The Electron |

**In General**
> s.a. constants and variation;
fermions; history of physics;
matter.

* __History__: 1892, H A Lorentz,
proposal of the electron and use to explain properties of matter; 1897, J J
Thomson, discovery of the electron as cathode rays; 1924, W Pauli, proposal
of an inner degree of freedom, later associated by Kronig and by Goudsmit
and Uhlenbeck with an inner rotational motion; 1927, C J Davisson &
L H Germer, observation of electron diffraction by a crystal.

* __Charge__: Its absolute value is
*e* = 1.60217733(49) × 10^{−19} C.

* __Mass__:
*m*_{e}
= 9.109 3826(16) × 10^{−31} kg ≈
10^{−27} g or 511 keV/*c*^{2},
with variation |*μ*^{·}/*μ*_{0}|
< 3 × 10^{−14} yr^{−1},
*μ*_{0} = *m*_{p} /
*m*_{e}.

* __Electric dipole moment__:
Since 1950, experimenters have been trying to measure the electron's electric dipole moment
*p*_{e} and getting increasingly stringent
upper limits, but no clear signal; Initially, the quest seemed dubious because a non-zero
*p*_{e} would break symmetries that were then
thought to be inviolate; By the mid 1960s it was clear that those symmetries are in fact broken,
but the standard model, which incorporates the known symmetry violations, predicts a value
*p*_{e} = 10^{−39}
*e* · m, far too small to measure; However, beyond-the-standard-model theories predict
much higher values, that should be measurable with molecular-beam techniques; 1996, Experimental
bound *p*_{e} ≤ 10^{−27}
*e* · m; 2011, Experimental bound *p*_{e}
≤ 1.05 × 10^{−28} *e*
· m with 90% c.l.; 2012, Bounds from studies of electrons in solids are not yet as sensitive,
but have been improving; 2013, *p*_{e}
≤ 8.7 × 10^{−29} *e*
· m with 90% c.l.; 2018, *p*_{e} ≤
1.1 × 10^{−29} *e* · m.

* __Magnetic dipole moment__: As of 2006,
*g*/2 = 1.001 159 652 180 85 (76); As of 2008, 1.001 159 652 180 73 (28); For an electron
bound to an atom *g* deviates from a value close to 2 by terms that depend on the ion's
nuclear charge and the fine structure constant; The most successful prediction in phsyics.

@ __General references__:
Majorana NC(37) [and positron];
Feynman PR(49) [positron];
issue PT(97)oct;
Mac Gregor 92;
Wilczek SA(12)jun [120th birthday];
Knuth a1511-in [current understanding];
Lincoln TPT(16)apr.

@ __Internal structure__: Robinson PLA(95);
Hofer qp/96,
PhyA(98)qp [and photons];
Pavšič et al HJ(95)qp/98.

@ __Mass__: Levshakov et al MNRAS(02)ap/01 [variation
of *m*_{p}/*m*_{e}];
Beier et al PRL(02);
Cardone et al ht/05-ch;
Jantzen & Ruffini GRG(12) [Fermi's analysis of the contribution of the electromagnetic field];
> s.a. energy [self-energy].

@ __Magnetic dipole moment__: Welton PR(48) [and electromagnetic field fluctuations];
Aspden IJTP(77) [heuristic model];
Vázquez IJTP(79)
[corrections to *g* due to a Coulomb field];
Jáuregui & de la Peña PLB(81),
Rivas phy/01 [and spin];
Awobode NCB(02);
Steinmann CMP(03) [careful definition];
Brodsky et al NPB(04) [non-perturbative];
McCartor ht/04;
Rosencwaig ht/06 [and self-energy, Casimir approach];
Awobode NCB(06);
Aoyama et al PRL(07) [theory, 8th-order contribution];
Hanneke et al PRL(08);
Giulini SHPMP(08) [spin];
Lush a0905 ["hidden momentum"];
Masood & Haseeb IJMPA(12)-a1204 [corrections at finite temperature];
de Rafael NPPS(12)-a1210 [update, standard model];
Mandache a1307 [physical origin];
Jung JHEP(13) [theoretical bound];
Davies cosmos(18)jul [the most successful prediction in phsyics];
Gabrielse et al a1904 [towards an improved measurement];
> s.a. Gyromagnetic Ratio; modified QED.

@ __Electric dipole moment__: Bernreuther & Suzuki RMP(91);
Hudson et al Nat(11)may
+ news nat(11)may,
bbc(11)may,
pw(11)may,
pt(11)jun;
Eckel et al PRL(12) [in solids];
ACME Collaboration Sci(14)jan-a1310
+ news SA(13)nov,
pw(13)nov,
news sn(18)oct,
Nakai & Reece pt(18)nov [new experimental upper bounds].

**Models and Related Topics** > s.a. particle models [including description
as black holes]; particle nature and description; spinning particles.

* __Positron__: 2002, evidence that in a
gas it can form bound states with molecules [@ Gilbert et al
PRL(02)].

* __Decay__: The electron is the lightest
known charged particle, so its decay (for example into a neutrino and a photon) would
imply that charge is not always conserved; There are tight bounds on this process, and the
electron lifetime is at least 6.6 × 10^{28} yr.

* __Fractionalization__: The phenomenon by
which the electron splits into separate quasiparticles which carry its spin and its
charge, and into real Majorana fermions which carry its Fermi statistics.

* __Speculative__:
2000, H Maris proposed that electrons can break up into smaller "electrinos"
[@ news pn(00)sep].

@ __Extended electron models__: Dirac PRS(62) [charged conducting surface];
Yaghjian 06 [Lorentz-Abraham charged sphere model];
Likhtman ht/06 [string model];
Rahaman et al ASS(11)-a0904 [charged perfect fluid];
Hofer FP(11)-a1002 [geometric-algebra model];
Burinskii AIP(12)-a1104-GRF;
Hofer JPCS(12) [and experiment];
Damour CRP-a1710 [Poincaré's 1905 model].

@ __Geometrical models__: Visser PLA(89) [electromagnetism + Newtonian gravity];
Pavšič et al PLB(93)qp/02 [Dirac equation from Clifford algebras];
Hofer qp/99-in;
Ray & Bhadra IJMPD(04)gq/02 [Einstein-Cartan theory];
Giulini HSPMP(08)-a0710 [spin and special relativity];
Gsponer JMP(08) [pointlike, in Colombeau's theory];
Atiyah et al JHEP(15)-a1412 [5D Ricci-flat, evolving Taub-NUT geometry];
> s.a. gauge transformations [Maxwell theory].

@ __Other models__:
Rosen IJTP(78) [theoretical approach to mass];

Fryberger PRD(81);
Caldirola LNC(83);
Burinskii JPCS(12)-a1109 [closed heterotic string];
Burinskii a1112-proc;
Kazakov & Nikitin AP(12)
[electron freely evolving in a photon bath, and effective infrared non-divergence].

@ __Positron__: Farmelo CP(10) [and Dirac];
Leone & Robotti EJP(10),
AJP(12)jun [early history];
Cretu SHPMP-a1910 [history].

@ __Fractionalization__:
Xu & Sachdev PRL(10)
+ news physorg(10)aug;
news nat(12)apr.

@ __Decay__: Pradhan ht/03;
Klapdor-Kleingrothaus et al PLB(06),
Agostini et al PRL(15) [lower bounds on lifetime].

@ __Angular momentum__: Stewart CJP(09)qp/07;
O'Connell JPA(16)-a1603 [interaction with the angular momentum of the electromagnetic field];
Białynicki-Birula & Białynicka-Birula PRL(17)-a1611 [relativistic wave packets carrying angular momentum];
Bliokh et al PRA(17)-a1706 [position, spin and orbital angular momentum operators];
Damski a1908 [spin angular momentum],
a1908 [electromagnetic angular momentum].

@ __Related topics__: Matteucci AJP(90)dec [wave behavior];
Rivas JPA(03)phy/01 [dynamical equations];
Matteucci et al EJP(09) [wave behavior];
Cetto et al QS:MF(17)-a1707 [origin of electron spin and related wave function antisymmetry];
> s.a. locality; lorentz-symmetry
violation; Stochastic Electrodynamics.

**Applications and Experiments** > s.a. bose-einstein condensates;
condensed-matter physics; Density Functional
Method; Luttinger Liquid.

@ __Gas of free electrons__: Verzegnassi et al a1706 [effect of a magnetic field, qft treatment].

@ __Electrons in materials / lattices__: Alloul 11 [in solids];
news pw(12)oct [nanocloaking devices for electrons inside materials];
Bach & Delle Site ch(14)-a1406 [open problems in many-electron theory];
Klopp & Veniaminov a1408 [interacting, in a random background];
news brown(14)oct [electron bubbles in ultracold liquid helium];
news upi(16)feb [electrons in graphene behaving as fluid];
Martin et al 16;
Quinn a1706 [strongly correlated regime];
> s.a. Hofstadter's Butterfly.

@ __Experiments and techniques__: Richter Phy(12)feb [controlling electron spin and geometric phase];
Sancho a1601 [charge distribution, via Kapitza-Dirac diffraction];
Rashidi et al PRL(18) [mechanical control of single electrons].

@ __Magnetic moment, measurements__:
Odom et al PRL(06)
+ pn(06)jul [best measurement];
Gabrielse pw(07)feb [implications];
Vogel CP(09) [and test of QED];
Sturm et al PRL(11) [in a bound state, stringent test to date of QED].

@ __Magnetic moment, effects__: Mera et al PRB(13)-a1206
[in a ferromagnet, interaction with conduction band electrons and with phonons].

> __ Related topics__: see aharonov-bohm effect;
diffraction; scattering;
Wigner Crystal.

You know, it would be sufficient to really understand the electron – Albert Einstein

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send feedback and suggestions to bombelli at olemiss.edu – modified 15 oct 2019