Clifford Algebra  

In General > s.a. Gamma Matrices.
$ Def: Given an n-dimensional vector space V with metric , define the matrices {a} satisfying {a, b} = 2 ab I; Then the Clifford algebra is the 2n-dimensional vector space generated by

A:= {I, a , ab , ..., a_1,...a_n} ,      a...c:= [a ... c] .

* 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 R, which includes a notion of direction.
* Properties: For all A, A2 = I, and A B = CABC, with |CAB| = 1.
* Representations: It has 1! equivalence class of IRRs (Pauli's fundamental theorem).
* Relationships: From a representation of the Clifford algebra we get one of the Lie algebra of O() by ab:= [a b] .
@ General references: Hestenes 66, in(86), & Sobczyk 84; Chisholm & Common ed-86; Crumeyrolle 90; Porteous 95; Snygg 97 [III]; Pavsic 01-gq/06.
@ Representations: Harnett JPA(92) [on 4D bivectors]; Schray et al ht/94 [octonionic]; West ht/98; Ulrych AACA(08)-a0707 [with hyperbolic numbers].
@ Related topics: {S Rajeev, RL 21.01.1983}; 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].

In Physics > s.a. bell inequality; dirac field theory; kaluza-klein models; particle statistics; unified theories; {& clifford manifold below}.
* Applications: The Maxwell equations may be written in a very compact form with the help of Clifford numbers.
@ And quantum mechanics: Finkelstein IJTP(82) [and quantum sets]; Baugh et al JMP(01)ht/00; Ferrante mp/02 [and fiber bundles]; Beil & Ketner IJTP(03).
@ And electromagnetic theory: Gull et al FP(93); > s.a. electromagnetism.
@ And special relativity: Baylis & Sobczyk mp/04.
@ And general relativity: Cohen gq/02 [quantum gravity]; Capelas de Oliveira & Rodrigues IJMPD(04)mp/03 [spinor fields]; Francis & Kosowsky AP(04)gq/03 [techniques].
@ Spinning particles: Pezzaglia gq/99-in [in curved spacetime]; Rodrigues JMP(04)mp/02; da Rocha & Vaz mp/04, mp/04, mp/04; Coquereaux mp/05-in [and fundamental interactions].
@ 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]; Castro & Pavsic IJTP(03)ht/02 [and conformal group]; Rausch de Traubenberg ht/05-in [rev].

Related Topics
* Clifford analysis: The theory of functions from Rn 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: Pavsic FP(03)gq/02-in [intro], ht/04-in, FP(05)ht [and generalized quantum field theory and strings].


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