Informal Pizza Seminar

Inflation with w=+1

Subodh Patil

McGill University

We'll discuss a way in which we can obtain a period of exponential inflation, without the use of potentials. In contrast to recent attempts at obtaining inflation from a purely kinetic scalar field, we find that we do not need to introduce higher derivative actions, nor do we need to modify gravity in any way, and that we generically obtain exponential, as opposed to power law inflation. Moreover, unlike all previous approaches, we do not require w = -1. We discuss the significance of this observation in light of the cosmological constant problem. Our inflaton is a scalar field with the `wrong sign' kinetic energy. We take the perspective that this is due to some temporary instability in our system at high energies and offer several examples of physically well defined systems that temporarily exhibit such behaviour. We'll also discuss how one gracefully exits from this type of inflation.