SU(4) lattice gauge theory with decuplet fermions: Schr\"odinger functional analysis

We complete a program of study of SU(N) gauge theories coupled to two flavors of fermions in the two-index symmetric representation by performing numerical simulations in SU(4). The beta function, defined and calculated via the Schr\"odinger functional, runs more slowly than the two-loop perturbative result. The mass anomalous dimension levels off in strong coupling at a value of about 0.45, rendering this theory unsuitable for walking technicolor. A large-N comparison of this data with results from SU(2) and SU(3) reveals striking regularities.Comment: 15 pages, 15 figure

Determining the conformal window: SU(2) gauge theory with N_f = 4, 6 and 10 fermion flavours

We study the evolution of the coupling in SU(2) gauge field theory with $N_f=4$, 6 and 10 fundamental fermion flavours on the lattice. These values are chosen close to the expected edges of the conformal window, where the theory possesses an infrared fixed point. We use improved Wilson-clover action, and measure the coupling in the Schr\"odinger functional scheme. At four flavours we observe that the couping grows towards the infrared, implying QCD-like behaviour, whereas at ten flavours the results are compatible with a Banks-Zaks type infrared fixed point. The six flavour case remains inconclusive: the evolution of the coupling is seen to become slower at the infrared, but the accuracy of the results falls short from fully resolving the fate of the coupling. We also measure the mass anomalous dimension for the $N_f=6$ case.Comment: 22 pages, 12 figures. Proof readin

Individual response to different forms of resistance training in school-aged boys

The aim of this study was to examine individual responses to different forms of resistance training on measures of jumping and sprinting performance in school-aged boys. Eighty boys were categorized into two maturity groups (pre- or post-PHV) and randomly assigned to a plyometric training, resistance training, combined training, or control group. Intervention groups participated in training twice weekly for six weeks, with measures of acceleration, maximal running velocity, squat jump height and reactive strength index collected pre and post intervention. In the pre-PHV cohort, plyometric training and combined training resulted in significantly more positive responders than the other two groups in both sprint variables (standardized residual values > 1.96). In the post-PHV cohort, significantly more positive responders for acceleration and squat jump height resulted from traditional strength training and combined training groups, compared with other groups. Conversely, plyometric training and combined training resulted in a significantly greater number of positive responders than the other two groups for maximal velocity and reactive strength index. Control participants rarely demonstrated meaningful changes in performance over the six-week period. Irrespective of maturation, it would appear that combined training provides the greatest opportunity for most individuals to make short-term improvements in jump and sprint performance. Taking maturation into account, our data show that a plyometric training stimulus is important for individuals in the pre-PHV stage of development, whether as a standalone method or in combination with traditional strength training, when attempting to improve jumping and sprinting ability. However, individuals in the post-PHV stage require a more specific training stimulus depending on the performance variable that is being targeted for improvement

Dilaton EFT framework for lattice data

We develop an effective-field-theory (EFT) framework to analyze the spectra emerging from lattice simulations of a large class of confining gauge theories. Simulations of these theories, for which the light-fermion count is not far below the critical value for transition to infrared conformal behavior, have indicated the presence of a remarkably light singlet scalar particle. We incorporate this particle by including a scalar field in the EFT along with the Nambu-Goldstone bosons (NGB's), and discuss the application of this EFT to lattice data. We highlight the feature that data on the NGB's alone can tightly restrict the form of the scalar interactions. As an example, we apply the framework to lattice data for an SU(3) gauge theory with eight fermion flavors, concluding that the EFT can describe the data well