Measurements of the pp→ZZ production cross section and the Z→4ℓ branching fraction, and constraints on anomalous triple gauge couplings at √s =13 TeV

• Main Authors: Abercrombie, Daniel Robert (Contributor), Allen, Brandon Leigh (Contributor), Azzolini, Virginia (Contributor), Barbieri, Richard Alexander (Contributor), Baty, Austin Alan (Contributor), Bi, Ran (Contributor), Brandt, Stephanie Akemi (Contributor), Busza, Wit (Contributor), Cali, Ivan Amos (Contributor), D'Alfonso, Mariarosaria (Contributor), Demiragli, Zeynep (Contributor), Gomez-Ceballos, Guillelmo (Contributor), Goncharov, Maxim (Contributor), Hsu, Dylan George (Contributor), Iiyama, Yutaro (Contributor), Innocenti, Gian Michele (Contributor), Klute, Markus (Contributor), Kovalskyi, Dmytro (Contributor), Lai, Yue Shi (Contributor), Lee, Yen-Jie (Contributor), Levin, Andrew Michael (Contributor), Luckey Jr, P David (Contributor), Maier, Benedikt (Contributor), Marini, Andrea Carlo (Contributor), McGinn, Christopher Francis (Contributor), Mironov, Camelia Maria (Contributor), Narayanan, Siddharth Madhavan (Contributor), Niu, Xinmei (Contributor), Paus, Christoph M. E. (Contributor), Roland, Christof E (Contributor), Roland, Gunther M (Contributor), Salfeld-Nebgen, Jakob Maxillian Henry (Contributor), Stephans, George S. F. (Contributor), Tatar, Kaya (Contributor), Velicanu, Dragos Alexandru (Contributor), Wang, J. (Contributor), Wang, Ta-Wei (Contributor), Wyslouch, Boleslaw (Contributor)
• Other Authors: Massachusetts Institute of Technology. Department of Physics (Contributor), Massachusetts Institute of Technology. Laboratory for Nuclear Science (Contributor)
• Format: Article
• Language: English
• Published: Springer Berlin Heidelberg, 2018-07-27T18:44:44Z.
• Subjects: Article
• Online Access: Get fulltext

 Four-lepton production in proton-proton collisions, pp → (Z/γ[superscript ∗]) (Z/γ[superscript ∗]) → 4ℓ, where ℓ= e or μ, is studied at a center-of-mass energy of 13 TeV with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 35.9fb[superscript -1]. The ZZ production cross section, σ(pp→ZZ)=17.2±0.5(stat)±0.7(syst)±0.4(theo)±0.4(lumi) pb, measured using events with two opposite-sign, same-flavor lepton pairs produced in the mass region 60 < m[subscript ℓ+ℓ-] < 120GeV, is consistent with standard model predictions. Differential cross sections are measured and are well described by the theoretical predictions. The Z boson branching fraction to four leptons is measured to be B(Z → 4ℓ) =4.83[superscript +0.23][subscript -0.22](stat)[superscript +0.32][subscript -0.29](syst)±0.08(theo)±0.12(lumi)×10[superscript -6] for events with a four-lepton invariant mass in the range 80 < m[subscript 4ℓ] < 100GeV and a dilepton mass m[subscript ℓℓ]> 4 GeV for all opposite-sign, same-flavor lepton pairs. The results agree with standard model predictions. The invariant mass distribution of the four-lepton system is used to set limits on anomalous ZZZ and ZZγ couplings at 95% confidence level: -0.0012 < f[superscript Z][subscript 4] < 0.0010, -0.0010 < f[superscript Z][subscript 5] < 0.0013, -0.0012 < f[superscript γ][subscript 4] < 0.0013, -0.0012 < f[superscript γ][subscript 5] < 0.0013.