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structure

Spin

definition
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module
IndisputableMonolith.QFT.SpinStatistics
domain
QFT
line
49 · github
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IndisputableMonolith.QFT.SpinStatistics on GitHub at line 49.

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formal source

  46/-! ## Spin Representation -/
  47
  48/-- Spin quantum number as a half-integer (n/2 for integer n). -/
  49structure Spin where
  50  /-- Twice the spin value (to keep integer arithmetic). -/
  51  twice : ℤ
  52  /-- Spin must be non-negative. -/
  53  nonneg : twice ≥ 0
  54
  55namespace Spin
  56
  57/-- Create a spin from an integer (s = n means spin n). -/
  58def ofInt (n : ℕ) : Spin := ⟨2 * n, by omega⟩
  59
  60/-- Create a half-integer spin (s = n/2). -/
  61def halfInt (n : ℕ) : Spin := ⟨n, by omega⟩
  62
  63/-- Spin 0. -/
  64def zero : Spin := ofInt 0
  65
  66/-- Spin 1/2 (electron, quarks). -/
  67def half : Spin := halfInt 1
  68
  69/-- Spin 1 (photon, W/Z, gluon). -/
  70def one : Spin := ofInt 1
  71
  72/-- Spin 3/2 (hypothetical gravitino). -/
  73def threeHalves : Spin := halfInt 3
  74
  75/-- Spin 2 (graviton). -/
  76def two : Spin := ofInt 2
  77
  78/-- The actual spin value as a real number. -/
  79noncomputable def value (s : Spin) : ℝ := s.twice / 2