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Publication# Search for ZZ resonances in the 2$\ell$2$\nu$ final state in proton-proton collisions at 13 TeV

Muhammad Ahmad, Benjamin William Allen, Georgios Anagnostou, Konstantin Androsov, Tagir Aushev, Michele Bianco, Roberto Castello, Xin Chen, Yixing Chen, Tian Cheng, Davide Cieri, Giuseppe Codispoti, Pratyush Das, Alessandro Degano, Milos Dordevic, Dipanwita Dutta, Matthias Finger, Francesco Fiori, Daniel Gonzalez, Seungkyu Ha, Csaba Hajdu, Peter Hansen, Ali Harb, Miao Hu, Alexis Kalogeropoulos, Viktor Khristenko, Donghyun Kim, Ji Hyun Kim, Sanjeev Kumar, Vineet Kumar, Ajay Kumar, Ekaterina Kuznetsova, Ho Ling Li, Jing Li, Wei Li, Shuai Liu, Zhen Liu, Hao Liu, Werner Lustermann, Bibhuprasad Mahakud, Maren Tabea Meinhard, Thomas Muller, Ioannis Papadopoulos, Vladimir Petrov, Quentin Python, Andrea Rizzi, Paolo Ronchese, Varun Sharma, Ashish Sharma, Lesya Shchutska, Wei Shi, Kun Shi, Muhammad Shoaib, Gurpreet Singh, Jan Steggemann, Marco Trovato, Andromachi Tsirou, David Vannerom, Joao Varela, Mingkui Wang, Jian Wang, Hui Wang, Qian Wang, Zheng Wang, Yi Wang, Siyuan Wang, Muhammad Waqas, Matthias Weber, Matthias Wolf, Wenjing Wu, Fan Xia, Meng Xiao, Zhirui Xu, Yong Yang, Kai Yi

2017

Journal paper

2017

Journal paper

Abstract

A search for heavy resonances decaying to a pair of Z bosons is performed using data collected with the CMS detector at the LHC. Events are selected by requiring two oppositely charged leptons (electrons or muons), consistent with the decay of a Z boson, and large missing transverse momentum, which is interpreted as arising from the decay of a second Z boson to two neutrinos. The analysis uses data from proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{−1}$. The hypothesis of a spin-2 bulk graviton (X) decaying to a pair of Z bosons is examined for 600 ≤ m$_{X}$ ≤ 2500 GeV and upper limits at 95% confidence level are set on the product of the production cross section and branching fraction of X → ZZ ranging from 100 to 4 fb. For bulk graviton models characterized by a curvature scale parameter $\tilde{k}=0.5$ in the extra dimension, the region m$_{X}$ < 800 GeV is excluded, providing the most stringent limit reported to date. Variations of the model considering the possibility of a wide resonance produced exclusively via gluon-gluon fusion or $\mathrm{q}\overline{\mathrm{q}}$ annihilation are also examined.

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Muhammad Ahmad, Benjamin William Allen, Georgios Anagnostou, Konstantin Androsov, Tagir Aushev, Michele Bianco, Roberto Castello, Yixing Chen, Xin Chen, Tian Cheng, Davide Cieri, Giuseppe Codispoti, Pratyush Das, Alessandro Degano, Milos Dordevic, Dipanwita Dutta, Matthias Finger, Francesco Fiori, Daniel Gonzalez, Seungkyu Ha, Csaba Hajdu, Peter Hansen, Ali Harb, Alexis Kalogeropoulos, Viktor Khristenko, Ji Hyun Kim, Donghyun Kim, Ajay Kumar, Sanjeev Kumar, Vineet Kumar, Ekaterina Kuznetsova, Wei Li, Ho Ling Li, Shuai Liu, Zhen Liu, Hao Liu, Werner Lustermann, Bibhuprasad Mahakud, Maren Tabea Meinhard, Thomas Muller, Ioannis Papadopoulos, Vladimir Petrov, Quentin Python, Andrea Rizzi, Paolo Ronchese, Ashish Sharma, Varun Sharma, Lesya Shchutska, Muhammad Shoaib, Gurpreet Singh, Jan Steggemann, Xin Sun, Marco Trovato, Andromachi Tsirou, David Vannerom, Joao Varela, Yi Wang, Qian Wang, Zheng Wang, Jian Wang, Mingkui Wang, Hui Wang, Siyuan Wang, Muhammad Waqas, Matthias Weber, Matthias Wolf, Fan Xia, Meng Xiao, Zhirui Xu, Yong Yang, Kai Yi

A search is presented for single production of a vector-like quark (T) decaying to a Z boson and a top quark, with the Z boson decaying leptonically and the top quark decaying hadronically. The search uses data collected by the CMS experiment in proton–proton collisions at a center-of-mass energy of 13 TeV in 2016, corresponding to an integrated luminosity of 35.9 fb−1 . The presence of forward jets is a particular characteristic of single production of vector-like quarks that is used in the analysis. For the first time, different T quark width hypotheses are studied, from negligibly small to 30% of the new particle mass. At the 95% confidence level, the product of cross section and branching fraction is excluded above values in the range 0.26–0.04 pb for T quark masses in the range 0.7–1.7 TeV, assuming a negligible width. A similar sensitivity is observed for widths of up to 30% of the T quark mass. The production of a heavy Z′ boson decaying to Tt, with T→tZ , is also searched for, and limits on the product of cross section and branching fractions for this process are set between 0.13 and 0.06 pb for Z′ boson masses in the range from 1.5 to 2.5 TeV.

2018Muhammad Ahmad, Benjamin William Allen, Georgios Anagnostou, Konstantin Androsov, Tagir Aushev, Michele Bianco, Roberto Castello, Xin Chen, Yixing Chen, Tian Cheng, Davide Cieri, Giuseppe Codispoti, Pratyush Das, Abhisek Datta, Alessandro Degano, Milos Dordevic, Dipanwita Dutta, Matthias Finger, Francesco Fiori, Daniel Gonzalez, Ruchi Gupta, Seungkyu Ha, Csaba Hajdu, Peter Hansen, Ali Harb, Miao Hu, Alexis Kalogeropoulos, Viktor Khristenko, Ji Hyun Kim, Donghyun Kim, Vineet Kumar, Sanjeev Kumar, Ajay Kumar, Ekaterina Kuznetsova, Ho Ling Li, Jing Li, Wei Li, Shuai Liu, Zhen Liu, Hao Liu, Werner Lustermann, Bibhuprasad Mahakud, Maren Tabea Meinhard, Thomas Muller, Ioannis Papadopoulos, Vladimir Petrov, Quentin Python, Andrea Rizzi, Paolo Ronchese, Varun Sharma, Ashish Sharma, Lesya Shchutska, Wei Shi, Kun Shi, Muhammad Shoaib, Gurpreet Singh, Jan Steggemann, Marco Trovato, Andromachi Tsirou, David Vannerom, Joao Varela, Zheng Wang, Yi Wang, Mingkui Wang, Jian Wang, Siyuan Wang, Hui Wang, Qian Wang, Muhammad Waqas, Matthias Weber, Matthias Wolf, Wenjing Wu, Fan Xia, Meng Xiao, Zhirui Xu, Yong Yang, Kai Yi

A search is presented for massive narrow resonances decaying either into two Higgs bosons, or into a Higgs boson and a W or Z boson. The decay channels considered are $\mathrm{H}\mathrm{H}\to \mathrm{b}\overline{\mathrm{b}}{\tau}^{+}{\tau}^{-}$ and $\mathrm{V}\mathrm{H}\to \mathrm{q}\overline{\mathrm{q}}{\tau}^{+}{\tau}^{-}$ , where H denotes the Higgs boson, and V denotes the W or Z boson. This analysis is based on a data sample of proton-proton collisions collected at a center-of-mass energy of 13 TeV by the CMS Collaboration, corresponding to an integrated luminosity of 35.9 fb$^{−1}$. For the TeV-scale mass resonances considered, substructure techniques provide ways to differentiate among the hadronization products from vector boson decays to quarks, Higgs boson decays to bottom quarks, and quark- or gluon-induced jets. Reconstruction techniques are used that have been specifically optimized to select events in which the tau lepton pair is highly boosted. The observed data are consistent with standard model expectations and upper limits are set at 95% confidence level on the product of cross section and branching fraction for resonance masses between 0.9 and 4.0 TeV. Exclusion limits are set in the context of bulk radion and graviton models:spin-0 radion resonances are excluded below a mass of 2.7 TeV at 95% confidence level. In the spin-1 heavy vector triplet framework, mass-degenerate W′ and Z′ resonances with dominant couplings to the standard model gauge bosons are excluded below a mass of 2.8 TeV at 95% confidence level. These are the first limits for massive resonances at the TeV scale with these decay channels at $\sqrt{s}=13$ TeV.

Muhammad Ahmad, Benjamin William Allen, Georgios Anagnostou, Konstantin Androsov, Tagir Aushev, Michele Bianco, Roberto Castello, Xin Chen, Yixing Chen, Tian Cheng, Davide Cieri, Giuseppe Codispoti, Pratyush Das, Abhisek Datta, Alessandro Degano, Milos Dordevic, Dipanwita Dutta, Matthias Finger, Francesco Fiori, Daniel Gonzalez, Ruchi Gupta, Seungkyu Ha, Csaba Hajdu, Peter Hansen, Ali Harb, Miao Hu, Alexis Kalogeropoulos, Viktor Khristenko, Ji Hyun Kim, Donghyun Kim, Ajay Kumar, Sanjeev Kumar, Vineet Kumar, Ekaterina Kuznetsova, Wei Li, Ho Ling Li, Jing Li, Shuai Liu, Zhen Liu, Hao Liu, Werner Lustermann, Bibhuprasad Mahakud, Maren Tabea Meinhard, Amr Mohamed, Thomas Muller, Ioannis Papadopoulos, Vladimir Petrov, Quentin Python, Andrea Rizzi, Paolo Ronchese, Ashish Sharma, Varun Sharma, Lesya Shchutska, Wei Shi, Kun Shi, Muhammad Shoaib, Gurpreet Singh, Jan Steggemann, Marco Trovato, Andromachi Tsirou, David Vannerom, Joao Varela, Hui Wang, Qian Wang, Mingkui Wang, Zheng Wang, Yi Wang, Siyuan Wang, Jian Wang, Muhammad Waqas, Matthias Weber, Matthias Wolf, Wenjing Wu, Fan Xia, Meng Xiao, Zhirui Xu, Yong Yang, Kai Yi

A search is presented for additional neutral Higgs bosons in the τ τ final state in proton-proton collisions at the LHC. The search is performed in the context of the minimal supersymmetric extension of the standard model (MSSM), using the data collected with the CMS detector in 2016 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{−1}$. To enhance the sensitivity to neutral MSSM Higgs bosons, the search includes production of the Higgs boson in association with b quarks. No significant deviation above the expected background is observed. Model-independent limits at 95% confidence level (CL) are set on the product of the branching fraction for the decay into τ leptons and the cross section for the production via gluon fusion or in association with b quarks. These limits range from 18 pb at 90 GeV to 3.5 fb at 3.2 TeV for gluon fusion and from 15 pb (at 90 GeV) to 2.5 fb (at 3.2 TeV) for production in association with b quarks, assuming a narrow width resonance. In the m$_{h}^{hod +}$ scenario these limits translate into a 95% CL exclusion of tan β > 6 for neutral Higgs boson masses below 250 GeV, where tan β is the ratio of the vacuum expectation values of the neutral components of the two Higgs doublets. The 95% CL exclusion contour reaches 1.6 TeV for tan β = 60.

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Luminosity

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In particle physics, a lepton is an elementary particle of half-integer spin (spin ) that does not undergo strong interactions. Two main classes of leptons exist: charged leptons (also known as the