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The X(3872) is an anomalous particle with a mass of 3871.68 MeV/c2 [1] which does not fit into the quark model because of its quantum numbers. It was first discovered in 2003 by the Belle experiment[2] in Japan and later confirmed by several other experimental collaborations. Several theories have been proposed for its nature,[3] such as a mesonic molecule or a diquark-antidiquark pair (tetraquark).

The quantum numbers of X(3872) have been determined by the LHCb Experiment at CERN in March 2013. The values for JPC is 1++.[4]

See also[edit]


  1. ^ Particle Data Group Live listings
  2. ^ Choi, S. -K.; Olsen, S.; Abe, K.; Abe, T.; Adachi, I.; Ahn, B.; Aihara, H.; Akai, K.; Akatsu, M.; Akemoto, M.; Asano, Y.; Aso, T.; Aulchenko, V.; Aushev, T.; Bakich, A.; Ban, Y.; Banerjee, S.; Bondar, A.; Bozek, A.; Bračko, M.; Brodzicka, J.; Browder, T.; Chang, P.; Chao, Y.; Chen, K. -F.; Cheon, B.; Chistov, R.; Choi, Y.; Choi, Y.; Danilov, M. (2003). "Observation of a Narrow Charmoniumlike State in Exclusive B±→K±π+π-J/ψ Decays". Physical Review Letters 91 (26). arXiv:hep-ex/0308029. Bibcode:2003PhRvL..91z2001C. doi:10.1103/PhysRevLett.91.262001. 
  3. ^ Eric S. Swanson, The new heavy mesons: A status report, Physics Reports, Volume 429, Issue 5, July 2006, Pages 243–305
  4. ^ LHCb collaboration: Determination of the X(3872) meson quantum numbers