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Scrutinizing CKM unitarity with a new measurement of the Kμ3/Kμ2 branching fraction


Cirigliano, Vincenzo; Crivellin, Andreas; Hoferichter, Martin; Moulson, Matthew (2023). Scrutinizing CKM unitarity with a new measurement of the Kμ3/Kμ2 branching fraction. Physics Letters B, 838:137748.

Abstract

Precision tests of first-row unitarity of the Cabibbo–Kobayashi–Maskawa matrix currently display two intriguing tensions, both at the 3σ level. First, combining determinations of from superallowed β decays with from kaon decays suggests a deficit in the unitarity relation. At the same time, a tension of similar significance has emerged between and decays. In this Letter, we point out that a measurement of the branching fraction at the level of 0.2% would have considerable impact on clarifying the experimental situation in the kaon sector, especially in view of tensions in the global fit to kaon data as well as the fact that the channel is currently dominated by a single experiment. Such a measurement, as possible for example at NA62, would further provide important constraints on physics beyond the Standard Model, most notably on the role of right-handed vector currents

Abstract

Precision tests of first-row unitarity of the Cabibbo–Kobayashi–Maskawa matrix currently display two intriguing tensions, both at the 3σ level. First, combining determinations of from superallowed β decays with from kaon decays suggests a deficit in the unitarity relation. At the same time, a tension of similar significance has emerged between and decays. In this Letter, we point out that a measurement of the branching fraction at the level of 0.2% would have considerable impact on clarifying the experimental situation in the kaon sector, especially in view of tensions in the global fit to kaon data as well as the fact that the channel is currently dominated by a single experiment. Such a measurement, as possible for example at NA62, would further provide important constraints on physics beyond the Standard Model, most notably on the role of right-handed vector currents

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Physics Institute
Dewey Decimal Classification:530 Physics
Scopus Subject Areas:Physical Sciences > Nuclear and High Energy Physics
Uncontrolled Keywords:Nuclear and High Energy Physics
Language:English
Date:1 March 2023
Deposited On:29 Dec 2023 10:18
Last Modified:29 Jun 2024 01:41
Publisher:Elsevier
ISSN:0370-2693
OA Status:Gold
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1016/j.physletb.2023.137748
Project Information:
  • : FunderSchweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
  • : Grant ID
  • : Project Title
  • Content: Published Version
  • Language: English
  • Licence: Creative Commons: Attribution 4.0 International (CC BY 4.0)