SMEFT vs HEFT for new physics searches at the LHC (Ilaria Brivio, Università di Bologna)

Marzo 27, 2024@2:00 pm–3:00 pm
Aula 501

Semina di Fenomenologia delle Particelle Elementari

Over a decade after the Higgs discovery, the hunt for physics beyond the Standard Model is incorporating more and more searches for small, non-resonant traces of new physics, that can be described by an Effective Field Theory (EFT).
The so-called Standard Model EFT (SMEFT) is now the standard framework used for these searches. The Higgs EFT (HEFT) is an alternative extension of the SM, which differs from SMEFT in the representation chosen for the scalar fields, a feature that results in a higher complexity and that, so far, has made HEFT less attractive for phenomenological studies.
Nevertheless, it is well-established that HEFT is more general than SMEFT, implying the existence of BSM scenarios which would be captured by the former but not by the latter. HEFT could also represent a useful candle to test the validity of the dimension-6 SMEFT approximation, an issue that has been raising significant concerns for LHC measurements.
After an introduction to the two frameworks, the first half of the talk will give an overview of the phenomenological characterization of HEFT and SMEFT. The second part will explore more formal aspects of the HEFT-SMEFT interplay, that build on a geometric description of the scalar sector.

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