# Unitarity-violation in generalized Higgs inflation models

## Abstract

Unitarity-violation presents a challenge for non-minimally coupled models of inflation based on weak-scale particle physics. We examine the energy scale of tree-level unitarity-violation in scattering processes for generalized models with multiple scalar fields where the inflaton is either a singlet scalar or the Higgs. In the limit that the non-minimal couplings are all equal (e.g. in the case of Higgs or other complex inflaton), the scale of tree-level unitarity-violation matches the existing result. However if the inflaton is a singlet, and if it has a larger non-minimal coupling than other scalars in the model, then this hierarchy increases the scale of tree-level unitarity-violation. A sufficiently strong hierarchy pushes the scale of tree-level unitarity-violation above the Planck scale. We also discuss models which attempt to resolve the issue of unitarity-violation in Higgs Inflation.

- Authors:

- Physics Department and Helsinki Institute of Physics, University of Helsinki, P.O. Box 64, FI-00014, Helsinki (Finland)
- Consortium for Fundamental Physics, Cosmology and Astroparticle Physics Group, Department of Physics, Lancaster University, LA1 4YB (United Kingdom)

- Publication Date:

- OSTI Identifier:
- 22279709

- Resource Type:
- Journal Article

- Journal Name:
- Journal of Cosmology and Astroparticle Physics

- Additional Journal Information:
- Journal Volume: 2012; Journal Issue: 11; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1475-7516

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; COSMOLOGY; HIGGS BOSONS; HIGGS MODEL; INFLATIONARY UNIVERSE; INFLATONS; SCALAR FIELDS; SCATTERING; UNITARITY

### Citation Formats

```
Lerner, Rose N., and McDonald, John, E-mail: rose.lerner@helsinki.fi, E-mail: j.mcdonald@lancaster.ac.uk.
```*Unitarity-violation in generalized Higgs inflation models*. United States: N. p., 2012.
Web. doi:10.1088/1475-7516/2012/11/019.

```
Lerner, Rose N., & McDonald, John, E-mail: rose.lerner@helsinki.fi, E-mail: j.mcdonald@lancaster.ac.uk.
```*Unitarity-violation in generalized Higgs inflation models*. United States. doi:10.1088/1475-7516/2012/11/019.

```
Lerner, Rose N., and McDonald, John, E-mail: rose.lerner@helsinki.fi, E-mail: j.mcdonald@lancaster.ac.uk. Thu .
"Unitarity-violation in generalized Higgs inflation models". United States. doi:10.1088/1475-7516/2012/11/019.
```

```
@article{osti_22279709,
```

title = {Unitarity-violation in generalized Higgs inflation models},

author = {Lerner, Rose N. and McDonald, John, E-mail: rose.lerner@helsinki.fi, E-mail: j.mcdonald@lancaster.ac.uk},

abstractNote = {Unitarity-violation presents a challenge for non-minimally coupled models of inflation based on weak-scale particle physics. We examine the energy scale of tree-level unitarity-violation in scattering processes for generalized models with multiple scalar fields where the inflaton is either a singlet scalar or the Higgs. In the limit that the non-minimal couplings are all equal (e.g. in the case of Higgs or other complex inflaton), the scale of tree-level unitarity-violation matches the existing result. However if the inflaton is a singlet, and if it has a larger non-minimal coupling than other scalars in the model, then this hierarchy increases the scale of tree-level unitarity-violation. A sufficiently strong hierarchy pushes the scale of tree-level unitarity-violation above the Planck scale. We also discuss models which attempt to resolve the issue of unitarity-violation in Higgs Inflation.},

doi = {10.1088/1475-7516/2012/11/019},

journal = {Journal of Cosmology and Astroparticle Physics},

issn = {1475-7516},

number = 11,

volume = 2012,

place = {United States},

year = {2012},

month = {11}

}