Des Johnston School of Mathematical and Computer Sciences Maxwell Institute for Mathematical Sciences HeriotWatt University Riccarton, Edinburgh EH14 4AS Scotland Email: D.A.Johnston at hw.ac.uk Office: CMS.04 Phone: +44 (0)131 4513255 Fax: +44 (0)131 4513249 AntiSocial Networks: Facebook, Twitter, Google+, Linkedin eprints: ArXiv, PURE Bibliometrics: Google Scholar, Scopus, Mendeley, INSPIRE, ORCID, ResearchGate, ReseacherID History: Maths department history 
Peering into the sun at AIMSSenegal 2017 Word cloud of research interests from scimeter.org using ArXiv 
(Fairly) Current Research Interests: First Order Phase Transitions
Recent research work along with Marco Mueller and Wolfhard Janke of Leipzig University has concentrated on several aspects of such first order transitions, in particular nonstandard scaling behaviour at first order transitions when the low temperature phases are highly degenerate. As luck would have it, an old favorite  the Gonihedric Ising model  provides an example of this. Collaborations with colleagues at Coventry University and a visitor from Sri Lanka, R.P.K.C.M. Ranasinghe, have also investigated the phase transitions of Potts models with socalled invisible states, which display unexpected first order transitions, clarifying why they occur. 
(Fairly) Recent Papers

PhD Era Research Interests: Nielsen Identities etc The framework for understanding particle physics over the past decades has been that of gauge symmetry. The Standard Model in particle physics was constructed by bolting together gauge theories for electromagnetism and the Strong and Weak interactions, with the essential additional ingredient of the Higgs Boson to generate mass while preserving the gauge symmetries. The mechanism for such mass generation is spontaneous symmetry breaking, where the vacuum solutions of the theory have less symmetry than the Lagrangian describing the theory.In order to perform perturbative calculations in such theories it is necessary (or at least convenient) to "fix the gauge", which leads to results for physical quantities, such as the mass of particles, which apparently depend on unphysical parameters introduced in the gauge fixing. My job in my thesis was to show with explicit calculations in a particular model that such dependence was illusory and that, in fact, all was well. The work made use of the socalled Nielsen Identities to demonstrate the gaugeindependence of physical quantities. What a preprint (my first...) used to look like in those prehistoric days before TeX (1984): Nielsen Identities in the 't Hooft Gauge What a thesis (my only...) used to look like in those prehistoric days before TeX (1986): Gauge Properties and Convexity of the Effective Potential 
Some Associated Published Papers

HeriotWatt Lectures HeriotWatt courses:
Maths Masterclass (schools talk):

AIMS Lectures AIMS Ghana course:
AIMS South Africa course:
AIMS Senegal course:
