750 GeV Diphotons from Supersymmetry with Dirac Gauginos

TL;DR

This paper proposes a supersymmetric model with Dirac gauginos to explain the 750 GeV diphoton excess, highlighting its unique production and decay mechanisms, and analyzing its consistency with experimental data and Higgs mass constraints.

Contribution

It introduces a supersymmetric extension with Dirac gauginos and additional adjoint superfields to account for the 750 GeV diphoton resonance, emphasizing its theoretical advantages and experimental viability.

Findings

The bino partner pseudoscalar can explain the 750 GeV excess.

The model achieves a balance between Dirac and Majorana gaugino masses.

Perturbative couplings up to high scales are possible within experimental constraints.

Abstract

Motivated by the recent excess in the diphoton invariant mass near 750 GeV, we explore a supersymmetric extension of the Standard Model that includes the minimal set of superpartners as well as additional Dirac partner chiral superfields in the adjoint representation for each gauge group. The bino partner pseudoscalar is identified as the 750 GeV resonance, while superpotential interactions between it and the gluino (wino) partners yield production via gluon fusion (decay to photon pairs) at one-loop. The gauginos and these additional adjoint superpartners are married by a Dirac mass and must also have Majorana masses. While a large wino partner Majorana mass is necessary to explain the excess, the gluino can be approximately Dirac-like, providing benefits consistent with being both "supersoft" (loop corrections to the scalar masses from Dirac gauginos are free of logarithmic enhancements) and "supersafe" (the experimental limits on the squark/gluino masses can be relaxed due to the reduced production rate). Consistency with the measured Standard Model-like Higgs boson mass is imposed, and a numerical exploration of the parameter space is provided. Models that can account for the diphoton excess are additionally characterized by having couplings that can remain perturbative up to very high scales, while remaining consistent with experimental constraints, the Higgs boson mass, and an electroweak scale which is not excessively fine tuned.