Unveiling Light-Quark Yukawa Flavor Structure via Dihadron Fragmentation at Lepton Colliders

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Main Authors: Cao, Qing-Hong, Wen, Xin-Kai, Yan, Bin, Zhang, Shutao
Format: Preprint
Published: 2025
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author Cao, Qing-Hong
Wen, Xin-Kai
Yan, Bin
Zhang, Shutao
author_facet Cao, Qing-Hong
Wen, Xin-Kai
Yan, Bin
Zhang, Shutao
contents Directly probing light-quark Yukawa couplings and their flavor structure remains a major challenge due to their smallness and overwhelming QCD backgrounds. In this Letter, we propose a theoretical framework to access these couplings at lepton colliders through transverse spin dependent azimuthal modulations in dihadron fragmentation. These modulations arise from the interference between Higgs mediated and Standard Model amplitudes in $e^-e^+\to q\bar{q}Z$, producing angular structures that are linearly sensitive to the Yukawa couplings $y_q$, in contrast to conventional observables that scale as $y_q^2$. By combining channels with an identified accompanying single hadron, $h^\prime=π^\pm,K^\pm$, and $p/\bar{p}$, this approach cleanly disentangles the up- and down-quark Yukawa contributions, yielding typical limits at the $\mathcal{O}(10^{-4})$ level and establishing fragmentation dynamics as a novel and complementary probe of the Higgs flavor structure.
format Preprint
id arxiv_https___arxiv_org_abs_2512_16492
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Unveiling Light-Quark Yukawa Flavor Structure via Dihadron Fragmentation at Lepton Colliders
Cao, Qing-Hong
Wen, Xin-Kai
Yan, Bin
Zhang, Shutao
High Energy Physics - Phenomenology
High Energy Physics - Experiment
Nuclear Experiment
Nuclear Theory
Directly probing light-quark Yukawa couplings and their flavor structure remains a major challenge due to their smallness and overwhelming QCD backgrounds. In this Letter, we propose a theoretical framework to access these couplings at lepton colliders through transverse spin dependent azimuthal modulations in dihadron fragmentation. These modulations arise from the interference between Higgs mediated and Standard Model amplitudes in $e^-e^+\to q\bar{q}Z$, producing angular structures that are linearly sensitive to the Yukawa couplings $y_q$, in contrast to conventional observables that scale as $y_q^2$. By combining channels with an identified accompanying single hadron, $h^\prime=π^\pm,K^\pm$, and $p/\bar{p}$, this approach cleanly disentangles the up- and down-quark Yukawa contributions, yielding typical limits at the $\mathcal{O}(10^{-4})$ level and establishing fragmentation dynamics as a novel and complementary probe of the Higgs flavor structure.
title Unveiling Light-Quark Yukawa Flavor Structure via Dihadron Fragmentation at Lepton Colliders
topic High Energy Physics - Phenomenology
High Energy Physics - Experiment
Nuclear Experiment
Nuclear Theory
url https://arxiv.org/abs/2512.16492