Towards non-perturbative quantization and the mass gap problem for the Yang-Mills Field
Alexey Sevastyanov (University of Aberdeen)
Tuesday 20th January, 2026 16:00-17:00
Maths 311B
Abstract
Abstract: In 2000 Jaffe and
Witten stated the long standing problem of exact quantization for the 4D Yang-
Mills field on the Minkowski space and the existence of a mass gap in the theory
as one on the Clay Institute Millenium problems. In this talk I shall explain
how to reduce the problem of quantization of the Yang-Mills field Hamiltonian to
a problem for defining a probability measure on an infinite-dimensional space of
gauge equivalence classes of connections, the so called Yang-Mills measure
associated to a 3D Yang-Mills theory on a Euclidean space. A formally
self-adjoint expression for the quantized Yang-Mills Hamiltonian as an operator
on the corresponding Lebesgue L_2-space will be presented.
In the case when the Yang-Mills field is
associated to the abelian group U(1) the Yang-Mills measure will be
defined. This measure is Gaussian and depends on a real parameter m>0. The
quantized Hamiltonian, which is the corresponding Ornstein–Uhlenbeck
operator, can be realized a self-adjoint operator in a Fock space. Its spectrum
has a gap separating the rest of the spectrum from the ground state zero
eigenvalue. This yields a non-standard quantization of the Hamiltonian of the
electromagnetic field.
Recently, based on Hairer's theory of regularity structures,
Chandra, Chevyrev, Hairer and Shen developed an approach for constructing Yang-
Mills measures for Euclidean Yang-Mills theories in 2D and 3D associated to
arbitrary compact Lie groups. Using the corresponding Langevin equation they
defined a Markov process, at least locally with respect to the evolution
parameter, on a space of gauge orbits for which the Yang-Mills measure should be
defined as the invariant measure provided that the process is globally defined
and converges. This result is proved in 2D by different means and the problem is
still open in the physically important 3D case. In this framework the quantized
Yang-Mills Hamiltonian is the generator of the stochastic process the
convergence of which is equivalent to the existence of the mass gap. If time
permits, I shall discuss my program and results for defining the Markov process
globally using Otto's approach to regularity structures.
The presentation in this talk will be self-
contained and requires no special background from the audience.
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