fourth generation of fundamental particles




A hypothetical fourth generation of fundamental particles (fermions), beyond the three currently observed.

Still consistent with experiment, suggested by flavour physics, and implied by Spin(16), Spin(18)Spin(18)-GUT.




  • David B. Cline, Beyond Truth and Beauty: A Fourth Family of Particles,Scientific American Vol. 259, No. 2 (AUGUST 1988), pp. 60-67 (jstor:24989195)

Experimental constraints

  • Alexander Lenz, Constraints on a fourth generation of fermions from Higgs Boson searches, Adv. High Energy Phys. 2013 (2013) 910275 (doi:10.1155/2013/910275)

  • Alexander Lenz, How to really kill a physics model, talk notes 2012 (pdf, pdf)

  • N.S. Mankoč Borštnik, H.B.F. Nielsen, Do Present Experiments Exclude the Fourth Family Quarks as Well as the Existence of More Than One Scalar?, Bled Workshops Phys. 17 (2016) no. 2, 128-146 (spire:1510166)

Motivation from flavour physics

Motivation from flavour-physics (B-meson decays)

  • A.K. Ciftci, R. Ciftci, S. Sultansoy, A Search for the Fourth SM Family Fermions and E 6E_6 Quarks at μ +μ \mu^+ \mu^- Colliders, Phys. Rev. D65 (2002) 055001 (arXiv:hep-ph/0106222)

  • Amarjit Soni, Ashutosh Kumar Alok, Anjan Giri, Rukmani Mohanta, Soumitra Nandi, The fourth family: a simple explanation for the observed pattern of anomalies in B-CP asymmetries, Phys. Lett. B683:302-305, 2010 (arXiv:0807.1971)

In string/grand-unified theory

In Spin(16)- and Spin(18)?-GUT (“SO(16)-, SO(18)-GUT”):

In heterotic string theory:

  • A.A. Maslikov, I.A. Naumov, G.G. Volkov, The Fermion Generations Problem in the Gust in the Free World-Sheet Fermion Formulation, Int. J. Mod. Phys. A11 (1996) 1117 (arXiv:hep-ph/9512429)

Last revised on September 29, 2019 at 12:35:11. See the history of this page for a list of all contributions to it.