Reflection‐Positive Construction of a Four‐Dimensional SU(N) Yang–Mills Theory With Mass Gap and Confinement

ABSTRACT In the Euclidean view, one must first require that positivity not be violated, and from this modest demand, together with locality, a great deal follows: starting from a reflection‐positive lattice formulation of pure Yang–Mills theory we obtain a transfer operator with a uniform gap, while large Wilson loops already show an area law by means of convergent character (polymer) expansions; a finite‐range, gauge‐covariant multiscale analysis then carries these features from one scale to the next with interlaced inequalities whose small defects can be summed, so that exponential clustering and a strictly positive string tension endure in the continuum; the Osterwalder–Schrader reconstruction turns these Euclidean facts into a Minkowski theory with a self‐adjoint Hamiltonian, the spectral gap lying above the vacuum and the linear potential for static charges appearing, which gives a concrete picture of confinement; the construction depends on no special regulator, for a single‐scale Lipschitz control and a telescoping argument bind all admissible reflection‐positive slicings into a unique limiting measure and thus secure universality; moreover, the same framework admits entry from weak coupling, so that the continuum reached from strong coupling meets the one approached along an asymptotically free trajectory, yielding one and the same theory; in my view this is how mathematical clarity and physical insight cooperate: positivity, locality, and renormalization working together so that the mass gap and confinement are not marvels to be assumed, but natural properties of the non‐Abelian vacuum.