First Observation and Dynamical Study of the D⁺_s→ f₀(980) μ⁺ν_μ Decay

@misc{collaboration2026first,
  title = {{First Observation and Dynamical Study of the $D^+_s\to f_0(980) μ^+ν_μ$ Decay}},
  author = {BESIII Collaboration and M. Ablikim and M. N. Achasov and P. Adlarson and X. C. Ai and C. S. Akondi and R. Aliberti and A. Amoroso and Q. An and Y. H. An and M. S. Anderson and Y. Bai and O. Bakina and H. R. Bao and X. L. Bao and M. Barbagiovanni and V. Batozskaya and K. Begzsuren and N. Berger and M. Berlowski and M. B. Bertani and D. Bettoni and F. Bianchi and E. Bianco and A. Bortone and I. Boyko and R. A. Briere and A. Brueggemann and D. Cabiati and H. Cai and M. H. Cai and X. Cai and A. Calcaterra and G. F. Cao and N. Cao and S. A. Cetin and X. Y. Chai and J. F. Chang and T. T. Chang and G. R. Che and Y. Z. Che and C. H. Chen and Chao Chen and G. Chen and H. S. Chen and H. Y. Chen and M. L. Chen and S. J. Chen and S. M. Chen and T. Chen and W. Chen and X. R. Chen and X. T. Chen and X. Y. Chen and Y. B. Chen and Y. Q. Chen and Z. K. Chen and J. Cheng and L. N. Cheng and S. K. Choi},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.15655},
  eprint = {2609.15655},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.15655},
}

TY  - UNPB
TI  - First Observation and Dynamical Study of the D^+_s→ f_0(980) μ^+ν_μ Decay
AU  - BESIII Collaboration
AU  - M. Ablikim
AU  - M. N. Achasov
AU  - P. Adlarson
AU  - X. C. Ai
AU  - C. S. Akondi
AU  - R. Aliberti
AU  - A. Amoroso
AU  - Q. An
AU  - Y. H. An
AU  - M. S. Anderson
AU  - Y. Bai
AU  - O. Bakina
AU  - H. R. Bao
AU  - X. L. Bao
AU  - M. Barbagiovanni
AU  - V. Batozskaya
AU  - K. Begzsuren
AU  - N. Berger
AU  - M. Berlowski
AU  - M. B. Bertani
AU  - D. Bettoni
AU  - F. Bianchi
AU  - E. Bianco
AU  - A. Bortone
AU  - I. Boyko
AU  - R. A. Briere
AU  - A. Brueggemann
AU  - D. Cabiati
AU  - H. Cai
AU  - M. H. Cai
AU  - X. Cai
AU  - A. Calcaterra
AU  - G. F. Cao
AU  - N. Cao
AU  - S. A. Cetin
AU  - X. Y. Chai
AU  - J. F. Chang
AU  - T. T. Chang
AU  - G. R. Che
AU  - Y. Z. Che
AU  - C. H. Chen
AU  - Chao Chen
AU  - G. Chen
AU  - H. S. Chen
AU  - H. Y. Chen
AU  - M. L. Chen
AU  - S. J. Chen
AU  - S. M. Chen
AU  - T. Chen
AU  - W. Chen
AU  - X. R. Chen
AU  - X. T. Chen
AU  - X. Y. Chen
AU  - Y. B. Chen
AU  - Y. Q. Chen
AU  - Z. K. Chen
AU  - J. Cheng
AU  - L. N. Cheng
AU  - S. K. Choi
PY  - 2026
DA  - 2026/09/14
PB  - arXiv
DO  - 10.48550/arxiv.2609.15655
UR  - https://arxiv.org/abs/2609.15655
AB  - Using 7.33 fb^−1 of e^+e^- annihilation data recorded with the BESIII detector at center-of-mass energies from 4.128 to 4.226 GeV, we report the first observation and dynamical study of the semileptonic decay D^+_s→ f_0(980) μ^+ν_μ. The absolute branching fraction of D^+_s→ f_0(980) μ^+ν_μ with $ f_{0}(980)\to π^+ π^-$ is (1.59 ± 0.18_stat ± 0.11_syst) ×10^−3. Combining this result with our earlier BESIII measurement of ℬ(D^+_s→ f_0(980) e^+ν_e), their ratio is found to be (ℬ(D^+_s→ f_0(980) μ^+ν_μ))/(ℬ(D^+_s→ f_0(980)e^+ν_e)) = 0.92±0.13_stat±0.08_syst, in agreement with the Standard Model expectation of lepton flavor universality. From a dynamical analysis of the D_s^+ → f_0(980)μ^+ν_μ decay with a simple pole parametrization for the hadronic transition form factor, the product of the form factor f^f_0(980)_+(0) and the c→ s Cabibbo-Kobayashi-Maskawa matrix element |V_cs| is determined to be f^f_0(980)_+(0)|V_cs|=0.490±0.059_stat±0.025_syst. Averaging with our previously reported result for the D_s^+ → f_0(980)e^+ν_e decay, we obtain f^f_0(980)_+(0)|V_cs|=0.500±0.016_stat±0.020_syst. Using |V_cs| from the CKMfitter group, we extract f^f_0(980)_+(0)=0.514±0.017_stat±0.021_syst. This represents the most precise determination of the D_s → f_0(980) transition form factor to date, and provides stringent tests of various theoretical models.
ER  -