Matching from quark to hadronic operators: external source vs spurion methods

Fuente: arXiv
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Main Authors: Li, Gang, Song, Chuan-Qiang, Yu, Jiang-Hao
Format: Preprint
Published: 2025
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author Li, Gang
Song, Chuan-Qiang
Yu, Jiang-Hao
author_facet Li, Gang
Song, Chuan-Qiang
Yu, Jiang-Hao
contents Various weak processes at the hadronic scale have been utilized to search for new physics at high energy scale, which can be described by the QCD chiral Lagrangian matched from the low-energy effective theory (LEFT). Utilizing the chiral symmetry $SU(2)_L\times SU(2)_R \to SU(2)_V$ at the quark and hadronic levels, we make a comprehensive comparison of various matching methods, including the external source method, conventional spurion method, and our systematic spurion method. Although different methods show agreements for dimension-6 LEFT operator matching, we find that for higher-dimensional operators, the external source method is quite limited or inapplicable, the conventional spurion methods needs to introduce more and more spurions, while our spurion method does not need to introduce any new spurions than the ones in the dimension-6 matching. Using minimal set of spurions, we thus establish an one-to-one correspondence between the LEFT and chiral operators, with several examples, such as derivative operators at dimensions 7 and 8 with a single bilinear, four-quark operators at the dimension-9 level with two quark bilinears, which can be applied to the study of neutrino/electron scatterings and neutrinoless double beta decay.
format Preprint
id arxiv_https___arxiv_org_abs_2507_02538
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Matching from quark to hadronic operators: external source vs spurion methods
Li, Gang
Song, Chuan-Qiang
Yu, Jiang-Hao
High Energy Physics - Phenomenology
Nuclear Theory
Various weak processes at the hadronic scale have been utilized to search for new physics at high energy scale, which can be described by the QCD chiral Lagrangian matched from the low-energy effective theory (LEFT). Utilizing the chiral symmetry $SU(2)_L\times SU(2)_R \to SU(2)_V$ at the quark and hadronic levels, we make a comprehensive comparison of various matching methods, including the external source method, conventional spurion method, and our systematic spurion method. Although different methods show agreements for dimension-6 LEFT operator matching, we find that for higher-dimensional operators, the external source method is quite limited or inapplicable, the conventional spurion methods needs to introduce more and more spurions, while our spurion method does not need to introduce any new spurions than the ones in the dimension-6 matching. Using minimal set of spurions, we thus establish an one-to-one correspondence between the LEFT and chiral operators, with several examples, such as derivative operators at dimensions 7 and 8 with a single bilinear, four-quark operators at the dimension-9 level with two quark bilinears, which can be applied to the study of neutrino/electron scatterings and neutrinoless double beta decay.
title Matching from quark to hadronic operators: external source vs spurion methods
topic High Energy Physics - Phenomenology
Nuclear Theory
url https://arxiv.org/abs/2507.02538