Speaker
Description
In our study, we apply the statefinder diagnostic tool to the phantom dark energy $(DE)$ models, including the big rip (BR), the little sibling of the big rip $(LSBR)$, and the little rip $(LR)$. The statefinder diagnostics are plotted according to the best fit extracted from each model using a Markov Chain Monte Carlo method. Our results demonstrate that, in the high-redshift region, the phantom DE models exhibit strong degeneracy with each other and with the $\Lambda$CDM model, even with different parameter values. However, this degeneracy is broken in the low-redshift region through the use of $S_3^{(1)}$ and $S_4^{(1)}$ diagnostics. Furthermore, we observe that the statefinder diagnostic tool shows the rich behavior of the $LSBR$ model as it can be quintessence-like or phantom-like depending on the $\Omega_{lsbr}$ parameter, in contrast to the $LR$ model which is only phantom-like. We also perform a direct comparison of the phantom $DE$ models using the $\left \{ S_{3}^{(1)}, S_{4}^{(1)} \right \}$ and $\left \{S_{3}^{(1)}, S_{3}^{(2)} \right \}$ planes and demonstrate that the separation between the models is visible at the current state of the models. Overall, we find that the statefinder diagnostic tool is robust in distinguishing between different DE models and even models of the same type with different equations of state (EoS), which lead to different fates of the Universe.
