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Christophe Clément

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This paper presents the combinations of single-top-quark production cross-section measurements by the ATLAS and CMS Collaborations, using data from LHC proton-proton collisions at

\sqrt{s}

= 7 and 8 TeV corresponding to integrated luminosities of 1.17 to 5.1 fb

^{−1}

\sqrt{s}

= 7 TeV and 12.2 to 20.3 fb

^{−1}

\sqrt{s}

= 8 TeV. These combinations are performed per centre-of-mass energy and for each production mode: t-channel, tW, and s-channel. The combined t-channel cross-sections are 67.5 ± 5.7 pb and 87.7 ± 5.8 pb at

\sqrt{s}

= 7 and 8 TeV respectively. The combined tW cross-sections are 16.3 ± 4.1 pb and 23.1 ± 3.6 pb at

\sqrt{s}

= 7 and 8 TeV respectively. For the s-channel cross-section, the combination yields 4.9 ± 1.4 pb at

\sqrt{s}

= 8 TeV. The square of the magnitude of the CKM matrix element V

_{tb}

multiplied by a form factor f

_{LV}

is determined for each production mode and centre-of-mass energy, using the ratio of the measured cross-section to its theoretical prediction. It is assumed that the top-quark-related CKM matrix elements obey the relation |V

_{td}

|, |V

_{ts}

| ≪ |V

_{tb}

|. All the |f

_{LV}

_{tb}

^{2}

determinations, extracted from individual ratios at

\sqrt{s}

= 7 and 8 TeV, are combined, resulting in |f

_{LV}

_{tb}

| = 1.02 ± 0.04 (meas.) ± 0.02 (theo.). All combined measurements are consistent with their corresponding Standard Model predictions.

Springer2019

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This paper presents combinations of inclusive and differential measurements of the charge asymmetry (A

_{C}

) in top quark pair

\left(\mathrm{t}\overline{\mathrm{t}}\right)

events with a lepton+jets signature by the ATLAS and CMS Collaborations, using data from LHC proton-proton collisions at centre-of-mass energies of 7 and 8 TeV. The data correspond to integrated luminosities of about 5 and 20 fb

^{−1}

for each experiment, respectively. The resulting combined LHC measurements of the inclusive charge asymmetry are A

_{C}^{CHC7}

= 0.005 ± 0.007 (stat) ± 0.006(syst) at 7 TeV and A

_{C}^{CHC8}

= 0.0055 ± 0.0023 (stat) ± 0.0025 (syst) at 8 TeV. These values, as well as the combination of A

_{C}

measurements as a function of the invariant mass of the

\mathrm{t}\overline{\mathrm{t}}

system at 8 TeV, are consistent with the respective standard model predictions.

2018

Measurements of the Higgs boson production and decay rates and constraints on its couplings from a combined ATLAS and CMS analysis of the LHC pp collision data at $ \sqrt{s}=7 $ and 8 TeV

Muhammad Ahmad, Benjamin William Allen, Georgios Anagnostou, Konstantin Androsov, Spyridon Argyropoulos, Alexandre Aubin, Nicolas Berger, Michele Bianco, Alexey Boldyrev, Simone Campana, João Carvalho, Roberto Castello, Juan Ramon Castiñeiras De Saa, Matevz Cerv, Susan Cheatham, Yixing Chen, Xin Chen, Chunhui Chen, Tian Cheng, Davide Cieri, Christophe Clément, Giuseppe Codispoti, Tommaso Colombo, Géraldine Conti, Greig Alan Cowan, Alessandro Degano, Sergey Denisov, Charles Dietz, Milos Dordevic, Dipanwita Dutta, Matthias Finger, Francesco Fiori, Julia Fischer, Daniel Gonzalez, Jun Guo, Yifei Guo, Ruchi Gupta, Seungkyu Ha, Csaba Hajdu, Peter Hansen, Ali Harb, James Henderson, Haoshuang Ji, Yi Jiang, Shan Jin, Alexis Kalogeropoulos, Viktor Khristenko, Donghyun Kim, Sun Hee Kim, Ji Hyun Kim, Vineet Kumar, Ajay Kumar, Sanjeev Kumar, Ekaterina Kuznetsova, Federica Legger, Ho Ling Li, Qi Li, Lei Li, Bing Li, Xuan Li, Yiming Li, Wei Li, Peter Lichard, Hao Liu, Bo Liu, Jian Liu, Kun Liu, Zhen Liu, Lulu Liu, Dong Liu, Shuai Liu, Werner Lustermann, Alexander Madsen, Bibhuprasad Mahakud, Andreas Alexander Maier, Gino Marceca, Ruslan Mashinistov, Lorenzo Massa, Maren Tabea Meinhard, Jean-Pierre Meyer, Thomas Muller, Snezana Nektarijevic, Marzio Nessi, Konstantinos Nikolopoulos, Preema Rennee Pais, Ioannis Papadopoulos, Vladimir Petrov, Quentin Python, Yang Qin, Robert Richter, Andrea Rizzi, Paolo Ronchese, Manfredi Ronzani, Eduardo Ros, Stefano Rosati, Edoardo Rossi, Daniela Salvatore, Sourav Sen, Ashish Sharma, Varun Sharma

Combined ATLAS and CMS measurements of the Higgs boson production and decay rates, as well as constraints on its couplings to vector bosons and fermions, are presented. The combination is based on the analysis of five production processes, namely gluon fusion, vector boson fusion, and associated production with a W or a Z boson or a pair of top quarks, and of the six decay modes H → ZZ, W W , γγ, ττ, bb, and μμ. All results are reported assuming a value of 125.09 GeV for the Higgs boson mass, the result of the combined measurement by the ATLAS and CMS experiments. The analysis uses the CERN LHC proton-proton collision data recorded by the ATLAS and CMS experiments in 2011 and 2012, corresponding to integrated luminosities per experiment of approximately 5 fb

^{−1}

\sqrt{s}=7

TeV and 20 fb

^{−1}

\sqrt{s}=8

TeV. The Higgs boson production and decay rates measured by the two experiments are combined within the context of three generic parameterisations: two based on cross sections and branching fractions, and one on ratios of coupling modifiers. Several interpretations of the measurements with more model-dependent parameterisations are also given. The combined signal yield relative to the Standard Model prediction is measured to be 1.09 ± 0.11. The combined measurements lead to observed significances for the vector boson fusion production process and for the H → ττ decay of 5.4 and 5.5 standard deviations, respectively. The data are consistent with the Standard Model predictions for all parameterisations considered.

2016