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theorem

boson_symmetric

proved
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module
IndisputableMonolith.QFT.SpinStatistics
domain
QFT
line
144 · github
papers citing
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IndisputableMonolith.QFT.SpinStatistics on GitHub at line 144.

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formal source

 141
 142/-- **THEOREM (Boson Phase)**: Integer spin particles acquire +1
 143    under the full 8-tick cycle (2π rotation). -/
 144theorem boson_symmetric (s : Spin) (h : s.isInteger) :
 145    cyclePhase s = 1 := by
 146  unfold cyclePhase Spin.value Spin.isInteger at *
 147  -- s.twice is even, so s.twice % 2 = 0
 148  have heven : s.twice % 2 = 0 := h
 149  -- Get k such that s.twice = 2k
 150  have ⟨k, hk⟩ := Int.even_iff.mpr heven
 151  -- The phase is exp(2πi × (twice/2)) = exp(2πi × k) = 1
 152  have h_rewrite : 2 * π * I * (s.twice / 2 : ℝ) = (k : ℂ) * (2 * π * I) := by
 153    rw [hk]
 154    push_cast
 155    ring
 156  rw [h_rewrite, Complex.exp_int_mul_two_pi_mul_I]
 157
 158/-! ## Particle Statistics Classification -/
 159
 160/-- Particle statistics type. -/
 161inductive Statistics where
 162  | fermiDirac
 163  | boseEinstein
 164deriving DecidableEq, Repr
 165
 166/-- Determine statistics from spin. -/
 167def statisticsFromSpin (s : Spin) : Statistics :=
 168  if s.isHalfInteger then Statistics.fermiDirac else Statistics.boseEinstein
 169
 170/-- **THEOREM (Spin-Statistics)**: Half-integer spin implies Fermi-Dirac statistics. -/
 171theorem spin_statistics_fermion (s : Spin) (h : s.isHalfInteger) :
 172    statisticsFromSpin s = Statistics.fermiDirac := by
 173  simp [statisticsFromSpin, h]
 174