Scrutinising the Higgs sector

17 December 2021

Higgs hunting 2021

Higgs hunting featured
Virtual look Some of the speakers at the September workshop. Image credits: L. Fayard

The 11th Higgs Hunting workshop took place remotely between 20 and 22 September 2021, with more than 300 registered participants engaging in lively discussions about the most recent results in the Higgs sector. ATLAS and CMS presented results based on the full LHC Run-2 dataset (up to 140 fb-1) recorded at 13 TeV. While all results remain compatible with Standard Model expectations, the precision of the measurements benefited from significant reductions in statistical uncertainties, more than three times smaller with the 13 TeV data than in previous LHC results at 7 and 8 TeV. This also brought into sharp relief the role of systematic uncertainties, which in some cases are becoming dominant.

The status of theory improvements and phenomenological interpretations, such as those from effective field theory, were also presented. Highlights included the Higgs pair-production process, which is particularly challenging at the LHC due to its low rate. ATLAS and CMS showed greatly improved sensitivity in various final states, thanks to improvements in analysis techniques. Also shown were results on the scattering of weak vector bosons, a process that is strongly related to the Higgs sector, highlighting large improvements from both the larger datasets and the higher collision energy available in Run 2.

Several searches for phenomena beyond the Standard Model – in particular for additional Higgs bosons – were presented. No significant excesses have yet been found.

The historical talk “The LHC timeline: a personal recollection (1980-2012)” was given by Luciano Maiani, former CERN Director-General, and concluding talks were given by Laura Reina (Florida) and Paolo Meridiani (Rome). A further highlight was the theory talk from Nathaniel Craig, who discussed the progress being made in addressing six open questions. Does the Higgs boson have a size? Does it interact with itself? Does it mediate a Yukawa force? Does it fulfill the naturalness strategy? Does it preserve causality? And does it realise electroweak symmetry?

The next Higgs Hunting workshop will be held in Orsay and Paris from 12 to 14 September 2022.

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