Particles: Nature and Description |

**In General** > s.a. field theories; geometrical
models; lagrangian systems; Ontology;
particle statistics; physics paradigms.

* __History__: Initially
particles were thought of as singularities in the fields by many, but few
now really think so; There have been attempts to consider them as black holes,
geons and other solitons and localized solutions of non-linear field equations,
or tachyons; 1999, So far none of those models is widely accepted.

@ __Levels of description__:
Rimini FP(97) [composition];
Gies & Wetterich PRD(02)ht/01 [elementary vs composite, renormalization];
Cui ht/01.

@ __Nature and description__: DeWitt in(79);
Ne'eman PLA(94) [mass and localizability];
Buchholz NPB(96)ht/95,
in(94)ht/95;
Lanz & Melsheimer LNP(98)qp/97 [as derived entities];
Dolby gq/03-proc [observer dependence];
Goldstein et al SHPMP(05)qp/04 [existence/reality, and Bohm theory];
Colosi & Rovelli CQG(09)gq/04 [global Fock states vs local particle states];
Butterfield FP(05) [endurance vs perdurance];
Wang gq/07 [as quasiparticles in superconductor];
Nambu IJMPA(08);
Muller & Seevinck PhSc(09)-a0905,
Caulton & Butterfield BJPS-a1106 [discernibility];
French & Krause 10 [identity];
Colin & Wiseman JPA(11)-a1107 [beable status for positions];
Swain a1110-fs [and pomerons];
Dreyer a1212-FQXi [particles as excitations of a background];
Zeh ZfN-a1304;
Carcassi et al JPComm(18)-a1702 [mechanics from a few simple physical assumptions];
Lazarovici EJPS(18)-a1809 [against fields, superiority of a pure particle ontology].

@ __From (quantum) field theory__: Derrick JMP(64) [non-linear scalar field, negative result];
Davies in(84);
Clifton & Halvorson BJPS(01)qp/00 [and quantum field theory];
Cortez et al in(02)gq/05 [including holography, sigma models];
Arteaga AP(09)
[particle-like excitations of non-vacuum states];
Dybalski PhD(08)-a0901
[and spectral theory of automorphism groups];
Pessa a0907;
Bain SHPMP(11) [against conventional view];
Pienaar et al PRA(11) [as spacetime qubits];
Hobson AJP(13)mar-a1204 [there are no particles],
comment Sassoli de Bianchi AJP(13)sep-a1202 [quantum "fields" are not fields];
Glazek & Trawinski FBS(17)-a1612 [effective particles];
> s.a. geons; solitons;
locality in quantum field theory; solutions
of general relativity with matter.

@ __Many-particle systems__: Atiyah & Sutcliffe PRS(02)ht/01 [configuration space geometry];
Kundt FP(07) [and fundamental physics];
Svrcek ch(13)-a1207 [mechanics vs field theory];
da Costa & Holik a1305
[undefined particle number in quantum mechanics].

@ __Parametrizations__:
Guven PRD(91) [proper time];
> s.a. time.

@ __Flux-across-surfaces theorem__: Dürr & Pickl JMP(03)mp/02 [Dirac particles].

@ __Charged particles__:
Bagan et al ht/01-proc [in gauge theory].

@ __Unstable particles__:
Saller ht/01 [time representations].

> __Related topics__:
see Bag Model; Center of Mass;
composite particle models; composite
quantum systems; Elementarity; energy
[self-energy]; interactions; mass [including
mass generation]; mirrors; monopoles;
particle effects; Relational Theories;
symplectic structures and special
types; twistors.

**Classical Particles **
> s.a. classical systems; mass;
relativistic particles; spinning particles.

* __Description__: Paradigms commonly used to
describe particles are the material point, the test particle and the diluted particle (droplet model).

* __And quantum theory__: Their entanglement-free
behavior can be seen to emerge in the "islands of classicality" of quantum theory;
> s.a. classical-quantum limit.

* __Non-relativistic__: The dynamics can be
derived from an action of the form

*S*[*x*_{i};
*t*_{1}, *t*_{2}]
= \(\int_1^2\) d*t* [\(1\over2\)*m*
∑_{i} (*x*^{
·}_{i})^{2}
− *V*(*x*_{i})] .

@ __In curved spacetime__: Baleanu & Güler JPA(01)ht [Hamilton-Jacobi];
Marques & Bezerra CQG(02)gq/01 [cosmic string];
Kowalski & Rembieliński AP(13)-a1304 [on a double cone];
Banerjee & Mukherjee a1907 [new action].

@ __Other backgrounds__:
Chavchanidze & Tskipuri mp/01 [SU(2) group];
Musielak & Fry AP(09) [free particles in Galilean spacetime];
Knauf & Schumacher ETDS(12)-a1111 [random potential];
Ivetić et al CQG(14)-a1307 [curved Snyder space].

@ __Symmetries__: Haas & Goedert JPA(99)mp/02 [2D, Noether];
Jahn & Sreedhar AJP(01)oct-mp [invariance group].

@ __Related topics__: Fuenmayor et al PRD(02)ht/01 [loop representation, with gauge theory];
van Holten phy/01 [dual fluid interpretation];
Kryukov JPCS(13)-a1302 [as Dirac delta functions, and quantum theory];
> s.a. parametrized theories; Relational Theories.

**Quantum Particles**
> s.a. Complementarity; quantum particle models;
Schmidt Decomposition; Wave-Particle Duality.

* __Issue__: It can be argued
that there can be no relativistic, quantum theory of localizable particles
and, thus, that relativity and quantum mechanics can be reconciled only in
the context of quantum field theory.

@ __General references__: Bloch & Burba PRD(74) [presence in a spacetime region and detector];
Huang PRA(08) [quasiclassical quantum states];
Aerts IJTP(10) [particles as conceptual entities];
Vaccaro PRS(12)-a1105 [wave/particle and translational symmetry/asymmetry];
Srikanth & Gangopadhyay a1201 [particle identities as uncertain];
Vaidman PRA(13)-a1304 [the past of a quantum particle];
Flores a1305.

@ __No evidence / objective existence__:
Nissenson a0711;
Blood a0807;
Zeh FP(10)-a0809 [discreteness is an illusion];
Fraser SHPMP(08);
Sassoli de Bianchi FS(11)-a1008;
Jantzen PhSc(11)jan
[permutation symmetry is incompatible with particle ontology].

@ __With special relativity__: Halvorson & Clifton PhSc(02)qp/01;
> s.a. locality in quantum mechanics; pilot-wave quantum theory.

> __Related topics__: see Quantum Carpet;
uncertainty principle [*τ* and *m* as operators];
wigner functions.

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