First evidence of CP violation in beauty baryon to charmonium decays

LHCb Collaboration

doi:10.1016/j.scib.2025.12.028

First evidence of CP violation in beauty baryon to charmonium decays

LHCb Collaboration

Physics and Astronomy

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Abstract

A study of the difference in the CP asymmetries between Λ_b⁰ → J/ψpπ⁻ and Λ_b⁰→J/ψpK⁻ decays, ΔA_CP, is performed using proton-proton collision data collected by the LHCb experiment in the years 2015–2018, corresponding to an integrated luminosity of 6 fb⁻¹. This quantity is measured to be ΔA_CP= (4.03 ± 1.18 ± 0.23)%, where the first uncertainty is statistical and the second is systematic. When combined with the previous LHCb result, a value of ΔA_CP = (4.31 ± 1.06 ± 0.28)% is obtained, corresponding to a significance of 3.9σ against the CP symmetry hypothesis. Studies of triple-product asymmetries, which provide an additional probe of CP violation, show no significant deviation from CP symmetry.

Original language	English
Pages (from-to)	547-557
Number of pages	11
Journal	Science Bulletin
Volume	71
Issue number	3
Early online date	29 Dec 2025
DOIs	https://doi.org/10.1016/j.scib.2025.12.028
Publication status	Published - 16 Feb 2026

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Publisher Copyright:
© 2025 The Authors

Keywords

B physics
CP violation
Flavour physics
LHCb experiment
Standard Model
Triple-product asymmetries

ASJC Scopus subject areas

General

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title = "First evidence of CP violation in beauty baryon to charmonium decays",

abstract = "A study of the difference in the CP asymmetries between Λb0 → J/ψpπ− and Λb0→J/ψpK− decays, ΔACP, is performed using proton-proton collision data collected by the LHCb experiment in the years 2015–2018, corresponding to an integrated luminosity of 6 fb−1. This quantity is measured to be ΔACP = (4.03 ± 1.18 ± 0.23)\%, where the first uncertainty is statistical and the second is systematic. When combined with the previous LHCb result, a value of ΔACP = (4.31 ± 1.06 ± 0.28)\% is obtained, corresponding to a significance of 3.9σ against the CP symmetry hypothesis. Studies of triple-product asymmetries, which provide an additional probe of CP violation, show no significant deviation from CP symmetry.",

keywords = "B physics, CP violation, Flavour physics, LHCb experiment, Standard Model, Triple-product asymmetries",

author = "\{LHCb Collaboration\} and R. Aaij and C. Jayaweera and D. Johnson and C. Lazzeroni and M.J. Madurai and N. Sahoo and M.W. Slater and D.J.D. Thompson and F.C. Volle and N.K. Watson and E. Whiter and William Rose",

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doi = "10.1016/j.scib.2025.12.028",

language = "English",

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T1 - First evidence of CP violation in beauty baryon to charmonium decays

AU - LHCb Collaboration

AU - Aaij, R.

AU - Jayaweera, C.

AU - Johnson, D.

AU - Lazzeroni, C.

AU - Madurai, M.J.

AU - Sahoo, N.

AU - Slater, M.W.

AU - Thompson, D.J.D.

AU - Volle, F.C.

AU - Watson, N.K.

AU - Whiter, E.

A2 - Rose, William

PY - 2026/2/16

Y1 - 2026/2/16

N2 - A study of the difference in the CP asymmetries between Λb0 → J/ψpπ− and Λb0→J/ψpK− decays, ΔACP, is performed using proton-proton collision data collected by the LHCb experiment in the years 2015–2018, corresponding to an integrated luminosity of 6 fb−1. This quantity is measured to be ΔACP = (4.03 ± 1.18 ± 0.23)%, where the first uncertainty is statistical and the second is systematic. When combined with the previous LHCb result, a value of ΔACP = (4.31 ± 1.06 ± 0.28)% is obtained, corresponding to a significance of 3.9σ against the CP symmetry hypothesis. Studies of triple-product asymmetries, which provide an additional probe of CP violation, show no significant deviation from CP symmetry.

AB - A study of the difference in the CP asymmetries between Λb0 → J/ψpπ− and Λb0→J/ψpK− decays, ΔACP, is performed using proton-proton collision data collected by the LHCb experiment in the years 2015–2018, corresponding to an integrated luminosity of 6 fb−1. This quantity is measured to be ΔACP = (4.03 ± 1.18 ± 0.23)%, where the first uncertainty is statistical and the second is systematic. When combined with the previous LHCb result, a value of ΔACP = (4.31 ± 1.06 ± 0.28)% is obtained, corresponding to a significance of 3.9σ against the CP symmetry hypothesis. Studies of triple-product asymmetries, which provide an additional probe of CP violation, show no significant deviation from CP symmetry.

KW - B physics

KW - CP violation

KW - Flavour physics

KW - LHCb experiment

KW - Standard Model

KW - Triple-product asymmetries

UR - https://www.scopus.com/pages/publications/105030019184

U2 - 10.1016/j.scib.2025.12.028

DO - 10.1016/j.scib.2025.12.028

M3 - Article

AN - SCOPUS:105030019184

SN - 2095-9273

VL - 71

SP - 547

EP - 557

JO - Science Bulletin

JF - Science Bulletin

IS - 3

ER -

First evidence of CP violation in beauty baryon to charmonium decays

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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