In statistical mechanics and quantum field theory, a dangerously irrelevant operator (or dangerous irrelevant operator) is an operator which is irrelevant at a renormalization group fixed point, yet affects the infrared (IR) physics significantly (e.g.
A dangerously irrelevant operator (DIO) in statistical mechanics and quantum field theory is an operator that is insignificant at a fixed point of the renormalization group, yet has a significant impact on infrared physics.