This paper introduces WCxf, a novel exchange format designed to facilitate the sharing and interoperability of Wilson coefficients for local operators in effective field theories (EFTs) beyond the Standard Model (BSM). The Wilson coefficients encapsulate low-energy effects of new physics models while enabling model-independent analyses and separating low-energy phenomenology from short-distance physics.
Overview and Objectives
The WCxf format serves to bridge model-specific Wilson coefficient calculators, renormalisation group (RG) runners, and observable calculators. It is constructed to be unambiguous by uniquely fixing operators and their normalization within each basis, extensible by supporting new EFTs and bases, and robust by using industry-standard file formats like JSON and YAML. This exchange format enhances collaboration across various EFTs, particularly the Standard Model Effective Field Theory (SMEFT) and weak effective theory (WET), facilitating the integration of public codes dealing with BSM physics.
WCxf organizes data into three types of files: EFT files, basis files, and Wilson coefficient files. These files define the specific theory, basis and operators, and numerical values of the coefficients respectively. The format eliminates ambiguities by fixing operator sets and normalizations in specific bases. Additionally, it allows for extensibility, enabling users to define new bases or EFTs to suit particular needs. The robustness of the format is achieved through the adoption of JSON and YAML file formats, which offer widespread compatibility and facilitate easy data exchange.
The authors have implemented WCxf in several public codes including flavio, EOS, FlavorKit, SPheno, DsixTools, and wilson, among others. These implementations enable seamless sharing and transformation of Wilson coefficient data between different frameworks and scales, supporting a cohesive and integrated approach to probing BSM scenarios.
Implications for BSM Analyses
The development of WCxf addresses several challenges inherent in BSM analyses, particularly the complexity of exchanging numerical data of Wilson coefficients across multiple computational tools. By defining a standard for data exchange, WCxf provides a critical infrastructure for conducting global likelihood analyses across diverse domains such as flavour physics, electroweak precision tests, and Higgs physics. Furthermore, WCxf supports model-specific analyses, allowing researchers to focus on the implications of new physics models on low-energy observables.
Future Directions
Looking forward, the extensibility of WCxf paves the way for integrating additional bases and EFTs, expanding its utility within the research community. Collaboration is encouraged for the continuous evolution of the WCxf repository, ensuring it stays aligned with the growing landscape of BSM research. The ongoing development and integration of WCxf into public codes will support more precise and comprehensive studies of new physics, driving advances in both theoretical and experimental physics domains.
In summary, WCxf is a significant contribution to the field, providing a unified approach to handling Wilson coefficients in BSM analyses. Its features enhance interoperability and facilitate collaborative research efforts, marking a substantial step forward in advancing the understanding of physics beyond the Standard Model.