[Paper Review] Goldstini Give the Higgs a Boost

J. J. Thaler, Zoe Thomas|arXiv (Cornell University)|Mar 8, 2011

Particle physics theoretical and experimental studies22 references3 citations

TL;DR

This paper shows that in multi-sector supersymmetry models with uneaten goldstini, the lightest observable-sector supersymmetric particle (LOSP) can decay dominantly to a Higgs boson and an uneaten goldstino, even without higgsino content. This occurs via enhanced operators not constrained by supercurrents, leading to boosted Higgs production in SUSY cascades, especially when an R symmetry is present.

ABSTRACT

Supersymmetric collider phenomenology depends crucially on whether the lightest observable-sector supersymmetric particle (LOSP) decays, and if so, what the LOSP decay products are. For instance, in SUSY models where the gravitino is lighter than the LOSP, the LOSP decays to its superpartner and a longitudinal gravitino via supercurrent couplings. In this paper, we show that LOSP decays can be substantially modified when there are multiple sectors that break supersymmetry, where in addition to the gravitino there are light uneaten goldstini. As a particularly striking example, a bino-like LOSP can have a near 100% branching fraction to a higgs boson and an uneaten goldstino, even if the LOSP has negligible higgsino fraction. This occurs because the uneaten goldstino is unconstrained by the supercurrent, allowing additional operators to mediate LOSP decay. These operators can be enhanced in the presence of an R symmetry, leading to copious boosted higgs production in SUSY cascade decays.

Motivation & Objective

• To understand how multiple supersymmetry-breaking sectors affect the decay of the lightest observable-sector supersymmetric particle (LOSP).
• To investigate whether uneaten goldstini can mediate new decay channels for the LOSP, bypassing standard supercurrent constraints.
• To explore the implications of such decays for SUSY collider phenomenology, particularly in enhancing Higgs boson production.
• To determine the role of R symmetry in enhancing decay branching fractions to Higgs + goldstino final states.

Proposed method

• Analyzing multi-sector supersymmetry models where more than one sector breaks supersymmetry, leading to multiple goldstini, including uneaten ones.
• Identifying that uneaten goldstini are not constrained by supercurrent couplings, allowing additional effective operators to mediate LOSP decays.
• Constructing effective field theory operators involving the LOSP, Higgs boson, and uneaten goldstino, which are not suppressed by the supercurrent structure.
• Applying R symmetry to the model to enhance the coupling strength of these new operators, increasing decay branching fractions.
• Calculating branching ratios for LOSP decays into Higgs + uneaten goldstino, especially in the case of a bino-like LOSP.
• Assessing the phenomenological impact on SUSY cascade decays, particularly the production of boosted Higgs bosons.

Experimental results

Research questions

• RQ1 Can uneaten goldstini mediate significant decay modes for the LOSP in multi-sector SUSY models?
• RQ2 How do the decay branching fractions of the LOSP change when additional operators involving uneaten goldstini are introduced?
• RQ3 What is the role of R symmetry in enhancing the coupling between the LOSP, Higgs boson, and uneaten goldstino?
• RQ4 Can a bino-like LOSP decay predominantly into a Higgs boson and an uneaten goldstino despite having negligible higgsino component?
• RQ5 What are the collider signatures of such decays, particularly in terms of boosted Higgs production?

Key findings

• A bino-like LOSP can have a near 100% branching fraction to a Higgs boson and an uneaten goldstino, even with negligible higgsino content.
• The decay is mediated by effective operators not constrained by supercurrent couplings, which are allowed due to the presence of uneaten goldstini.
• These operators can be significantly enhanced in the presence of an R symmetry, leading to large branching ratios.
• The decay mechanism allows for copious production of boosted Higgs bosons in SUSY cascade decays.
• The phenomenon arises due to the absence of supercurrent suppression for uneaten goldstini, enabling new decay pathways.
• This mechanism provides a novel source of boosted Higgs bosons in supersymmetric models with multiple SUSY-breaking sectors.