Two scalar field cosmological models in f(R,T) gravity with cosmic transit
and varying cosmological constant have been investigated. The time-dependent
cosmological constant Ξ(t) is positive and tends to a very small value
at the present epoch. The scalar field pressure pΟβ shows a sign
flipping for normal scalar field. For the phantom field, the scalar potential
V(Ο) is negative and the energy density ΟΟβ=Ekβ+V takes negative
values when the equation of state parameter ΟΟβ<β1. While the weak
energy condition WEC implies that the total energy density
Ο=βiβΟiββ₯0, we still can have a negative Ο term as long as
the total Ο is positive. In the current work we argue that the WEC,
Ο=βiβΟiββ₯0 and piβ+Οiββ₯0, is not violated. For a
scalar field Ο, The condition ΟΟβ+pΟβ=ΟΟβ(1+ΟΟβ)=2Ekββ₯0 allows for ΟΟβ<0 if ΟΟβ<β1.
The cosmology in both models has been probed using a given function a(t)
deduced from the desired cosmic behavior which is the opposite of the
conventional viewpoint