|  Clifford Algebra | 
In General > s.a. Gamma Matrices;
  Geometric Algebra.
  $ Def: Given an n-dimensional vector space V
    with metric η, define the matrices {γa}
    satisfying {γa,
    γb}
    = 2 ηab I; Then the Clifford algebra
    is the 2n-dimensional vector space generated by
ΓA:= {I, γa , γab , ..., γa1, ..., an} , γa ... c:= γ[a ... γc] .
  * Outer product: Given by
    ab:= a · b + a ∧ b;
    in 3 dimensions, a ∧ b = i a × b;
    It is associative; Corresponds to an extension of \(\mathbb R\), which
    includes a notion of direction.
  * Properties: For all A,
    γA2
    = I, and γA
    γB
    = CAB
    γC,
    with |CAB| = 1.
  * Representations: It has 1!
    equivalence class of irreducible representations (Pauli's fundamental theorem).
  * Relationships: From a representation
    of the Clifford algebra we get one of the Lie algebra of O(η) by
    Σab:=
    \(1\over2\)Γ[a
    Γb] .
  @ General references: Hestenes 66,
    in(86),
    & Sobczyk 84;
    Chisholm & Common ed-86;
    Crumeyrolle 90;
    Porteous 95;
    Snygg 97 [III];
    Pavšič 01-gq/06;
    Lundholm & Svensson a0907-ln [emphasis on applications];
    Lachièze-Rey a1007-conf [intro];
    Garling 11;
    Todorov BulgJP(11)-a1106 [intro];
    Boudet 11;
    Klawitter 15;
    de Gosson acad(16) [in symplectic geometry and quantum mechanics];
    Shirokov a1709-ln.
  @ Representations:
    Harnett JPA(92) [on 4D bivectors];
    Schray & Manogue FP(96)ht/94 [octonionic];
    West ht/98 [rev];
    Ulrych AACA(08)-a0707 [with hyperbolic numbers];
    Toppan & Verbeek JMP(09)-a0903 ["alphabetic"];
    Budinich a1805 [complex representations].
  @ Related topics: Ablamowicz et al CzJP(03)mp [classification of idempotents];
    Beil & Ketner IJTP(03) [and Peirce logic];
    da Rocha & Vaz AACA(06)mp [generalized, over Peano spaces];
    Aragon-Camarasa et al a0810-proc [with Mathematica];
    Dadbeh a1104 [inverses and determinants, up to dimension 5];
    Hanson a1104
      [real Clifford algebra as a Clifford module over itself];
    Formiga a1209
      [all possibles products between generators of the 4D Clifford algebra];
    Kuusela a1905 [Mathematica package].
  > Online resources:
    see Wikipedia page.
In Physics
  > s.a. bell inequality; kaluza-klein models;
  particle statistics; unified theories;
  {& clifford manifold below}.
  * Electromagnetism: The Maxwell
    equations may be written in a compact form with the help of Clifford numbers.
  * Quantum mechanics: There have
    been attempts at formulating quantum theory based on Clifford numbers instead of
    complex numbers, but it is more difficult than, for example, with quaternions,
    because this is not a division algebra.
  @ Quantum theory:
    Finkelstein IJTP(82) [and quantum sets];
    Baugh et al JMP(01)ht/00;
    Ferrante mp/02 [and fiber bundles];
    Beil & Ketner IJTP(03);
    Hiley & Callaghan a1011;
    Binz et al FP(13)-a1112 [in symplectic geometry and quantum mechanics];
    Hiley LNP-a1211 [starting from the notion of process].
  @ Electromagnetic theory: Gull et al FP(93);
    Dressel et al PRP(15)-a1411 [comprehensive introduction];
    > s.a. electromagnetism.
  @ Special relativity: Baylis & Sobczyk IJTP(04)mp;
    Chappell et al a1101 [representation of 3D space];
    Chappell et al PLoS(12)-a1106,
    a1205
      [algebraic alternative to Minkowski spacetime, Clifford multivectors];
    Castro FP(12)
      [extended relativity theories, superluminal particles];
    > s.a. Rigid Body.
  @ Classical gravity:
    Capelas de Oliveira & Rodrigues IJMPD(04)mp/03 [and spinor fields];
    Francis & Kosowsky AP(04)gq/03 [techniques];
    Hestenes a0807-MGXI [gauge gravity and electroweak theory];
    Castro IJTP(13)
      [Lanczos-Lovelock and f(R) gravity].
  @ Quantum gravity: Cohen AACA-gq/02;
    Pavšič a1104;
    Castro FP(14)
      [black-hole entropy, rainbow metrics, generalized dispersion & uncertainty relations].
  @ Spinning particles:
    Pezzaglia gq/99-proc [in curved spacetime];
    Rodrigues JMP(04)mp/02;
    da Rocha & Vaz IJGMP(07)mp/04,
    mp/04,
    mp/04;
    Coquereaux mp/05-ln [rev, and fundamental interactions];
    > s.a. dirac field theory; fermions.
  @ Quantum field theory, particle physics:
    Pavšič a1104,
    JPCS(13)-a1210 [quantum field theory];
    Daviau & Bertrand JModP(14)-a1408,
    15 [Standard Model];
    Arnault a2105 [emergence from quantum automata].
  @ Other applications: Dimakis & Müller-Hoissen CQG(91) [applications of clifforms in field theory];
    Garrett PW(92)sep; Baylis 96;
    Chernitskii IJMMS(02)ht/00 [Born-Infeld theory];
    Castro & Pavšič IJTP(03)ht/02 [and the conformal group];
    Rausch de Traubenberg ht/05-ln [rev];
    Berrondo et al AJP(12)oct
      [unifying the inertia and Riemann curvature tensors];
    Trindade et al a2005 [quantum information];
    > s.a. Kustaanheimo-Stiefel Transformation.
Related Topics
  > s.a. differential geometry; graph theory [operators].
  * Clifford analysis: The theory
    of functions from \(\mathbb R\)n
    to the universal Clifford algebras, generalizing holomorphic functions.
  * Clifford manifold:
    A "C-space" consisting not only of points, but also of 1-loops, 2-loops, etc.
  @ Clifford analysis: Brackx, Delanghe & Sommen 82.
  @ Clifford manifold: Pavšič FP(03)gq/02-conf [intro],
    ht/04-talk,
FP(05)ht [and generalized quantum field theory and strings].
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