Viable Gravity-Mediated Supersymmetry Breaking

TL;DR

This paper introduces a comprehensive gravity-mediated supersymmetry breaking model that naturally suppresses flavor violations by employing a D-term dominated sector with an emergent U(1)_R symmetry, leading to distinctive gaugino mass patterns and a novel Z' gauge boson.

Contribution

The model uniquely combines D-term driven supersymmetry breaking with an accidental U(1)_R symmetry, ensuring flavor safety and predicting Dirac gaugino masses and a light Z' gauge boson.

Findings

Gauginos acquire Dirac masses from gravity-mediated D-terms.

The gluino mass hierarchy naturally suppresses flavor violations.

A light Z' gauge boson with distinctive couplings is predicted.

Abstract

We present a complete, viable model of gravity-mediated supersymmetry breaking that is safe from all flavor constraints. The central new idea is to employ a supersymmetry breaking sector without singlets, but with D-terms comparable to F-terms, causing supersymmetry breaking to be dominantly communicated through U(1)_R-symmetric operators. We construct a visible sector that is an extension of the MSSM where an \emph{accidental} U(1)_R symmetry emerges naturally. Gauginos acquire Dirac masses from gravity-mediated D-terms, and tiny Majorana masses from anomaly-mediated contributions. Contributions to soft breaking scalar (mass)^2 arise from flavor-arbitrary gravity-induced F-terms plus one-loop finite flavor-blind contributions from Dirac gaugino masses. Renormalization group evolution of the gluino causes it to naturally increase nearly an order of magnitude larger than the squark masses. This hierarchy, combined with an accidentially U(1)_R-symmetric visible sector, nearly eliminates all flavor violation constraints on the model. If we also freely tune couplings and phases within the modest range 0.1-1, while maintaining nearly flavor-anarchic Planck-suppression contributions, we find our model to be safe from Delta m_K, epsilon_K, and mu -> e lepton flavor violation. Dangerous U(1)_R-violating K\"ahler operators in the Higgs sector are eliminated through a new gauged U(1)_X symmetry that is spontaneously broken with electroweak symmetry breaking. Kinetic mixing between U(1)_X and U(1)_Y is present with loop-suppressed (but log-enhanced) size epsilon. The Z' associated with this U(1)_X has very peculiar couplings -- it has order one strength to Higgs doublets and approximately epsilon strength to hypercharge. The Z' could be remarkably light and yet have escaped direct and indirect detection.