nLab fourth generation of fundamental particles

Redirected from "4th generation of fermions".

Contents

Context

Fields and quanta

fields and particles in particle physics

and in the standard model of particle physics:

force field gauge bosons

photon - electromagnetic field (abelian Yang-Mills field)
W, Z, B-boson - electroweak field (Yang-Mills field)
gluon - strong nuclear force (Yang-Mills field)
graviton - field of gravity
infraparticle

scalar bosons

Higgs boson, inflaton (scalar field)

matter field fermions (spinors, Dirac fields)

flavors of fundamental fermions in the standard model of particle physics:
generation of fermions	1st generation	2nd generation	3d generation
quarks ( $q$ )
up-type	up quark ( $u$ )	charm quark ( $c$ )	top quark ( $t$ )
down-type	down quark ( $d$ )	strange quark ( $s$ )	bottom quark ( $b$ )
leptons
charged	electron	muon	tauon
neutral	electron neutrino	muon neutrino	tau neutrino

bound states:
mesons	light mesons: pion ( $u d$ ) ρ-meson ( $u d$ ) ω-meson ( $u d$ ) f1-meson a1-meson	strange-mesons: ϕ-meson ( $s \bar s$ ), kaon, K-meson ( $u s$ , $d s$ ) eta-meson ( $u u + d d + s s$ ) charmed heavy mesons*: D-meson ( $u c$ , $d c$ , $s c$ ) J/ψ-meson ( $c \bar c$ )	bottom heavy mesons: B-meson ( $q b$ ) ϒ-meson ( $b \bar b$ )
baryons	nucleons: proton $(u u d)$ neutron $(u d d)$

(also: antiparticles)

effective particles

Goldstone bosons

hadrons (bound states of the above quarks)

meson
- scalar meson
  - σ-meson
  - pion
  - kaon
  - D-meson
  - B-meson
- vector meson
  - ω-meson
  - ρ-meson
  - f1-meson
  - a1-meson
  - b1-meson
  - h1-meson
  - K*-meson
- tensor meson
- quarkonium
  - charmonium
  - ϒ-meson
exotic meson
- XYZ meson
- tetraquark
baryon
- nucleon
  - proton
  - neutron
  - chemical element
    - carbon
    - nitrogen
- Lambda baryon
- pentaquark

solitons

in grand unified theory

minimally extended supersymmetric standard model

superpartners

bosinos:

gravitino - field of supergravity (Rarita-Schwinger field)
gaugino - super Yang-Mills field
gluino

sfermions:

squark

dark matter candidates

WIMP
axion

Exotica

auxiliary fields

Idea
References

General
Experimental constraints
Motivation from flavour physics
In string/grand-unified theory

Idea

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), $Spin(18)$ -GUT.

References

General

Exposition and review:

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)
Bob Holdom, WS Hou, Tobias Hurth, Michelangelo L Mangano, Saleh Sultansoy, Gokhan Ünel Four statements about the fourth generation, PMC Phys A 3, 4 (2009) (doi:10.1186/1754-0410-3-4)

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 $E_6$ Quarks at $\mu^+ \mu^-$ 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”):

Frank Wilczek, Anthony Zee, Families from spinors, Phys. Rev. D 25, 553 (1982) (doi:10.1103/PhysRevD.25.55310.1103/PhysRevD.25.553)
Goran Senjanović, Frank Wilczek, Anthony Zee, Reflections on mirror fermions, Physics Letters B Volume 141, Issues 5–6, 5 July 1984, Pages 389-394 Physics Letters B (doi:10.1016/0370-2693(84)90269-7)
Homero Martínez, Alejandra Melfo, Fabrizio Nesti, Goran Senjanović, Three Extra Mirror or Sequential Families: a Case for Heavy Higgs and Inert Doublet, Phys. Rev. Lett.106:191802, 2011 (arXiv:1101.3796)
Luca di Lucio, p. 44 of: Aspects of Symmetry Breaking in Grand Unified Theories, 2011 (pdf)
Michael McGuigan, Dark Horse, Dark Matter: Revisiting the $SO(16) \times SO(16)'$ Nonsupersymmetric Model in the LHC and Dark Energy Era (arXiv:1907.01944)

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 January 8, 2020 at 09:00:42. See the history of this page for a list of all contributions to it.