On the Alignment Limit of the NMSSM Higgs Sector

TL;DR

This paper explores the alignment limit of the NMSSM Higgs sector, showing it allows for a more natural electroweak symmetry breaking and predicts Higgs properties similar to the Standard Model, with testable LHC signatures.

Contribution

It derives analytical alignment conditions in the NMSSM, identifying a natural parameter space compatible with a 125 GeV Higgs and perturbativity up to the Planck scale.

Findings

Alignment limit leads to a natural electroweak symmetry breaking region.

Predicted Higgs properties match the Standard Model.

Distinct Higgs and Higgsino spectra with testable LHC signatures.

Abstract

The Next-to-Minimal Supersymmetric extension of the Standard Model (NMSSM) with a Higgs boson of mass 125 GeV can be compatible with stop masses of order of the electroweak scale, thereby reducing the degree of fine-tuning necessary to achieve electroweak symmetry breaking. Moreover, in an attractive region of the NMSSM parameter space, corresponding to the "alignment limit" in which one of the neutral Higgs fields lies approximately in the same direction in field space as the doublet Higgs vacuum expectation value, the observed Higgs boson is predicted to have Standard-Model-like properties. We derive analytical expressions for the alignment conditions and show that they point toward a more natural region of parameter space for electroweak symmetry breaking, while allowing for perturbativity of the theory up to the Planck scale. Moreover, the alignment limit in the NMSSM leads to a well defined spectrum in the Higgs and Higgsino sectors, and yields a rich and interesting Higgs boson phenomenology that can be tested at the LHC. We discuss the most promising channels for discovery and present several benchmark points for further study.