Handbook of LHC Higgs cross sections: 4. Deciphering the nature of the Higgs sector

This Report summarizes the results of the activities of the LHC Higgs Cross Section Working Groupin the period 2014-2016. The main goal of the working groupwas to present the state-of-the-art of Higgs physics at the LHC, integrating all new results that have appeared in the last few years. The first part compiles the most up-to-date predictions of Higgs bosonproduction cross sections and decay branching ratios, parton distribution functions, and off-shell Higgs bosonproduction and interference effects. The second part discusses the recent progress in Higgs effective field theorypredictions, followed by the third part on pseudo-observables, simplified template cross section and fiducial cross section measurements, which give the baseline framework for Higgs bosonproperty measurements. The fourth part deals with the beyond the Standard Modelpredictions of various benchmark scenarios of Minimal Supersymmetric Standard Model, extended scalar sector, Next-to- Minimal Supersymmetric Standard Modeland exotic Higgs bosondecays. This report follows three previous working-groupreports: Handbook of LHC Higgs Cross Sections: 1. Inclusive Observables (CERN-2011-002), Handbook of LHC Higgs Cross Sections: 2. Differential Distributions (CERN-2012-002), and Handbook of LHC Higgs Cross Sections: 3. Higgs properties (CERN-2013-004). The current report serves as the baseline reference for Higgs physics in LHC Run 2 and beyond.