From HandWiki

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


  1. "Oddball Particle Surprises Physicists at Fermilab". redOrbit. 19 March 2009. 
  2. Handwerk, Brian (20 March 2009). "Strange Particle Created; May Rewrite How Matter's Made". National Geographic News. 
  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-Duque, C; Nieves, J; Pavón Valderrama, M (2012). "Heavy Quark Spin Symmetry and SU(3)-Flavour Partners of the X(3872)". Nuclear Physics A 914: 482–487. doi:10.1016/j.nuclphysa.2013.01.025. Bibcode2013NuPhA.914..482H. 
  6. Dorigo, Tommaso (September 26, 2013). "DZERO Confirms The Y(4140) And Its Excitation"
  7. D0 Collaboration; Abbott, B; Acharya, B. S; Adams, M; Adams, T; Agnew, J. P; Alexeev, G. D; Alkhazov, G et al. (2014). "Search for the X(4140) state in B+→J/ψφK+ decays with the D0 detector". Physical Review D 89 (12004): 012004. doi:10.1103/PhysRevD.89.012004. Bibcode2014PhRvD..89a2004A. 
  8. Shen, C. P. (2010). "Evidence for a New Resonance and Search for the Y(4140) in the γγ→ϕJ/ψ Process". Physical Review Letters 104 (11): 112004. doi:10.1103/PhysRevLett.104.112004. PMID 20366468. Bibcode2010PhRvL.104k2004S. 
  9. LHCb collaboration; Aaij, R; Adeva, B; Adinolfi, M; Ajaltouni, Z; Akar, S; Albrecht, J; Alessio, F et al. (2017). "Observation of J/ψφ structures consistent with exotic states from amplitude analysis of B+→J/ψφK+ decays". Physical Review Letters 118 (2): 022003. doi:10.1103/PhysRevLett.118.022003. PMID 28128595. Bibcode2017PhRvL.118b2003A. 
  10. LHBc collaboration; Aaij, R; Adeva, B; Adinolfi, M; Ajaltouni, Z; Akar, S; Albrecht, J; Alessio, F et al. (2017). "Amplitude analysis of B+→J/ψφK+ decays". Physical Review D 95 (12002): 012002. doi:10.1103/PhysRevD.95.012002. Bibcode2017PhRvD..95a2002A. 

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Further reading