The Jiangmen Underground Neutrino Observatory (JUNO) started physics data taking on 26 August 2025. JUNO consists of a 20-kton liquid scintillator central detector, surrounded by a 35 kton water pool serving as a Cherenkov veto, and almost 1000 m$^{2}$ of plastic scintillator veto on top. The detector is located in a shallow underground laboratory with an overburden of 1800 m.w.e. This paper presents the performance results of the detector, extensively studied during the commissioning of the water phase, the subsequent liquid scintillator filling phase, and the first physics runs. The liquid scintillator achieved an attenuation length of 20.6 m at 430 nm, while the high coverage PMT system and scintillator together yielded about 1785 photoelectrons per MeV of energy deposit at the detector centre, measured using the 2.223 MeV $\textit{γ}$ from neutron captures on hydrogen with an Am-C calibration source. The reconstructed energy resolution is 3.4% for two 0.511 MeV $\textit{γ}$ at the detector centre and 2.9% for the 0.93 MeV quenched $^{214}$Po alpha decays from natural radioactive sources. The energy non-linearity is calibrated to better than 1%. Intrinsic contaminations of $^{238}$U and $^{232}$Th in the liquid scintillator are below 10$^{-16}$ g/g, assuming secular equilibrium. The water Cherenkov detector achieves a muon detection efficiency better than 99.9% for muons traversing the liquid scintillator volume. During the initial science runs, the data acquisition duty cycle exceeded 97.8%, demonstrating the excellent stability and readiness of JUNO for high-precision neutrino physics.

Chile

Angel Abusleme

France

Thomas Adam

Germany

Kai Adamowicz

China

David Adey

Pakistan

Shakeel Ahmad

Rizwan Ahmed

Finland

Timo Ahola

Italy

Sebastiano Aiello

Fengpeng An

Guangpeng An

United Kingdom

Costas Andreopoulos

Giuseppe Andronico

João Pedro Athayde Marcondes de André

Russia

Nikolay Anfimov

Vito Antonelli

Tatiana Antoshkina

Thailand

Burin Asavapibhop

Didier Auguste

Margherita Buizza Avanzini

Slovakia

Andrej Babic

Jingzhi Bai

Weidong Bai

Nikita Balashov

Roberto Barbera

Andrea Barresi

Davide Basilico

Eric Baussan

Beatrice Bellantonio

Marco Bellato

JeanLuc Beney

Marco Beretta

Antonio Bergnoli

Enrico Bernieri

Nikita Bessonov

David Biaré

Daniel Bick

Lukas Bieger

Svetlana Biktemerova

Thilo Birkenfeld

David Blum

Simon Blyth

Sara Boarin

Manuel Boehles

Anastasia Bolshakova

Mathieu Bongrand

Aurélie Bonhomme

Clément Bordereau

Matteo Borghesi

Augusto Brigatti

Timothee Brugiere

Riccardo Brugnera

Riccardo Bruno

Jonas Buchholz

Antonio Budano

Max Buesken

Mario Buscemi

Severino Bussino

Jose Busto

Ilya Butorov

Marcel Büchner

Anatael Cabrera

Barbara Caccianiga

Boshuai Cai

Hao Cai

Xiao Cai

Yanke Cai

Yi-zhou Cai

Zhiyan Cai

Stéphane Callier

Steven Calvez

Antonio Cammi

Agustin Campeny

Dechang Cai

Chuanya Cao

Dewen Cao

Guofu Cao

Jun Cao

Yaoqi Cao

Rossella Caruso

Aurelio Caslini

Cédric Cerna

Vanessa Cerrone

Daniele Cesini

Chi Chan

Jinfan Chang

Yun Chang

Milo Charavet

Tim Charissé

Auttakit Chatrabhuti

Chao Chen

Guoming Chen

Haitao Chen

Haotian Chen

Jiahui Chen

Jian Chen

Jing Chen

Junyou Chen

Lihao Chen

Mali Chen

Mingming Chen

Initial performance results of the JUNO detector * We acknowledge financial and institutional supportfrom the Chinese Academy of Sciences, the National KeyR&D Program of China, the People's Government of Guangdong Province, and the Tsung–Dao Lee Institute of Shanghai Jiao Tong University in China.We appreciate the contributions from the Institut Na-tional de Physique Nucléaire et de Physique des Partic-ules (IN2P3) in France, the Istituto Nazionale di Fisica Nucleare (INFN) in Italy, the Fonds de la Recherche Sci-entifique (F.R.S.–FNRS) and the Institut Interuni-versitaire des Sciences Nucléaires (IISN) in Belgium, and the Conselho Nacional de Desenvolvimento Científico eTecnológico (CNPq) in Brazil.We also acknowledge the support of the AgenciaNacional de Investigación y Desarrollo (ANID) and the ANID–Millennium Science Initiative Program (ICN2019044) in Chile; the European Structural and In-vestment Funds, the Ministry of Education, Youth and Sports, and the Charles University Research Center inthe Czech Republic; the Deutsche Forschungsgemeinsch-aft (DFG), the Helmholtz Association, and the Cluster ofExcellence PRISMA+ in Germany; and the Joint Insti-tute for Nuclear Research (JINR) and Lomonosov Mo-scow State University in Russia.We further thank the Slovak Research and Develop-ment Agency in the Slovak Republic, the National Science and Technology Council (NSCT) and MOE, China, the Program Management Unit for Hu-man Resources & Institutional Development, Research and Innovation (PMU–B), Chulalongkorn University, and Suranaree University of Technology in Thailand, the Science and Technology Facilities Council (STFC) in the United Kingdom, and the University of California atIrvine and the National Science Foundation (NSF) in the United States

An $\textit{SU}$(3) flavor projection operator technique is implemented to construct the baryon-meson scattering amplitude within the framework of the $1/N_c$ expansion of quantum chromodynamics (QCD), where $N_c$ represents the number of color charges. The operator technique is implemented to evaluate not only the lowest-order scattering amplitude but also effects from the first-order perturbative $\textit{SU}$(3) flavor symmetry breaking and strong isospin breaking. The most general expression is obtained by explicitly accounting for the effects of the decuplet-octet baryon mass difference. At order ${\cal{O}}(1/N_c^2)$ , a large number of unknown operator coefficients appear, and therefore, there is little additional predictive power unless leading and subleading terms are retained. Although the resultant expression is sufficiently general that it can be applied to any incoming and outgoing baryons and pseudo scalar mesons, provided that the Gell-Mann--Nishijima scheme is respected, results for $N\pi\to N\pi$ scattering processes are explicitly considered.

Víctor Miguel Banda Guzmán

Rubén Flores-Mendieta

Johann Hernández

Use of $\textit{SU}$(3) flavor projection operators to construct baryon-meson scattering amplitudes in the 1/ N$_{c}$ expansion * The authors are grateful to Consejo Nacional de Humanidades, Ciencias y Tecnologías (Mexico) for support through the $\textit{Ciencia de Frontera}$ project CF-2023-I-162

We accurately compute the renormalization group (RG) exponents <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>Y</mi><mi>q</mi></msub></math> of large <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>q</mi></math> fields at the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>O</mi><mo stretchy="false">(</mo><mn>2</mn><mo stretchy="false">)</mo></math> invariant fixed point in three dimensions. We build on an iterative approach that has been previously proposed and is implemented by using the worm algorithm. We simulate an improved XY model, that has next-to-next-to-nearest couplings in addition to nearest ones. In the worm update we incorporate weights, which allows us to obtain accurate results up to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>q</mi><mo>=</mo><mn>64</mn></math>. For example we get <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>Y</mi><mi>q</mi></msub><mo>=</mo><mn>1.76370</mn><mo stretchy="false">(</mo><mn>12</mn><mo stretchy="false">)</mo></math>, 0.89167(23), and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>−</mo><mn>0.11203</mn><mo stretchy="false">(</mo><mn>34</mn><mo stretchy="false">)</mo></math> for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>q</mi><mo>=</mo><mn>2</mn></math>, 3, and 4, respectively. The comparison with the large <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>q</mi></math> effective field theory gives an excellent agreement down to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>q</mi><mo>=</mo><mn>4</mn></math> and provides accurate estimates of the parameters of the effective field theory.

Martin Hasenbusch

Precision estimates of large charge RG exponents <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>Y</mi><mi>q</mi></msub></math> in the 3D XY universality class

The BESIII Collaboration has recently observed a resonant structure <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi><mo stretchy="false">(</mo><mn>4500</mn><mo stretchy="false">)</mo></math> in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><mo stretchy="false">→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><msup><mi>K</mi><mo>+</mo></msup><msup><mi>K</mi><mo>−</mo></msup></math>, whose origin remains unresolved. In this study, we analyze the cross section line shape of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><mo stretchy="false">→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><msup><mi>K</mi><mo>+</mo></msup><msup><mi>K</mi><mo>−</mo></msup></math> by taking into account the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>4415</mn><mo stretchy="false">)</mo></math> state and intermediate charmed meson loops. By treating <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>4415</mn><mo stretchy="false">)</mo></math> as both a pure <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi></math>-wave state and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi><mo>−</mo><mi>D</mi></math> mixed states, and introducing the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>Z</mi><mrow><mi>c</mi><mi>s</mi></mrow><mrow><mo stretchy="false">(</mo><mo>′</mo><mo stretchy="false">)</mo></mrow></msubsup></math> resonance, we find that the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi><mo stretchy="false">(</mo><mn>4500</mn><mo stretchy="false">)</mo></math> peak at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>4.5</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math> arises from the triangle singularity mechanism in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>Z</mi><mrow><mi>c</mi><mi>s</mi></mrow><mrow><mo stretchy="false">(</mo><mo>′</mo><mo stretchy="false">)</mo></mrow></msubsup></math>-mediated rescattering processes, supporting its interpretation as a threshold effect rather than a conventional resonance.

Xiao-Yun Wang

Liu-Lin Wang

Xiao-Hai Liu

Qiang Zhao

Threshold effects as the origin of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi><mo stretchy="false">(</mo><mn>4500</mn><mo stretchy="false">)</mo></math> observed in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><mo stretchy="false">→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><msup><mi>K</mi><mo>+</mo></msup><msup><mi>K</mi><mo>−</mo></msup></math>

We investigate the soft behavior of the tree-level Rutherford scattering processes mediated via $\textit{t}$-channel one-graviton exchange. We consider two types of Rutherford scattering processes: a low-energy massless structureless projectile (up to spin-1) hits a static massive composite particle carrying various spins (up to spin-2), and slowly moving light projectile hits a heavy static composite target. The unpolarized cross sections in the first type exhibit universal forms at the first two orders in $ 1/M $ expansion, yet differ at the next-to-next-to-leading order, though some terms at this order still remain universal or depend on the target spin in a definite manner. The unpolarized cross sections in the second type are universal at the lowest order in projectile velocity expansion and through all orders in $ 1/M $ , independent on the spins of both projectile and target. The universality partially breaks down at relative order- $ v^2/M^2 $ , albeit some terms at this order still depend on the target spin in a specific manner.

Yu Jia

Jichen Pan

United States

Jia-Yue Zhang

Soft pattern of gravitational Rutherford scattering from heavy target mass expansion * This work is supported in part by the National Natural Science Foundation of China (11925506, 12475090). J.-Y. Z. is supported in part by the US Department of Energy (DE-AC05-06OR23177), under which Jefferson Science Associates, LLC operates Jefferson Lab.

Quantum teleportation, a protocol that has received extensive and intensive attention in quantum information processing, allows a quantum state to be transferred from one particle to another. In this study, we analytically investigate fidelity ( <italic>F</italic>), logarithmic negativity (LN), local quantum uncertainty (LQU) and local quantum Fisher information (LQFI) as a discord-like measure of quantum correlations in <math altimg='si1.svg'><mrow><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>&#8722;</mo></msup><mo>&#8594;</mo><mtext>Y</mtext><mover accent='true'><mtext>Y</mtext><mo>&#175;</mo></mover></mrow></math> processes at BESIII through noisy channels, using experimental feasible parameters, where Y and <math altimg='si3.svg'><mover accent='true'><mtext>Y</mtext><mo>&#175;</mo></mover></math> refer to the spin-1/2 hyperon and its antihyperon, respectively. We discuss the dependence of LN, LQU and LQFI on the scattering angle <italic>&#952;</italic> for different hyperon-antihyperon pairs ( <math altimg='si6.svg'><mrow><mstyle mathvariant='normal'><mi>&#923;</mi></mstyle><mover accent='true'><mstyle mathvariant='normal'><mi>&#923;</mi></mstyle><mo>&#175;</mo></mover></mrow></math>, <math altimg='si38.svg'><mrow><msup><mstyle mathvariant='normal'><mi>&#926;</mi></mstyle><mn>0</mn></msup><mover accent='true'><msup><mstyle mathvariant='normal'><mi>&#926;</mi></mstyle><mn>0</mn></msup><mo>&#175;</mo></mover></mrow></math>, <math altimg='si17.svg'><mrow><msup><mstyle mathvariant='normal'><mi>&#926;</mi></mstyle><mo>&#8722;</mo></msup><mover accent='true'><msup><mstyle mathvariant='normal'><mi>&#926;</mi></mstyle><mo>+</mo></msup><mo>&#175;</mo></mover></mrow></math>, <math altimg='si39.svg'><mrow><msup><mstyle mathvariant='normal'><mi>&#931;</mi></mstyle><mo>+</mo></msup><mover accent='true'><msup><mstyle mathvariant='normal'><mi>&#931;</mi></mstyle><mo>&#8722;</mo></msup><mo>&#175;</mo></mover></mrow></math>), produced by electron-positron annihilation via charmonium decay. Without a dephasing effect, we show that, LN, LQU, and LQFI vanish at <math altimg='si40.svg'><mrow><mi>&#966;</mi><mo linebreak='goodbreak'>=</mo><mo>&#177;</mo><mi>&#960;</mi></mrow></math> and are symmetric around <math altimg='si14.svg'><mrow><mi>&#966;</mi><mo linebreak='goodbreak'>=</mo><mi>&#960;</mi><mo linebreak='goodbreak'>/</mo><mn>2</mn></mrow></math>. Furthermore, LN reaches its maximum when the scattering angle equals <math altimg='si14.svg'><mrow><mi>&#966;</mi><mo linebreak='goodbreak'>=</mo><mi>&#960;</mi><mo linebreak='goodbreak'>/</mo><mn>2</mn></mrow></math>, while LQU and LQFI reach their maxima at different angles. We also explore the LN, LQU, and LQFI for different <math altimg='si32.svg'><mrow><mtext>Y</mtext><mover accent='true'><mtext>Y</mtext><mo>&#175;</mo></mover></mrow></math> pairs subjected to three distinct types of decoherence channels. Specifically, we show that amplitude damping (AD) and phase damping (PD) lead to a decrease in LN, LQU, and LQFI with an increasing decoherence parameter <italic>s</italic>. In contrast, the phase flip (PF) channel exhibits symmetric behavior around <math altimg='si41.svg'><mrow><mi>s</mi><mo linebreak='goodbreak'>=</mo><mn>1</mn><mo linebreak='goodbreak'>/</mo><mn>2</mn></mrow></math>. Besides, we realize for teleportation, optimal fidelity for different hyperon-antihyperon pairs ( <math altimg='si6.svg'><mrow><mstyle mathvariant='normal'><mi>&#923;</mi></mstyle><mover accent='true'><mstyle mathvariant='normal'><mi>&#923;</mi></mstyle><mo>&#175;</mo></mover></mrow></math>, <math altimg='si38.svg'><mrow><msup><mstyle mathvariant='normal'><mi>&#926;</mi></mstyle><mn>0</mn></msup><mover accent='true'><msup><mstyle mathvariant='normal'><mi>&#926;</mi></mstyle><mn>0</mn></msup><mo>&#175;</mo></mover></mrow></math>, <math altimg='si17.svg'><mrow><msup><mstyle mathvariant='normal'><mi>&#926;</mi></mstyle><mo>&#8722;</mo></msup><mover accent='true'><msup><mstyle mathvariant='normal'><mi>&#926;</mi></mstyle><mo>+</mo></msup><mo>&#175;</mo></mover></mrow></math>, <math altimg='si39.svg'><mrow><msup><mstyle mathvariant='normal'><mi>&#931;</mi></mstyle><mo>+</mo></msup><mover accent='true'><msup><mstyle mathvariant='normal'><mi>&#931;</mi></mstyle><mo>&#8722;</mo></msup><mo>&#175;</mo></mover></mrow></math>). We discuss the influence of noisy channels, specifically (AD, PF and PD), on the fidelity of quantum teleportation and on quantum correlations that can exist even beyond entanglement. Furthermore, the results show that the fidelity remains above the classical limit of 2/3 in all three channels, even as the noise increases. This is a significant finding because it shows that not all quantum noise is detrimental. These results can have promising applications in quantum information and particle physics.

Morocco

Elhabib Jaloum

Mohamed Amazioug

Quantum teleportation, entanglement, LQU and LQFI in <math altimg='si1.svg'><mrow><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>&#8722;</mo></msup><mo>&#8594;</mo><mtext>Y</mtext><mover accent='true'><mtext>Y</mtext><mo>&#175;</mo></mover></mrow></math> processes at BESIII through noisy channels

To resolve ambiguities from multiple solutions in experimental measurements, we construct a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>χ</mi><mn>2</mn></msup></math> function incorporating constraints such as isospin conservation and amplitude relations. By minimizing the global <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>χ</mi><mn>2</mn></msup></math>, we identify physical solutions for seven hidden-charm decay channels of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi><mo stretchy="false">(</mo><mn>4230</mn><mo stretchy="false">)</mo></math>. Crucially, the physical solution for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi><mo stretchy="false">(</mo><mn>4230</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup><mi>J</mi><mo>/</mo><mi>ψ</mi></math> corresponds to the largest among four experimental solutions, potentially modifying inputs for theoretical calculations. Additionally, we predict <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Γ</mi><mrow><mi>e</mi><mi>e</mi></mrow></msub><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><mi>Y</mi><mo stretchy="false">(</mo><mn>4230</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup><msup><mi>ψ</mi><mo>′</mo></msup><mo stretchy="false">)</mo></math> based on our results, acknowledging substantial uncertainties in current measurements.

Jie Yuan

Yadi Wang

Kai Zhu

Pinpointing physical solutions in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi><mo stretchy="false">(</mo><mn>4230</mn><mo stretchy="false">)</mo></math> decays

In the present work, we perform a combined analysis of the cross sections for $$e^+ e^- \rightarrow K^+ K^-$$ and $$e^+ e^- \rightarrow K_S^0 K_L^0$$ by including the interference between direct coupling process and resonance intermediate process. When setting the isospin factor as a free parameter, we can well reproduce the structures in the cross sections for $$e^+ e^- \rightarrow K^+ K^-$$ and $$e^+ e^- \rightarrow K_S^0 K_L^0,$$ however, the isospin factor deviates with the isospin symmetry conservation predicted value of one. By fixing the isospin factor to be one, we find the cross sections for $$e^+ e^-\rightarrow K^+ K^-$$ can be accurately fitted, while the same model parameters fail to adequately reproduce the observed cross section for the process $$e^+ e^- \rightarrow K_S^0 K_L^0,$$ which indicate that there should be contributions from other vector meson states, such as $$\rho (2150)$$ and $$\omega (2220).$$ The combined analysis with $$\phi (2170),$$ $$\omega (2220)$$ and $$\rho (2150)$$ indicate that the inclusion of $$\rho (2150)$$ can improve the descriptions of the cross sections for $$e^+ e^-\rightarrow K^+ K^-$$ and $$e^+ e^- \rightarrow K_S^0 K_L^0.$$

Dian-Yong Chen

Jing Liu

Yu Bai

Chun-Hua Liu

Wen-Biao Yan

Zhao-Xia Meng

A combined analysis of $\textit{Y}$(2240) in the $$e^+ e^- \rightarrow K^+ K^-$$ and $$e^+ e^- \rightarrow K_S^0 K_L^0$$ processes

Based on a sample of $2.7\times10^{9}$ $\psi(3686)$ events collected by the BESIII detector operating at the BEPCII collider, the decay $\psi(3686)\to\gamma\chi_{cJ}, \chi_{cJ}\to\eta\eta\eta^{\prime}$ is analyzed. The decay modes $\chi_{c1}$ and $\chi_{c2}\to\eta\eta\eta^{\prime}$ are observed for the first time, and their corresponding branching fractions are determined to be ${\cal{B}}(\chi_{c1}\to\eta\eta\eta^{\prime}) = $ $ (1.40\, \pm 0.13\, (\text{stat.}) \pm 0.09\, (\text{sys.})) \times 10^{-4}$ and ${\cal{B}}(\chi_{c2}\to\eta\eta\eta^{\prime}) = (4.18\, \pm 0.84\, (\text{stat.}) \pm 0.48\, (\text{sys.})) \times 10^{-5}$ . An upper limit on the branching fraction of $\chi_{c0}\to\eta\eta\eta^{\prime}$ is set as $2.59 \times 10^{-5}$ at a 90% confidence level (CL). A partial wave analysis (PWA) of the decay $\chi_{c1}\to\eta\eta\eta^{\prime}$ is performed to search for the $1^{-+}$ exotic state $\eta_1(1855)$ . The PWA result indicates that the structure in the $\eta\eta^{\prime}$ mass spectrum is attributed to $f_0(1500)$ , while in the $\eta\eta$ mass spectrum, it is attributed to the $0^{++}$ phase space. The upper limit of ${\cal{B}}(\chi_{c1}\to\eta_{1}(1855)\eta) \cdot {\cal{B}}(\eta_{1}(1855)\to\eta\eta^{\prime}) \lt $ $ 9.79 \times 10^{-5}$ is set based on the PWA at 90% CL.

M. Ablikim

M.N. Achasov

Sweden

P. Adlarson

X.C. Ai

R. Aliberti

A. Amoroso

Q. An

Y. Bai

O. Bakina

Y. Ban

H.R. Bao

Poland

V. Batozskaya

Mongolia

K. Begzsuren

N. Berger

M. Berlowski

M. Bertani

D. Bettoni

F. Bianchi

E. Bianco

A. Bortone

I. Boyko

R.A. Briere

A. Brueggemann

H. Cai

M.H. Cai

X. Cai

A. Calcaterra

G.F. Cao

N. Cao

Türkiye

S.A. Cetin

X.Y. Chai

J.F. Chang

G.R. Che

Y.Z. Che

C.H. Chen

G. Chen

H.S. Chen

H.Y. Chen

M.L. Chen

S.J. Chen

S.L. Chen

S.M. Chen

T. Chen

X.R. Chen

X.T. Chen

Search for $\textit{η}$ $_{1}$(1855) in $\textit{χ}$ $\textit{cJ}$ → $\textit{ηηη}$′ decays * Supported in part by National Key R&D Program of China (2023YFA1606000, 2023YFA1606704); National Natural Science Foundation of China (NSFC) (11635010, 11935015, 11935016, 11935018, 12025502, 12035009, 12035013, 12061131003, 12192260, 12192261, 12192262, 12192263, 12192264, 12192265, 12221005, 12225509, 12235017, 12361141819); the Chinese Academy of Sciences (CAS) Large-Scale Scientific Facility Program; CAS (YSBR-101); 100 Talents Program of CAS; The Institute of Nuclear and Particle Physics (INPAC) and Shanghai Key Laboratory for Particle Physics and Cosmology; Agencia Nacional de Investigación y Desarrollo de Chile (ANID), Chile (ANID PIA/APOYO AFB230003); German Research Foundation DFG (FOR5327); Istituto Nazionale di Fisica Nucleare, Italy; Knut and Alice Wallenberg Foundation (2021.0174, 2021.0299); Ministry of Development of Turkey (DPT2006K-120470); National Research Foundation of Korea ( NRF-2022R1A2C1092335); National Science and Technology fund of Mongolia; National Science Research and Innovation Fund (NSRF) via the Program Management Unit for Human Resources Institutional Development, Research and Innovation of Thailand ( B50G670107); Polish National Science Centre (2024/53/B/ST2/00975); Swedish Research Council (2019.04595); U. S. Department of Energy (DE-FG02-05ER41374)