Stochastic evolution of scalar fields with continuous symmetries during inflation. (arXiv:2002.07201v1 [hep-ph])

<a href="http://arxiv.org/find/hep-ph/1/au:+Adshead_P/0/1/0/all/0/1">Peter Adshead</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Pearce_L/0/1/0/all/0/1">Lauren Pearce</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Shelton_J/0/1/0/all/0/1">Jessie Shelton</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Weiner_Z/0/1/0/all/0/1">Zachary J. Weiner</a>

During inflation, scalar fields with masses less than the Hubble scale

acquire vacuum expectation values (vevs) via stochastic processes driven by

quantum fluctuations. For nearly massless spectator scalars transforming

nontrivially under a continuous symmetry group, we demonstrate that the

evolution of the vev depends on the dimensionality of the scalar field space.

Fields in larger representations both attain larger vacuum expectation values

and converge more rapidly to equilibrium. We present an argument demonstrating

how this higher-dimensional evolution can be obtained in unitary gauge for

fields transforming under local symmetries with a mass gap that is small

compared to the Hubble scale. Finally, we show that accounting for the full

number of degrees of freedom in the Standard Model Higgs multiplet tightens

Higgs stability constraints on the inflationary scale at the percent level and

has more dramatic consequences for both the vev and the energy stored in the

Higgs field after inflation.

During inflation, scalar fields with masses less than the Hubble scale

acquire vacuum expectation values (vevs) via stochastic processes driven by

quantum fluctuations. For nearly massless spectator scalars transforming

nontrivially under a continuous symmetry group, we demonstrate that the

evolution of the vev depends on the dimensionality of the scalar field space.

Fields in larger representations both attain larger vacuum expectation values

and converge more rapidly to equilibrium. We present an argument demonstrating

how this higher-dimensional evolution can be obtained in unitary gauge for

fields transforming under local symmetries with a mass gap that is small

compared to the Hubble scale. Finally, we show that accounting for the full

number of degrees of freedom in the Standard Model Higgs multiplet tightens

Higgs stability constraints on the inflationary scale at the percent level and

has more dramatic consequences for both the vev and the energy stored in the

Higgs field after inflation.

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