Getting a flavour for New Physics with precision measurements of tree-level beauty decays

Lead Research Organisation: University of Warwick
Department Name: Physics

Abstract

Elementary particle physics has an incredibly successful underlying theoretical framework known as the Standard Model which has produced a succession of successful predictions and subsequent discoveries in recent decades. This culminated in the discovery of the Higgs Boson in 2012, which was the last missing piece of the Standard Model. However, there are still a multitude of observed phenomena which the Standard Model cannot explain and the focus of this research is understanding the matter-antimatter asymmetry of the universe.

In the hot early universe matter and antimatter should have been created in equal amounts; this is the simple conversion of energy into matter via Einstein's famous equation, E=mc^2. Once the universe cooled the matter and antimatter would have "annihlated" to leave behind an abundance of electromagnetic radiation. This electromagnetic radiation we see today as the cosmic microwave background, the static seen on an untuned televsion. However, there is clearly an imbalance as we also see large amounts of matter, which make up the stars, galaxies and ourselves whilst no antimatter is left at all. We can understand some part of this as being due to charge-parity symmetry (that which relates matter to antimatter) being broken. In the intial stages of matter-antimatter creation charge-parity violation results in a small excess of matter, which goes on to make up the observable universe of today, after the majority annihilates with the antimatter to leave behind the electromagnetic radiation still echoing around the universe. The problem is that the amount of charge-parity violation predicted by the theoretical framework underlying our understanding of elementary particle physics is nowhere near enough (a factor several billion off) to account for the observed matter to electromagnetic radiation ratio of the universe.

This project uses data from the Large Hadron Collider to look for new fundamental physics particles which can help to explain the matter-antimatter discrepancy. By analysing millions of matter and antimatter decays produced at the LHCb experiment we can observe the subtle differences between them. The parameters we determine in this project are of particular interest because they can be measured completely independently of any input from the theoretical framework, i.e. independently of any prior knowledge. We can then use these parameters to prove the existence, and predict the behaviour, of new fundamental physics particles which explain why we live in a matter dominated universe and hence why we have atoms, molecules and life itself.

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ST/R004536/1 31/03/2019 29/09/2019 £465,427
ST/R004536/2 Transfer ST/R004536/1 30/09/2019 30/03/2024 £418,850
 
Description Departmental Funded PhD Student
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Sector Academic/University
Country United Kingdom
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Description LHCb Upgrade II: Maximising HL-LHC Discovery Potential (Bridging Funding)
Amount £18,771 (GBP)
Funding ID ST/V003178/1 
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Description Monash Warwick Alliance Particle Physics
Amount £458,519 (GBP)
Organisation University of Warwick 
Sector Academic/University
Country United Kingdom
Start 09/2020 
End 10/2025
 
Description Heavy Flavour Averaging Group (HFLAV) 
Organisation Heavy Flavor Averaging Group
Sector Public 
PI Contribution I perform the world averages for CKM angles alpha, beta and gamma. Write the section of the HFLAV document on Unitarity Angles.
Collaborator Contribution There are roughly 20 collaborators in this group and between us we produce a large report of many important measurement in heavy flavour physics every 2 years.
Impact Publication of the HFLAV report on heavy flavour averages every 2 years. We also provide input to the European Strategy for Particle Physics.
Start Year 2016
 
Description LHCb Collaboration 
Organisation European Organization for Nuclear Research (CERN)
Department CERN LHC LHCb
Country Switzerland 
Sector Public 
PI Contribution I have been working on analysis of LHCb data and contributing to performance tasks for the experiment. I have acted as an internal reviewer on several occasions for the collaboration. I currently hold a management position within the collaboration.
Collaborator Contribution Have input of common software and data formats. Sharing of resources.
Impact Several publications.
Start Year 2014
 
Description Particle Data Group (PDG) 
Organisation Particle Data Group
Country United States 
Sector Academic/University 
PI Contribution I provide the numbers for the world averages of CKM angles (alpha, beta and gamma). I have written the review on "Determination of CKM angles from B hadrons"
Collaborator Contribution The PDG comprises many authors from many institutes. Between us we put together the world averages for almost all measurements made in particle and nuclear physics.
Impact Publication of the Particle Data Group 2020 (in progress) with online update in 2019.
Start Year 2019
 
Title GammaCombo framework 
Description A package for statistical analysis in High Energy Physics. 
Type Of Technology Software 
Year Produced 2019 
Open Source License? Yes  
Impact Used in several LHCb collaboration publications and studies 
URL https://gammacombo.github.io
 
Description YouTube video on the new results from LHCb 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Produced a short video on YouTube explaining recent exciting results from LHCb.
Year(s) Of Engagement Activity 2021
URL https://www.youtube.com/watch?v=NgBEhX8eiWM