Massless-Massive Amplitude Correspondence III: Massive Amplitude Bases in the SMEFT
Abstract
We develop a systematic correspondence between massless contact amplitudes in an unbroken theory and massive contact amplitudes after spontaneous symmetry breaking. Our construction employs the spin-transversality (ST) massive amplitude basis, with the systematic high energy expansion through minimal-helicity-chirality (MHC) amplitudes. The resulting U(2)=SU(2)× U(1)t description of a massive particle makes the semi-standard Young-tableau construction of massless Lorentz structures directly applicable to massive amplitudes. When the leading-order MHC component has a massless contact limit, it is one-to-one matched directly to its UV amplitude. Otherwise, five exceptional classes of ST amplitudes are identified, their first non-zero descendant components are matched through conserved current couplings to the massless contact amplitude. We apply the framework to the one-flavor electroweak sector of the Standard Model Effective Field Theory (SMEFT) through dimension eight, obtaining explicit relations between unbroken-phase Wilson coefficients and broken-phase ST amplitude coefficients for amplitudes with three to eight external particles.
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BibTeX
@misc{ni2026masslessmassive,
title = {{Massless-Massive Amplitude Correspondence III: Massive Amplitude Bases in the SMEFT}},
author = {Yu-Han Ni and Hao Sun and Yi-Ning Wang and Chao Wu and Jiang-Hao Yu},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.11767},
eprint = {2609.11767},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.11767},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Massless-Massive Amplitude Correspondence III: Massive Amplitude Bases in the SMEFT
AU - Yu-Han Ni
AU - Hao Sun
AU - Yi-Ning Wang
AU - Chao Wu
AU - Jiang-Hao Yu
PY - 2026
DA - 2026/09/10
PB - arXiv
DO - 10.48550/arxiv.2609.11767
UR - https://arxiv.org/abs/2609.11767
AB - We develop a systematic correspondence between massless contact amplitudes in an unbroken theory and massive contact amplitudes after spontaneous symmetry breaking. Our construction employs the spin-transversality (ST) massive amplitude basis, with the systematic high energy expansion through minimal-helicity-chirality (MHC) amplitudes. The resulting U(2)=SU(2)× U(1)_t description of a massive particle makes the semi-standard Young-tableau construction of massless Lorentz structures directly applicable to massive amplitudes. When the leading-order MHC component has a massless contact limit, it is one-to-one matched directly to its UV amplitude. Otherwise, five exceptional classes of ST amplitudes are identified, their first non-zero descendant components are matched through conserved current couplings to the massless contact amplitude. We apply the framework to the one-flavor electroweak sector of the Standard Model Effective Field Theory (SMEFT) through dimension eight, obtaining explicit relations between unbroken-phase Wilson coefficients and broken-phase ST amplitude coefficients for amplitudes with three to eight external particles.
ER -