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.
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.
Publications
Aaij R
(2023)
A study of $$C\!P$$ violation in the decays $${ {B} ^\pm } \rightarrow [{ {K} ^+} { {K} ^-} { {\uppi } ^+} { {\uppi } ^-} ]_{D} h^{\pm }$$ ($$h = K, \pi $$) and $${ {B} ^\pm } \rightarrow [{ {\uppi } ^+} { {\uppi } ^-} { {\uppi } ^+} { {\uppi } ^-} ]_{D} h^{\pm }$$
in The European Physical Journal C
Aaij R
(2021)
Measurement of the CKM angle ? in B± ? DK± and B± ? Dp± decays with D ? $$ {K}_{\mathrm{S}}^0 $$h+h-
in Journal of High Energy Physics
Aaij R
(2022)
Observation of the B 0 ? D ¯ * 0 K + p - and B s 0 ? D ¯ * 0 K - p + decays
in Physical Review D
Aaij R
(2024)
Improved Measurement of CP Violation Parameters in B_{s}^{0}?J/?K^{+}K^{-} Decays in the Vicinity of the ?(1020) Resonance.
in Physical review letters
Aaij R
(2021)
Precise measurement of the f s / f d ratio of fragmentation fractions and of B s 0 decay branching fractions
in Physical Review D
Aaij R
(2019)
Measurement of the B c - meson production fraction and asymmetry in 7 and 13 TeV p p collisions
in Physical Review D
Aaij R
(2022)
Measurement of the charm mixing parameter y C P - y C P K p using two-body D 0 meson decays
in Physical Review D
Amhis Y
(2021)
Averages of b-hadron, c-hadron, and $$\tau $$-lepton properties as of 2018 Heavy Flavor Averaging Group (HFLAV)
in The European Physical Journal C
Dembinski H
(2022)
Custom Orthogonal Weight functions (COWs) for event classification
in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Garra Ticó J
(2020)
Study of the sensitivity to CKM angle ? under simultaneous determination from multiple B meson decay modes
in Physical Review D
Description | Departmental Funded PhD Student |
Amount | £100,000 (GBP) |
Organisation | University of Warwick |
Sector | Academic/University |
Country | United Kingdom |
Start | 09/2020 |
End | 04/2024 |
Description | LHCb Upgrade II: Maximising HL-LHC Discovery Potential |
Amount | £143,386 (GBP) |
Funding ID | ST/V003755/1 |
Organisation | Science and Technologies Facilities Council (STFC) |
Sector | Public |
Country | United Kingdom |
Start | 09/2021 |
End | 09/2024 |
Description | LHCb Upgrade II: Maximising HL-LHC Discovery Potential (Bridging Funding) |
Amount | £18,771 (GBP) |
Funding ID | ST/V003178/1 |
Organisation | Science and Technologies Facilities Council (STFC) |
Sector | Public |
Country | United Kingdom |
Start | 09/2020 |
End | 09/2021 |
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 | The flavour of New Physics in the loops of hadronic beauty decays |
Amount | £1,284,264 (GBP) |
Funding ID | EP/X014746/1 |
Organisation | United Kingdom Research and Innovation |
Sector | Public |
Country | United Kingdom |
Start | 09/2022 |
End | 09/2027 |
Description | The flavour of New Physics in the loops of hadronic beauty decays |
Amount | £1,284,265 (GBP) |
Funding ID | EP/X014746/1 |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 09/2022 |
End | 04/2023 |
Title | Custom Orthogonal Weight functions |
Description | A method for estimating the empirical density of a signal component in a control dimension(s) based on a fit to a mixed sample of signal and background in a discriminating dimension. |
Type Of Material | Data analysis technique |
Year Produced | 2022 |
Provided To Others? | Yes |
Impact | Adapted and implemented by several High Energy Physics analyses. |
URL | https://sweights.readthedocs.io/en/latest/ |
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 |
Title | sweights |
Description | A python package for implementing the sweights and COWs signal weighting methods. |
Type Of Technology | Software |
Year Produced | 2022 |
Open Source License? | Yes |
Impact | Used by several High Energy Physics analyses. |
URL | https://sweights.readthedocs.io/en/latest/ |
Description | Science Advisor for Netflix Show |
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 | I am the scientific advisor on a Netflix science-fiction show called "Three Body Problem" which will be released later in 2023. |
Year(s) Of Engagement Activity | 2022,2023 |
Description | Talk at Polesworth School |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Schools |
Results and Impact | Outreach talk on discovery at Polesworth School |
Year(s) Of Engagement Activity | 2022 |
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 |