The Y(4140)particle is an electrically neutral exotic hadron candidate that is about 4.4 times heavier than the proton. It was observed at Fermilab and announced on 17 March 2009.[1] This particle is extremely rare and was detected in only 20 of billions of collisions.[2]
Since it decays into J/ψ and φmesons, it has been suggested that this particle is composed of charm quarks and charm antiquarks, possibly even a four quark combination.[3]
The existence of the particle has been confirmed by members of the CMS collaboration at the Large Hadron Collider on November 14, 2012[4][5] and by the DØ experiment at the Tevatron on September 25, 2013.[6][7] The Belle experiment[8] has searched for this particle but found no evidence for its existence.
The LHCb experiment observes a peak at the same position in the J/ψϕ invariant mass, but it is best described as a Ds±Ds∗∓ cusp, and is much broader than the previous measurements of the Y(4140).[9][10]
The Particle Data Group has renamed Y(4140) to follow naming conventions to X(4140).