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Title: Chiral charge erasure via thermal fluctuations of magnetic helicity

Abstract

We consider a relativistic plasma of fermions coupled to an Abelian gauge field and carrying a chiral charge asymmetry, which might arise in the early Universe through baryogenesis. It is known that on large length scales, λ≳1/(αμ{sub 5}), the chiral anomaly opens an instability toward the erasure of chiral charge and growth of magnetic helicity. Here the chemical potential μ{sub 5} parametrizes the chiral asymmetry and α is the fine-structure constant. We study the process of chiral charge erasure through the thermal fluctuations of magnetic helicity and contrast with the well-studied phenomenon of Chern-Simons number diffusion. Through the fluctuation-dissipation theorem we estimate the amplitude and time scale of helicity fluctuations on the length scale λ, finding δ H∼λT and τ∼αλ{sup 3}T{sup 2} for a relativistic plasma at temperature T. We argue that the presence of a chiral asymmetry allows the helicity to grow diffusively for a time t∼T{sup 3}/(α{sup 5}μ{sub 5}{sup 4}) until it reaches an equilibrium value H∼μ{sub 5}T{sup 2}/α, and the chiral asymmetry is partially erased. If the chiral asymmetry is small, μ{sub 5}

Authors:
 [1];  [2]
  1. Kavli Institute for Cosmological Physics, University of Chicago,Chicago, Illinois 60637 (United States)
  2. Institut de Théorie des Phénoménes Physiques, Ecole Polytechnique Fédérale de Lausanne,CH-1015 Lausanne (Switzerland)
Publication Date:
Sponsoring Org.:
SCOAP3, CERN, Geneva (Switzerland)
OSTI Identifier:
22572076
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2016; Journal Issue: 05; Other Information: PUBLISHER-ID: JCAP05(2016)029; OAI: oai:repo.scoap3.org:15561; cc-by Article funded by SCOAP3. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 License. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ASYMMETRY; CHIRALITY; COSMOLOGY; FINE STRUCTURE; FLUCTUATIONS; GAUGE INVARIANCE; HELICITY; MAGNETIC FIELDS; NONLUMINOUS MATTER; RELATIVISTIC RANGE; STANDARD MODEL; U-1 GROUPS; UNIVERSE

Citation Formats

Long, Andrew J., and Sabancilar, Eray. Chiral charge erasure via thermal fluctuations of magnetic helicity. United States: N. p., 2016. Web. doi:10.1088/1475-7516/2016/05/029.
Long, Andrew J., & Sabancilar, Eray. Chiral charge erasure via thermal fluctuations of magnetic helicity. United States. doi:10.1088/1475-7516/2016/05/029.
Long, Andrew J., and Sabancilar, Eray. Wed . "Chiral charge erasure via thermal fluctuations of magnetic helicity". United States. doi:10.1088/1475-7516/2016/05/029.
@article{osti_22572076,
title = {Chiral charge erasure via thermal fluctuations of magnetic helicity},
author = {Long, Andrew J. and Sabancilar, Eray},
abstractNote = {We consider a relativistic plasma of fermions coupled to an Abelian gauge field and carrying a chiral charge asymmetry, which might arise in the early Universe through baryogenesis. It is known that on large length scales, λ≳1/(αμ{sub 5}), the chiral anomaly opens an instability toward the erasure of chiral charge and growth of magnetic helicity. Here the chemical potential μ{sub 5} parametrizes the chiral asymmetry and α is the fine-structure constant. We study the process of chiral charge erasure through the thermal fluctuations of magnetic helicity and contrast with the well-studied phenomenon of Chern-Simons number diffusion. Through the fluctuation-dissipation theorem we estimate the amplitude and time scale of helicity fluctuations on the length scale λ, finding δ H∼λT and τ∼αλ{sup 3}T{sup 2} for a relativistic plasma at temperature T. We argue that the presence of a chiral asymmetry allows the helicity to grow diffusively for a time t∼T{sup 3}/(α{sup 5}μ{sub 5}{sup 4}) until it reaches an equilibrium value H∼μ{sub 5}T{sup 2}/α, and the chiral asymmetry is partially erased. If the chiral asymmetry is small, μ{sub 5}},
doi = {10.1088/1475-7516/2016/05/029},
journal = {Journal of Cosmology and Astroparticle Physics},
number = 05,
volume = 2016,
place = {United States},
year = {Wed May 11 00:00:00 EDT 2016},
month = {Wed May 11 00:00:00 EDT 2016}
}