Global fit to Higgs signal strengths and couplings and implications for extended Higgs sectors

Abstract

28 pages, 14 figuresThe most recent LHC data have provided a considerable improvement in the precision with which various Higgs production and decay channels have been measured. Using all available public results from ATLAS, CMS and the Tevatron, we derive for each final state the combined confidence level contours for the signal strengths in the (gluon fusion + ttH associated production) versus (vector boson fusion + VH associated production) space. These "combined signal strength ellipses" can be used in a simple, generic way to constrain a very wide class of New Physics models in which the couplings of the Higgs boson deviate from the Standard Model prediction. Here, we use them to constrain the reduced couplings of the Higgs boson to up-quarks, down-quarks/leptons and vector boson pairs. We also consider New Physics contributions to the loop-induced gluon-gluon and photon-photon couplings of the Higgs, as well as invisible/unseen decays. Finally, we apply our fits to some simple models with an extended Higgs sector, in particular to Two-Higgs-Doublet models of Type I and Type II, the Inert Doublet model, and the Georgi-Machacek triplet Higgs model

LHC bounds on lepton number violation mediated by doubly and singly-charged scalars

“…Their gauge interactions are detailed in section 3, where we work out the corresponding Feynman rules. Both sections are more technical and can be skipped if the reader is only interested 8 We also assume that the mass splitting between the different components of the multiplet is small and hence the mixing with heavier scalar multiplets and with the SM Higgs. Otherwise, cascade decays within the multiplet (of electroweak strength) would be overwhelming [75][76][77].…”

“…However, both decays can naturally have a similar rate in more elaborated models [24-27, 29-32, 73, 74]. 8 (iv ) We extend the SM with an extra TeV scalar multiplet at a time, neglecting possible mixing effects with other heavier scalar multiplets except to allow for the decay of the TeV scalar multiplet into gauge bosons. The only models we shall work out in detail are those with scalar multiplets with components of charge 2 at most, which are those of smaller isospin, too.…”

“…No departure from the Standard Model (SM) predictions has been observed at the LHC, yet; being the properties of the recently discovered Higgs boson apparently SM-like, too [1][2][3][4][5][6][7][8][9]. This was also preferred by electroweak (EW) precision data [10,11] (see for previous fits [12,13] and for an up-date [14][15][16]), thus making the discovery of new physics (NP) in the first LHC run unlikely.…”

W′ signatures with odd Higgs particles

“…We note, however, that H 0 could also be the LOP (forλ >λ) and a viable dark matter candidate. Even though it is part of an SU(2) W triplet that is degenerate at tree-level, electroweak loops split the H ± and H 0 masses [12][13][14].…”

A new tool for the study of the CP-violating NMSSM

“…• LHC_Higgs_CPV.f: the inclusion of LHC limits on neutral or charged Higgs searches as well as the confrontation to the signals at ∼ 125 GeV -after [83] -are in progress.…”