The Minimal SUSY $B-L$ Model: From the Unification Scale to the LHC

TL;DR

This paper performs a comprehensive statistical analysis of the minimal SUSY $B-L$ model, exploring its parameter space from high energy to the LHC scale, and finds it generally requires less fine-tuning than the MSSM.

Contribution

It introduces a detailed parameter scan of the $B-L$ MSSM, identifying viable regions consistent with experimental constraints and comparing fine-tuning levels to the MSSM.

Findings

The $B-L$ MSSM can satisfy all experimental constraints within a wide parameter space.

It generally requires less fine-tuning than the MSSM.

Predicted sparticle spectra and LSP configurations are diverse and robust.

Abstract

This paper introduces a random statistical scan over the high-energy initial parameter space of the minimal SUSY $B-L$ model--denoted as the $B-L$ MSSM. Each initial set of points is renormalization group evolved to the electroweak scale--being subjected, sequentially, to the requirement of radiative $B-L$ and electroweak symmetry breaking, the present experimental lower bounds on the $B-L$ vector boson and sparticle masses, as well as the lightest neutral Higgs mass of $\sim$125 GeV. The subspace of initial parameters that satisfies all such constraints is presented, shown to be robust and to contain a wide range of different configurations of soft supersymmetry breaking masses. The low-energy predictions of each such "valid" point - such as the sparticle mass spectrum and, in particular, the LSP - are computed and then statistically analyzed over the full subspace of valid points. Finally, the amount of fine-tuning required is quantified and compared to the MSSM computed using an identical random scan. The $B-L$ MSSM is shown to generically require less fine-tuning.