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A search for events containing four top quarks ( tt¯tt¯ ) is reported from proton–proton collisions recorded by the CMS experiment at s=13 TeV and corresponding to an integrated luminosity of 2.6 fb −1 . The analysis considers the single-lepton (e or μ )+jets and the opposite-sign dilepton ( μ+μ− , μ±e∓ , or e+e− )+jets channels. It uses boosted decision trees to combine information on the global event and jet properties to distinguish between tt¯tt¯ and tt¯ production. The number of events observed after all selection requirements is consistent with expectations from background and standard model signal predictions, and an upper limit is set on the cross section for tt¯tt¯ production in the standard model of 94 fb at 95% confidence level ( 10.2 × the prediction), with an expected limit of 118 fb. This is combined with the results from the published CMS search in the same-sign dilepton channel, resulting in an improved limit of 69 fb at 95% confidence level ( 7.4 × the prediction), with an expected limit of 71 fb. These are the strongest constraints on the rate of tt¯tt¯ production to date.
Jian Wang, Matthias Finger, Qian Wang, Yiming Li, Matthias Wolf, Varun Sharma, Yi Zhang, Konstantin Androsov, Jan Steggemann, Leonardo Cristella, Xin Chen, Davide Di Croce, Arvind Shah, Rakesh Chawla, Chao Wang, João Miguel das Neves Duarte, Tagir Aushev, Tian Cheng, Yixing Chen, Werner Lustermann, Andromachi Tsirou, Alexis Kalogeropoulos, Andrea Rizzi, Ioannis Papadopoulos, Paolo Ronchese, Hua Zhang, Siyuan Wang, Jessica Prisciandaro, Peter Hansen, Tao Huang, David Vannerom, Michele Bianco, Sebastiana Gianì, Kun Shi, Wei Shi, Abhisek Datta, Wei Sun, Jian Zhao, Thomas Berger, Federica Legger, Doohyun Kim, Bertrand François, Bandeep Singh, Ji Hyun Kim, Donghyun Kim, Dipanwita Dutta, Zheng Wang, Sanjeev Kumar, Wei Li, Yong Yang, Geng Chen, Yi Wang, Ajay Kumar, Ashish Sharma, Georgios Anagnostou, Joao Varela, Csaba Hajdu, Muhammad Ahmad, Ekaterina Kuznetsova, Ioannis Evangelou, Matthias Weber, Muhammad Shoaib, Milos Dordevic, Vineet Kumar, Vladimir Petrov, Francesco Fiori, Quentin Python, Meng Xiao, Sourav Sen, Viktor Khristenko, Fan Xia, Xiao Wang, Kai Yi, Jing Li, Rajat Gupta, Zhen Liu, Muhammad Waqas, Hui Wang, Seungkyu Ha, Maren Tabea Meinhard, Giorgia Rauco, Ali Harb, Benjamin William Allen, Long Wang, Pratyush Das, Miao Hu, Anton Petrov, Xin Gao, Chen Chen, Valérie Scheurer, Giovanni Mocellin, Muhammad Ansar Iqbal, Lukas Layer
Jian Wang, Matthias Finger, Qian Wang, Yiming Li, Matthias Wolf, Varun Sharma, Yi Zhang, Konstantin Androsov, Jan Steggemann, Leonardo Cristella, Xin Chen, Davide Di Croce, Arvind Shah, Rakesh Chawla, Chao Wang, João Miguel das Neves Duarte, Tagir Aushev, Tian Cheng, Yixing Chen, Werner Lustermann, Andromachi Tsirou, Alexis Kalogeropoulos, Andrea Rizzi, Ioannis Papadopoulos, Paolo Ronchese, Hua Zhang, Siyuan Wang, Jessica Prisciandaro, Peter Hansen, Tao Huang, David Vannerom, Michele Bianco, Sebastiana Gianì, Kun Shi, Wei Shi, Abhisek Datta, Wei Sun, Jian Zhao, Thomas Berger, Federica Legger, Doohyun Kim, Bertrand François, Bandeep Singh, Ji Hyun Kim, Donghyun Kim, Dipanwita Dutta, Zheng Wang, Sanjeev Kumar, Wei Li, Yong Yang, Geng Chen, Yi Wang, Ajay Kumar, Ashish Sharma, Georgios Anagnostou, Joao Varela, Csaba Hajdu, Muhammad Ahmad, Ekaterina Kuznetsova, Ioannis Evangelou, Matthias Weber, Muhammad Shoaib, Milos Dordevic, Vineet Kumar, Vladimir Petrov, Francesco Fiori, Quentin Python, Meng Xiao, Sourav Sen, Viktor Khristenko, Fan Xia, Xiao Wang, Kai Yi, Jing Li, Rajat Gupta, Zhen Liu, Muhammad Waqas, Hui Wang, Seungkyu Ha, Maren Tabea Meinhard, Giorgia Rauco, Ali Harb, Benjamin William Allen, Long Wang, Pratyush Das, Miao Hu, Anton Petrov, Xin Gao, Chen Chen, Valérie Scheurer, Giovanni Mocellin, Muhammad Ansar Iqbal, Lukas Layer
Jian Wang, Matthias Finger, Qian Wang, Yiming Li, Matthias Wolf, Varun Sharma, Yi Zhang, Konstantin Androsov, Jan Steggemann, Leonardo Cristella, Xin Chen, Davide Di Croce, Arvind Shah, Rakesh Chawla, Chao Wang, João Miguel das Neves Duarte, Tagir Aushev, Tian Cheng, Yixing Chen, Werner Lustermann, Andromachi Tsirou, Alexis Kalogeropoulos, Andrea Rizzi, Ioannis Papadopoulos, Paolo Ronchese, Hua Zhang, Siyuan Wang, Jessica Prisciandaro, Peter Hansen, Tao Huang, David Vannerom, Michele Bianco, Sebastiana Gianì, Kun Shi, Wei Shi, Abhisek Datta, Wei Sun, Jian Zhao, Thomas Berger, Federica Legger, Doohyun Kim, Bertrand François, Bandeep Singh, Ji Hyun Kim, Donghyun Kim, Dipanwita Dutta, Zheng Wang, Sanjeev Kumar, Wei Li, Yong Yang, Geng Chen, Yi Wang, Ajay Kumar, Ashish Sharma, Georgios Anagnostou, Joao Varela, Csaba Hajdu, Muhammad Ahmad, Ekaterina Kuznetsova, Ioannis Evangelou, Matthias Weber, Muhammad Shoaib, Milos Dordevic, Vineet Kumar, Vladimir Petrov, Francesco Fiori, Meng Xiao, Sourav Sen, Viktor Khristenko, Xiao Wang, Kai Yi, Jing Li, Rajat Gupta, Zhen Liu, Muhammad Waqas, Hui Wang, Seungkyu Ha, Maren Tabea Meinhard, Giorgia Rauco, Ali Harb, Long Wang, Pratyush Das, Miao Hu, Anton Petrov, Xin Gao, Chen Chen, Valérie Scheurer, Giovanni Mocellin, Muhammad Ansar Iqbal, Lukas Layer