This book presents the proceedings of The International Workshop on Frontiers in High Energy Physics (FHEP 2019), held in Hyderabad, India. It highlights recent, exciting experimental findings from LHC, KEK, LIGO and several other facilities, and discusses new ideas for the unified treatment of cosmology and particle physics and in the light of new observations, which could pave the way for a better understanding of the universe we live in. As such, the book provides a platform to foster collaboration in order to provide insights into this important field of physics.

The Higgs boson discovery at the Large Hadron Collider in 2012 relied on boosted decision trees. Since then, high energy physics (HEP) has applied modern machine learning (ML) techniques to all stages of the data analysis pipeline, from raw data processing to statistical analysis. The unique requirements of HEP data analysis, the availability of high-quality simulators, the complexity of the data structures (which rarely are image-like), the control of uncertainties expected from scientific measurements, and the exabyte-scale datasets require the development of HEP-specific ML techniques. While these developments proceed at full speed along many paths, the nineteen reviews in this book offer a self-contained, pedagogical introduction to ML models' real-life applications in HEP, written by some of the foremost experts in their area.

Frontiers in Physics – FPHY – is now in its eighth year. Up to last year, the journal received a slowly increasing trickle of manuscripts, and then during the summer… Boom! The number of manuscripts we receive started increasing exponentially. This is of course a signal to us who are associated with the journal that we are on the right track to build a first-rate journal spanning the entire field of physics. And it is not the only signal. We also see it in other indicators such as the number of views and downloads, Impact Factor and the Cite Score. Should we be surprised at this increase? If I were to describe FPHY in one word, it would be “innovation”. Attaching the names of the reviewers that have endorsed publication permanently to the published paper is certainly in this class. It ensures that the reviewers are accountable; furthermore, the level of transparency this implies ensures that any conflict of interest is detected at the very beginning of the process. The review process itself is innovative. After an initial review that proceeds traditionally, the reviewers and authors enter a back-and-forth dialog that irons out any misunderstanding. The reviewers retain their anonymity throughout the process. The entire review process and any question concerning editorial decisions is fully in the hands of active scientists. The Frontiers staff is not allowed to make any such decision. They oversee the process and make sure that the manuscript and the process leading to publication or rejection upholds the standard. FPHY is of course a gold open access journal. This is the only scientific publication model that is compatible with the information revolution. A journal’s prestige is traditionally associated with how difficult it is to publish there. Exclusivity as criterion for desirability, is a mechanism we know very well from the consumer market. However, is this criterion appropriate for scientific publishing? It is almost by definition not possible to predict the importance of a new idea – otherwise it would not have been new. So, why should journals make decisions on publishing based on predicting the possible importance of a given work. This can only be properly assessed after publication. Frontiers has removed “importance” from the list of criteria for publication. That the work is new, is another matter: the work must be new and scientifically correct. It would seem that removing the criterion of “importance” would be a risky one, but it turns out not to be. The Specialty Chief Editors who lead the 18 sections that constitute FPHY, have made this selection of papers published in FPHY in 2019. We have chosen the papers that we have found most striking. Even though this is far from a random selection, they do give a good idea of what PFHY is about. Enjoy! We certainly did while making this selection. Professor Alex Hansen (Field Chief Editor)

This book honors the remarkable science and life of Shoucheng Zhang, a condensed matter theorist known for his work on topological insulators, the quantum Hall effect, spintronics, superconductivity, and other fields. It contains the contributions displayed at the Shoucheng Zhang Memorial Workshop held on May 2-4, 2019 at Stanford University.

This book provides a remarkable and complete survey of important questions at the interface between theoretical particle physics and cosmology. After discussing the theoretical and experimental physics revolution that led to the rise of the Standard Model in the past century, the author reviews all the major open puzzles, among them the hierarchy problem, the small value of the cosmological constant, the matter-antimatter asymmetry, and the dark matter enigma, including the state-of-the-art regarding proposed solutions. Also addressed are the rapidly expanding fields of thermal dark matter, cosmological first-order phase transitions and gravitational-wave signatures. In addition, the book presents the original and interdisciplinary PhD research work of the author relating to Weakly-Interacting-Massive-Particles around the TeV scale, which are among the most studied dark matter candidates. Motivated by the absence of experimental evidence for such particles, this thesis explores the possibility that dark matter is much heavier than what is conventionally assumed.

In June 2016, a group of 167 physicists from 31 countries have met in Erice to participate in the 54th Course of the International School of Subnuclear Physics. The main focus of this year's course has been the new frontiers of Physics in the LHC-2 Era and in all labs the world over, as well as the new frontiers in related fields.