Observation of the antimatter hypernucleus $${}_{\bar{{\boldsymbol{\lambda }}}}{}^{{\bf{4}}}\bar{{\bf{h}}}$$

Observation of the antimatter hypernucleus $${}_{\bar{{\boldsymbol{\lambda }}}}{}^{{\bf{4}}}\bar{{\bf{h}}}$$

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ABSTRACT At the origin of the Universe, an asymmetry between the amount of created matter and antimatter led to the matter-dominated Universe as we know it today. The origins of this


asymmetry remain unknown so far. High-energy nuclear collisions create conditions similar to the Universe microseconds after the Big Bang, with comparable amounts of matter and


antimatter1,2,3,4,5,6. Much of the created antimatter escapes the rapidly expanding fireball without annihilating, making such collisions an effective experimental tool to create heavy


antimatter nuclear objects and to study their properties7,8,9,10,11,12,13,14, hoping to shed some light on the existing questions on the asymmetry between matter and antimatter. Here we


report the observation of the antimatter hypernucleus \({}_{\bar{\Lambda }}{}^{4}\bar{{\rm{H}}}\), composed of a \(\bar{\Lambda }\), an antiproton and two antineutrons. The discovery was


made through its two-body decay after production in ultrarelativistic heavy-ion collisions by the STAR experiment at the Relativistic Heavy Ion Collider15,16. In total, 15.6 candidate


\({}_{\bar{\Lambda }}{}^{4}\bar{{\rm{H}}}\) antimatter hypernuclei are obtained with an estimated background count of 6.4. The lifetimes of the antihypernuclei \({}_{\bar{\Lambda


}}{}^{3}\bar{{\rm{H}}}\) and \({}_{\bar{\Lambda }}{}^{4}\bar{{\rm{H}}}\) are measured and compared with the lifetimes of their corresponding hypernuclei, testing the symmetry between matter


and antimatter. Various production yield ratios among (anti)hypernuclei (hypernuclei and/or antihypernuclei) and (anti)nuclei (nuclei and/or antinuclei) are also measured and compared with


theoretical model predictions, shedding light on their production mechanisms. Access through your institution Buy or subscribe This is a preview of subscription content, access via your


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subscriptions * Read our FAQs * Contact customer support SIMILAR CONTENT BEING VIEWED BY OTHERS UNVEILING THE DYNAMICS OF LITTLE-BANG NUCLEOSYNTHESIS Article Open access 05 February 2024 NEW


DIRECTIONS IN HYPERNUCLEAR PHYSICS Article 14 September 2021 MEASUREMENT OF ANTI-3HE NUCLEI ABSORPTION IN MATTER AND IMPACT ON THEIR PROPAGATION IN THE GALAXY Article Open access 12


December 2022 DATA AVAILABILITY All raw data for this study were collected using the STAR detector at Brookhaven National Laboratory and are not available to the public. Derived data


supporting the findings of this study are publicly available in the HEPData repository (https://www.hepdata.net/record/145132) or from the corresponding author on request. CODE AVAILABILITY


The codes to process raw data collected by the STAR detector are publicly available on GitHub77 (https://github.com/star-bnl). The codes to analyse the produced data are not publicly


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(2024). Download references ACKNOWLEDGEMENTS We thank the RHIC Operations Group and RCF at BNL, the NERSC Center at LBNL, and the Open Science Grid consortium for providing resources and


support. This work was supported in part by the Office of Nuclear Physics within the US DOE Office of Science, the US National Science Foundation, National Natural Science Foundation of


China, Chinese Academy of Science, the Ministry of Science and Technology of China and the Chinese Ministry of Education, the Higher Education Sprout Project by Ministry of Education at


NCKU, the National Research Foundation of Korea, Czech Science Foundation and Ministry of Education, Youth and Sports of the Czech Republic, Hungarian National Research, Development and


Innovation Office, New National Excellency Programme of the Hungarian Ministry of Human Capacities, Department of Atomic Energy and Department of Science and Technology of the Government of


India, the National Science Centre and WUT ID-UB of Poland, the Ministry of Science, Education and Sports of the Republic of Croatia, German Bundesministerium für Bildung, Wissenschaft,


Forschung and Technologie (BMBF), Helmholtz Association, Ministry of Education, Culture, Sports, Science, and Technology (MEXT), Japan Society for the Promotion of Science (JSPS) and Agencia


Nacional de Investigación y Desarrollo (ANID) of Chile. We thank the Joint Department for Nuclear Physics, co-founded by the Lanzhou University and Institute of Modern Physics, Chinese


Academy of Sciences, for the contributions of its students J. Wu and F. Zhao to this paper. AUTHOR INFORMATION Author notes * Deceased: W. B. Schmidke AUTHORS AND AFFILIATIONS * American


University in Cairo, New Cairo, Egypt M. I. Abdulhamid & A. Hamed * Texas A&M University, College Station, TX, USA B. E. Aboona, C. A. Gagliardi, Y. Liu, S. Mioduszewski & J.


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S. Fazio * National Cheng Kung University, Tainan, Taiwan C. J. Feng, H. Huang, Y. Yang & Z. J. Zhang * Purdue University, West Lafayette, IN, USA Y. Feng, H-S. Li, C. W. Robertson, M.


J. Skoby, B. Srivastava, F. Wang & W. Xie * Southern Connecticut State University, New Haven, CT, USA E. Finch * Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China


C. Fu, X. H. He, Q. Hu, C. Liu, T. Lu, A. K. Pandey, H. Qiu, S. Singha, X. Sun, J. Wu, X. Zhang, Y. Zhang & F. Zhao * Technische Universität Darmstadt, Darmstadt, Germany T. Galatyuk, S.


Harabasz & F-J. Seck * Temple University, Philadelphia, PA, USA N. Ghimire, J. D. Nam, B. R. Pokhrel, M. Posik & B. Surrow * Valparaiso University, Valparaiso, IN, USA A. Gibson, D.


Grosnick, T. D. S. Stanislaus & D. G. Underwood * Indian Institute of Science Education and Research, Tirupati, India K. Gopal, C. Jena, N. R. Sahoo, R. Sharma, S. R. Sharma & P.


Sinha * University of Chinese Academy of Sciences, Beijing, China C. Hu & G. Xie * Central China Normal University, Wuhan, China Y. Huang, C. Li, H. Liu, L. Liu, Z. Liu, X. F. Luo, K.


Mi, S. S. Shi, Y. Wang, J. Wu, Y. Xu, Y. Zhang, S. Zhou & Y. Zhou * University of Science and Technology of China, Hefei, China X. Ju, D. Li, X. Li, Y. Li, Z. Li, J. Luo, K. Shen, F. Si,


 Y. Su, Y. Sun, Z. Tang, I. Upsal, K. Wang, Y. Wang, X. Wu, W. Zha, Y. Zhang & J. Zhou * Wayne State University, Detroit, MI, USA A. Khanal, G. McNamara, J. Putschke, D. J. Stewart, V.


Verkest & S. A. Voloshin * Warsaw University of Technology, Warsaw, Poland D. P. Kikoła, D. Mallick, D. Pawlowska, J. Pluta, P. Roy Chowdhury, S. K. Tripathy, D. Wielanek & H.


Zbroszczyk * Frankfurt Institute for Advanced Studies, Frankfurt, Germany I. Kisel, I. Vassiliev & M. Zyzak * Lehigh University, Bethlehem, PA, USA A. G. Knospe, T. Protzman, R. Reed 


& B. C. Schaefer * Wuhan University of Science and Technology, Wuhan, China H. Li * Guangxi Normal University, Guilin, China Y. Lin * South China Normal University, Guangzhou, China G.


Liu, S. Yang, Z. Ye, D. Zhang & W. Zhang * University of Texas, Austin, TX, USA C. Markert & R. L. Ray * National Institute of Science Education and Research, Homi Bhabha National


Institute, Jatni, India B. Mohanty & M. M. Mondal * Sejong University, Seoul, South Korea S. Oh * Rutgers University, Piscataway, NJ, USA T. Pani, D. Roy & S. Salur * Institute of


Nuclear Physics PAN, Cracow, Poland B. Pawlik * Max-Planck-Institut für Physik, Munich, Germany N. Schmitz & P. Seyboth * Creighton University, Omaha, NE, USA J. Seger & D. Tlusty *


Ball State University, Muncie, IN, USA M. J. Skoby * Huzhou University, Huzhou, China Y. Sun, J. S. Wang & H. Xu * Michigan State University, East Lansing, MI, USA T. Tarnowsky & G.


D. Westfall * Argonne National Laboratory, Argonne, IL, USA D. G. Underwood & M. Zurek * United States Naval Academy, Annapolis, MD, USA R. Witt * Chongqing University, Chongqing, China


S. Zhang CONSORTIA STAR COLLABORATION * M. I. Abdulhamid * , B. E. Aboona * , J. Adam * , L. Adamczyk * , J. R. Adams * , I. Aggarwal * , M. M. Aggarwal * , Z. Ahammed * , E. C. Aschenauer *


, S. Aslam * , J. Atchison * , V. Bairathi * , J. G. Ball Cap * , K. Barish * , R. Bellwied * , P. Bhagat * , A. Bhasin * , S. Bhatta * , S. R. Bhosale * , J. Bielcik * , J. Bielcikova * , 


J. D. Brandenburg * , C. Broodo * , X. Z. Cai * , H. Caines * , M. Calderón de la Barca Sánchez * , D. Cebra * , J. Ceska * , I. Chakaberia * , P. Chaloupka * , B. K. Chan * , Z. Chang * , 


A. Chatterjee * , D. Chen * , J. Chen * , J. H. Chen * , Z. Chen * , J. Cheng * , Y. Cheng * , S. Choudhury * , W. Christie * , X. Chu * , H. J. Crawford * , M. Csanád * , G. Dale-Gau * , A.


Das * , I. M. Deppner * , A. Dhamija * , P. Dixit * , X. Dong * , J. L. Drachenberg * , E. Duckworth * , J. C. Dunlop * , J. Engelage * , G. Eppley * , S. Esumi * , O. Evdokimov * , O.


Eyser * , R. Fatemi * , S. Fazio * , C. J. Feng * , Y. Feng * , E. Finch * , Y. Fisyak * , F. A. Flor * , C. Fu * , C. A. Gagliardi * , T. Galatyuk * , T. Gao * , F. Geurts * , N. Ghimire *


, A. Gibson * , K. Gopal * , X. Gou * , D. Grosnick * , A. Gupta * , W. Guryn * , A. Hamed * , Y. Han * , S. Harabasz * , M. D. Harasty * , J. W. Harris * , H. Harrison-Smith * , W. He * , 


X. H. He * , Y. He * , N. Herrmann * , L. Holub * , C. Hu * , Q. Hu * , Y. Hu * , H. Huang * , H. Z. Huang * , S. L. Huang * , T. Huang * , X. Huang * , Y. Huang * , Y. Huang * , T. J.


Humanic * , M. Isshiki * , W. W. Jacobs * , A. Jalotra * , C. Jena * , A. Jentsch * , Y. Ji * , J. Jia * , C. Jin * , X. Ju * , E. G. Judd * , S. Kabana * , D. Kalinkin * , K. Kang * , D.


Kapukchyan * , K. Kauder * , D. Keane * , A. Khanal * , Y. V. Khyzhniak * , D. P. Kikoła * , D. Kincses * , I. Kisel * , A. Kiselev * , A. G. Knospe * , H. S. Ko * , L. K. Kosarzewski * , L.


Kumar * , M. C. Labonte * , R. Lacey * , J. M. Landgraf * , J. Lauret * , A. Lebedev * , J. H. Lee * , Y. H. Leung * , N. Lewis * , C. Li * , D. Li * , H-S. Li * , H. Li * , W. Li * , X. Li


* , Y. Li * , Y. Li * , Z. Li * , X. Liang * , Y. Liang * , R. Licenik * , T. Lin * , Y. Lin * , M. A. Lisa * , C. Liu * , G. Liu * , H. Liu * , L. Liu * , T. Liu * , X. Liu * , Y. Liu * , 


Z. Liu * , T. Ljubicic * , O. Lomicky * , R. S. Longacre * , E. M. Loyd * , T. Lu * , J. Luo * , X. F. Luo * , L. Ma * , R. Ma * , Y. G. Ma * , N. Magdy * , D. Mallick * , R. Manikandhan * ,


 S. Margetis * , C. Markert * , G. McNamara * , O. Mezhanska * , K. Mi * , S. Mioduszewski * , B. Mohanty * , M. M. Mondal * , I. Mooney * , J. Mrazkova * , M. I. Nagy * , A. S. Nain * , J.


D. Nam * , M. Nasim * , D. Neff * , J. M. Nelson * , D. B. Nemes * , M. Nie * , G. Nigmatkulov * , T. Niida * , T. Nonaka * , G. Odyniec * , A. Ogawa * , S. Oh * , K. Okubo * , B. S. Page *


, R. Pak * , S. Pal * , A. Pandav * , A. K. Pandey * , T. Pani * , A. Paul * , B. Pawlik * , D. Pawlowska * , C. Perkins * , J. Pluta * , B. R. Pokhrel * , M. Posik * , T. Protzman * , V.


Prozorova * , N. K. Pruthi * , M. Przybycien * , J. Putschke * , Z. Qin * , H. Qiu * , C. Racz * , S. K. Radhakrishnan * , A. Rana * , R. L. Ray * , R. Reed * , C. W. Robertson * , M.


Robotkova * , M. A. Rosales Aguilar * , D. Roy * , P. Roy Chowdhury * , L. Ruan * , A. K. Sahoo * , N. R. Sahoo * , H. Sako * , S. Salur * , S. Sato * , B. C. Schaefer * , W. B. Schmidke * ,


 N. Schmitz * , F-J. Seck * , J. Seger * , R. Seto * , P. Seyboth * , N. Shah * , P. V. Shanmuganathan * , T. Shao * , M. Sharma * , N. Sharma * , R. Sharma * , S. R. Sharma * , A. I. Sheikh


* , D. Shen * , D. Y. Shen * , K. Shen * , S. S. Shi * , Y. Shi * , Q. Y. Shou * , F. Si * , J. Singh * , S. Singha * , P. Sinha * , M. J. Skoby * , N. Smirnov * , Y. Söhngen * , Y. Song *


, B. Srivastava * , T. D. S. Stanislaus * , M. Stefaniak * , D. J. Stewart * , Y. Su * , M. Sumbera * , C. Sun * , X. Sun * , Y. Sun * , Y. Sun * , B. Surrow * , M. Svoboda * , Z. W. Sweger


* , A. C. Tamis * , A. H. Tang * , Z. Tang * , T. Tarnowsky * , J. H. Thomas * , A. R. Timmins * , D. Tlusty * , T. Todoroki * , S. Trentalange * , P. Tribedy * , S. K. Tripathy * , T.


Truhlar * , B. A. Trzeciak * , O. D. Tsai * , C. Y. Tsang * , Z. Tu * , J. Tyler * , T. Ullrich * , D. G. Underwood * , I. Upsal * , G. Van Buren * , J. Vanek * , I. Vassiliev * , V. Verkest


* , F. Videbæk * , S. A. Voloshin * , F. Wang * , G. Wang * , J. S. Wang * , J. Wang * , K. Wang * , X. Wang * , Y. Wang * , Y. Wang * , Y. Wang * , Z. Wang * , J. C. Webb * , P. C.


Weidenkaff * , G. D. Westfall * , D. Wielanek * , H. Wieman * , G. Wilks * , S. W. Wissink * , R. Witt * , J. Wu * , J. Wu * , X. Wu * , X. Wu * , B. Xi * , Z. G. Xiao * , G. Xie * , W. Xie


* , H. Xu * , N. Xu * , Q. H. Xu * , Y. Xu * , Y. Xu * , Z. Xu * , Z. Xu * , G. Yan * , Z. Yan * , C. Yang * , Q. Yang * , S. Yang * , Y. Yang * , Z. Ye * , Z. Ye * , L. Yi * , K. Yip * , Y.


Yu * , H. Zbroszczyk * , W. Zha * , C. Zhang * , D. Zhang * , J. Zhang * , S. Zhang * , W. Zhang * , X. Zhang * , Y. Zhang * , Y. Zhang * , Y. Zhang * , Y. Zhang * , Z. J. Zhang * , Z.


Zhang * , Z. Zhang * , F. Zhao * , J. Zhao * , M. Zhao * , J. Zhou * , S. Zhou * , Y. Zhou * , X. Zhu * , M. Zurek *  & M. Zyzak CONTRIBUTIONS All authors contributed to all research


steps and writing of the paper. ETHICS DECLARATIONS COMPETING INTERESTS The authors declare no competing interests. PEER REVIEW PEER REVIEW INFORMATION _Nature_ thanks Benjamin Dönigus and


the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available. ADDITIONAL INFORMATION PUBLISHER’S NOTE Springer Nature remains


neutral with regard to jurisdictional claims in published maps and institutional affiliations. EXTENDED DATA FIGURES AND TABLES EXTENDED DATA FIG. 1 ILLUSTRATION OF THE DECAY TOPOLOGY OF A


HYPERNUCLEUS AND THE VARIABLES FOR THE SELECTION CRITERIA. The arrows indicate the relation between variables and their corresponding geometric distances. EXTENDED DATA FIG. 2 RECONSTRUCTION


EFFICIENCY AS A FUNCTION OF _L_/(_Β__Γ_) OBTAINED FROM THE EMBEDDING MONTE CARLO TECHNIQUE. Hypernuclei have stricter topological cuts than antihypernuclei to suppress knock-out 3He and


4He, resulting in lower efficiencies. EXTENDED DATA FIG. 3 \({}_{\Lambda }{}^{3}{\rm{H}}\), \({}_{\bar{\Lambda }}{}^{3}\bar{{\rm{H}}}\), \({}_{\Lambda }{}^{4}{\rm{H}}\) and


\({}_{\bar{\Lambda }}{}^{4}\bar{{\rm{H}}}\) candidate invariant-mass distributions in different _L_/_β__γ_ intervals. EXTENDED DATA FIG. 4 _D__N_/_D_(_L_/_Β__Γ_) AS A FUNCTION OF _L_/_Β__Γ_


FOR Λ AND \(\BAR{\LAMBDA }\). The exponential fits are applied to obtain their lifetimes. EXTENDED DATA FIG. 5 EFFICIENCY CORRECTED _P__T_ SPECTRA FOR 3HE, \({}^{3}\BAR{{\RM{HE}}}\),


\({}_{\LAMBDA }{}^{3}{\RM{H}}\), AND \({}_{\BAR{\LAMBDA }}{}^{3}\BAR{{\RM{H}}}\). The spectra are in the phase space of ∣_y_∣ < 0.7 with only minimum-bias triggered events. The spectra


are not normalized by the number of events. The lines represent the BW-function fits. SUPPLEMENTARY INFORMATION PEER REVIEW FILE RIGHTS AND PERMISSIONS Springer Nature or its licensor (e.g.


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Observation of the antimatter hypernucleus \({}_{\bar{{\boldsymbol{\Lambda }}}}{}^{{\bf{4}}}\bar{{\bf{H}}}\). _Nature_ 632, 1026–1031 (2024). https://doi.org/10.1038/s41586-024-07823-0


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