Gauge invariance
Gauge invariance
For any compact simple gauge group G, a non-trivial quantum Yang–Mills theory exists on ℝ⁴ and has a mass gap Δ > 0. Construct the theory in a mathematically complete way (Wightman or equivalent) and prove the gap.
Gauge invariance —lemma→ Yang–Mills
Gauge invariance —implies→ Mass gap > 0