The
bottom quark or
b quark, also known as the
beauty quark, is a third-generation
quark with a charge of -
e. Although all quarks are described in a similar way by
quantum chromodynamics, the bottom quark's large bare mass (around , a bit more than four times the mass of a
proton), combined with low values of the
CKM matrix elements
Vub and
Vcb, gives it a distinctive signature that makes it relatively easy to identify experimentally (using a technique called
B-tagging). Because three generations of quark are required for
CP violation (see
CKM matrix),
mesons containing the bottom quark are the easiest particles to use to investigate the phenomenon; such experiments are being performed at the
BaBar,
Belle and
LHCb experiments.