Letter
Open Access

Flavor-violating Higgs and $Z$ boson decays at a future circular lepton collider

Jernej F. Kamenik ^1,2,*, Arman Korajac^1,2,†, Manuel Szewc ^3,‡, Michele Tammaro^1,§, and Jure Zupan^3,∥

¹Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
²Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia
³Department of Physics, University of Cincinnati, Cincinnati, Ohio 45221, USA

^*jernej.kamenik@cern.ch
^†arman.korajac@ijs.si
^‡szewcml@ucmail.uc.edu
^§michele.tammaro@ijs.si
^∥zupanje@ucmail.uc.edu

Phys. Rev. D 109, L011301 – Published 17 January, 2024

DOI: https://doi.org/10.1103/PhysRevD.109.L011301

Abstract

Recent advances in $b$ , $c$ , and $s$ quark tagging coupled with novel statistical analysis techniques will allow future high energy and high statistics electron-positron colliders, such as the FCC-ee, to place phenomenologically relevant bounds on flavor violating Higgs and $Z$ decays to quarks. We assess the FCC-ee reach for $Z / h \to b s, c u$ decays as a function of jet tagging performance. We also update the standard model (SM) predictions for the corresponding branching ratios, as well as the indirect constraints on the flavor violating Higgs and $Z$ couplings to quarks. Using the type III two Higgs doublet model as an example of beyond the standard model physics, we show that the searches for $h \to b s, c u$ decays at FCC-ee can probe new parameter space not excluded by indirect searches. We also reinterpret the FCC-ee reach for $Z \to b s, c u$ in terms of the constraints on models with vectorlike quarks.

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Supplemental Material

References (83)

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Phys. Rev. D 109, L011301– Published 17 January, 2024

Vol. 109, Iss. 1 — 1 January 2024

Received 17 July 2023
Accepted 20 December 2023

DOI: https://doi.org/10.1103/PhysRevD.109.L011301

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

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Flavor-violating Higgs and $Z$ boson decays at a future circular lepton collider

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Flavor-violating Higgs and Z boson decays at a future circular lepton collider

Abstract

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Supplemental Material

References (83)

Flavor-violating Higgs and $Z$ boson decays at a future circular lepton collider