Naturalness and Higgs Decays in the MSSM with a Singlet

TL;DR

The paper investigates how adding a singlet to the MSSM can dramatically alter Higgs decays, beyond NMSSM expectations, by employing a general operator framework. Through mixing between the singlet and MSSM Higgs states and a rich set of soft and supersymmetric operators, the authors map out a broad landscape of Higgs decays, including single- and two-stage cascades that produce 4, 6, or 8 parton final states. They show that such decays can ease LEP constraints and allow notably natural spectra with light stops and Higgs masses as low as 82 GeV, but they require careful tuning and invoke D-term SUSY breaking or heavy colored states. The work also outlines experimental implications, urging reanalysis of LEP data and future collider searches, particularly for multi-jet and multi-photon final states, to fully test these nonstandard Higgs scenarios.

Abstract

The simplest extension of the supersymmetric standard model - the addition of one singlet superfield - can have a profound impact on the Higgs and its decays. We perform a general operator analysis of this scenario, focusing on the phenomenologically distinct scenarios that can arise, and not restricting the scope to the narrow framework of the NMSSM. We reexamine decays to four b quarks and four tau's, finding that they are still generally viable, but at the edge of LEP limits. We find a broad set of Higgs decay modes, some new, including those with four gluon final states, as well as more general six and eight parton final states. We find the phenomenology of these scenarios is dramatically impacted by operators typically ignored, specifically those arising from D-terms in the hidden sector, and those arising from weak-scale colored fields. In addition to sensitivity of m_Z, there are potential tunings of other aspects of the spectrum. In spite of this, these models can be very natural, with light stops and a Higgs as light as 82 GeV. These scenarios motivate further analyses of LEP data as well as studies of the detection capabilities of future colliders to the new decay channels presented.