JUNO sensitivity to invisible decay modes of neutrons
Authors:   JUNO Collaboration, Abusleme Angel , Adam Thomas , Adamowicz Kai , Ahmad Shakeel , Ahmed Rizwan , Aiello Sebastiano , An Fengpeng , An Qi , Andronico Giuseppe , Anfimov Nikolay , Antonelli Vito , Antoshkina Tatiana , de André João Pedro Athayde Marcondes , Auguste Didier , Bai Weidong , Balashov Nikita , Baldini Wander , Barresi Andrea , Basilico Davide , Baussan Eric , Bellato Marco , Beretta Marco , Bergnoli Antonio , Bick Daniel , Bieger Lukas , Biktemerova Svetlana , Birkenfeld Thilo , Blake Iwan , Blyth Simon , Bolshakova Anastasia , Bongrand Mathieu , Breton Dominique , Brigatti Augusto , Brugnera Riccardo , Bruno Riccardo , Budano Antonio , Busto Jose , Cabrera Anatael , Caccianiga Barbara , Cai Hao , Cai Xiao , Cai Yanke , Cai Zhiyan , Callier Stéphane , Calvez Steven , Cammi Antonio , Campeny Agustin , Cao Chuanya , Cao Guofu , Cao Jun , Caruso Rossella , Cerna Cédric , Cerrone Vanessa , Chang Jinfan , Chang Yun , Chatrabhuti Auttakit , Chen Chao , Chen Guoming , Chen Pingping , Chen Shaomin , Chen Xin , Chen Yiming , Chen Yixue , Chen Yu , Chen Zelin , Chen Zhangming , Chen Zhiyuan , Chen Zikang , Cheng Jie , Cheng Yaping , Cheng Yu Chin , Chepurnov Alexander , Chetverikov Alexey , Chiesa Davide , Chimenti Pietro , Chin Yen-Ting , Chou Po-Lin , Chu Ziliang , Chukanov Artem , Claverie Gérard , Clementi Catia , Clerbaux Barbara , Molla Marta Colomer , Lorenzo Selma Conforti Di , Coppi Alberto , Corti Daniele , Csakli Simon , Cui Chenyang , Corso Flavio Dal , Dalager Olivia , Datta Jaydeep , De La Taille Christophe , Deng Zhi , Deng Ziyan , Ding Xiaoyu , Ding Xuefeng , Ding Yayun , Dirgantara Bayu , Dittrich Carsten , Dmitrievsky Sergey , Dohnal Tadeas , Dolzhikov Dmitry , Donchenko Georgy , Dong Jianmeng , Doroshkevich Evgeny , Dou Wei , Dracos Marcos , Druillole Frédéric , Du Ran , Du Shuxian , Duan Yujie , Dugas Katherine , Dusini Stefano , Duyang Hongyue , Eck Jessica , Enqvist Timo , Fabbri Andrea , Fahrendholz Ulrike , Fan Lei , Fang Jian , Fang Wenxing , Fedoseev Dmitry , Feng Li-Cheng , Feng Qichun , Ferraro Federico , Fournier Amélie , Fritsch Fritsch , Gan Haonan , Gao Feng , Gao Feng , Garfagnini Alberto , Gavrikov Arsenii , Giammarchi Marco , Giudice Nunzio , Gonchar Maxim , Gong Guanghua , Gong Hui , Gornushkin Yuri , Grassi Marco , Gromov Maxim , Gromov Vasily , Gu Minghao , Gu Xiaofei , Gu Yu , Guan Mengyun , Guan Yuduo , Guardone Nunzio , Guizzetti Rosa Maria , Guo Cong , Guo Wanlei , Hagner Caren , Han Hechong , Han Ran , Han Yang , He Jinhong , He Miao , He Wei , He Xinhai , Heinz Tobias , Hellmuth Patrick , Heng Yuekun , Herrera Rafael , Hor YuenKeung , Hou Shaojing , Hsiung Yee , Hu Bei-Zhen , Hu Hang , Hu Jun , Hu Peng , Hu Shouyang , Hu Tao , Hu Yuxiang , Hu Zhuojun , Huang Guihong , Huang Hanxiong , Huang Jinhao , Huang Junting , Huang Kaixuan , Huang Shengheng , Huang Wenhao , Huang Xin , Huang Xingtao , Huang Yongbo , Hui Jiaqi , Huo Lei , Huo Wenju , Huss Cédric , Hussain Safeer , Imbert Leonard , 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Hao , Liao Jiajun , Liao Yilin , Liao Yuzhong , Limphirat Ayut , Lin Guey-Lin , Lin Shengxin , Lin Tao , Ling Jiajie , Ling Xin , Lippi Ivano , Liu Caimei , Liu Fang , Liu Fengcheng , Liu Haidong , Liu Haotian , Liu Hongbang , Liu Hongjuan , Liu Hongtao , Liu Hongyang , Liu Jianglai , Liu Jiaxi , Liu Jinchang , Liu Min , Liu Qian , Liu Qin , Liu Runxuan , Liu Shenghui , Liu Shubin , Liu Shulin , Liu Xiaowei , Liu Xiwen , Liu Xuewei , Liu Yankai , Liu Zhen , Loi Lorenzo , Lokhov Alexey , Lombardi Paolo , Lombardo Claudio , Loo Kai , Lu Chuan , Lu Haoqi , Lu Jingbin , Lu Junguang , Lu Meishu , Lu Peizhi , Lu Shuxiang , Lu Xianguo , Lubsandorzhiev Bayarto , Lubsandorzhiev Sultim , Ludhova Livia , Lukanov Arslan , Luo Fengjiao , Luo Guang , Luo Jianyi , Luo Shu , Luo Wuming , Luo Xiaojie , Lyashuk Vladimir , Ma Bangzheng , Ma Bing , Ma Qiumei , Ma Si , Ma Xiaoyan , Ma Xubo , Maalmi Jihane , Mai Jingyu , Malabarba Marco , Malyshkin Yury , Mandujano Roberto Carlos , Mantovani Fabio , Mao Xin , Mao Yajun , Mari Stefano M. , Marini Filippo , Martini Agnese , Mayer Matthias , Mayilyan Davit , Mednieks Ints , Meng Yue , Meraviglia Anita , Meregaglia Anselmo , Meroni Emanuela , Miramonti Lino , Mohan Nikhil , Montuschi Michele , Reveco Cristobal Morales , Nastasi Massimiliano , Naumov Dmitry V. , Naumova Elena , Navas-Nicolas Diana , Nemchenok Igor , Thi Minh Thuan Nguyen , Nikolaev Alexey , Ning Feipeng , Ning Zhe , Nunokawa Hiroshi , Oberauer Lothar , Ochoa-Ricoux Juan Pedro , Olshevskiy Alexander , Orestano Domizia , Ortica Fausto , Othegraven Rainer , Paoloni Alessandro , Parker George , Parmeggiano Sergio , Patsias Achilleas , Pei Yatian , Pelicci Luca , Peng Anguo , Peng Haiping , Peng Yu , Peng Zhaoyuan , Percalli Elisa , Perrin Willy , Perrot Frédéric , Petitjean Pierre-Alexandre , Petrucci Fabrizio , Pilarczyk Oliver , Rico Luis Felipe Piñeres , Popov Artyom , Poussot Pascal , Previtali Ezio , Qi Fazhi , Qi Ming , Qi Xiaohui , Qian Sen , Qian Xiaohui , Qian Zhen , Qiao Hao , Qin Zhonghua , Qiu Shoukang , Qu Manhao , Qu Zhenning , Ranucci Gioacchino , Re Alessandra , Rebii Abdel , Redchuk Mariia , Reina Gioele , Ren Bin , Ren Jie , Ren Yuhan , Ricci Barbara , Rientong Komkrit , Rifai Mariam , Roche Mathieu , Rodphai Narongkiat , Romani Aldo , Roskovec Bedřich , Ruan Xichao , Rybnikov Arseniy , Sadovsky Andrey , Saggese Paolo , Sandanayake Deshan , Sangka Anut , Sava Giuseppe , Sawangwit Utane , Schever Michaela , Schwab Cédric , Schweizer Konstantin , Selyunin Alexandr , Serafini Andrea , Settimo Mariangela , Shao Junyu , Sharov Vladislav , Shi Hexi , Shi Jingyan , Shi Yanan , Shutov Vitaly , Sidorenkov Andrey , Šimkovic Fedor , Singhal Apeksha , Sirignano Chiara , Siripak Jaruchit , Sisti Monica , Smirnov Mikhail , Smirnov Oleg , Sokolov Sergey , Songwadhana Julanan , Soonthornthum Boonrucksar , Sotnikov Albert , Sreethawong Warintorn , Stahl Achim , Stanco Luca , Stankevich Konstantin , Steiger Hans , Steinmann Jochen , Sterr Tobias , Stock Matthias Raphael , Strati Virginia , Strizh Michail , Studenikin Alexander , Su Aoqi , Su Jun , Su Jun , Sun Guangbao , Sun Shifeng , Sun Xilei , Sun Yongjie , Sun Yongzhao , Sun Zhengyang , Suwonjandee Narumon , Takenaka Akira , Tan Xiaohan , Tang Jian , Tang Jingzhe , Tang Qiang , Tang Quan , Tang Xiao , Hariharan Vidhya Thara , Tkachev Igor , Tmej Tomas , Torri Marco Danilo Claudio , Triossi Andrea , Trzaska Wladyslaw , Tung Yu-Chen , Tuve Cristina , Ushakov Nikita , Vedin Vadim , Venettacci Carlo , Verde Giuseppe , Vialkov Maxim , Viaud Benoit , Vollbrecht Cornelius Moritz , Sturm Katharina von , Vorobel Vit , Voronin Dmitriy , Votano Lucia , Walker Pablo , Wang Caishen , Wang Chung-Hsiang , Wang En , Wang Guoli , Wang Hanwen , Wang Jian , Wang Jun , Wang Li , Wang Lu , Wang Meng , Wang Meng , Wang Mingyuan , Wang Qianchuan , Wang Ruiguang , Wang Sibo , Wang Siguang , Wang Wei , Wang Wenshuai , Wang Xi , Wang Xiangyue , Wang Yangfu , Wang Yaoguang , Wang Yi , Wang Yi , Wang Yifang , Wang Yuanqing , Wang Yuyi , Wang Zhe , Wang Zheng , Wang Zhimin , Watcharangkool Apimook , Wei Wei , Wei Wei , Wei Wenlu , Wei Yadong , Wei Yuehuan , Wen Liangjian , Weng Jun , Wiebusch Christopher , Wirth Rosmarie , Wu Chengxin , Wu Diru , Wu Qun , Wu Yinhui , Wu Yiyang , Wu Zhi , Wurm Michael , Wurtz Jacques , Wysotzki Christian , Xi Yufei , Xia Dongmei , Xian Shishen , Xiang Ziqian , Xiao Fei , Xiao Xiang , Xie Xiaochuan , Xie Yijun , Xie Yuguang , Xin Zhao , Xing Zhizhong , Xu Benda , Xu Cheng , Xu Donglian , Xu Fanrong , Xu Hangkun , Xu Jiayang , Xu Jilei , Xu Jing , Xu Jinghuan , Xu Meihang , Xu Xunjie , Xu Yin , Xu Yu , Yan Baojun , Yan Qiyu , Yan Taylor , Yan Xiongbo , Yan Yupeng , Yang Changgen , Yang Chengfeng , Yang Fengfan , Yang Jie , Yang Lei , Yang Pengfei , Yang Xiaoyu , Yang Yifan , Yang Yixiang , Yang Zekun , Yao Haifeng , Ye Jiaxuan , Ye Mei , Ye Ziping , Yermia Frédéric , You Zhengyun , Yu Boxiang , Yu Chiye , Yu Chunxu , Yu Guojun , Yu Hongzhao , Yu Miao , Yu Xianghui , Yu Zeyuan , Yu Zezhong , Yuan Cenxi , Yuan Chengzhuo , Yuan Ying , Yuan Zhenxiong , Yue Baobiao , Zafar Noman , Zamogilnyi Kirill , Zavadskyi Vitalii , Zeng Fanrui , Zeng Shan , Zeng Tingxuan , Zeng Yuda , Zhan Liang , Zhang Aiqiang , Zhang Bin , Zhang Binting , Zhang Feiyang , Zhang Hangchang , Zhang Haosen , Zhang Honghao , Zhang Jialiang , Zhang Jiawen , Zhang Jie , Zhang Jingbo , Zhang Jinnan , Zhang Junwei , Zhang Lei , Zhang Peng , Zhang Ping , Zhang Qingmin , Zhang Shiqi , Zhang Shu , Zhang Shuihan , Zhang Siyuan , Zhang Tao , Zhang Xiaomei , Zhang Xin , Zhang Xuantong , Zhang Yibing , Zhang Yinhong , Zhang Yiyu , Zhang Yongpeng , Zhang Yu , Zhang Yuanyuan , Zhang Yumei , Zhang Zhenyu , Zhang Zhijian , Zhao Jie , Zhao Rong , Zhao Runze , Zhao Shujun , Zhao Tianhao , Zheng Hua , Zheng Yangheng , Zhou Jing , Zhou Li , Zhou Nan , Zhou Shun , Zhou Tong , Zhou Xiang , Zhou Xing , Zhu Jingsen , Zhu Kangfu , Zhu Kejun , Zhu Zhihang , Zhuang Bo , Zhuang Honglin , Zong Liang , Zou Jiaheng ,   JUNO Collaboration
Published: January 2025

Abstract
We explore the decay of bound neutrons in the JUNO liquid scintillator detector into invisible particles (e.g.,

$$n\rightarrow 3 \nu $$

n
→
3
ν

or

$$nn \rightarrow 2 \nu $$

n
n
→
2
ν

), which do not produce an observable signal. The invisible decay includes two decay modes:

$$ n \rightarrow { inv} $$

n
→

inv

and

$$ nn \rightarrow { inv} $$

n
n
→

inv

. The invisible decays of s-shell neutrons in

$$^{12}\textrm{C}$$

12

C

will leave a highly excited residual nucleus. Subsequently, some de-excitation modes of the excited residual nuclei can produce a time- and space-correlated triple coincidence signal in the JUNO detector. Based on a full Monte Carlo simulation informed with the latest available data, we estimate all backgrounds, including inverse beta decay events of the reactor antineutrino

$${\bar{\nu }}_e$$

ν

¯

e

, natural radioactivity, cosmogenic isotopes and neutral current interactions of atmospheric neutrinos. Pulse shape discrimination and multivariate analysis techniques are employed to further suppress backgrounds. With two years of exposure, JUNO is expected to give an order of magnitude improvement compared to the current best limits. After 10 years of data taking, the JUNO expected sensitivities at a 90% confidence level are

$$\tau /B( n \rightarrow { inv} ) > 5.0 \times 10^{31} \, \textrm{years}$$

τ
/
B

(
n
→

inv

)

>
5.0
×

10
31

years

and

$$\tau /B( nn \rightarrow { inv} ) > 1.4 \times 10^{32} \, \textrm{years}$$

τ
/
B

(
n
n
→

inv

)

>
1.4
×

10
32

years

.