|  Symmetries in Quantum Physics | 
In General > s.a. hilbert space; particle
  statistics; symplectic manifolds and structures.
  * Idea: One has to specify the
    action of a transformation under consideration as an operator on the Hilbert
    space, and check what it does to observables.
  * Applications: A symmetry gives
    many properties of a system, due to linearity, using group representations;
    The parameters that classify particles (mass and the various quantum numbers),
    are just a characterization of how they transform under all symmetry groups of the
    laws of nature; A particle "is" how it transforms under these symmetries.
  * Appoaches: In the Dirac approach,
    gauge symmetries are generated by first-class constraints; In the Faddeev-Jackiw
    approach, gauge, reparametrization and other symmetries are generated by the null
    eigenvectors of the sympletic matrix.
  @ Simple: Lee 88;
    Gross PT(95)dec.
  @ General references: Wigner PAPS(49);
    Sakurai 64;
    Houtappel et al RMP(65);
    Greiner & Müller 94;
    Wotzasek AP(95)ht [Faddeev-Jackiw approach];
    Fano & Rau 96;
    Chaichian & Hagedorn 97;
    Wilczek NPPS(98)ht/97 [examples];
    Larsson mp/01 [deepest];
    Kim NPPS(01)ht [particles];
    Kempf PRD(01) [symmetric operators and unitary transformations];
    Khruschov a0807 [symmetry algebras from observables];
    Ziaeepour JPCS(15)-a1502 [symmetry as a foundational concept];
    Lombardi & Fortin EJTP-a1602 [role of symmetry in the interpretation of quantum mechanics];
    Marletto & Vedral a2005
      [the concept of 'classical measuring apparatus' is untenable];
    > s.a. Wigner's Theorem.
  @ Invariant actions: Michel CRAS(71);
    Gaeta LMP(93);
    Hurth & Skenderis NPB(99) [construction of quantum field theories].
  @ Symmetry reduction: D'Avanzo et al IJGMP(05)mp [algebras of differential operators];
    Wu PRD(09)-a0801 [in quantum field theory];
    Torre JMP(09)-a0901 [and quasi-free states];
    Bates et al RVMP(09) [singularly reduced systems];
    Hochs & Mathai AiM(15)-a1309 [result on commutation of quantization with reduction];
    Kumar & Sarovar JPA(14)-a1412;
    > s.a. loop quantum gravity.
  > Related topics:
    see quantum systems; open quantum systems.
Types of Symmetries
  > s.a. conformal symmetry [including scale symmetry];
  CPT symmetry; Permutations.
  * In general: Permutations
    of particles (exact); Continuous spacetime transformations (exact); Discrete
    transformations, C, P, T, G-parity, etc (only CPT exact); Gauge transformations
    (only some are exact).
  * Gauge symmetries: They are
    stronger, more restrictive versions of internal symmetries; They can be related
    to constraints in the classical theory, but a more general approach uses null
    vectors of the symplectic structure; In quantum field theory, they are associated
    with spin-1 (vector) fields, which are massless if the symmetry is exact.
  * Chiral symmetry: Associated
    with spin-1/2 particles, which are massless if the symmetry is exact.
  @ Particle physics, in general:
    Kibble CP(65),
    reprint CP(09).
  @ Time translation: Lehto et al PLB(89) [in quantum field theory];
    Nagata & Nakamura IJTP(09) [as a constraint on non-local realism];
    > s.a. crystals [breaking].
  @ Gauge symmetries:
    Bergmann & Flaherty JMP(78);
    Ying et al ht/99 [integral view];
    Pons SHPMP(05)phy/04 [Dirac's analysis].
  @ Chiral symmetry: Brown & Rho PRP(02) [in nuclear physics].
  @ In quantum field theory, other:
    Łopuszański 90 [lecture notes];
    Connes & Marcolli JGP(06)ht/05 [universal symmetry as motivic Galois group];
    Jaffe & Ritter a0704 [representations of spacetime symmetries];
    Bangu SHPMP(08)
      [Gell-Mann–Ne'eman Ω− prediction
      on the basis of symmetry classification scheme];
    Wallace SHPMP(09) [vs classical fields];
    Lowdon a1509
      [non-manifest symmetries, and their anomalies];
    Trautner a1608-PhD
      [outer automorphisms of symmetries, "symmetries of symmetries"];
    > s.a. klein-gordon fields [symmetry reduction].
Deformations, Violations, Quantum-Motivated Generalizations
  > s.a. anomalies; deformations;
  symmetry breaking.
  * Idea: The fact that a classical
    theory has a certain symmetry does not imply that the corresponding quantum theory has
    that symmetry, because of possible anomalies.
  @ Generalizations: Taylor JMP(80) [generalized groups];
    Mezey & Maruani MolP(90) [fuzzy, "syntopy"];
    Oeckl JGP(02)mp/01 [in terms of quantum groups];
    Lukierski in(05)ht/04 [deformations];
    Kunzinger & Popovych a0903-proc [re non-classical symmetries];
    Schreiber & Škoda a1004-ln [categorified symmetries in quantum field theory];
    > s.a. quantum group.
  @ Related topics: Balachandran et al NPB(87) [central extensions of symmetry groups upon quantization];
    Bohr & Ulfbeck RMP(95) [and origin of quantum mechanics].
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