Real scalar phase transitions : a nonperturbative analysis

We study the thermal phase transitions of a generic real scalar field, without a Z(2)-symmetry, referred to variously as an inert, sterile or singlet scalar, or phi(3) + phi(4) theory. Such a scalar field arises in a wide range of models, including as the inflaton, or as a portal to the dark sector. At high temperatures, we perform dimensional reduction, matching to an effective theory in three dimensions, which we then study both perturbatively to three-loop order and on the lattice. For strong first-order transitions, with large tree-level cubic couplings, our lattice Monte-Carlo simulations agree with perturbation theory within error. However, as the size of the cubic coupling decreases, relative to the quartic coupling, perturbation theory becomes less and less reliable, breaking down completely in the approach to the Z(2)-symmetric limit, in which the transition is of second order. Notwithstanding, the renormalisation group is shown to significantly extend the validity of perturbation theory. Throughout, our calculations are made as explicit as possible so that this article may serve as a guide for similar calculations in other theories.Peer reviewe

The detection of trace volatiles from complex matrices using gas chromatography mass spectrometry (GCMS) techniques and selected ion flow tube mass spectrometry (SIFT-MS) assessment of volatiles produced from nitric oxide producing smart dressings

Volatile compounds (VCs) hold the potential to diagnose and monitor disease states in a cost effective, rapid, and most importantly non-invasive manner. Gas chromatography mass spectrometry (GC-MS) has been in use since the 1960s and remains the gold standard for qualitative VC analysis. Within this thesis three novel methods and/or utilisations of mass spectrometry are described. Chapter 2 describes and benchmarks a metal oxide sensor (MOS) coupled to a standard GC-MS instrument. Testing this system to the headspace of 12 stool samples the sensor detected a mean 1.6 more peaks per sample then the MS. This superior sensitivity exhibited by the MOS sensor should allow for greater discriminatory abilities to differentiate samples into clinically relevant groups. It has become increasingly important to qualitatively and quantitatively assess the VCs for use in monitoring health. Chapter 3 describes a novel method for the quantification of VCs from the headspace of stool samples analysed using GC-MSis presented. Using 13C labelled carbon compounds as internal standards a method has been designed which quantifies the compounds withinin the stool; 15 compounds were quantified. The EDX110 dressing has been developed by Edixomed Ltd; uses hydrogel technology to generate nitric oxide (NO) to enhance wound healing. A series of experiments first allowed for the development of a robust and reproducible method of real-time quantification. The effect of pH was assessed using citric acid buffered with sodium citrate, pH values3, 3.6, 4.2, 4.8, 5.4, and 6.2 were all analysed. NO production showed an inverse correlation; pH 3 producing 81 μg of NO and pH 6.2 only producing 7μg. With the exception of pH 3 HONO and NO2 remained relatively consistent across the pH values with a median 3 and 0.9μg respectively

Perturbative effective field theory expansions for cosmological phase transitions

Guided by previous non-perturbative lattice simulations of a two-step electroweak phase transition, we reformulate the perturbative analysis of equilibrium thermodynamics for generic cosmological phase transitions in terms of effective field theory (EFT) expansions. Based on thermal scale hierarchies, we argue that the scale of many interesting phase transitions is in-between the soft and ultrasoft energy scales, which have been the focus of studies utilising high-temperature dimensional reduction. The corresponding EFT expansions provide a handle to control the perturbative expansion, and allow us to avoid spurious infrared divergences, imaginary parts, gauge dependence and renormalisation scale dependence that have plagued previous studies. As a direct application, we present a novel approach to two-step electroweak phase transitions, by constructing separate effective descriptions for two consecutive transitions. Our approach provides simple expressions for effective potentials separately in different phases, a numerically inexpensive method to determine thermodynamics, and significantly improves agreement with the non-perturbative lattice simulations.Comment: 58 pages, 14 figure

First-order electroweak phase transitions : A nonperturbative update

Publisher Copyright: © 2022 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.We study first-order electroweak phase transitions nonperturbatively, assuming any particles beyond the Standard Model are sufficiently heavy to be integrated out at the phase transition. Utilizing high temperature dimensional reduction, we perform lattice Monte Carlo simulations to calculate the main quantities characterizing the transition: the critical temperature, the latent heat, the surface tension and the bubble nucleation rate, updating and extending previous lattice studies. We focus on the region where the theory gives first-order phase transitions due to an effective reduction in the Higgs self-coupling and give a detailed comparison with perturbation theory.Peer reviewe

A framework for material flow assessment in manufacturing systems

Improving material efficiency is widely accepted as one of the key challenges facing manufacturers in the future. Increasing material consumption is having detrimental impacts on the environment as a result of their extraction, processing, and disposal. It is clear that radical improvements in material efficiency are required to avoid further environmental damage and sustain the manufacturing sector. Current resource management approaches are predominantly used to improve material consumption solely in economic terms. Meanwhile, environmental assessment methodologies can determine sources of significant environmental impact related to a product; however, a methodology to effectively assess material efficiency in production systems is currently not available. This paper highlights the benefits of material flow modeling within manufacturing systems to support advances in increased material efficiency, proposing a framework for “material flow assessment in manufacturing” that promotes greater understanding of material flow and flexibility to explore innovative options for improvement

Vacuum bubble collisions : From microphysics to gravitational waves

We comprehensively study the effects of bubble wall thickness and speed on the gravitational wave emission spectrum of collisions of two vacuum bubbles. We numerically simulate a large dynamical range, making use of symmetry to reduce the dimensionality. The high-frequency slope of the gravitational wave spectrum is shown to depend on the thickness of the bubble wall, becoming steeper for thick-wall bubbles, in agreement with recent fully 3 + 1 dimensional lattice simulations of many-bubble collisions. This dependence is present, even for highly relativistic bubble wall collisions. We use the reduced dimensionality as an opportunity to investigate dynamical phenomena which may underlie the observed differences in the gravitational wave spectra. These phenomena include "trapping," which occurs most for thin-wall bubbles, and oscillations behind the bubble wall, which occur for thick-wall bubbles.Peer reviewe

An examination of application scale for material flow assessment in manufacturing systems

Evaluation of material flow in manufacturing systems can be used as a way of identifying and implementing options for improvements in material efficiency in the factory. We have previously developed a framework for material flow assessment in manufacturing systems (MFAM), which incorporates material flow information in both quantitative and qualitative terms as materials travel through a user-defined system. In this paper we examine the potential for application of the MFAM at various system scales, ranging from individual process scale, to manufacturing cell, factory, enterprise, and local or global supply chain scale divisions. Here we describe guidelines for setting the appropriate system boundary. In addition we highlight the potential material efficiency improvement options available in each case, in terms of the scope of improvements and the potential for integration within future strategic planning processes

Worldline sphaleron for thermal Schwinger pair production

With increasing temperatures, Schwinger pair production changes from a quantum tunneling to a classical, thermal process, determined by a worldline sphaleron. We show this and calculate the corresponding rate of pair production for both spinor and scalar quantum electrodynamics, including the semiclassical prefactor. For electron-positron pair production from a thermal bath of photons and in the presence of an electric field, the rate we derive is faster than both perturbative photon fusion and the zero temperature Schwinger process. We work to all-orders in the coupling and hence our results are also relevant to the pair production of (strongly coupled) magnetic monopoles in heavy-ion collisions.Peer reviewe

Schwinger pair production of magnetic monopoles : Momentum distribution for heavy-ion collisions

Magnetic monopoles may be produced by the dual Schwinger effect in strong magnetic fields. Today, the strongest known magnetic fields in the Universe are produced fleetingly in heavy-ion collisions. We use the complex worldline instanton method to calculate the momentum distribution of magnetic monopoles produced in heavy-ion collisions, in an approximation that includes the effect of the magnetic field to all orders but neglects monopole self-interactions. The result saturates the preparation time-energy uncertainty principle, and yields a necessary ingredient for experimental monopole searches in heavy-ion collisions.Peer reviewe