The Y(4140)

particle In the physical sciences, a particle (or corpuscule in older texts) is a small localized object which can be described by several physical or chemical properties, such as volume, density, or mass. They vary greatly in size or quantity, from ...

is an electrically neutral

exotic hadron Exotic hadrons are subatomic particles composed of quarks and gluons, but which – unlike "well-known" hadrons such as protons, neutrons and mesons – consist of more than three valence quarks. By contrast, "ordinary" hadrons contain just tw ...

candidate that is about 4.4 times heavier than the proton. It was observed 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 ...

and announced on 17 March 2009. This particle is extremely rare and was detected in only 20 of billions of collisions. Since it decays into J/ψ and φ

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, ...

s, it has been suggested that this particle is composed of

charm quark The charm quark, charmed quark or c quark (from its symbol, c) is the third-most massive of all quarks, a type of elementary particle. Charm quarks are found in hadrons, which are subatomic particles made of quarks. Examples of hadrons containin ...

s and charm antiquarks, possibly even a four quark combination. The existence of the particle has been confirmed by members of the

CMS CMS may refer to: Computing * Call management system * CMS-2 (programming language), used by the United States Navy * Code Morphing Software, a technology used by Transmeta * Collection management system for a museum collection * Color manag ...

collaboration at the Large Hadron Collider on November 14, 2012 and by the

DØ experiment The DØ experiment (sometimes written D0 experiment, or DZero experiment) was a worldwide collaboration of scientists conducting research on the fundamental nature of matter. DØ was one of two major experiments (the other was the CDF experim ...

at the

Tevatron The Tevatron was a circular particle accelerator (active until 2011) in the United States, at the Fermi National Accelerator Laboratory (also known as ''Fermilab''), east of Batavia, Illinois, and is the second highest energy particle collider ...

on September 25, 2013. The

Belle experiment The Belle experiment was a particle physics experiment conducted by the Belle Collaboration, an international collaboration of more than 400 physicists and engineers, at the High Energy Accelerator Research Organisation (KEK) in Tsukuba, Ibarak ...

has searched for this particle but found no evidence for its existence. 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 observes a peak at the same position in the J/ψϕ invariant mass, but it is best described as a D_s^±D_s^∗∓ cusp, and is much broader than the previous measurements of the Y(4140). The Particle Data Group has renamed Y(4140) to follow naming conventions to X(4140).

References

External links

Press release kit for the Y(4140).
Contains images of decay modes and resonance data.

See also

References

External links

Further reading