GAMBIT: a Global and Modular Beyond the Standard Model Inference Tool

The most exiting part of physics is the search for new phenomena. One example is the mysterious dark matter that seems to be everywhere in the Universe, yet we have no idea what it is made up of. And this is only one of the many phenomena that are not explained by our current best understanding of the laws and constituents of the microcosm, the so-called Standard Model. What this project aims to do is to create a software tool that will give scientists a better way to investigate new proposed models beyond the Standard Model. The main challenge of the project is to deal with the huge amounts of results that are now available from many currently running experiments such as the Large Hadron Collider (LHC), and that will be available from future experiments such as the Cherenkov Telescope Array (CTA). These complex datasets require sophisticated computing solutions and statistical methods in order to be used together to their fullest potential in the search for new physics. Our hope is that the tools developed in the project will be very important in these searches, for example in pinning down the properties of dark matter. The project is part of the GAMBIT Collaboration, an international collaboration of some 30 physicist, each one a specialist in a particular field or experiment. GAMBIT stands for "a Global And Modular Bsm Inference Tool", so this software is planned to be very generic and modular, meaning that, with time, it can be applied to other problems outside of new physics searches. In fact, it has the potential to be applied to any problem which has a large number of unknown parameters to be determined by a large dataset. The Norwegian side of the collaboration has in the project period focused mainly on the use of results from the LHC, in close collaboration with some of the other nodes. One of the main tasks has been the construction of ColliderBit, the part of the GAMBIT software which takes care of the analysis of LHC results. During the first year of the project the main focus was on recruiting two good postdoctoral researchers, as well as laying the foundations for the GAMBIT software tool together with the rest of the collaboration. To coordinate the work a week long workshop was held in Geilo in January 2015. At the end of the first year the software was near a functioning first beta version, and first tests on physics models were close. The second year of the project concentrated on developing the software towards a final first public version. Two PhD-students at the University of Oslo who were involved in work on GAMBIT defended their thesis, and presented preliminary results there. Alongside continuing development, GAMBIT was tested on two different new physics models: the so-called scalar singlet model, and on a model with supersymmetry. At the end of the second year the software, as well as its documentation and the first physics results, was close to completion, and ready for submittal to a leading physics journal for publication after a planned internal collaboration review. The primary aim of the project, the release of the GAMBIT software version 1.0.0, together with the first physics papers using the new tool, was completed (slightly delayed) in the third project year (May 2017). The software is described in six manual papers which deal with the different components, and the first physics results with GAMBIT are presented in three separate articles, one analysing the so-called scalar singlet model, one discussing supersymmetry motivated by Grand Unified Theory models, and one article on more generic supersymmetry. All results were published in European Physics Journal C, and seven of these papers have significant contributions from the University of Oslo and this project. In the relative short time period from publication to the end of the project all of these papers have been heavily cited, the most with over 60 citations. Project focus then shifted, as planned, from pure development work towards exploitation of GAMBIT in order to complete the milestones in the later part of the project. For the remainder of the third project year and the fourth, focus has been on studies of more and more general models of supersymmetry, as well as other alternative models for dark matter such as portal models with more Higgs bosons and models with axions. At the same time a sequence of improved GAMBIT versions were released, and we are now at version 1.3.0. The project was completed with a GAMBIT workshop in Oslo in September 2018 where several of these physics studies were finalized. At the end of the project two of the physics studies have been published as preprints and submitted to journals, while the completion of two more is close at hand. The prospects for a productive exploitation of GAMBIT over the next years is very good.

Hovedmålet med prosjektet har vært å skape et mykvareverktøy for globale parameterskann av høydimensjonale parameterrom som er basert på åpen kildekode og alment tilgjengelig. Dette verktøyet, GAMBIT (a Global And Modular Bsm Inference Tool), publiserte vi i sammarbeid med resten av GAMBIT kollaborasjonen i mai 2017, som det første av sitt slag i verden. Sammen med GAMBIT publiserte kollaborasjonen en serie med seks artikler som beskrev koden, samt tre artikler som tok den i bruk for å studere et sett med fysikkmodeller som blant annet forsøker å forklare fenomenet mørk materie. Alle artiklene har siden blitt tungt sitert av fagfeller. Det at det nå finnes et verktøy som GAMBIT har stor betydning for arbeidet med å lete etter ny fysikk ved LHC på CERN eller i andre eksperimenter. Vi er for eksempel blitt kontaktet av ATLAS kollaborasjonen ved LHC som vil bruke våre resultater for å forbedre sine søk etter supersymmetriske partikler.

Beyond the SM (BSM) physics is well motivated, e.g. from the existence of Dark Matter (DM), and is expected to show up in multiple experiments, such as accelerator searches (LHC), neutrino mass and mixing data, and direct and indirect DM search experiment s. Some of these already show tantalizing hints of DM or other BSM physics. To make robust conclusions about the level of support for a BSM scenario from such varied sources, a simultaneous statistical fit of all the data, fully taking into account rele vant uncertainties, assumptions and correlations is necessary. The same is true for determining the preferred regions of parameter space within a particular model. This is a highly non-trivial task, on the border of theory and experiment, astrophysics and particle physics, and requires an excellent understanding not only of the theories and experiments involved, but also an efficient use of specialized statistical techniques and computer codes. Whilst partial progress has been made, the magnitude of the t ask and degree of technical difficulty have left it largely unexplored for the majority of BSM theories and datasets. With the start-up of the LHC, vast amounts of new data are rapidly becoming available, quickly making even the analyses that have been do ne in the past year obsolete. The research in this proposal is part of a collaboration that plans to revolutionize this emerging field, by taking publicly available data from the LHC and astrophysics experiments, and vastly expanding the scope of models to which it is applied. The aim is to develop modular tools in a framework that makes it possible to explore any BSM model, with almost all of the relevant particle and astrophysical data recorded. The focus of the project in this application is the inter face to, and use of collider data, in this framework. After a period of development we will apply the tools to the best motivated BSM models in order to investigate the impact of present, and any future, discoveries