IR fixed point and low-momentum gluon propagator

Assuming the gluon propagator to be finite at g s 2 / 4 π ≡ α → α * , where α * = α ( 0 ) , we derive its low-momentum asymptotics. In some cases the results modify the known ones. In our work, we also establish the field-theoretical nature of a universal phenomenological parameter introduced in works [1] and determining the behaviour of Green’s functions in the infrared region. The importance of studying the renormalization group parameters in the vicinity of the infrared stable point is emphasized.