theorem
proved
tactic proof
V_reciprocal_symm
show as:
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formal statement (Lean)
69theorem V_reciprocal_symm {phi_inf : ℝ} (h : -1 < phi_inf) :
70 V phi_inf = V ((1 + phi_inf)⁻¹ - 1) := by
proof body
Tactic-mode proof.
71 unfold V
72 have h_arg_pos : (0 : ℝ) < 1 + phi_inf := by linarith
73 have h_eq : 1 + ((1 + phi_inf)⁻¹ - 1) = (1 + phi_inf)⁻¹ := by ring
74 rw [h_eq]
75 exact Cost.Jcost_symm h_arg_pos
76
77/-- The squared-form expression for `V`:
78`V(φ_inf) = φ_inf² / (2 (1 + φ_inf))`. Standard quadratic potential
79near the vacuum, deviates at large displacement. -/