[Paper Review] Radiative Gaugino Masses

Glennys R. Farrar, A. Masiero|ArXiv.org|Oct 28, 1994

Black Holes and Theoretical Physics1 references3 citations

TL;DR

This paper proposes a radiative mechanism for generating gaugino masses in supersymmetric theories where gauginos are massless at tree level, with masses arising via loop corrections due to R-symmetry breaking. For low SUSY-breaking scales (~400 GeV), gluino and lightest neutralino masses are typically 1–2.5 GeV; for higher scales (several TeV), radiative corrections yield gluino masses of 50–300 GeV and neutralino masses of 10–30 GeV, with the gluino as the lightest supersymmetric particle in natural scenarios.

ABSTRACT

We investigate the possibility that gauginos are massless at tree level and that the U(1) R-invariance is broken spontaneously by Higgs vevs, like the chiral symmetry of quarks in the standard model, or else explicitly by dimension 2 or 3 SUSY-breaking terms in the low energy effective Lagrangian. Gluino and lightest neutralino masses then depend on only a few parameters. For a SUSY-breaking scale

Motivation & Objective

• To explore a mechanism where gauginos acquire mass radiatively despite being massless at tree level.
• To investigate the phenomenological consequences of U(1) R-symmetry breaking via Higgs vacuum expectation values or dimension-2/3 SUSY-breaking terms.
• To determine the resulting gaugino masses in scenarios with low or high SUSY-breaking scales.
• To assess whether the gluino can be the lightest supersymmetric particle (LSP) in such radiative models.
• To analyze the impact of renormalization group running on stop masses and their sensitivity to the radiative mass generation mechanism.

Proposed method

• Assumes gauginos are massless at tree level and that R-symmetry is broken either spontaneously via Higgs vevs or explicitly via dimension-2 or 3 terms in the effective Lagrangian.
• Applies one-loop radiative corrections to generate gaugino masses, with the dominant contributions arising from R-symmetry breaking effects.
• Uses renormalization group equations (RGEs) to track the running of soft SUSY-breaking parameters, particularly stop masses.
• Performs numerical analysis of the resulting gaugino masses as a function of the SUSY-breaking scale and R-symmetry breaking parameters.
• Incorporates sensitivity analysis to RGE effects in stop masses, refining the mass predictions.
• Constructs a simplified effective theory framework to isolate the key dynamics of radiative gaugino mass generation.

Experimental results

Research questions

• RQ1 Can gaugino masses be generated radiatively even when they are zero at tree level due to R-symmetry?
• RQ2 What are the resulting gluino and lightest neutralino masses for different SUSY-breaking scales?
• RQ3 How does the presence of R-symmetry breaking via Higgs vevs or dimension-2 terms affect the gaugino mass spectrum?
• RQ4 Under what conditions is the gluino the lightest supersymmetric particle (LSP) in this radiative mechanism?
• RQ5 How sensitive are the predicted gaugino masses to the renormalization group evolution of stop masses?

Key findings

• For a SUSY-breaking scale of approximately 400 GeV, the gluino and lightest neutralino masses are predicted to be in the range of 1–2.5 GeV.
• When the SUSY-breaking scale is several TeV or higher, radiative corrections generate gluino masses of order 50–300 GeV.
• The lightest neutralino mass is predicted to be in the range of 10–30 GeV for high-scale SUSY breaking.
• In scenarios where R-invariance is broken only by Higgs vevs or via dimension-2 terms, the gluino is generically the lightest supersymmetric particle (LSP).
• The model shows sensitivity to the renormalization group running of stop masses, which can affect the final gaugino mass predictions.
• The phenomenology is significantly modified compared to conventional models, with the gluino as LSP implying distinct collider and cosmological signatures.