Abstract
We present a phenomenological study of Dirac electroweakinos in a $U(1)_R$ extension of the MSSM with a strictly $R$-symmetric Higgs sector (MRSSM) and gauge-mediated supersymmetry breaking. One of the distinguishing features of the MRSSM is that the lightest chargino can be lighter than the lightest neutralino. Decays from the NLSP chargino to the gravitino LSP will produce exotic signals. We apply LHC-13 mass limits from both prompt and long-lived searches to the chargino NLSP regime of the MRSSM. Imposing the additional constraints coming from the 125 GeV Higgs and from the electroweak sector, regions of the parameter space are found where the gravitino LSP, chargino NLSP scenario survives all current bounds. We also show that the fine-tuning of the model can reach a level slightly better than sub-percent with our choice of parameters.
Highlights
Weak scale supersymmetry persists as a compelling, well-motivated extension of the standard model (SM) that tackles its incompleteness in different fronts
Using the exclusions set by the CMS displaced dijet analysis [35] (100 μm ≲ ddecay ≲ 60 cm), next-to-lightest-supersymmetric particle (NLSP) mass limits as stringent as 600 GeV were set for a Oð10Þ cm travel length
Some studies have deepened into the UV aspects of Dirac gauginos, revealing that there are persistent issues to be taken care of, for example the analog of the GMSB μ − Bμ problem between the Dirac gaugino masses and their corresponding adjoint Ba-terms [45]
Summary
Weak scale supersymmetry persists as a compelling, well-motivated extension of the standard model (SM) that tackles its incompleteness in different fronts. A supersymmetric extension of the SM needs to be natural, i.e., no large mass hierarchies, when one insists on employing supersymmetry as a stabilizing symmetry for the EW scale against radiative corrections [3] This is achieved through a low-scale spectrum of squarks, gluinos and light electroweakinos, which are respectively detected as jets and missing transverse energy (ET) at colliders. R-symmetry respected by the Dirac masses onto all other interactions This variant of supersymmetry is known as the minimal R-symmetric supersymmetric standard model (MRSSM).
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