Types of Particles |

**In General** > s.a. Bosons; fermions;
particle models, classical and quantum;
particle physics and effects.

* __Classification__:
Labeling is provided by the irreducible representations of the lorentz
group; > s.a. BMS Group.

* __Remark__: Particle multiplets
are usually written down as if they were column vectors; They are not; They are
actually to be thought of as (orthonormal) bases in some vector space that carries
the representation of the group in question; The column vectors are the states.

* __Numbers__: The number of baryons in
the observable universe is of the order of \(10^{80}\), as is the number of electrons;
The number of photons is about \(10^{89}\), as is the estimated number of neutrinos;
According to D Page, the number of gravitons could be more than twenty orders of
magnitude larger yet.

* __Supersymmetric partners__: All
known bosons are assumed to have a partner denoted by the suffix "-ino"
and all fermions one denoted by the prefix "s-"; These particles should
decay into an extremely weakly interacting Lightest Supersymmetric Particle, of
at least 40 GeV; The 2002 lower bound on the gluino mass is 195 GeV.

@ __General properties__: Millikan & Richman ht/01 [mass formula and geometry];
Glashow a1106
[search for hidden attributes shared by quarks and leptons];
Furey PLB(15)-a1603
[quarks and leptons from division algebras, charge quantization from a number operator];
Page a1605 [number of gravitons in the observable universe];
Saar & Groote AACA(17)-a1606 [massless particles are not limiting cases of massive particles].

@ __Electric dipole moments__:
Fortson et al PT(03)jun [fundamental];
> s.a. electromagnetism; neutron;
particle physics [beyond the standard model].

@ __Other properties__:
volume PLB(90)239;
Barnett et al (PDG) PRD(96),
RMP(96),
PLB(04);
Tanabashi et al PRD(18);
> s.a. Gyromagnetic Ratio; statistics.

**Leptons**
> s.a. electron [including positron]; equivalence principle
and quantum equivalence principle; neutrino.

* __Idea__: Weakly interacting
particles, *e*, *μ*, *τ*, and the neutrinos.

* __Lepton number__: We would
know that it can be violated if we had conclusive evidence for neutrinoless
double-beta decay, a process beyond the standard model.

* __Tau lepton__: Its mass is
1776.61 ± 0.13 (stat) ± 0.35 (syst) MeV.

* __Lepton universality__: The fact
that in the standard model of particle physics, the electron, muon, and tau
particle interact with other particles, either via the electromagnetic or the
weak force, in identical ways; 2014, This claim has been challenged by an LHC
experiment on *B* meson decay.

@ __Tau lepton__: Stahl 00 [r PT(00)jul];
Eidelman & Passera MPLA(07) [anomalous magnetic moment];
Belous et BELLE PRL(07) [mass].

@ __Related topics__:
Particle Data Group PLB(04) [list];
Belle Collaboration PLB(05) [search for lepton flavor violation];

Roberts & Marciano ed-09 [lepton dipole moments];
Aaij et al PRL(14) [test result on lepton universality];
> s.a. Singletons; symmetry breaking;
torsion [interactions].

**Muon**
> s.a. QED phenomenology; supersymmetry.

* __Applications__: Muon spin rotation
(muSR) method to map magnetic fields from the detection of decay positrons; 2005,
Muons suggested as probes of containers in search for hidden nuclear materials.

* __Anomalous magnetic moment,
g−2__: A discrepancy with theory may possibly indicate
supersymmetric particles.

*

@

@

>

**Other Types** > s.a. particle statistics
[paraparticles]; quantum particles [superparticles].

* __Fundamental particles vs quasiparticles__:
Quasiparticles arise as collective states of fundamental fields, often in condensed-matter
systems, and may constitute a longer list of particles than found in the standard model,
for example because they are not constrained by Lorentz invariance.

@ __New particles__: Fairbairn et al PRP(07) [stable massive, search];
De Angelis et al PRD(07) [proposal of light spin-0 boson];
news SciNews(15)jul [observation of massless Weyl fermions];
Criado et al a2105 [higher-spin, at colliders].

@ __Special field configurations__:
Ward ht/05-en;
Feranchuk & Feranchuk Sigma(07)-a0712 [electrons and positrons in QED].

@ __Fakeons__:
Anselmi CQG(19)-a1809 [and microcausality violation];
Piva a1905-GRF [and gravity];
Anselmi & Marino CQG-a1909 [gravitational waves and the Hubble constant];
Anselmi a1911-proc [and quantum gravity].

@ __Gauge and Higgs bosons__:
Eidelman et al PLB(04);
Particle Data Group PLB(04);
> s.a. electroweak theory [*W*, *Z*];
higgs boson.

> __Known particles__:
see graviton; hadrons [including baryons, mesons, quarks];
photon; QCD [gluons].

> __Field configurations__:
see field theory; geon; instanton;
Kink; Magnon; Meron;
monopole; Phonon;
Quasiparticle; Roton;
Skyrmion; soliton;
Sphaleron.

> __Predicted particles__:
see Axino; axion;
Gravitino; GUTs [leptoquarks].

> __More hypothetical particles__:
see Hyperphoton; Notoph;
Newtorites; Paraphoton;
Preons; Pyrgon; tachyon.

**Online Resources** > see Particle Data Group website.

main page
– abbreviations
– journals – comments
– other sites – acknowledgements

send feedback and suggestions to bombelli at olemiss.edu – modified 24 may 2021