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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 φ mesons, 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).

See also[edit]


  1. ^ "Oddball Particle Surprises Physicists at Fermilab". redOrbit. 19 March 2009. Retrieved 2009-03-21. 
  2. ^ Handwerk, Brian (20 March 2009). "Strange Particle Created; May Rewrite How Matter's Made". National Geographic News. Retrieved 2009-03-21. 
  3. ^ Minard, Anne (18 March 2009). "New Particle Throws Monkeywrench in Particle Physics". Universe Today. 
  4. ^ Riesselmann, Kurt (December 4, 2012). "Experiment confirms existence of odd particle". Phys.Org.
  5. ^ Hidalgo-Duquea, C., Nievesa, J., Pavón Valderrama, M. (November 29, 2012). "Heavy Quark Spin Symmetry and SU(3)-Flavour Partners of the X(3872)".
  6. ^ Dorigo, Tommaso (September 26, 2013). "DZERO Confirms The Y(4140) And Its Excitation"
  7. ^ D0 Collaboration (September 25, 2013). "Search for the X(4140) state in B+->J/psi phi K+ decays with the D0 detector"
  8. ^ Shen, C. P.; et al. (2010). "Evidence for a New Resonance and Search for the Y(4140) in the γγ→ϕJ/ψ Process". Physical Review Letters. 104: 112004. Bibcode:2010PhRvL.104k2004S. PMID 20366468. arXiv:0912.2383Freely accessible. doi:10.1103/PhysRevLett.104.112004. 
  9. ^ http://arxiv.org/abs/1606.07895
  10. ^ http://arxiv.org/abs/1606.07898

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Further reading[edit]