A comparison of experimental measurements and theoretical predictions for the branching fraction ratio ℬ(Ds0(2317)+→Ds*γ)/ℬ(Ds0(2317)+→Dsπ0).

The international Belle and Belle II collaborations recently observed a previously undiscovered decay mode of the Ds0(2317)+ particle for the first time: electromagnetic radiative decay.

This breakthrough provides key experimental evidence to help solve the long-standing mystery surrounding the particle's mass, and offers valuable insights into the fundamental interactions that bind matter together.

The findings were published in the highly prestigious journal Physical Review Letters and were highlighted by the American Physical Society as "Featured in Physics".

Utilizing the world's largest ee→cc data sample, collected by the Belle and Belle II experiments at energies near 10.58 GeV, the research team discovered the Ds0(2317)+→Ds*γ process with a statistical significance exceeding 10 standard deviations.

Furthermore, they measured the branching fraction ratio of this radiative decay relative to the strong decay process Ds0(2317)+→Dsπ0 to be approximately 7 percent. This value is lower than the predictions of most quark-antiquark models, yet higher than those of most molecular state models.

This discrepancy indicates that the Ds0(2317)+ particle likely possesses a more complex internal structure than previously thought.

Associate Professor Li Yubo from the School of Physics at Xi'an Jiaotong University and Professor Shen Chengping from Fudan University are the principal contributors to the work. The paper is co-authored by all members of the Belle and Belle II collaborations, with names listed in alphabetical order by surname.