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  • 1
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    Online Resource
    Combination of the W boson polarization measurements in top quark decays using ATLAS and CMS data at $$ \sqrt{s} $$ = 8 TeV
    Springer Science and Business Media LLC ; 2020
    In:  Journal of High Energy Physics Vol. 2020, No. 8 ( 2020-08)
    Details
    In: Journal of High Energy Physics, Springer Science and Business Media LLC, Vol. 2020, No. 8 ( 2020-08)
    Abstract: The combination of measurements of the W boson polarization in top quark decays performed by the ATLAS and CMS collaborations is presented. The measurements are based on proton-proton collision data produced at the LHC at a centre-of-mass energy of 8 TeV, and corresponding to an integrated luminosity of about 20 fb − 1 for each experiment. The measurements used events containing one lepton and having different jet multiplicities in the final state. The results are quoted as fractions of W bosons with longitudinal ( F 0 ), left-handed ( F L ), or right-handed ( F R ) polarizations. The resulting combined measurements of the polarization fractions are F 0 = 0 . 693 ± 0 . 014 and F L = 0 . 315 ± 0 . 011. The fraction F R is calculated from the unitarity constraint to be F R = − 0 . 008 ± 0 . 007. These results are in agreement with the standard model predictions at next-to-next-to-leading order in perturbative quantum chromodynamics and represent an improvement in precision of 25 (29)% for F 0 ( F L ) with respect to the most precise single measurement. A limit on anomalous right-handed vector ( V R ), and left- and right-handed tensor ( g L , g R ) tWb couplings is set while fixing all others to their standard model values. The allowed regions are [ − 0 . 11 , 0 . 16] for V R , [ − 0 . 08 , 0 . 05] for g L , and [ − 0 . 04 , 0 . 02] for g R , at 95% confidence level. Limits on the corresponding Wilson coefficients are also derived.
    Type of Medium: Online Resource
    ISSN: 1029-8479
    URL: Article
    DOI: 10.1007/JHEP08(2020)051
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2020
    detail.hit.zdb_id: 2027350-2
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  • 2
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    Online Resource
    Combination of inclusive top-quark pair production cross-section measurements using ATLAS and CMS data at $$ \sqrt{s} $$ = 7 and 8 TeV
    Springer Science and Business Media LLC ; 2023
    In:  Journal of High Energy Physics Vol. 2023, No. 7 ( 2023-07-27)
    Details
    In: Journal of High Energy Physics, Springer Science and Business Media LLC, Vol. 2023, No. 7 ( 2023-07-27)
    Abstract: A combination of measurements of the inclusive top-quark pair production cross-section performed by ATLAS and CMS in proton–proton collisions at centre-of-mass energies of 7 and 8 TeV at the LHC is presented. The cross-sections are obtained using top-quark pair decays with an opposite-charge electron–muon pair in the final state and with data corresponding to an integrated luminosity of about 5 fb − 1 at $$ \sqrt{s} $$ s = 7 TeV and about 20 fb − 1 at $$ \sqrt{s} $$ s = 8 TeV for each experiment. The combined cross-sections are determined to be 178 . 5 ± 4 . 7 pb at $$ \sqrt{s} $$ s = 7 TeV and $$ {243.3}_{-5.9}^{+6.0} $$ 243.3 − 5.9 + 6.0 pb at $$ \sqrt{s} $$ s = 8 TeV with a correlation of 0.41, using a reference top-quark mass value of 172.5 GeV. The ratio of the combined cross-sections is determined to be R 8 / 7 = 1 . 363 ± 0 . 032. The combined measured cross-sections and their ratio agree well with theory calculations using several parton distribution function (PDF) sets. The values of the top-quark pole mass (with the strong coupling fixed at 0.118) and the strong coupling (with the top-quark pole mass fixed at 172.5 GeV) are extracted from the combined results by fitting a next-to-next-to-leading-order plus next-to-next-to-leading-log QCD prediction to the measurements. Using a version of the NNPDF3.1 PDF set containing no top-quark measurements, the results obtained are $$ {m}_t^{\textrm{pole}}={173.4}_{-2.0}^{+1.8} $$ m t pole = 173.4 − 2.0 + 1.8 GeV and $$ {\alpha}_{\textrm{s}}\left({m}_Z\right)={0.1170}_{-0.0018}^{+0.0021} $$ α s m Z = 0.1170 − 0.0018 + 0.0021 .
    Type of Medium: Online Resource
    ISSN: 1029-8479
    URL: Article
    DOI: 10.1007/JHEP07(2023)213
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2023
    detail.hit.zdb_id: 2027350-2
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  • 3
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    Combinations of single-top-quark production cross-section measurements and |fLVVtb| determinations at $$ \sqrt{s} $$ = 7 and 8 TeV with the ATLAS and CMS experiments
    Springer Science and Business Media LLC ; 2019
    In:  Journal of High Energy Physics Vol. 2019, No. 5 ( 2019-05)
    Details
    In: Journal of High Energy Physics, Springer Science and Business Media LLC, Vol. 2019, No. 5 ( 2019-05)
    Abstract: 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 $$ \sqrt{s} $$ s = 7 and 8 TeV corresponding to integrated luminosities of 1.17 to 5.1 fb −1 at $$ \sqrt{s} $$ s = 7 TeV and 12.2 to 20.3 fb −1 at $$ \sqrt{s} $$ 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 $$ \sqrt{s} $$ s = 7 and 8 TeV respectively. The combined tW cross-sections are 16.3 ± 4.1 pb and 23.1 ± 3.6 pb at $$ \sqrt{s} $$ s = 7 and 8 TeV respectively. For the s -channel cross-section, the combination yields 4.9 ± 1.4 pb at $$ \sqrt{s} $$ 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 V tb | 2 determinations, extracted from individual ratios at $$ \sqrt{s} $$ s = 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.
    Type of Medium: Online Resource
    ISSN: 1029-8479
    URL: Article
    DOI: 10.1007/JHEP05(2019)088
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2019
    detail.hit.zdb_id: 2027350-2
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