Interacting 3-form dark energy models: Distinguishing interactions and avoiding the Little Sibling of the Big Rip

In this paper we consider 3-form dark energy (DE) models with interactions in the dark sector. We aim to distinguish the phenomenological interactions that are defined through the dark matter (DM) and the DE energy densities. We do our analysis mainly in two stages. In the first stage, we identify the noninteracting 3-form DE model which generically leads to an abrupt late-time cosmological event which is known as the little sibling of the Big Rip (LSBR). We classify the interactions which can possibly avoid this late-time abrupt event. We also study the parameter space of the model that is consistent with the interaction between DM and DE energy densities at present as indicated by recent studies based on BAO and SDSS data. In the later stage, we observationally distinguish those interactions using the statefinder hierarchy parameters {S-3((1)), S-4((1))}, {S-3((1)), S-5((1))}. We also compute the growth factor parameter (z) for the various interactions we consider herein and use the composite null diagnostic (CND) {S-3((1)),c (z)} as a tool to characterise those interactions by measuring their departures from the concordance model. In addition, we make a preliminary analysis of our model in light of the recently released data by SDSS III on the measurement of the linear growth rate of structure. (C) 2016 Elsevier B.V. All rights reserved.