Quantum field theories of the dark universe
Lead Research Organisation:
University of Nottingham
Department Name: Sch of Physics & Astronomy
Abstract
The successes of the Standard Models of particle physics and cosmology have been unprecedented. Together, they are able to explain our observations from the dynamics and interactions of subatomic particles on the smallest scales to the evolution of the Universe on its largest scales. However, important questions remain unanswered.
Known particle physics describes only the visible 5% of the Universe. To explain how galaxies formed, and how the stars and gas that they are made of move, we need dark matter. To explain why distant galaxies are accelerating away from us, we need dark energy. The nature of this "dark universe" remains a mystery, and unravelling its secrets is one of the most important and challenging problems in fundamental physics.
In addition, the Standard Models cannot explain how matter came to dominate over antimatter to leave behind the 5% of visible matter. Worse still, measurements of the masses of the heaviest known elementary particles - the Higgs boson and top quark - indicate that our universe may reside in an unstable state that could decay to a catastrophically different one due to the predictions of quantum theory.
To resolve these problems and to explain the nature of the dark universe, we must modify the Standard Model of particle physics or Einstein's theory of gravity, or both.
I aim to do precisely this by introducing new particles described by "scalar fields", which give rise to new forces of nature. Once coupled directly to gravity or, equivalently, to the Higgs boson, these "scalar-tensor theories" become sensitive to the density of their local environment. This allows them to evade tests of gravity in our Solar System but still produce new forces elsewhere in the universe, providing a rich array of behaviours and the potential to describe the dark universe. Moreover, new scalar fields can resolve the weaknesses in our model of particle physics, helping to stabilise the state of our universe or change the way that the hot plasma of the early universe evolved.
I will develop new theoretical tools to confront these models with the full rigour of the mathematical framework that underpins fundamental physics known as quantum field theory. This will allow me to address key theoretical uncertainties that are preventing us from making accurate predictions for experiment and observation. My research will determine definitively whether models of the dark universe based on extra scalar particles can explain the observed content and evolution of the Universe, while standing up to experiment as consistent extensions of known particle physics.
I will establish an internationally leading research group at the University of Nottingham, based within its Particle Cosmology Group, which is home to extensive and complementary expertise in areas of astrophysics and cosmology that will benefit this programme. Additional collaborators will include members of the University's Astronomy and Quantum Gravity Groups, and renowned researchers in theory and experiment from other leading research institutions in the UK and overseas, including the Institute for Particle Physics Phenomenology at Durham University and CERN. I will exploit existing and future data from particle-physics experiments, such as those at CERN's Large Hadron Collider; from ground-based and satellite observatories, such as the Dark Energy Survey and the LIGO gravitational-wave observatory; and from experiments using quantum measurement techniques to look for new forces of nature.
My programme will pioneer a novel interdisciplinary approach to the dark universe, which simultaneously challenges theoretical models on their empirical consistency with data and their mathematical consistency within quantum theory. It will either rule these models out or provide a catalogue of viable ones, along with reliable predictions that will help to guide future experimental and observational efforts to uncover the mysteries of the dark universe.
Known particle physics describes only the visible 5% of the Universe. To explain how galaxies formed, and how the stars and gas that they are made of move, we need dark matter. To explain why distant galaxies are accelerating away from us, we need dark energy. The nature of this "dark universe" remains a mystery, and unravelling its secrets is one of the most important and challenging problems in fundamental physics.
In addition, the Standard Models cannot explain how matter came to dominate over antimatter to leave behind the 5% of visible matter. Worse still, measurements of the masses of the heaviest known elementary particles - the Higgs boson and top quark - indicate that our universe may reside in an unstable state that could decay to a catastrophically different one due to the predictions of quantum theory.
To resolve these problems and to explain the nature of the dark universe, we must modify the Standard Model of particle physics or Einstein's theory of gravity, or both.
I aim to do precisely this by introducing new particles described by "scalar fields", which give rise to new forces of nature. Once coupled directly to gravity or, equivalently, to the Higgs boson, these "scalar-tensor theories" become sensitive to the density of their local environment. This allows them to evade tests of gravity in our Solar System but still produce new forces elsewhere in the universe, providing a rich array of behaviours and the potential to describe the dark universe. Moreover, new scalar fields can resolve the weaknesses in our model of particle physics, helping to stabilise the state of our universe or change the way that the hot plasma of the early universe evolved.
I will develop new theoretical tools to confront these models with the full rigour of the mathematical framework that underpins fundamental physics known as quantum field theory. This will allow me to address key theoretical uncertainties that are preventing us from making accurate predictions for experiment and observation. My research will determine definitively whether models of the dark universe based on extra scalar particles can explain the observed content and evolution of the Universe, while standing up to experiment as consistent extensions of known particle physics.
I will establish an internationally leading research group at the University of Nottingham, based within its Particle Cosmology Group, which is home to extensive and complementary expertise in areas of astrophysics and cosmology that will benefit this programme. Additional collaborators will include members of the University's Astronomy and Quantum Gravity Groups, and renowned researchers in theory and experiment from other leading research institutions in the UK and overseas, including the Institute for Particle Physics Phenomenology at Durham University and CERN. I will exploit existing and future data from particle-physics experiments, such as those at CERN's Large Hadron Collider; from ground-based and satellite observatories, such as the Dark Energy Survey and the LIGO gravitational-wave observatory; and from experiments using quantum measurement techniques to look for new forces of nature.
My programme will pioneer a novel interdisciplinary approach to the dark universe, which simultaneously challenges theoretical models on their empirical consistency with data and their mathematical consistency within quantum theory. It will either rule these models out or provide a catalogue of viable ones, along with reliable predictions that will help to guide future experimental and observational efforts to uncover the mysteries of the dark universe.
Publications
Alexandre J
(2022)
Discrete spacetime symmetries, second quantization, and inner products in a non-Hermitian Dirac fermionic field theory
in Physical Review D
Alexandre, J.
(2023)
Oscillation probabilities for a PT-symmetric non-Hermitian two-state system
Alonso I
(2022)
Cold atoms in space: community workshop summary and proposed road-map
in EPJ Quantum Technology
Chernodub M
(2022)
IR/UV mixing from local similarity maps of scalar non-Hermitian field theories
in Physical Review D
Chernodub Maxim N.
(2024)
Anomalous dispersion, superluminality and instabilities in two-flavour theories with local non-Hermitian mass mixing
in arXiv e-prints
Copeland E
(2022)
Fifth forces and broken scale symmetries in the Jordan frame
in Journal of Cosmology and Astroparticle Physics
Millington P
(2022)
Non-Hermiticity: a new paradigm for model building in particle physics
Sablevice E
(2024)
Poincaré symmetries and representations in pseudo-Hermitian quantum field theory
in Physical Review D
Title | FeynMG |
Description | FeynMG (https://gitlab.com/feynmg/FeynMG/) is a symbolic algebra package, developed in Wolfram Mathematica (https://www.wolfram.com/mathematica/), that allows modified theories of gravity, in particular so-called scalar-tensor theories of gravity, and their interactions with the elementary particles of the Standard Model of particle physics to be recast in a format that can be further processed by the existing high energy physics package FeynRules (https://feynrules.irmp.ucl.ac.be). From within FeynRules, the diagrammatic rules that describe the resulting particle interactions can be output in a format that is compatible with common particle physics analysis software pipelines, thereby automating phenomenological studies of a wide range of modified theories of gravity at particle physics experiments. The accompanying paper is https://doi.org/10.48550/arXiv.2211.14300. |
Type Of Material | Computer model/algorithm |
Year Produced | 2023 |
Provided To Others? | Yes |
Impact | This code has dramatically increased the ease and efficiency with which modified theories of gravity can be studied in terms of particle physics phenomenology, and it is already being applied within the PI's research group to undertake such studies. |
URL | https://gitlab.com/feynmg/FeynMG/ |
Description | Institute for Particle Physics Phenomenology (IPPP) Associateship: Connecting particle physics and modified gravity through Higgs portals |
Organisation | Durham University |
Department | Institute for Particle Physics Phenomenology (IPPP) |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | PI holds an Institute for Particle Physics Phenomenology (IPPP) Associateship (extended due to the COVID-19 pandemic), which is designed to promote collaboration between his research group and members of the IPPP. From November 2021 onwards, this helped to support efforts by the PI (Peter Millington) and collaborators from the University of Nottingham (Sergio Sevillano Muñoz and Edmund J Copeland) to co-develop the symbolic algebra code FeynMG (https://gitlab.com/feynmg/FeynMG), led by Sergio Sevillano Muñoz, for automating phenomenological studies of modified theories of gravity at particle physics experiments by making use of the existing FeynRules framework (https://feynrules.irmp.ucl.ac.be). |
Collaborator Contribution | The code FeynMG was co-developed with Michael Spannowsky of the Institute for Particle Physics Phenomenology (IPPP). |
Impact | Code: FeynMG (https://gitlab.com/feynmg/FeynMG) Working paper: Sergio Sevillano Muñoz, Edmund J Copeland, Peter Millington and Michael Spannowsky, "FeynMG: a FeynRules extension for scalar-tensor theories of gravity" preprint (2023), https://doi.org/10.48550/arXiv.2211.14300. |
Start Year | 2019 |
Description | Royal Society International Exchange: Non-Hermitian field theories for particle physics and solid state physics |
Organisation | François Rabelais University or University of Tours |
Country | France |
Sector | Academic/University |
PI Contribution | The PI holds a Royal Society International Exchanges grant (extended due to the COVID-19 pandemic) to support bilateral exchanges and promote collaboration with the Co-I Maxim Chernodub of the Université de Tours in applications of non-Hermitian quantum theory in particle physics and solid state physics. This partnership is aimed at capitalising on the PI's leading expertise in non-Hermitian quantum field theory. |
Collaborator Contribution | This partnership is aimed at capitalising on the Co-I's leading expertise at the interface between theoretical solid state physics and high energy physics. |
Impact | Primary research article: Maxim N Chernodub and Peter Millington, "IR/UV mixing from local similarity maps of scalar non-Hermitian field theories", Phys. Rev. D 105 (2022) no. 7, 076020 (https://doi.org/10.1103/PhysRevD.105.076020). |
Start Year | 2021 |
Description | School Talk, Nottinghamshire |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Schools |
Results and Impact | PI delivered a schools talk "Big Bangs: smashing particles and our teenage universe" at a secondary school and sixth form in Nottinghamshire, 10 November 2021. This led to additional discussion with the school teachers about other resources and programmes that could enrich their science curriculum. |
Year(s) Of Engagement Activity | 2021 |
Description | Seminar, Institute for Particle Physics Phenomenology (IPPP) |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Other audiences |
Results and Impact | PI delivered an invited seminar "Second quantization in non-Hermitian field theories" remotely at the Institute for Particle Physics Phenomenology (IPPP), Durham University, 27 January 2022. This was followed by extensive discussion that raised the profile of this emerging area of research. |
Year(s) Of Engagement Activity | 2022 |
URL | https://conference.ippp.dur.ac.uk/event/1076/ |
Description | Seminar, Korea Institute for Advanced Study (KIAS) |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | PI delivered an invited seminar "Non-Hermiticity: a new paradigm for model building in particle physics" remotely at the Korea Institute for Advanced Study (KIAS), Seoul, Republic of Korea, 7 December 2021. This was followed by extensive discussion that raised the profile of this emerging area of research. |
Year(s) Of Engagement Activity | 2021 |
URL | https://indico.kias.re.kr/event/76/ |