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Observation of the electromagnetic Dalitz transition J/ψ→ e+ e- ηc
Abstract
Using (10.087±0.044)×109 J/ψ events collected with the BESIII detector at the e+e- BEPCII collider, we present the first observation of the electromagnetic Dalitz decay J/ψ→ e+ e- ηc. The relative branching fraction R ≡ (Γ(J/ψ→ e+e-ηc))/(Γ(J/ψ→ γηc)) is determined to be (0.65±0.02stat.±0.07sys.)%, where the first uncertainty is statistical and the second systematic. The q2-dependent form factors are also extracted, and no significant deviation from the theoretical prediction is seen.
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BibTeX
@misc{collaboration2026observation,
title = {{Observation of the electromagnetic Dalitz transition $J/ψ\to e^+ e^- η_c$}},
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 = oct,
doi = {10.48550/arxiv.2610.09626},
eprint = {2610.09626},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.09626},
}
RIS
TY - UNPB
TI - Observation of the electromagnetic Dalitz transition J/ψ→ e^+ e^- η_c
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 - 2026/10/07
PB - arXiv
DO - 10.48550/arxiv.2610.09626
UR - https://arxiv.org/abs/2610.09626
AB - Using (10.087±0.044)×10^9 J/ψ events collected with the BESIII detector at the e^+e^- BEPCII collider, we present the first observation of the electromagnetic Dalitz decay J/ψ→ e^+ e^- η_c. The relative branching fraction R ≡ (Γ(J/ψ→ e^+e^-η_c))/(Γ(J/ψ→ γη_c)) is determined to be (0.65±0.02_stat.±0.07_sys.)%, where the first uncertainty is statistical and the second systematic. The q^2-dependent form factors are also extracted, and no significant deviation from the theoretical prediction is seen.
ER -