GoKawiilThe protons and neutrons that make up the majority of everyday matter consist of fundamental particles called up quarks and down quarks. Less common is the unstable strange quark, which can turn into an up quark. This transformation, which serves as a key test of conventional physics theory, can be measured in the decay of particles called lambda hyperons. However, over the past 35 years, this decay has received little experimental attention because some of its characteristics could not be measured. Now, in a paper in Nature, the BESIII Collaboration1 reports an experiment that ‘tagged’ the lambda hyperon decay through quantum entanglement with the particle’s antimatter partner. The authors find that a key decay parameter is consistent with conventional theory, in conflict with previous measurements.
Nature 657, 42-44 (2026)
doi: https://doi.org/10.1038/d41586-026-02123-1
References The BESIII Collaboration. Nature 657, 92–97 (2026). Seng, C.-Y., Galviz, D., Marciano, W. J. & Meißner, U.-G. Phys. Rev. D 105, 013005 (2022). Cabibbo, N., Swallow, E. C. & Winston, R. Annu. Rev. Nucl. Part. Sci. 53, 39–75 (2003). Dworkin, J. et al. Phys. Rev. D 41, 780–800 (1990). The BESIII Collaboration. Nature Phys. 15, 631–634 (2019). Batozskaya, V., Kupsc, A., Salone, N. & Wiechnik, J. Phys. Rev. D 108, 016011 (2023). Baltrusaitis, R. M. et al. Phys. Rev. Lett. 56, 2140–2143 (1986). Navas, S. et al. Phys. Rev. D 110, 030001 (2024). Bacchio, S. & Konstantinou, A. Phys. Rev. Lett. 135, 231901 (2025). The BESIII Collaboration. Preprint at arXiv https://doi.org/10.48550/arXiv.2512.15273 (2025). Download references
Competing Interests The author declares no competing interests.
Related Articles
Subjects