Publication

First evidence of CP violation in beauty baryon to charmonium decays

Aurelio Bay
2026

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 6fb-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.

Official source

https://infoscience.epfl.ch/entities/publication/2b8d949a-cc97-42ef-b1ab-3bedabeea84c

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Aurelio Bay
2026

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/2b8d949a-cc97-42ef-b1ab-3bedabeea84c

About this result

Related concepts (32)

CP violation

In particle physics, CP violation is a violation of CP-symmetry (or charge conjugation parity symmetry): the combination of C-symmetry (charge symmetry) and P-symmetry (parity symmetry). CP-symmetry states that the laws of physics should be the same if a particle is interchanged with its antiparticle (C-symmetry) while its spatial coordinates are inverted ("mirror" or P-symmetry). The discovery of CP violation in 1964 in the decays of neutral kaons resulted in the Nobel Prize in Physics in 1980 for its discoverers James Cronin and Val Fitch.

LHCb experiment

The LHCb (Large Hadron Collider beauty) experiment is a particle physics detector experiment collecting data at the Large Hadron Collider at CERN. LHCb is a specialized b-physics experiment, designed primarily to measure the parameters of CP violation in the interactions of b-hadrons (heavy particles containing a bottom quark). Such studies can help to explain the matter-antimatter asymmetry of the Universe. The detector is also able to perform measurements of production cross sections, exotic hadron spectroscopy, charm physics and electroweak physics in the forward region.

Pentaquark

A pentaquark is a human-made subatomic particle, consisting of four quarks and one antiquark bound together; they are not known to occur naturally, or exist outside of experiments specifically carried out to create them. As quarks have a baryon number of + 1/3, and antiquarks of − 1/3, the pentaquark would have a total baryon number of 1, and thus would be a baryon. Further, because it has five quarks instead of the usual three found in regular baryons ( 'triquarks'), it is classified as an exotic baryon.

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First evidence of CP violation in beauty baryon to charmonium decays

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