Observation of ?c+?np+? and search for ?c+?na0980+

The BESIII collaboration

doi:10.1007/JHEP08(2026)009

Observation of ?c+?np+? and search for ?c+?na0980+

The BESIII collaboration

Institute of Higher Research

CAS - Institute of High Energy Physics
Budker Institute of Nuclear Physics of the Siberian Branch of the RAS
Novosibirsk State University
Uppsala University
Zhengzhou University

Research output: Contribution to journal › Article › peer-review

Abstract

By analysing 6.1 fb^-1 of data collected at centre-of-mass energies between s=4.600 and 4.843 GeV with the BESIII detector at the BEPCII collider, we observe the decay ?c+?np+? for the first time with a statistical significance of 9.5s. The ratio of branching fractions B?c+?np+?/B?c+??p+? is measured to be 0.155 ± 0.031_stat. ± 0.012_syst. Taking the world average of B?c+??p+? as reference, the absolute branching fraction is calculated to be B?c+?np+?=2.94±0.59stat.±0.23syst.±0.13ref.×10-3. The intermediate process ?c+?na0980+ is also searched for in the p⁺? invariant mass spectrum. Since no significant signal is found, the upper limit on B?c+?na0980+×Ba0980+?p+? is set to 8.4 × 10^-4 at 90% confidence level. A sophisticated deep learning approach using a Transformer-based architecture is employed to distinguish signals from prevalent hadronic backgrounds, complemented by thorough validation and systematic uncertainty quantification.

Original language	English
Article number	9
Journal	Journal of High Energy Physics
Volume	2026
Issue number	8
DOIs	https://doi.org/10.1007/JHEP08(2026)009
State	Published - Aug 2026

Keywords

Branching fraction
Charm Physics
Particle and Resonance Production
e-e Experiments

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10.1007/JHEP08(2026)009

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@article{37e198a0cf4848aeaefc477a4f268bc6,

title = "Observation of ?c+?np+? and search for ?c+?na0980+",

abstract = "By analysing 6.1 fb-1 of data collected at centre-of-mass energies between s=4.600 and 4.843 GeV with the BESIII detector at the BEPCII collider, we observe the decay ?c+?np+? for the first time with a statistical significance of 9.5s. The ratio of branching fractions B?c+?np+?/B?c+??p+? is measured to be 0.155 ± 0.031stat. ± 0.012syst. Taking the world average of B?c+??p+? as reference, the absolute branching fraction is calculated to be B?c+?np+?=2.94±0.59stat.±0.23syst.±0.13ref.{\texttimes}10-3. The intermediate process ?c+?na0980+ is also searched for in the p+? invariant mass spectrum. Since no significant signal is found, the upper limit on B?c+?na0980+{\texttimes}Ba0980+?p+? is set to 8.4 {\texttimes} 10-4 at 90\% confidence level. A sophisticated deep learning approach using a Transformer-based architecture is employed to distinguish signals from prevalent hadronic backgrounds, complemented by thorough validation and systematic uncertainty quantification.",

keywords = "Branching fraction, Charm Physics, Particle and Resonance Production, e-e Experiments",

author = "M. Ablikim and Achasov, \{M. N.\} and P. Adlarson and Ai, \{X. C.\} and S. Kabana and \{The BESIII collaboration\}",

note = "Publisher Copyright: {\textcopyright} The Author(s) 2026.",

year = "2026",

month = aug,

doi = "10.1007/JHEP08(2026)009",

language = "English",

volume = "2026",

journal = "Journal of High Energy Physics",

issn = "1126-6708",

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T1 - Observation of ?c+?np+? and search for ?c+?na0980+

AU - Ablikim, M.

AU - Achasov, M. N.

AU - Adlarson, P.

AU - Ai, X. C.

AU - Kabana, S.

AU - The BESIII collaboration

N1 - Publisher Copyright: © The Author(s) 2026.

PY - 2026/8

Y1 - 2026/8

N2 - By analysing 6.1 fb-1 of data collected at centre-of-mass energies between s=4.600 and 4.843 GeV with the BESIII detector at the BEPCII collider, we observe the decay ?c+?np+? for the first time with a statistical significance of 9.5s. The ratio of branching fractions B?c+?np+?/B?c+??p+? is measured to be 0.155 ± 0.031stat. ± 0.012syst. Taking the world average of B?c+??p+? as reference, the absolute branching fraction is calculated to be B?c+?np+?=2.94±0.59stat.±0.23syst.±0.13ref.×10-3. The intermediate process ?c+?na0980+ is also searched for in the p+? invariant mass spectrum. Since no significant signal is found, the upper limit on B?c+?na0980+×Ba0980+?p+? is set to 8.4 × 10-4 at 90% confidence level. A sophisticated deep learning approach using a Transformer-based architecture is employed to distinguish signals from prevalent hadronic backgrounds, complemented by thorough validation and systematic uncertainty quantification.

AB - By analysing 6.1 fb-1 of data collected at centre-of-mass energies between s=4.600 and 4.843 GeV with the BESIII detector at the BEPCII collider, we observe the decay ?c+?np+? for the first time with a statistical significance of 9.5s. The ratio of branching fractions B?c+?np+?/B?c+??p+? is measured to be 0.155 ± 0.031stat. ± 0.012syst. Taking the world average of B?c+??p+? as reference, the absolute branching fraction is calculated to be B?c+?np+?=2.94±0.59stat.±0.23syst.±0.13ref.×10-3. The intermediate process ?c+?na0980+ is also searched for in the p+? invariant mass spectrum. Since no significant signal is found, the upper limit on B?c+?na0980+×Ba0980+?p+? is set to 8.4 × 10-4 at 90% confidence level. A sophisticated deep learning approach using a Transformer-based architecture is employed to distinguish signals from prevalent hadronic backgrounds, complemented by thorough validation and systematic uncertainty quantification.

KW - Branching fraction

KW - Charm Physics

KW - Particle and Resonance Production

KW - e-e Experiments

UR - https://www.scopus.com/pages/publications/105047841981

U2 - 10.1007/JHEP08(2026)009

DO - 10.1007/JHEP08(2026)009

M3 - Article

AN - SCOPUS:105047841981

SN - 1126-6708

VL - 2026

JO - Journal of High Energy Physics

JF - Journal of High Energy Physics

IS - 8

M1 - 9

ER -

Observation of ?c+?np+? and search for ?c+?na0980+

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Keywords

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