Measurement of the jet mass in high transverse momentum Z(→bb‾)γ production at √s=13TeV using the ATLAS detector
Aad, Georges; Abbott, Brad; Abbott, Dale C.; Abdinov, Ovsat Bahram oglu; Abed Abud, Adam; Abeling, Kira; Abhayasinghe, Deshan Kavishka; Abidi, Syed Haider; AbouZeid, Ossama Sherif Alexander; Abraham, Nadine L.; Bjørke, Kristian; Bugge, Magnar Kopangen; Cameron, David Gordon; Catmore, James Richard; Feigl, Simon; Garonne, Vincent; Gramstad, Eirik; Hellesund, Simen; Morisbak, Vanja; Oppen, Henrik; Ould-Saada, Farid; Pedersen, Maiken; Read, Alexander Lincoln; Røhne, Ole Myren; Sandaker, Heidi; Vadla, Knut Oddvar Høie; Buanes, Trygve; Djuvsland, Julia Isabell; Eigen, Gerald; Fomin, Nikolai; Latour, Bertrand Pascal Christian; Lee, Graham Richard; Lipniacka, Anna; Mæland, Steffen; Stugu, Bjarne Sandvik; Træet, Are Sivertsen; Abramowicz, Halina; Abreu, Henso; Abulaiti, Yiming; Acharya, Bobby S.; Achkar, Baida; Adachi, Shunsuke; Adam, Lennart; Adam-Bourdarios, Claire; Adamczyk, Leszek; Adamek, Lukas; Adelman, Jareed; Adersberger, Michael; Adigüzel, Aytül; Adorni, Sofia; ATLAS, Collaboration
Journal article, Peer reviewed
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Original versionPhysics Letters B. 2021, 812:135991. 10.1016/j.physletb.2020.135991
The integrated fiducial cross-section and unfolded differential jet mass spectrum of high transverse momentum Z → bb decays are measured in Zγ events in proton–proton collisions at √s = 13 TeV. The data analysed were collected between 2015 and 2016 with the ATLAS detector at the Large Hadron Collider and correspond to an integrated luminosity of 36.1 fb−1. Photons are required to have a transverse momentum pT > 175 GeV. The Z → bb decay is reconstructed using a jet with pT > 200 GeV, found with the anti-kt R = 1.0 jet algorithm, and groomed to remove soft and wide-angle radiation and to mitigate contributions from the underlying event and additional proton–proton collisions. Two different but related measurements are performed using two jet grooming definitions for reconstructing the Z → bb decay: trimming and soft drop. These algorithms differ in their experimental and phenomenological implications regarding jet mass reconstruction and theoretical precision. To identify Z bosons, b-tagged R = 0.2 track-jets matched to the groomed large-R calorimeter jet are used as a proxy for the b-quarks. The signal yield is determined from fits of the data-driven background templates to the different jet mass distributions for the two grooming methods. Integrated fiducial cross-sections and unfolded jet mass spectra for each grooming method are compared with leading-order theoretical predictions. The results are found to be in good agreement with Standard Model expectations within the current statistical and systematic uncertainties.