https://doi.org/10.1140/epjc/s10052-017-5366-8
Regular Article - Theoretical Physics
Higgs characterisation in the presence of theoretical uncertainties and invisible decays
1
SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
2
Institut für Experimentalphysik, Universität Hamburg, 22761, Hamburg, Germany
3
Department of Physics, Institute for Particle Physics Phenomenology, Durham University, Durham, DH1 3LE, UK
* e-mail: roman.kogler@uni-hamburg.de
Received:
23
August
2017
Accepted:
4
November
2017
Published online:
21
November
2017
While the Higgs characterisation programme is well under way, 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 
, 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 
framework, we show explicitly that this method does not provide complementary sensitivity for scale-separated new physics 
, which is favoured in beyond the Standard Model scenarios that relate astrophysics and collider phenomenology in the light of non-observation of new physics during run 1 of the LHC.
© The Author(s), 2017
