RG/Pade Estimate of the Three-Loop Contribution to the QCD Static Potential Function

The three renormalization-group-accessible three-loop coefficients of powers of logarithms within the \bar{MS} series momentum-space for the QCD static potential are calculated and compared to values obtained via asymptotic Pad\'e-approximant methods. The leading and next-to-leading logarithmic coefficients are both found to be in exact agreement with their asymptotic Pad\'e-predictions. The predicted value for the third RG-accessible coefficient is found to be within 7% relative |error| of its true value for n_f leq 6, and is shown to be in exact agreement with its true value in the n_f \to \infty limit. Asymptotic Pad\'e estimates are also obtained for the remaining (RG-inaccessible) three-loop coefficient. Comparison is also made with recent estimates of the three-loop contribution to the configuration-space static-potential function.Comment: 13 pages, LaTeX, additional discussion on the result

Estimate of the Three-Loop MS bar Contribution to sigma(W_L^+ W_L^- --> Z_L Z_L)

The three-loop contribution to the MS bar single-Higgs-doublet standard-model cross-section $\sigma(W_L^+ W_L^- \to Z_L Z_L)$ at s = (5M_H)^2 is estimated via least-squares matching of the asymptotic Pade-approximant prediction of the next order term, a procedure that has been previously applied to QCD corrections to correlation functions and decay amplitudes. In contrast to these prior applications, the expansion parameter for the W_L^+ W_L^- \to Z_L Z_L process is the non-asymptotically-free quartic scalar-field coupling of the standard model, suggesting that the least-squares matching be performed over the "infrared" mu^2 <= s region of the scale parameter. All three coefficients of logarithms within the three-loop term obtained by such matching are found to be within 6.6% relative error of their true values, as determined via renormalization-group methods. Surprisingly, almost identical results are obtained by performing the least squares matching over the mu^2 >= s region.Comment: 9 pages, LaTeX, 3 figures adde

Infrared Consistency of NSVZ and DRED Supersymmetric Gluodynamics

Pade approximant methods are applied to known terms of the DRED beta- function for N = 1 supersymmetric SU(3) Yang-Mills theory. Each of the [N|M] approximants with N + M less than or equal to 4 (M not equal to zero) constructed from this series exhibits a positive pole which precedes any zeros of the approximant, consistent with the same infrared-attractor pole behaviour known to characterise the exact NSVZ beta-function. A similar Pade-approximant analysis of truncations of the NSVZ series is shown consistently to reproduce the geometric-series pole of the exact NSVZ beta function.Comment: LaTeX, 15 page

The Canonical Structure of the First Order Einstein-Hilbert Action with a Flat Background

It has been shown that the canonical structure of the first order Einstein-Hilbert (1EH) action involves three generations of constraints and that these can be used to find the generator of a gauge transformation which leaves the action invariant; this transformation is a diffeomorphism with field-dependent gauge function while on shell. In this paper we examine the relationship between the canonical structure of this action and that of the first order spin-2 (1S2) action, which is the weak field limit of the Einstein-Hilbert action. We find that the weak field limit of the Possion Brackets (PB) algebra of first class constraints associated with the 1EH action is not that of the 1S2 action.Comment: 9 pages, LaTeX2e, published versio

Dynamical spin effects in the pion

We take into account dynamical spin effects in the holographic light-front pion wavefunction in order to predict the pion radius, decay constant, the pion electromagnetic and photon-to-pion transition form factors. We report a striking improvement in the description of all data.Comment: 4 pages, 2 figures. Proceedings Contribution for the 9th International Workshop on Diffraction in High Energy Physics (Diffraction 2016), Santa Tecla di Acireale, Catania, Italy, September 2-8, 201