Publication

Measurement of the phase between strong and electromagnetic amplitudes in the decay J/ψ → ϕη

2025

Abstract

The first direct measurement of the relative phase between the strong and electromagnetic amplitudes for a J/ψ decaying into a vector-pseudoscalar final state is performed using 26 energy points of e + e − annihilation data between 3 . 00 GeV and 3.12 GeV. The data sets were collected by the BESIII detector with a total integrated luminosity of 452 pb − 1 . By investigating the interference pattern in the cross section lineshape of e + e − → ϕη , the relative phase between the strong and electromagnetic amplitudes of J/ψ decay is determined to be within [133 °, 228 ° ] at 68% confidence level.

Official source

https://infoscience.epfl.ch/entities/publication/84098ccb-6afd-4fe0-adea-dbabbf28f85e

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2025

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/84098ccb-6afd-4fe0-adea-dbabbf28f85e

About this result

Related concepts (32)

J/psi meson

The _J/psi (J/psi) meson ˈdʒeɪ_ˈsaɪ_ˈmiːzɒn is a subatomic particle, a flavor-neutral meson consisting of a charm quark and a charm antiquark. Mesons formed by a bound state of a charm quark and a charm anti-quark are generally known as "charmonium" or psions. The _J/Psi is the most common form of charmonium, due to its spin of 1 and its low rest mass. The _J/Psi has a rest mass of 3.0969GeV/c2, just above that of the _charmed eta (2.9836GeV/c2), and a mean lifetime of 7.2e-21s.

Phase (waves)

In physics and mathematics, the phase (symbol φ or φ) of a wave or other periodic function of some real variable (such as time) is an angle-like quantity representing the fraction of the cycle covered up to . It is expressed in such a scale that it varies by one full turn as the variable goes through each period (and goes through each complete cycle). It may be measured in any angular unit such as degrees or radians, thus increasing by 360° or as the variable completes a full period.

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.

Related publications (12)

Measurement of the phase between strong and electromagnetic amplitudes in the decay J/ψ → ϕη

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