Lattice QCD without topology barriers

As the continuum limit is approached, lattice QCD simulations tend to get trapped in the topological charge sectors of field space and may consequently give biased results in practice. We propose to bypass this problem by imposing open (Neumann) boundary conditions on the gauge field in the time direction. The topological charge can then flow in and out of the lattice, while many properties of the theory (the hadron spectrum, for example) are not affected. Extensive simulations of the SU(3) gauge theory, using the HMC and the closely related SMD algorithm, confirm the absence of topology barriers if these boundary conditions are chosen. Moreover, the calculated autocorrelation times are found to scale approximately like the square of the inverse lattice spacing, thus supporting the conjecture that the HMC algorithm is in the universality class of the Langevin equation.Comment: Plain TeX source, 26 pages, 4 figures include

Loop expansion in Yang-Mills thermodynamics

We argue that a selfconsistent spatial coarse-graining, which involves interacting (anti)calorons of unit topological charge modulus, implies that real-time loop expansions of thermodynamical quantities in the deconfining phase of SU(2) and SU(3) Yang-Mills thermodynamics are, modulo 1PI resummations, determined by a finite number of connected bubble diagrams.Comment: 15 pages, 2 figures, v5: discussion of much more severely constrained nonplanar situation included in Sec.

Non-renormalizability of the HMC algorithm

In lattice field theory, renormalizable simulation algorithms are attractive, because their scaling behaviour as a function of the lattice spacing is predictable. Algorithms implementing the Langevin equation, for example, are known to be renormalizable if the simulated theory is. In this paper we show that the situation is different in the case of the molecular-dynamics evolution on which the HMC algorithm is based. More precisely, studying the phi^4 theory, we find that the hyperbolic character of the molecular-dynamics equations leads to non-local (and thus non-removable) ultraviolet singularities already at one-loop order of perturbation theory.Comment: Plain TeX source, 23 pages, 3 figures included; v2: typos corrected, agrees with published versio

Resummation scheme for 3d Yang-Mills and the two-loop magnetic mass for hot gauge theories

Perturbation theory for non-Abelian gauge theories at finite temperature is plagued by infrared divergences caused by magnetic soft modes $\sim g^2T$, which correspond to the fields of a 3d Yang-Mills theory. We revisit a gauge invariant resummation scheme to solve this problem by self-consistent mass generation using an auxiliary scalar field, improving over previous attempts in two respects. First, we generalise earlier SU(2) treatments to SU(N). Second, we obtain a gauge independent two-loop gap equation, correcting an error in the literature. The resulting two-loop approximation to the magnetic mass represents a $\sim 15$ correction to the leading one-loop value, indicating a reasonable convergence of the resummation.Comment: 16 pages, 3 figure

Author Correction: The mTORC1/4E-BP1 axis represents a critical signaling node during fibrogenesis

Correction to: Nature Communications https://doi.org/10.1038/s41467-018-07858-8, published online 2 January 2019

The power of perturbation theory

We study quantum mechanical systems with a discrete spectrum. We show that the asymptotic series associated to certain paths of steepest-descent (Lefschetz thimbles) are Borel resummable to the full result. Using a geometrical approach based on the PicardLefschetz theory we characterize the conditions under which perturbative expansions lead to exact results. Even when such conditions are not met, we explain how to define a different perturbative expansion that reproduces the full answer without the need of transseries, i.e. non-perturbative effects, such as real (or complex) instantons. Applications to several quantum mechanical systems are presented

Initial validation of the mindful eating scale

Published Mindfulness, 2013, 5(6), pp. 719-729. The final publication is available at Springer via http://dx.doi.org/10.1007/s12671-013-0227-5Self-report scales for mindfulness are now widely used in applied settings, and have made a contribution to research, for instance in demonstrating mediation effects. To date there are no convincing data as to whether mindfulness skills generalise fully across life domains, and so some researchers have developed mindfulness scales for particular domains of behaviour. We present the development of a self-report scale to measure mindfulness with respect to eating behaviours

Stress factors and stress management interventions: the heuristic of “bottom up” an update from a systematic review

Organizations have increasingly sought to adopt innovative interventions to prevent stress-related issues. In the field of manufacturing, however, the effectiveness of these interventions remains unclear because a systematic and specific review of existing primary evidence has not been undertaken. The present systematic literature review sought to address the foregoing limitation in the literature by summarizing the main source of stress and effectiveness of stress management interventions as grounded in the context of manufacturing. Our review was limited to only randomized clinical trials (RCTs) and quasi-experimental studies and concerned employees from the manufacturing sector. Twenty-two studies on primary, secondary and tertiary interventions across four continents (Asia, Europe, USA and South America) were selected and analyzed in terms of stress factors, methodological properties and outcomes. Most of these were RCT studies (68% Vs 32%) with a majority of secondary interventions (N = 11, 50%), followed by primary (N = 5, 22%), tertiary (N = 3, 13%), and two (9%) mixed interventions. The main outcomes included an improvement of psychological wellbeing, decreased stress reactivity and an increment of general health. There was a predominance of interventions utilizing skills programs and/or cognitive-behavioral techniques. The main source of stress reported related to professional identity, organizational deficiencies, interpersonal conflicts, physical complaints and poor work environment. Taken together, the findings provide important theoretical and practical implications for advancing the study of stress factors and the use of stress management interventions in the workplace. The prerequisite for a successful intervention is to address the real problems experienced by professionals and help them to cope with their difficult situations. The strategy of “bottom-up” offers a potential means of enhancing employees’ health and well-being; however, the most effective means of implementing these interventions needs to be understood better