HEPfit: a code for the combination of indirect and direct constraints on high energy physics models

Abstract

HEPfit is a flexible open-source tool which, given the Standard Model or any of its extensions, allows to (i) fit the model parameters to a given set of experimental observables; (ii) obtain predictions for observables. HEPfit can be used either in Monte Carlo mode, to perform a Bayesian Markov Chain Monte Carlo analysis of a given model, or as a library, to obtain predictions of observables for a given point in the parameter space of the model, allowing HEPfit to be used in any statistical framework. In the present version, around a thousand observables have been implemented in the Standard Model and in several new physics scenarios. In this paper, we describe the general structure of the code as well as models and observables implemented in the current release.

Hadronic Vacuum Polarization:(g−2)μversus Global Electroweak Fits

“…We find that with modern data and theory calculations the EW fit is sufficiently powerful to provide an independent determination of Δα ð5Þ had , without assuming any prior input. We will perform this determination using the Bayesian statistics implemented in the HEPFIT package [60]. Results that assume the relative change in the cross section to be energy independent [compared to the e þ e − data and below the scale indicated in brackets, as explained below Eqs.…”

Global Fit to Modified Neutrino Couplings and the Cabibbo-Angle Anomaly

“…However, extensions with righthanded neutrinos lead necessarily to destructive interference with the SM, whereas here we will also be interested in the most general case allowing for an arbitrary phase of the NP contribution. The connection to, and correlations with, the Cabibbo-angle anomaly were not considered before and, in addition, we will use the publicly available HEPFIT software [54] to perform a Bayesian analysis, while previous analyses were based on frequentist inference.…”

“…which in turn also changes Γ Z , to which it contributes. We included the modifications of these observables into the EW implementations of HEPFIT [54]; see the Supplemental Material [62], which includes Refs. , for further details.…”

“…Before presenting the results, let us briefly discuss the statistical inference procedure we adopted. Our analysis is PHYSICAL REVIEW LETTERS 125, 071802 (2020) performed in a Bayesian framework using the publicly available HEPFIT package [54], whose Markov chain Monte Carlo (MCMC) determination of posteriors is powered by the Bayesian Analysis Toolkit (BAT) [88].…”

Higgs-boson phenomenology: a broad perspective.

“…This For the purpose of illustration of these studies that should all be considered as very exploratory, we collect in Figs. 6, 7, and 8 results obtained by the HEPFIT collaboration [37]. They are expressed in terms of coefficients of dimension 6 operators in the so-called Warsaw basis [38], and involve only operators that enters either in EWPO observables or in Higgs-boson signal-strength predictions.…”