B–Bbar oscillation

Neutral B meson oscillations (or
B
–
B
oscillations) are one of the manifestations of the neutral particle oscillation, a fundamental prediction of the Standard Model of particle physics. It is the phenomenon of B mesons changing (or oscillating) between their matter and antimatter forms before their decay. The
B
_s meson can exist as either a bound state of a strange antiquark and a bottom quark, or a strange quark and bottom antiquark. The oscillations in the neutral B sector are analogous to the phenomena that produce long and short-lived neutral kaons.

B
_s–
B
_s mixing was observed by the CDF experiment at Fermilab in 2006 and by LHCb at CERN in 2011 and 2021.