Deviation from $\Lambda$CDM: Pressure Parametrization

Understand

Most parametrizations for dark energy involve the equation of state $w$ of the dark energy.

• In this work, we choose the pressure of the dark energy to parametrize.
• As $p = constant$ essentially gives a cosmological constant, we use the Taylor expansion around this behavior $p = -p_{0} + (1-a)p_{1} + ....$ to study the small deviations from the cosmological constant.
• In our model, the departure from the cosmological constant behavior has been modeled by the presence of extra K-essence fields while keeping the cosmological constant term untouched.