Particle Physics

The Monash Particle Physics group focuses its research on the theoretical, phenomenological and experimental aspects of high energy particle physics and particle cosmology.

We are part of a small international team who collaborate on the world's leading dynamical model of high-energy particle collisions, PYTHIA. The program is designed to simulate the physics processes that can occur in collisions between high-energy particles, like at the LHC collider at CERN. A combination of quantum field theory and phenomenological models are combined to trace the evolution from simple initial states towards complex final states.

Essentially all matter in the universe is made up of up and down quarks, electrons and neutrinos. However, in nature this family of particles is replicated three times over and we have no understanding of why that is the case. At the LHCb experiment at the Large Hadron Collider and the COMET experiment under construction in Japan we study the interactions between these generations as a way of probing physical effects at very high energy scales.

The Standard Model of elementary particles cannot explain the cosmic domination of matter over antimatter, it cannot account for dark matter particles and their abundance, and it cannot justify the observed properties of the Higgs boson. We study the predictions of the Standard Model and extensions for observables that can be studied experimentally. The aim of the research is to interact closely with experimentalists to come up with the best strategies for new physics searches. We are part of the development of GAMBIT, the Global And Modular Beyond-the-Standard-Models Inference Tool which is able to assess the experimental plausibility of a given BSM model.

	Head of Group Professor Ulrik Egede	Experimental High Energy Physics Search for phenomena not described by the Standard Model of particle physics Application of artificial intelligence in real-time processing and data selection Development of Big Data processing tools Phenomenology of electroweak penguin decays Analysis of lepton non-universality in the decays of b-hadrons Detector developments for upgrades of the LHCb detector
	Professor Csaba Balazs	Particle astrophysics and particle cosmology Symmetry breaking and phase transitions in the Early Universe Gravitational wave probes of fundamental physics and dark matter Cosmic matter-antimatter asymmetry, baryogenesis Dark matter properties and detection Inflation and dark energy models Theories beyond the standard models of particles and cosmology
	Dr Tom Hadavizadeh	Experimental particle physics Analysis of rare decays of particles containing beauty quarks Measurements of matter-antimatter differences in decays of particles containing charm quarks The production of charm and beauty quarks via the strong force Simulations of particle collisions
	Professor Jordan Nash	Higgs boson physics Particle Physics Lepton Flavour Violation Particle Detectors
	Professor Peter Skands	Theoretical High Energy Physics Particle Physics Phenomenology Collider Physics Quantum Chromodynamics Computer Physics, Monte Carlo Event Generators Collaborations: PYTHIA, VINCIA, LHC@home/Test4Theory
	Dr Ludovic Scyboz	Theoretical high-energy particle physics Quantum Chromodynamics Monte-Carlo event generators, parton showers & resummation Higgs boson phenomenology & Effective Field Theories
	Professor German Valencia	Particle Physics Phenomenology Collider Physics - LHC. Physics beyond the standard model Flavour physics. Puzzles involving the different fermions in the standard model Effective field theories, chiral perturbation theory, hadronic physics

Research Fellows

	Dr Sam Dekkers	Experimental particle physics Particle detectors and electronics Muon physics LHCb physics
	Dr Jack Helliwell	Theoretical high energy physics Collider phenomenology Event generators and parton showers Quantum Chromodynamics
	Dr Riley Henderson	Experimental particle physics Parton shower algorithms for MC event generators. Precision tests of the Standard Model and searches for unknown physical phenomena Understanding and simulating the production and decay of rare heavy hadrons
	Dr Xiao Wang	Particle cosmology Gravitational waves in the early universe Physics beyond standard model Electroweak first-order phase transition

PhD Students

• Jade Abidi, Theory
• Mohamed Aboudonia, Theory
• Claire Bergman, Theory
• Riccardo Bonacci, Experiment: LHCb
• Gleb Chizhik, Experiment: LHCb
• Alec Christakakis, Experiment: LHCb
• Thomas Harris, Experiment: LHCb
• Alexander Jelavic, Experiment: LHCb, Monash Warwick Alliance
• Wan-Xia Li, Experiment: LHCb
• Flynn Linton, Theory
• Frank Liu, Experiment: LHCb
• Isaac Lobo, Experiment: LHCb
• Alex Miles, Experiment: COMET
• Giacomo Morgante, Theory
• Louis Parker, Theory
• Liam Pinchbeck, Theory
• Hira Sohail, Theory
• William Searle, Theory
• Rongrong Song, Experiment: LHCb
• Eliot Walton, Experiment: LHCb, Monash Warwick Alliance
• Jonathan Zuk, Theory

Research

Researchers in the School are tackling some of the most profound questions in science, such as the origin of space, time and matter. We study the basic elements of matter that make up our universe and the physical laws that govern them. Our research encompasses both Standard Model physics, such as electroweak interactions, quantum chromodynamics, which describes quarks and gluons, and physics beyond the standard model, including: dark matter, dark energy, supersymmetry, the origin of neutrino masses, matter-antimatter asymmetries, extra dimensions and quantum cosmology. We are involved in developing new theoretical models, understanding the relationship between theory and experiments, making experimental measurements and developing new particle physics detectors.

Virtual Colliders

Experimental flavour physics

Essentially all matter in the universe is made up of up and down quarks, electrons and neutrinos. However, in nature this family of particles is replicated three times over. The study of the particles and their interactions is called flavour physics. There is not as yet any theoretical understanding of why there are three generations and if they are really behaving identically or not. The Monash group is involved in two flavour physics experiments.

At the COMET experiment under construction in Japan, the world’s most intense source of muons is stopped inside the experiment to search for muon to electron conversion. This is a process that would see a muon decay directly to an electron without producing any neutrinos. The process is forbidden in the Standard Model and a discovery could fundamentally change the understanding of how particles interact. The Monash group is responsible for the main part of trigger electronics, software developments and simulation studies.

In the LHCb experiment, large amounts of hadrons containing b-quarks are produced from the proton-proton collisions of the Large Hadron Collider. We are heavily involved in the analysis of so-called penguin decays where results in recent years have provided some very interesting deviations from the Standard Model expectations. We are taking advantage of virtual collider group to develop new analyses that further our understanding of hadrons with heavy quarks in hadron collisions. This collaboration also aids us with the role of being responsible for the event generator usage in LHCb. The group is responsible for the software within the collaboration that allows all collaborators to access the data from the experiment that is distributed across the globe. For the upgrade of the LHCb detector we are involved in how to develop machine learning algorithms that will be executed in hardware as part of the trigger for the electromagnetic calorimeter.

Beyond the Standard Model physics

The Standard Model of elementary particles cannot explain the cosmic domination of matter over antimatter, it cannot account for dark matter particles and their abundance, and it cannot justify the observed properties of the Higgs boson.  Many Beyond the Standard Model extensions were proposed but it is unclear which of these theories have more merits than others.

We study the predictions of the standard model and extensions for observables that can be studied experimentally. The theory aspects include model building, collider physics calculations, electroweak corrections and hadronic physics. The aim is to interact closely with experimentalists to come up with the best strategies for new physics searches.

Co-lead by Monash researchers, a whole community is working on a comprehensive approach to isolating traces of new physics in a wide range of experimental data.  They developed GAMBIT, the Global And Modular Beyond-the-Standard-Models Inference Tool which, when run on a supercomputer, is able to assess the experimental plausibility of a given BSM model.

Particle Cosmology

In spite of being the fundamental component of all visible matter, baryonic matter accounts for less than twenty percent of the whole matter content of the Universe. From a number of cosmological and astrophysical source we know the remaining eighty percent of matter in the Universe consists of dark matter, yet we do not know what dark matter is and where it originated. Research lead my members of the Monash group studies the nature of dark matter, it's origin and the prospects for experimental exploration.

The fundamental symmetries of Nature require that the Universe contains the same amount of matter and anti-matter, yet anti-matter is absent in the visible Universe. Researchers at Monash study the origin of matter through baryogenesis, the mechanism of generating this matter-antimatter asymmetry in the early Universe, often associated with a strong cosmological phase transition.

With the resent observation of gravitational waves for the first time, a new window has been opened to explore the history of the Universe though gravitational waves. Any strong first-order phase transition in the early Universe can produce a visible spectrum of gravitational waves that is detectable by current or near future detectors. The Monash particle cosmology group studies the consequences of these cosmological phase transitions in a number of models, including those from electroweak symmetry breaking or phase transitions inspired by the unification of forces.

Monash Warwick Alliance in Particle Physics (MWAPP)

From 2020 onwards the Monash (Australia) and Warwick (UK) particle physics groups have formed an alliance. This creates a world-leading research centre that will enhance the international standing of both Universities. An investment of A$1.8M (Monash) + £0.6M (Warwick) is available on top of significant resources of A$2.2M (Monash) + £0.9M (Warwick) from existing sources. The alliance is initially funded until 2025 but is anticipated to become self-sustaining beyond that. Through this funding, both groups will be able to expand their activities with a new academic, several postdocs and several PhD students. The PhD students will spend time at both universities and will obtain a degree from both.

Some of the most high profile measurements in particle physics, like measurements of the b anomalies that are currently getting a lot of exposure, are limited in their precision by insufficient modelling of the theoretical effects. There are also limitations from the ability to carry out large-scale simulations. Improving both the accuracy and the efficiency of simulations will benefit from the combined experimental and phenomenological knowledge at Warwick and Monash.The alliance will also explore how break-throughs in the understanding of effects such as creation of doubly heavy hadrons, parton showers and colour reconnections can be achieved through better designed experimental measurements.