Lilith: a tool for constraining new physics from Higgs measurements

Abstract

The properties of the observed Higgs boson with mass around 125 GeV can be affected in a variety of ways by new physics beyond the Standard Model (SM). The wealth of experimental results, targeting the different combinations for the production and decay of a Higgs boson, makes it a nontrivial task to assess the patibility of a non-SM-like Higgs boson with all available results. In this paper we present Lilith, a new public tool for constraining new physics from signal strength measurements performed at the LHC and the Tevatron. Lilith is a Python library that can also be used in C and C++/ROOT programs. The Higgs likelihood is based on experimental results stored in an easily extensible XML database, and is evaluated from the user input, given in XML format in terms of reduced couplings or signal strengths.The results of Lilith can be used to constrain a wide class of new physics scenarios.

Hierarchical versus degenerate 2HDM: The LHC run 1 legacy at the onset of run 2

“…The Higgs signal strength constraints can then be obtained by performing a Δχ 2 likelihood fit to the 2HDM parameters c β−α and t β , for which we use the public codes LILITH [63] and HIGGSSIGNALS [64,65]. The values of ϵ i in (14) may be obtained from the experimental analyses and are provided in both these programs (e.g.…”

Study of the Electroweak Symmetry Breaking Sector for the LHC

“…[39]). The direct limit over the a parameter, at a confidence level of 2σ (≈ 95%), is • ATLAS [127] [130] for constraining the Effective Lagrangian. P.P.…”

“…Furthermore, the next NLO extra counterterms are needed, Note the 1/16π 2 factor, which comes from the normalization of ref. [130]. On the a 1 , a 2 and a 3 parameters, there are only weaker constraints based on electroweak precision observables from LEP and purely SM one-loop calculations.…”

Status and discovery prospects for light pseudoscalars in the NMSSM

“…In NMSSMTools [4,5] these are implemented as three separate constraints on the ZZ, γγ and bb reduce couplings, taken from Lilith [6]. HiggsSignals [7] on the other hand, does an overall fit to all channels simultaneously.…”