Ralph Kenna

By the decision of the Academic Council of the ICMP of the National Acad. Sci. of Ukraine of February 11, 2019 the title of Doctor honoris causa was conferred on Ralph Kenna (Coventry, England) for the studies which provided explanation of scaling and universality in complex systems of many interacting agents, pioneering interdisciplinary applications of statistical physics as well as for his personal initiative in different forms of collaboration with Ukraine and his engagement in preparation of young scientists.

Ralph Kenna was born in Athlone, County Westmeath, Ireland. After obtaining a BSc and Master’s degree at Trinity College Dublin in 1988, he won a scholarship for postgraduate studies in Austria funded by the European Council. His PhD studies at the University of Graz (with Professor Christian Lang) were further supported by the Austrian Research Fund. He was awarded by the University of Graz and defended his dissertation (Dr. rer. nat., with distinction) in 1993. Subsequently, he was an EU Marie Curie Research Fellow at the University of Liverpool (1994-1997) and at Trinity College Dublin (1997-1999). He began lecturing in Trinity College from 1998-2002. Since 2002 he is affiliated to Coventry University (England), first as a senior lecturer, then a reader, and since 2012 as a full professor. In 2005 he co-founded the Applied Mathematics Research Centre in Coventry University. In 2016 he co-funded and is a co-director of L4 collaboration and Doctoral college on Statistical physics of complex systems. He pioneered the co-tutelle concept in the UK. He is a Fellow of the Institute of Mathematics and its Applications, Member of the Institute of Physics, Board Member of the Middle European Cooperation on Statistical Physics, etc.

The scientific interests of Ralph Kenna mainly concern field theory, statistical physics of phase transitions and complex systems. In particular, he has solved long-standing problems regarding the question of the properties of the BKT (Berezinskii – Kosterlitz – Thouless) phase transition in the 2d XY model and the scaling behaviour of partition function zeroes. He attracted the attention of the community in 2006 with his remarkable work (with two collaborators from Edinburgh and Leipzig) on scaling relations for logarithmic corrections at continuous phase transitions. This research includes the important problem of scaling behaviour at the upper critical dimension, where it is well known that there are multiplicative logarithmic corrections to scaling. Ralph Kenna and his coworkers have achieved a remarkable tour de force in the analysis of the standard scaling laws between critical exponents and they have proposed new general scaling relations among the correction exponents. These were totally unknown and unexpected relations which led to a major clarification of physics right at the upper critical dimension. These new scaling relations will surely find their place in future textbooks on critical phenomena. He later provided a remarkable analysis of the site-diluted variant of the canonical 2d Ising model. The pure model has a logarithmic divergence of the specific heat, and so is marginal regarding the effect of dilution according to the "Harris criterion". Ralph Kenna and co-workers showed that the site-diluted systems obey strong scaling, but with accurately determined multiplicative logarithmic corrections. Once again this work resolved an outstanding controversy. He recently contributed to the clarification of the so-called dangerous irrelevant variables mechanism above the upper critical dimension. In a paper first published in this journal, a new exponent ϙ (koppa) was introduced that governs the emergence of mean-field theory. More recently he also turned his attention to non-equilibrium models in low dimensions.

In recent times, Ralph Kenna used his deep background in statistical physics and experience with efficient methodologies to conduct scientometric analyses of management and policy of science and even studies of humanities through complexity theory and sociophysics. With a collaborator from Nancy he developed a theory for critical mass of research groups and measured these for a multitude of academic disciplines. This work on measuring research quality has made significant impact in the media and with policy makers all over the world. His scientometrical predictions for REF2014 and subsequent analysis were extensively quoted verbatim in the “Metrics Tide” report, which impacted on the structure of REF2021 itself. He has also pioneered the application of network theory to investigate societies depicted in mythological narratives, opening the way to quantitative research in comparative mythology. In this respect his research might be considered as the origin of a well-defined direction in the interdisciplinary field of “mythematics” (as aptly noted by one of his students). His studies in this field have evoked numerous discussions in academic papers and in the popular press. The results obtained and the methods proposed have been positively recognized by academics, science policy makers and the general public. A further important feature of these studies in sociophysics is that they put the results obtained into the broader context of complex systems, where the social characteristics are seen as emergent features of a society and where quantitative characteristics of social relations are used to classify different groups according to their universal properties.

Ralph is an excellent lecturer, knowing how to explain complicated things in a simple way, a person who has a good ability to lead the work of a group as well as to carry out individual research, and a gifted scientist. He published over 30 common papers with Ukrainian colleagues. Due to Ralph’ activity, ICMP hosted 62 foreign researchers and 17 researchers from ICMP had a chance to visit European research centres during the last five years.

Ralph Kenna's work is always characterised by elegance and precision, which allow him to reach clear conclusions leading to milestone advances in the comprehension of hard statistical physics problems. He has combined incisive physical insight with expert technical analysis so as to overcome barriers to understanding and move frontiers forward.