Constraining new physics from Higgs measurements with Lilith: update to LHC Run 2 results

Abstract

Lilith is a public Python library for constraining new physics from Higgs signal strength measurements. We here present version 2.0 of Lilith together with an updated XML database which includes the current ATLAS and CMS Run 2 Higgs results for 36 fb −1 . Both the code and the database were extended from the ordinary Gaussian approximation employed in Lilith-1.1 to using variable Gaussian and Poisson likelihoods. Moreover, Lilith can now make use of correlation matrices of arbitrary dimension. We provide detailed validations of the implemented experimental results as well as a status of global fits for reduced Higgs couplings, Two-Higgs-doublet models of Type I and Type II, and invisible Higgs decays. Lilith-2.0 is available on GitHub and ready to be used to constrain a wide class of new physics scenarios. arXiv:1908.03952v2 [hep-ph] 4 Oct 20191 For a discussion of the use and usability of signal strength results, and recommendations on their presentation, see [3].2 When µ(X, Y ) is not directly available, µ = effX,Y × µ(X, Y ) is used, introducing appropriate efficiency factors effX,Y . For inclusive combinations of production channels for the same Y , the efficiencies become effX = σ SM (X)/ σ SM (X).3 In other words, the Lagrangian has the same tensor structure as the SM, see e.g. the discussion in [3].

O new physics, where art thou? A global search in the top sector

“…where σ SM is the SM prediction, σ k are contributions arising from the interference of a single dimension-6 operator with the SM, and σ kl arise from the interference of two rate measurements or the total cross section, because they offer the best statistics and often minimize theoretical uncertainties. From global Higgs-electroweak analyses we know that a modified momentum dependence can be constrained most efficiently by high-energy tails of kinematic distributions or simplified template cross sections [8][9][10][11][12][13]. † Similarly, we know that for many kinematic distributions the few bins with the highest momentum transfer include the relevant information on individual operators, whereas for several operators with a different high-energy behavior there often exist several relevant regimes [104].…”

“…Part of the SMEFT framework [1][2][3][4][5] was developed as a gauge-invariant description of anomalous gauge boson interactions at LEP [6,7]. Its biggest success has been the application to Higgs and electroweak boson measurements at the LHC [8][9][10][11][12][13]. Most recently, the same approach [14][15][16] has been used to systematically analyze top quark measurements at the LHC [17][18][19][20][21] and at future colliders [22,23] and their link to bottom sector [24].…”

Dilaton portal in strongly interacting twin Higgs models

“…For details on the implementation of Lilith-2 and experimental data used, see Refs. [81,82]. In Fig.…”

“…This is performed with Lilith-2 [81,82] which incorporates all of the relevant LHC Run-2 data. For the global χ 2 analysis Lilith-2 employs variable Gaussian and Poisson likelihoods with full LHC Run-2 data from ATLAS and CMS for 36 fb −1 .…”

Probing Higgs-portal dark matter with vector-boson fusion

“…(2.3) alone. In this region, more stringent but also more model-dependent bounds from the measurement of the Higgs-boson coupling strength may be applied to the Higgs-portal model [38,39].…”