Interplay between decoupling and non-decoupling effective field theories in electroweak phase transitions
Abstract
Gravitational-wave (GW) observations offer a promising probe of new physics associated with a strong first-order electroweak phase transition. Null results from direct searches and constraints from precision measurements, together with the comparatively weak constraints on Higgs self-interactions, motivate scenarios in which non-decoupling effects in the Higgs potential coexist with additional decoupling new physics. Previous Fisher matrix studies within the Standard Model effective field theory (SMEFT) have explored the sensitivity of future GW observations to new physics, focusing on transitions driven by the dimension-six operator (H† H)3. However, the validity of the truncated EFT expansion can become questionable in the parameter regions relevant to such transitions. We instead consider transitions driven by non-decoupling effects described by the nearly aligned Higgs effective field theory (naHEFT). We investigate whether GW observations can probe small corrections to the Higgs effective potential induced by decoupling effects in interactions other than Higgs self-interactions. As a representative benchmark for additional decoupling effects, we consider the dimension-six SMEFT operator (H† H)(q̅3 tRH̃) with Wilson coefficient CuH. Although we focus on this benchmark, the same framework can be applied to other dimension-six SMEFT operators. We perform two-parameter Fisher matrix analyses for DECIGO and BBO to quantify their expected sensitivity to CuH and the naHEFT mass scale Λ. For the benchmark configurations considered, the non-decoupling dynamics generates a detectable GW signal. We find that these small corrections can produce potentially measurable changes in the GW spectrum, even after accounting for the correlation between CuH and Λ.
Related
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BibTeX
@misc{hashino2026interplay,
title = {{Interplay between decoupling and non-decoupling effective field theories in electroweak phase transitions}},
author = {Katsuya Hashino and Daiki Ueda},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.28171},
eprint = {2609.28171},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.28171},
}
RIS
TY - UNPB
TI - Interplay between decoupling and non-decoupling effective field theories in electroweak phase transitions
AU - Katsuya Hashino
AU - Daiki Ueda
PY - 2026
DA - 2026/09/23
PB - arXiv
DO - 10.48550/arxiv.2609.28171
UR - https://arxiv.org/abs/2609.28171
AB - Gravitational-wave (GW) observations offer a promising probe of new physics associated with a strong first-order electroweak phase transition. Null results from direct searches and constraints from precision measurements, together with the comparatively weak constraints on Higgs self-interactions, motivate scenarios in which non-decoupling effects in the Higgs potential coexist with additional decoupling new physics. Previous Fisher matrix studies within the Standard Model effective field theory (SMEFT) have explored the sensitivity of future GW observations to new physics, focusing on transitions driven by the dimension-six operator (H^† H)^3. However, the validity of the truncated EFT expansion can become questionable in the parameter regions relevant to such transitions. We instead consider transitions driven by non-decoupling effects described by the nearly aligned Higgs effective field theory (naHEFT). We investigate whether GW observations can probe small corrections to the Higgs effective potential induced by decoupling effects in interactions other than Higgs self-interactions. As a representative benchmark for additional decoupling effects, we consider the dimension-six SMEFT operator (H^† H)(q̅_3 t_RH̃) with Wilson coefficient C_uH. Although we focus on this benchmark, the same framework can be applied to other dimension-six SMEFT operators. We perform two-parameter Fisher matrix analyses for DECIGO and BBO to quantify their expected sensitivity to C_uH and the naHEFT mass scale Λ. For the benchmark configurations considered, the non-decoupling dynamics generates a detectable GW signal. We find that these small corrections can produce potentially measurable changes in the GW spectrum, even after accounting for the correlation between C_uH and Λ.
ER -