TY - JOUR

T1 - Time-independent stochastic quantization, Dyson-Schwinger equations, and infrared critical exponents in QCD

AU - Zwanziger, Daniel

PY - 2003

Y1 - 2003

N2 - We derive the equations of time-independent stochastic quantization, without reference to an unphysical fifth time, from the principle of gauge equivalence. It asserts that probability distributions P that give the same expectation values for gauge-invariant observables 〈W〉-∫dAWP are physically indistinguishable. This method escapes the Gribov critique. We derive an exact system of equations that closely resembles the Dyson-Schwinger equations of Faddeev-Popov theory. The system is truncated and solved nonperturbatively, by means of a power law ansatz, for the critical exponents that characterize the asymptotic form at k≈0 of the gluon propagator in Landau gauge. For the transverse and longitudinal parts, we find, respectively, DT ∼(k2)-1-αT≈(k2) 0.043, suppressed and in fact vanishing, though weakly, and D l∼a(k2)-1-αL ≈a(k 2)-1.521, enhanced, with αT = -2αL. Although the longitudinal part vanishes with the gauge parameter a in the Landau-gauge limit a→0 there are vertices of order a-1 so, counterintuitively, the longitudinal part of the gluon propagator does contribute in internal lines in the Landau gauge, replacing the ghost that occurs in Faddeev-Popov theory. We compare our results with the corresponding results in Faddeev-Popov theory.

AB - We derive the equations of time-independent stochastic quantization, without reference to an unphysical fifth time, from the principle of gauge equivalence. It asserts that probability distributions P that give the same expectation values for gauge-invariant observables 〈W〉-∫dAWP are physically indistinguishable. This method escapes the Gribov critique. We derive an exact system of equations that closely resembles the Dyson-Schwinger equations of Faddeev-Popov theory. The system is truncated and solved nonperturbatively, by means of a power law ansatz, for the critical exponents that characterize the asymptotic form at k≈0 of the gluon propagator in Landau gauge. For the transverse and longitudinal parts, we find, respectively, DT ∼(k2)-1-αT≈(k2) 0.043, suppressed and in fact vanishing, though weakly, and D l∼a(k2)-1-αL ≈a(k 2)-1.521, enhanced, with αT = -2αL. Although the longitudinal part vanishes with the gauge parameter a in the Landau-gauge limit a→0 there are vertices of order a-1 so, counterintuitively, the longitudinal part of the gluon propagator does contribute in internal lines in the Landau gauge, replacing the ghost that occurs in Faddeev-Popov theory. We compare our results with the corresponding results in Faddeev-Popov theory.

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U2 - 10.1103/PhysRevD.68.105001

DO - 10.1103/PhysRevD.68.105001

M3 - Article

AN - SCOPUS:0037660994

VL - 68

JO - Physical review D: Particles and fields

JF - Physical review D: Particles and fields

SN - 1550-7998

IS - 10

M1 - 105001

ER -