Plaquette expectation value and lattice free energy of three-dimensional SU(N) gauge theory

We use high precision lattice simulations to calculate the plaquette expectation value in three-dimensional SU(N) gauge theory for N=2,3,4,5,8. Using these results, we study the N-dependence of the first non-perturbative coefficient in the weak-coupling expansion of hot QCD. We demonstrate that, in the limit of large N, the functional form of the plaquette expectation value with ultraviolet divergences subtracted is 15.9(2)-44(2)/N^2.Comment: 14 pages, 6 figures. v2: references added; published versio

Pressure to order g8∗log(g)g^8*log(g) in ϕ4\phi^4-theory at weak coupling

We calculate the pressure of massless $\phi^4$-theory to order $g^8\log(g)$ at weak coupling. The contributions to the pressure arise from the hard momentum scale of order $T$ and the soft momentum scale of order $gT$. Effective field theory methods and dimensional reduction are used to separate the contributions from the two momentum scales: The hard contribution can be calculated as a power series in $g^2$ using naive perturbation theory with bare propagators. The soft contribution can be calculated using an effective theory in three dimensions, whose coefficients are power series in $g^2$. This contribution is a power series in $g$ starting at order $g^3$. The calculation of the hard part to order $g^6$ involves a complicated four-loop sum-integral that was recently calculated by Gynther, Laine, Schr\"oder, Torrero, and Vuorinen. The calculation of the soft part requires calculating the mass parameter in the effective theory to order $g^6$ and the evaluation of five-loop vacuum diagrams in three dimensions. This gives the free energy correct up to order $g^7$. The coefficients of the effective theory satisfy a set of renormalization group equations that can be used to sum up leading and subleading logarithms of $T/gT$. We use the solutions to these equations to obtain a result for the free energy which is correct to order $g^8\log(g)$. Finally, we investigate the convergence of the perturbative series.Comment: 29 pages and 12 figs. New version: we have pushed the calculations to g^8*log(g) using the renormalization group to sum up log(g) from higher orders. Published in JHE

The Stefan-Boltzmann law in a small box and the pressure deficit in hot SU(N) lattice gauge theory

The blackbody radiation in a box L^3 with periodic boundary conditions in thermal equilibrium at a temperature T is affected by finite-size effects. These bring about modifications of the thermodynamic functions which can be expressed in a closed form in terms of the dimensionless parameter LT. For instance, when LT~4 - corresponding to the value where the most reliable SU(N) gauge lattice simulations have been performed above the deconfining temperature T_c - the deviation of the free energy density from its thermodynamic limit is about 5%. This may account for almost half of the pressure deficit observed in lattice simulations at T~ 4 T_c.Comment: 9 pages, 2 figures v2:a side remark on the final result and references adde

Epistemology and public policy : Using a new typology to analyse the paradigm shift in Finnish transport futures research

The aim of the article is to present a new typology of paradigms of futures studies with specific focus on decision-making. Possible roles of futurists and other actors in long-term planning and decision-making processes are formed using logical analysis. The resulting seven schools of thought are interpreted in the light of literature of futures studies and planning theory. Connections to the philosophical discussion on the role of knowledge and values in policy recommendations are presented as well. Some futures studies methodological applications are attached to the paradigms. The new typology forms a gradient from technocracy performed by professionals to direct citizen participation. Finally, the paradigm shift of Finnish national transport futures studies is analysed using the new typology

Seasonal cycle of benthic denitrification and DNRA in the aphotic coastal zone, northern Baltic Sea

Current knowledge on the seasonality of benthic nitrate reduction pathways in the aphotic, density stratified coastal zone of the Baltic Sea is largely based on data from muddy sediments, neglecting the potential contribution of sandy sediments. To gain a more comprehensive understanding of seasonality in this part of the Baltic Sea coast, we measured rates of benthic denitrification, anammox and dissimilatory nitrate reduction to ammonium (DNRA) monthly in the ice-free period of 2016 in both sandy and muddy aphotic sediments, northwestern Gulf of Finland. No anammox was observed. The seasonal cycle of denitrification in both sediment types was related to the hydrography-driven development of bottom water temperature. The seasonal cycle of DNRA was less clear and likely connected to a combination of bottom water temperature, carbon to nitrogen ratio, and substrate competition with denitrification. Denitrification and DNRA rates were 50-80 and 20% lower in the sandy than in the muddy sediment. The share of DNRA in total nitrate reduction, however, was higher in the sandy than in the muddy sediment, being (by similar to 50%) the highest DNRA share in sandy sediments so far measured. Our data add to the small pool of published studies showing significant DNRA in both cold and/or sandy sediments and suggest that DNRA is currently underestimated in the Baltic coastal nitrogen filter. Our results furthermore emphasize that the various environmental conditions of a coastal habitat (light regime, hydrography, and geomorphology) affect biogeochemical element cycling and thus need to be considered in data interpretation.Peer reviewe