Tools for automatic Higgs calculations in general theories – HIGGSAUTOMATOR

The aim is to derive analytic results in generic quantum field theories, and obtain new conceptual approaches to the problems faced. In addition use is made of symbolic computational packages to compute higher-order processes. Symbolic calculation is then employed as a meta-tool to write numerical codes. The implementation of the esults in the form of a spectrum-generator-generator is being made public as each milestone is reached.

During the first 18 months of the project the general aim was to remove the remaining technical obstacles to providing codes for the calculation of the Higgs mass in generic renormalisable theories. The specific major milestone stated was that of solving the Goldstone boson catastrophe. In addition, the team was to complete two ancillary projects of calculating Higgs mass corrections in non-supersymmetric theories ; and providing code to calculate momentum-dependent contributions. Work could then begin on Phase 2.

I am pleased to report that the major milestone was indeed reached, disseminated in a publication (Avoiding the Goldstone Boson Catastrophe in general renormalisable field theories at two loops, by Johannes Braathen and Mark D. Goodsell. arXiv:1609.06977 [hep-ph]. 10.1007/JHEP12(2016)056. JHEP 1612 (2016) 056.), listed as publication 7 in table D.1. This was accomplished by the jeune chercheur and his PhD student, and was aided by discussion with the other group members (Pietro Slavich and Karim Benakli). In fact, the solution was unexpected, and goes beyond what was anticipated at the beginning: the paper proposed a new and simple technique for obtaining infra-red finite results in the calculation, gave explicit general formulas for tadpole and mass diagram calculations, and several other interesting results.

A paper «Avoiding the Goldstone Boson Catastrophe in general renormalisable field theories at two loops, by Johannes Braathen and Mark D. Goodsell. arXiv:1609.06977 [hep-ph]. 10.1007/JHEP12(2016)056. JHEP 1612 (2016) 056.),« contains the remarkable result that the infra-red problems due to the Goldstone Boson catastrophe can be solved by choosing to put the Goldstone Boson mass on-shell in calcualtions. It also showed that momentum dependence in the mass calcualation is not sufficient to cure the infra-red divergences in the diagrams, and that the solution proposed must be employed there. This allows fast and efficient calculation of the Higgs mass/extraction of the quartic coupling(s) in general theories.

9 papers published, two preprints submitted to the arXiv awaiting peer review, one CERN yellow report and one conference proceedings.

Although there are many indirect signs of new physics, it is certain that current bounds on new physics that can couple significantly to the Higgs boson present new challenges for understanding the mass of the Higgs, whatever new discoveries may or may not be made. The aim of this proposal is to develop theory and automatic tools to understand the implications for generic new physics of this quantity, taken in combination with the (new) information about the Higgs production and decays. The idea is to be able to use these experimentally well-determined quantities to automatically determine the viability of any new physics model. Specifically this will involve performing calculations and writing codes which will in turn write bespoke code for any given model to calculate the properties of the Higgs: mass, production and decays. This will give quantitative answers to questions such as: should we still be searching for superpartners at the LHC?