Characterising the Higgs boson to search for new physics
Lead Research Organisation:
Imperial College London
Department Name: Physics
Abstract
The discovery of the Higgs boson by the ATLAS and CMS detectors was the greatest success of the first run of the Large Hadron Collider (LHC) at CERN and represented a huge step forward in the experimental verification of the Standard Model (SM) of particle physics. In proton-proton collisions, the Higgs boson is produced and subsequently decays via a number of different processes. The SM, our best description of the fundamental interaction of particles, accurately predicts the rate at which each of these processes occurs.
Despite the remarkable success of the SM, we know it to be an incomplete picture. For example, it provides no explanation for the existence of dark matter. The LHC uniquely offers the opportunity to study Higgs production and decay and allow us to see how well nature agrees with the theoretical predictions. Any deviation from the predictions will be a clear sign of the existence of new physics and provide hints as to where physicists should be looking next. Moreover, if dark matter interacts with the Higgs boson, additional decays of the Higgs boson to dark matter particles will produce detectable signatures at the LHC, providing a link between the SM and dark matter. This research programme proposed is to probe potential new physics with the Higgs boson through a series of precision couplings and properties measurements building towards a full characterisation of the Higgs boson.
These measurements are a major focus of the LHC, CERN and in general of the European strategy for particle physics. The measurements can be interpreted in a number of theoretical models proposed to extend the SM. The aim of this research is to connect precision Higgs measurements with physics beyond the SM in order to fully characterise the Higgs boson which will be a key consideration in the design of future experiments in the search for new physics.
Despite the remarkable success of the SM, we know it to be an incomplete picture. For example, it provides no explanation for the existence of dark matter. The LHC uniquely offers the opportunity to study Higgs production and decay and allow us to see how well nature agrees with the theoretical predictions. Any deviation from the predictions will be a clear sign of the existence of new physics and provide hints as to where physicists should be looking next. Moreover, if dark matter interacts with the Higgs boson, additional decays of the Higgs boson to dark matter particles will produce detectable signatures at the LHC, providing a link between the SM and dark matter. This research programme proposed is to probe potential new physics with the Higgs boson through a series of precision couplings and properties measurements building towards a full characterisation of the Higgs boson.
These measurements are a major focus of the LHC, CERN and in general of the European strategy for particle physics. The measurements can be interpreted in a number of theoretical models proposed to extend the SM. The aim of this research is to connect precision Higgs measurements with physics beyond the SM in order to fully characterise the Higgs boson which will be a key consideration in the design of future experiments in the search for new physics.
People |
ORCID iD |
Nicholas Wardle (Principal Investigator / Fellow) |
Publications
Abdallah W
(2020)
Reinterpretation of LHC Results for New Physics: Status and recommendations after Run 2
in SciPost Physics
Albert A
(2017)
Towards the next generation of simplified Dark Matter models
in Physics of the Dark Universe
Cranmer K
(2022)
Publishing statistical models: Getting the most out of particle physics experiments
in SciPost Physics
Khachatryan V
(2017)
Searches for invisible decays of the Higgs boson in pp collisions at s $$ \sqrt{s} $$ = 7, 8, and 13 TeV
in Journal of High Energy Physics
Khachatryan V
(2017)
Search for light bosons in decays of the 125 GeV Higgs boson in proton-proton collisions at s = 8 $$ \sqrt{s}=8 $$ TeV
in Journal of High Energy Physics
Description | In the course of this award, a number of major steps forward in our understanding of the Higgs boson have been made. In particular, related to this award, the establishment of the coupling of the Higgs boson to top-quarks has been firmly established and there is strong evidence for the coupling to muons. The strongest direct constraint on the Higgs-electron coupling, an extremely small coupling due to the electron's mass, has been placed and published as a result of this award. A detailed description of the production mechanisms, owing to large amounts of data and sophisticated data analysis methods, has been produced using the diphoton decay channel and the precision now reached on measurements of couplings of the Higgs boson to SM particles has been significantly improved since discovery, through combinations of production and decay channels as published in Nature. A first interpretation of these combinations in the context of a very wide range of BSM models (through an effective field theory approach). The constraints on the Higgs boson decay to invisible particles has been pushed to the O(10%) level, which has allowed for competitive constraints on certain dark matter models to be placed, providing complementary information to direct searches for dark matter. The most comprehensive set of combined measurements of Higgs boson properties has been produced and published in Nature. These will serve as the guide for the benchmark and design of future accelerators including the HL-LHC and potentially Future colliders. |
Exploitation Route | The detailed study of the Higgs boson in the search for BSM physics is a major goal of the LHC and particle physics in general. The statistical tools and methodologies developed in this fellowship can be (and have been) used to further these precision measurements with more data and expand the sensitivity to BSM physics. The techniques developed in the context of EFTs are now a focal point of current PhD thesis research in my group, and the re-interpretation of precision Higgs boson measurements is becoming more widely adopted as a route to BSM exploration. |
Sectors | Digital/Communication/Information Technologies (including Software) Education |
Description | The current understanding of the Higgs boson, in part due to results produced through this award, are leading the discussion on the future of particle colliders and the field in general. The next major experiment in the field will necessarily have to address the precision Higgs boson measurement programme in the context of the search for new physics. A number of undergraduate and post-graduate students have been trained in statistical methods of the analysis of large datasets, computational methods for data collection and analysis and scientific presentation and communication skills through research projects associated to this award - these skills are very much in demand both within and outside academia. The ongoing discussion on publication of data, and statistical models at the LHC has been significantly advanced, which contributes to the wider discussion of FAIR science. |
First Year Of Impact | 2019 |
Sector | Digital/Communication/Information Technologies (including Software),Education |
Description | ExCALIBUR-HEP |
Amount | £29,717 (GBP) |
Funding ID | EP/V001116/1 |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 11/2020 |
End | 01/2022 |
Title | Simplified Likelihoods for the re-interpretation of Searches for new physics |
Description | This method allows for an accurate statistical re-interpretation of searches for physics beyond the standard model at the LHC. The methods being developed are easily accessible to a vast range of phenomenologists and theorists, meaning this searches are further impacting than previously. The methods are being developed under a series of workshops and papers which aim to refine these techniques for use with the extremely large datasets becoming available at the LHC, and in the future, the high lu |
Type Of Material | Improvements to research infrastructure |
Year Produced | 2017 |
Provided To Others? | Yes |
Impact | The use of these methods is relatively new but already we are seeing citations for papers which provide the necessary information to use the tools, and by extension the original note describing it. |
URL | https://cds.cern.ch/record/2242860?ln=en |
Description | Re-interpretation of LHC searches for new physics |
Organisation | International Institute of Physics |
Country | Brazil |
Sector | Charity/Non Profit |
PI Contribution | I have entered into collaboration with the Re-interpretations group at CERN, whose role it is to provide guidance for re-interpreting LHC results in the context of new physics. The group consists of theorists and experimentalists from the international HEP community. I was invited to help organise the latest regular workshop held in Natal, Brazil in November 2017, with travel being funded through the research grant. |
Collaborator Contribution | The other collaborators have agreed to co-author several papers based on the activities of the most recent workshop. |
Impact | So far, the main outcome has been the workshop at the international institute of physics in Natal, Brazil : https://www.iip.ufrn.br/eventsdetail.php?inf===QTUVUM . The workshop hosted members of the experimental and theoretical international HEP community. A number of publications are expected as a result of this workshop. |
Start Year | 2017 |
Description | iPPP Associateship |
Organisation | Durham University |
Department | Institute for Particle Physics Phenomenology (IPPP) |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | iPPP associateship started in October 2018 to fund collaboration based on Reinterpretations of LHC data to constrain BSM phenomena |
Collaborator Contribution | Associate partner fully provides the award for collaborative research activities. |
Impact | Workshop : "(Re)interpreting the results of new physics searches at the LHC", hosted at Imperial College organised with support from this collaboration. Dates 2-4 April 2019 |
Start Year | 2018 |
Description | HEP group open day |
Form Of Engagement Activity | Participation in an open day or visit at my research institution |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Schools |
Results and Impact | Talk and demonstration of CMS event reconstruction - prospective students were taken around the department in groups to view the different options for PhD studies. The purpose was to advertise the PhD programmes available in the group and increase application interest to the group. |
Year(s) Of Engagement Activity | 2020 |
Description | Physics at the LHC - Secondary school talk |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Schools |
Results and Impact | Visit to The Sandon School in Chelmsford, Essex to give a talk to GCSE Science students about "Physics at the LHC" and experiences as a particle physicist. Also engaged with 6th form Physics students in a discussion session centred around career paths for becoming a research scientist. |
Year(s) Of Engagement Activity | 2017 |