What is "inflaton"

n. (context physics English) A proposed particle that would have been responsible for inflation in the very early universe

The inflaton is a hypothetical scalar field that is supposed to be responsible for cosmic inflation in the very early universe. A quantized particle for this field is expected, similar to other quantum fields, called an inflaton. The field provides a mechanism by which a period of rapid expansion from 10 to 10 seconds after the initial expansion can be generated, forming the universe.

The basic process of inflation consists of three steps:

1. Prior to the expansion period, the inflaton field was at a higher-energy state.
2. Random quantum fluctuations triggered a phase transition whereby the inflaton field released its potential energy as matter and radiation as it settled to its lowest-energy state.
3. This action generated a repulsive force that drove the portion of the universe that is observable to us today to expand from approximately 10 metres in radius at 10 seconds to almost 1 metre in radius at 10 seconds.

The inflaton field's lowest energy state may or may not be a zero energy state. This depends on the chosen potential energy density of the field.

The term inflaton was derived from inflation following the typical naming style of other quantum fields such as photon, gluon, boson and fermion. The term was first used in a paper entitled ‘After Primordial Inflation’ by, D.V. Nanopoulos, K.A. Olive and M. Srednicki.

It is suggested that the Higgs boson might act as the inflaton.