MARTY - Modern ARtificial Theoretical phYsicist A C++ framework automating theoretical calculations Beyond the Standard Model

Abstract Studies Beyond the Standard Model (BSM) will become more and more important in the near future with the rapidly increasing amount of data from different experiments around the world. The full study of BSM models is in general an extremely time-consuming task involving long and difficult calculations. It is in practice not possible to do exhaustive predictions in these models by hand. Here we present MARTY, a new C++ framework that fully automates calculations from the Lagrangian to physical quantities such as amplitudes or cross-sections. It can fully simplify, automatically and symbolically, physical quantities in a very large variety of models and compute Wilson coefficients in effective theories. This will considerably facilitate BSM studies in flavour physics. Contrary to the existing public codes in this field MARTY aims at providing a unique, free, open-source, powerful and user-friendly tool for high-energy physicists studying predictive BSM models, in effective or full theories up to the one-loop level, which does not rely on any external package. With a few lines of code one can gather final expressions that may be evaluated numerically for statistical analysis. Program summary Program Title: MARTY CPC Library link to program files: https://doi.org/10.17632/y7n82jcj8d.1 Developer’s repository link: https://marty.in2p3.fr , https://fr.overleaf.com/project/5fb7c30c3175f910d2392059 Licensing provisions: GPLv3 Programming language: C++ Supplementary material: GNU-GSL [1], LoopTools [2] Nature of problem: From a given Lagrangian, Beyond the Standard Model phenomenology often requires one-loop theoretical calculations. Those calculations must be done analytically because a numerical evaluation of such quantities is not possible, the number of terms being too large for any computer to handle. Simplifications must be done analytically, and are very long and error prone justifying to automate them. This is why we need a computer algebra system dedicated to this task. Some packages written with Mathematica [3] - a private and closed software for symbolic manipulations - implement those calculations. There are multiple packages, the user needs to pay for Mathematica and the calculation of Wilson coefficients for BSM and at the one-loop level is actually hard to automate. Solution method: MARTY is a code written for BSM phenomenology that comes with its own computer algebra system, CSL, and automates the calculation of theoretical quantities at the one-loop level, in a very large variety of BSM model. Physicists now can have a unique C++ code, free and open-source, that can be used to do model building BSM and calculate any kind of amplitude, squared amplitude or Wilson coefficient BSM from the Lagrangian. From the developers point of view, having such a code, independent of any other framework using only the C++ standard library (C++17 standard), is a great opportunity to develop it even further, implementing new simplifications procedures, new calculation procedures and more. References: [1] GSL - GNU Scientific Library. https://www.gnu.org/software/gsl/ . [2] T. Hahn, M. Perez-Victoria, Automatized one loop calculations in four-dimensions and D-dimensions, Comput. Phys. Commun. 118 (1999) 153–165. arXiv:hep-ph/9807565 , doi: http://dx.doi.org/10.1016/S0010-4655(98)00173-8 . [3] Wolfram Research Inc., Mathematica. https://www.wolfram.com/mathematic .