PT Journal AU ATLAS and CMS Collaborations (Aaboud, Mea Alvarez Piqueras, D Aparisi Pozo, JA Bailey, AJ Barranco Navarro, L Cabrera Urban, S Castillo, FL Castillo Gimenez, V Cerda Alberich, L Costa, MJ Escobar, C Estrada Pastor, O Ferrer, A Fiorini, L Fullana Torregrosa, E Fuster, J Garcia, C Garcia Navarro, JE Gonzalez de la Hoz, S Gonzalvo Rodriguez, GR Higon-Rodriguez, E Jimenez Pena, J Lacasta, C Lozano Bahilo, JJ Madaffari, D Mamuzic, J Marti-Garcia, S Melini, D MiƱano, M Mitsou, VA Rodriguez Bosca, S Rodriguez Rodriguez, D Ruiz-Martinez, A Salt, J Santra, A Soldevila, U Sanchez, J Valero, A Valls Ferrer, JA Vos, M TI Combinations of single-top-quark production cross-section measurements and vertical bar f(LV)V(tb)vertical bar determinations at root s=7 and 8 TeV with the ATLAS and CMS experiments SO Journal of High Energy Physics JI J. High Energy Phys. PY 2019 BP 088 EP 81pp VL 05 IS 5 DI 10.1007/JHEP05(2019)088 LA English DE Hadron-Hadron scattering (experiments) AB 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 = 7 and 8 TeV corresponding to integrated luminosities of 1.17 to 5.1 fb(-1) at = 7 TeV and 12.2 to 20.3 fb(-1) at = 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 = 7 and 8 TeV respectively. The combined tW cross-sections are 16.3 +/- 4.1 pb and 23.1 +/- 3.6 pb at = 7 and 8 TeV respectively. For the s-channel cross-section, the combination yields 4.9 +/- 1.4 pb at = 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)V(tb)|(2) determinations, extracted from individual ratios at = 7 and 8 TeV, are combined, resulting in |f(LV)V(tb)| = 1.02 +/- 0.04 (meas.) +/- 0.02 (theo.). All combined measurements are consistent with their corresponding Standard Model predictions. ER