SPheno, a program for calculating supersymmetric spectra, SUSY particle decays and SUSY particle production at e+ e- colliders

TL;DR

SPheno provides a rigorous framework for predicting MSSM spectra, decays, and production at $e^+e^-$ colliders by solving two-loop RGEs with diverse high-scale boundary conditions. It combines complete one-loop mass formulas with targeted two-loop corrections for neutral Higgses and the $\mu$ parameter, enabling accurate mass spectra and mixing angles. The package also computes decay widths, branching ratios, production cross sections (including ISR and beam polarization), and key low-energy constraints such as $BR(b\to s\gamma)$, $a_\mu$, and $\Delta\rho$, all in a consistent DR/$\overline{DR}$-scheme framework and via iterative convergence. By supporting multiple high-scale models (mSUGRA, GMSB, AMSB, string-inspired EFTs) and SLHA input/output, SPheno serves as a versatile cross-check tool for model discrimination and reconstruction, with planned extensions to complex parameters, generation mixing, and higher-order corrections. The work thus advances precision SUSY phenomenology for future collider analyses and theory-experiment interplay.

Abstract

SPheno is a program that accurately calculates the supersymmetric particle spectrum within a high scale theory, such as minimal supergravity, gauge mediated supersymmetry breaking, anomaly mediated supersymmetry breaking, or string effective field theories. An interface exists for an easy implementation of other models. The program solves the renormalization group equations numerically to two--loop order with user-specified boundary conditions. The complete one--loop formulas for the masses are used which are supplemented by two--loop contributions in case of the neutral Higgs bosons and the mu parameter. The obtained masses and mixing matrices are used to calculate decay widths and branching ratios of supersymmetric particles as well as of Higgs bosons, b -> s gamma, Delta(rho) and (g-2)_muon. Moreover, the production cross sections of all supersymmetric particle as well as Higgs bosons at e+ e- colliders can be calculated including initial state radiation and longitudinal polarization of the incoming electrons/positrons. The program is structured such that it can easily be extend to include non-minimal models and/or complex parameters.

Figures (1)

• Figure 1: Algorithm used to calculate the SUSY spectrum, decay widths, production cross sections and low energy observables. Each step (represented by a box) is explained in the text. The initial step is the uppermost one. $M_{EWSB}$ is the scale at which the EWSB conditions are imposed, and $M_X$ is the scale at which the high energy SUSY breaking boundary conditions are imposed.