort was made by many particle physicists to name it "Beauty", paired along with "Truth". Poetic license gave way to pragmatics, and the quarks were named "top" and "bottom" instead.

The bottom quark can decay either into up or charm quark via weak interaction. Both these decays are suppressed by CKM matrix, making lifetimes of most bottom particles ( ~10-12 s ) somewhat higher than those of charmed particles (several times 10-13 s ), but lower than those of strange particles ( 10-10 - 10-8 s ).

Hadrons containing bottom quarks

Some of the hadrons containing bottom quarks include:

  • B down quark.
  • Bc and Bs mesons contain a bottom quark along with a strange quark respectively.
  • There are many bottomonium states, for example the upsilon meson (\Upsilon\,). These consist of a bottom quark and its antiparticle.
  • Bottom baryons have been observed, and are named in analogy with strange baryons (e.g. Λb0).
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Bottom_quark". A list of authors is available in Wikipedia.