Eur. Phys. J. C (2018) 78: 22
https://doi.org/10.1140/epjc/s10052-017-5390-8

Regular Article - Theoretical Physics

SpecBit, DecayBit and PrecisionBit: GAMBIT modules for computing mass spectra, particle decay rates and precision observables

¹ School of Physics and Astronomy, Monash University, Melbourne, VIC, 3800, Australia
² Australian Research Council Centre of Excellence for Particle Physics at the Tera-scale, Australia, http://www.coepp.org.au/
³ Department of Physics, University of Oslo, 0316, Oslo, Norway
⁴ Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, 10691, Stockholm, Sweden
⁵ Department of Physics, Stockholm University, 10691, Stockholm, Sweden
⁶ NORDITA, Roslagstullsbacken 23, 10691, Stockholm, Sweden
⁷ Department of Physics, Blackett Laboratory, Imperial College London, Prince Consort Road, London, SW7 2AZ, UK
⁸ LAPTh, Université de Savoie, CNRS, 9 chemin de Bellevue, B.P.110, 74941, Annecy-le-Vieux, France
⁹ Department of Physics, Harvard University, Cambridge, MA, 02138, USA
¹⁰ GRAPPA, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
¹¹ Department of Physics, University of Adelaide, Adelaide, SA, 5005, Australia

^* e-mail: benjamin.farmer@fysik.su.se

Received: 16 March 2017
Accepted: 16 November 2017
Published online: 12 January 2018

Abstract

We present the GAMBIT modules SpecBit, DecayBit and PrecisionBit. Together they provide a new framework for linking publicly available spectrum generators, decay codes and other precision observable calculations in a physically and statistically consistent manner. This allows users to automatically run various combinations of existing codes as if they are a single package. The modular design allows software packages fulfilling the same role to be exchanged freely at runtime, with the results presented in a common format that can easily be passed to downstream dark matter, collider and flavour codes. These modules constitute an essential part of the broader GAMBIT framework, a major new software package for performing global fits. In this paper we present the observable calculations, data, and likelihood functions implemented in the three modules, as well as the conventions and assumptions used in interfacing them with external codes. We also present 3-BIT-HIT, a command-line utility for computing mass spectra, couplings, decays and precision observables in the MSSM, which shows how the three modules can easily be used independently of GAMBIT.