29 research outputs found
Winding up superfluid in a torus via Bose Einstein condensation
Phase transitions are usually treated as equilibrium phenomena, which yields telltale universality classes with scaling behavior of relaxation time and healing length. However, in second-order phase transitions relaxation time diverges near the critical point (“critical slowing down”). Therefore, every such transition traversed at a finite rate is a non-equilibrium process. Kibble-Zurek mechanism (KZM) captures this basic physics, predicting sizes of domains – fragments of broken symmetry – and the density of topological defects, long-lived relics of symmetry breaking that can survive long after the transition. To test KZM we simulate Bose-Einstein condensation in a ring using stochastic Gross-Pitaevskii equation and show that BEC formation can spontaneously generate quantized circulation of the newborn condensate. The magnitude of the resulting winding numbers and the time-lag of BEC density growth – both experimentally measurable – follow scalings predicted by KZM. Our results may also facilitate measuring the dynamical critical exponent for the BEC transition
Lifestyle gambling, indebtedness and anxiety: A deviant leisure perspective
While once subject to wide-ranging state control, gambling has successfully culturally embedded itself within the normalised and legitimised forms of leisure such as the night-time economy, sports fandom and online forums of socialisation. Consequently, this article argues that existing research which conceptualises gambling as separate from everyday life is largely obsolete in the contemporary context. We argue here that gambling has become an integral feature of the wider masculine weekend leisure experience, intimately connected to an infantilised consumer identity that is peculiar to late-capitalism. This article, drawing upon ongoing ethnographic research among what we term ‘lifestyle gamblers’, utilises a deviant leisure perspective to problematise the myriad harms that emerge from this relationship, situated within a broader critique of consumerism and global capitalism. While social gambling is defended fiercely by the industry, this article argues that an identity-based culture of sports-betting that attaches fragile social and cultural capital to the allure of the gambling win encourages the chasing of losses and impulsive betting. Underscored by a culture of readily available and high-interest credit, we explore how gamblers in a technologically accelerated culture develop a pathological relationship to money as it becomes desublimated and loses its symbolic value. Such processes, exacerbated by the promise of consumer culture, have the potential to cast these young adults into a paralysing reality of indebtedness that is fraught with depression, stress, domestic instability and destructive behaviours of consumption
One-Loop Calculation of the Oblique S Parameter in Higgsless Electroweak Models
We present a one-loop calculation of the oblique S parameter within Higgsless
models of electroweak symmetry breaking and analyze the phenomenological
implications of the available electroweak precision data. We use the most
general effective Lagrangian with at most two derivatives, implementing the
chiral symmetry breaking SU(2)_L x SU(2)_R -> SU(2)_{L+R} with Goldstones,
gauge bosons and one multiplet of vector and axial-vector massive resonance
states. Using the dispersive representation of Peskin and Takeuchi and imposing
the short-distance constraints dictated by the operator product expansion, we
obtain S at the NLO in terms of a few resonance parameters. In
asymptotically-free gauge theories, the final result only depends on the
vector-resonance mass and requires M_V > 1.8 TeV (3.8 TeV) to satisfy the
experimental limits at the 3 \sigma (1\sigma) level; the axial state is always
heavier, we obtain M_A > 2.5 TeV (6.6 TeV) at 3\sigma (1\sigma). In
strongly-coupled models, such as walking or conformal technicolour, where the
second Weinberg sum rule does not apply, the vector and axial couplings are not
determined by the short-distance constraints; but one can still derive a lower
bound on S, provided the hierarchy M_V < M_A remains valid. Even in this less
constrained situation, we find that in order to satisfy the experimental limits
at 3\sigma one needs M_{V,A} > 1.8 TeV.Comment: 34 pages, 9 figures. Version published in JHEP. Some references and
sentences have been added to facilitate the discussio
Oblique S and T Constraints on Electroweak Strongly-Coupled Models with a Light Higgs
Using a general effective Lagrangian implementing the chiral symmetry breaking SU(2)L x SU(2)R -> SU(2){L+R}, we present a one-loop calculation of the oblique S and T parameters within electroweak strongly-coupled models with a light scalar. Imposing a proper ultraviolet behaviour, we determine S and T at next-to-leading order in terms of a few resonance parameters. The constraints from the global fit to electroweak precision data force the massive vector and axial-vector states to be heavy, with masses above the TeV scale, and suggest that the W+W- and ZZ couplings of the Higgs-like scalar should be close to the Standard Model value. Our findings are generic, since they only rely on soft requirements on the short-distance properties of the underlying strongly-coupled theory, which are widely satisfied in more specific scenarios
ISSN exercise & sport nutrition review: research & recommendations
Sports nutrition is a constantly evolving field with hundreds of research papers published annually. For this reason, keeping up to date with the literature is often difficult. This paper is a five year update of the sports nutrition review article published as the lead paper to launch the JISSN in 2004 and presents a well-referenced overview of the current state of the science related to how to optimize training and athletic performance through nutrition. More specifically, this paper provides an overview of: 1.) The definitional category of ergogenic aids and dietary supplements; 2.) How dietary supplements are legally regulated; 3.) How to evaluate the scientific merit of nutritional supplements; 4.) General nutritional strategies to optimize performance and enhance recovery; and, 5.) An overview of our current understanding of the ergogenic value of nutrition and dietary supplementation in regards to weight gain, weight loss, and performance enhancement. Our hope is that ISSN members and individuals interested in sports nutrition find this review useful in their daily practice and consultation with their clients