arXiv subjects

A. C. Mattingly

Publications and source records attributed to A. C. Mattingly.

4 recordsLinked to original sources

arXiv1994

$τ$ Decay and the QCD infrared fixed point

We apply the optimization procedure based on the Principle of Minimal Sensitivity to the third-order calculation of $R_τ$. Since the effective couplant remains finite, freezing to a value $α_s/π= 0.26$ at low energies, we can actually evaluate the defining integral of $R_τ$ and compare the optimized perturbation theory result to that of the optimized result obtained after the integral has been evaluated using contour techniques. The good agreement shows that the optimization procedure is consistent and suggests that the infrared fixed point is meaningful.

hep-ph↗

arXiv1993

Optimization of R(e+e-) and "Freezing" of the QCD Couplant at Low Energies

The new result for the third-order QCD corrections to R_{e^+e^-}, unlike the old, incorrect result, is nicely compatible with the principle-of-minimal-sensitivity optimization method. Moreover, it leads to infrared fixed-point behaviour: the optimized couplant, alpha_s/pi, for R(e+e-) does not diverge at low energies, but "freezes" to a value 0.26 below about 300 MeV. This provides some direct theoretical evidence, purely from perturbation theory, for the "freezing" of the couplant -- an idea that has long been a popular and successful phenomenological hypothesis. We use the "smearing" method of Poggio, Quinn, and Weinberg to compare the resulting theoretical prediction for R(e+e-) with experimental data down to the lowest energies, and find excellent agreement.

hep-ph↗

arXiv1992

Applying Optimized Perturbation Theory to QCD at Low Energies

We discuss the use of the optimization procedure based on the Principle of Minimal Sensitivity to the third-order calculation of {\mbox{${R_{e^+e^-}}$}}. The effective coupling constant remains finite allowing us to apply the Poggio-Quinn-Weinberg smearing method down to energies below 1 GeV, where we find good agreement between theory and experiment. The couplant freezes to a value of $α_s/π= 0.26$ at zero energy which is in remarkable concordance with values obtained phenomenologically.

hep-ph↗

arXiv1992

QCD Perturbation Theory at Low Energies

We apply the optimization procedure based on the Principle of Minimal Sensitivity to the third-order calculation of $\R$. The effective couplant remains finite, freezing to a value $α_s/π= 0.26$ at low energies. Using Poggio-Quinn-Weinberg smearing we find good agreement between theory and experiment right down to zero energy.

hep-ph↗