The meson is a
meson
In particle physics, a meson ( or ) is a type of hadronic subatomic particle composed of an equal number of quarks and antiquarks, usually one of each, bound together by the strong interaction. Because mesons are composed of quark subparticles, ...
composed of a
bottom antiquark and a
strange quark. Its
antiparticle
In particle physics, every type of particle is associated with an antiparticle with the same mass but with opposite physical charges (such as electric charge). For example, the antiparticle of the electron is the positron (also known as an antie ...
is the meson, composed of a bottom quark and a strange antiquark.
B–B oscillations
Strange B mesons are noted for their ability to
oscillate
Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum ...
between
matter
In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic part ...
and
antimatter
In modern physics, antimatter is defined as matter composed of the antiparticles (or "partners") of the corresponding particles in "ordinary" matter. Antimatter occurs in natural processes like cosmic ray collisions and some types of radioac ...
via a
box-diagram with measured by
CDF experiment at
Fermilab
Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a United States Department of Energy national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been opera ...
.
That is, a meson composed of a bottom quark and strange antiquark, the strange meson, can spontaneously change into an bottom antiquark and strange quark pair, the strange meson, and vice versa.
On 25 September 2006,
Fermilab
Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a United States Department of Energy national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been opera ...
announced that they had claimed discovery of previously-only-theorized B
s meson oscillation.
[
] According to Fermilab's press release:
Ronald Kotulak, writing for the
Chicago Tribune
The ''Chicago Tribune'' is a daily newspaper based in Chicago, Illinois, United States, owned by Tribune Publishing. Founded in 1847, and formerly self-styled as the "World's Greatest Newspaper" (a slogan for which WGN radio and television a ...
, called the particle "bizarre" and stated that the meson "may open the door to a new era of physics" with its proven interactions with the "spooky realm of antimatter".
Better understanding of the meson is one of the main objectives of the
LHCb
The LHCb (Large Hadron Collider beauty) experiment is one of eight particle physics detector experiments collecting data at the Large Hadron Collider at CERN. LHCb is a specialized b-physics experiment, designed primarily to measure the paramet ...
experiment conducted at the
Large Hadron Collider. On 24 April 2013,
CERN physicists in the LHCb collaboration announced that they had observed
CP violation
In particle physics, CP violation is a violation of CP-symmetry (or charge conjugation parity symmetry): the combination of C-symmetry (charge symmetry) and P-symmetry ( parity symmetry). CP-symmetry states that the laws of physics should be th ...
in the decay of strange mesons for the first time. Scientists found the B
s meson decaying into two
muons for the first time, with Large Hadron Collider experiments casting doubt on the scientific theory of
supersymmetry.
CERN physicist Tara Shears described the CP violation observations as "verification of the validity of the Standard Model of physics".
[
]
Rare decays
The rare decays of the B
s meson are an important test of the Standard Model. The branching fraction of the strange b-meson to a pair of muons is very precisely predicted with a value of Br(B
s→ µ
+µ
−)
SM = (3.66 ± 0.23) × 10
−9. Any variation from this rate would indicate possible physics beyond the Standard Model, such as supersymmetry. The first definitive measurement was made from a combination of LHCb and CMS experiment data:
This result is compatible with the Standard Model and set limits on possible extensions.
See also
*
B meson
In particle physics, B mesons are mesons composed of a bottom antiquark and either an up (), down (), strange () or charm quark (). The combination of a bottom antiquark and a top quark is not thought to be possible because of the top quark' ...
*
B– oscillation
References
External links
*
Mesons
Strange quark
B physics
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