Real versus Complex Fermion Bare Mass and Multi-Wall String Defect Annihilation
Abstract
Particle physics models beyond the Standard Model often contain global symmetries to address various unanswered questions. However, a common criticism of theories based on global symmetries is that such symmetries are generally expected to be explicitly violated by gravitational effects at the Planck scale. In the case of a global U(1) symmetry, this explicit breaking can reduce the symmetry to a discrete subgroup of U(1), leading to the formation of cosmic strings attached to multiple domain walls (DWs). These DWs are usually cosmologically problematic, since their slow scaling behavior can eventually dominate the energy density of the Universe, giving rise to the well-known cosmological DW problem, which is strongly constrained by Big Bang Nucleosynthesis. In this work, we propose a mechanism for the annihilation of these DWs. If a fermion coupled to the symmetry-breaking scalar has a small bare mass, radiative corrections generate a temperature-dependent vacuum bias that drives DW collapse. As an example, we consider a majoron model with right-handed neutrinos, where gravity-induced operators produce a string-wall network. We show that a real bare Majorana mass is sufficient to induce complete DW annihilation for even-dimensional gravity-induced operators, whereas odd-dimensional operators require a complex bare Majorana mass whose phase lifts the residual vacuum degeneracy, enabling complete annihilation.
Related
- 21-cm Constraints on S-wave Dark Matter Annihilation with Subhalo-enhanced Effects
- Annihilation feedback on elastic scattering in self-interacting dark matter
- Cosmic-Ray Signals from Dark Matter Annihilation into Scalars with Baryon Number
- Strong Constraints on Line Signals from Dark Matter Annihilation in a Nearby Subhalo
- Constraints on Dark Matter Annihilation from Starlight-Induced Inverse Compton Emission in Omega Centauri
BibTeX
@misc{atta2026real,
title = {{Real versus Complex Fermion Bare Mass and Multi-Wall String Defect Annihilation}},
author = {Utsav Atta and Tathagata Ghosh and Sudip Manna},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2606.08142},
eprint = {2606.08142},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.08142},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Real versus Complex Fermion Bare Mass and Multi-Wall String Defect Annihilation
AU - Utsav Atta
AU - Tathagata Ghosh
AU - Sudip Manna
PY - 2026
DA - 2026/10/09
PB - arXiv
DO - 10.48550/arxiv.2606.08142
UR - https://arxiv.org/abs/2606.08142
AB - Particle physics models beyond the Standard Model often contain global symmetries to address various unanswered questions. However, a common criticism of theories based on global symmetries is that such symmetries are generally expected to be explicitly violated by gravitational effects at the Planck scale. In the case of a global U(1) symmetry, this explicit breaking can reduce the symmetry to a discrete subgroup of U(1), leading to the formation of cosmic strings attached to multiple domain walls (DWs). These DWs are usually cosmologically problematic, since their slow scaling behavior can eventually dominate the energy density of the Universe, giving rise to the well-known cosmological DW problem, which is strongly constrained by Big Bang Nucleosynthesis. In this work, we propose a mechanism for the annihilation of these DWs. If a fermion coupled to the symmetry-breaking scalar has a small bare mass, radiative corrections generate a temperature-dependent vacuum bias that drives DW collapse. As an example, we consider a majoron model with right-handed neutrinos, where gravity-induced operators produce a string-wall network. We show that a real bare Majorana mass is sufficient to induce complete DW annihilation for even-dimensional gravity-induced operators, whereas odd-dimensional operators require a complex bare Majorana mass whose phase lifts the residual vacuum degeneracy, enabling complete annihilation.
ER -