A good review paper for some of the cosmological background motivation for dark
energy/cosmological constant is
`The Cosmological constant'
Sean M. Carroll
This can be found online for free at
a more advanced treatment of some of the ideas we will discuss is
`Quantum Gravity in Everyday Life: General Relativity as an Effective Field
It will be helpful if you are already familiar with some of the basics of
general relativity and
quantum field theory. A particularly good intro to QFT is:
`Quantum field theory in a nutshell'
(Princeton University Press)
but otherwise there are many standard texts like Ryder and Peskin&Schroeder
which are useful.
and to GR is
`Introducing Einstein's Relativity'
(Oxford University Press)
again their are many good books. If you haven't already it is worth investing in
one of each.