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arXiv · 1708.06355

Higgs characterisation in the presence of theoretical uncertainties and invisible decays

Christoph Englert·Roman Kogler·Holger Schulz·Michael Spannowsky
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Abstract

While the Higgs characterisation programme is well underway, direct signs for new physics beyond the Standard Model remain elusive. Performing a fit of fully differential Higgs production cross sections at the LHC to a subset of Higgs-relevant effective operators, we discuss the extent to which theoretical uncertainties can limit the sensitivity in such a new physics search programme. Extending the dimension-6 Higgs Effective Field Theory framework by introducing new light degrees of freedom that can contribute to an invisible (or undetectable) Higgs decay width $h \to ϕϕ$, we show how differential coupling fits can disentangle effects from non-Standard Model couplings and an invisible decay width, as present in many new physics scenarios, such as Higgs-portal dark matter. Including the so-called off-shell measurement that has been advocated as a sensitive determination of the Higgs width in the $κ$ framework, we show explicitly that this method does not provide complementary sensitivity for scale-separated new physics $Λ\gg m_h \gg m_ϕ$, which is favoured in beyond the Standard Model scenarios that relate astrophysics and collider phenomenology in light of non-observation of new physics during run 1 of the LHC.

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Christoph Englert, Roman Kogler, Holger Schulz, Michael Spannowsky. 2017-11-24. Higgs characterisation in the presence of theoretical uncertainties and invisible decays. https://doi.org/10.1140/epjc%2Fs10052-017-5366-8

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