In:
The European Physical Journal C, Springer Science and Business Media LLC, Vol. 80, No. 7 ( 2020-07)
Abstract:
Normalised multi-differential cross sections for top quark pair ( $$\hbox {t}{\bar{\hbox {t}}}$$ t t ¯ ) production are measured in proton-proton collisions at a centre-of-mass energy of 13 $$\,{\text {TeV}}$$ TeV using events containing two oppositely charged leptons. The analysed data were recorded with the CMS detector in 2016 and correspond to an integrated luminosity of $$35.9{\,{\text {fb}}^{-1}} $$ 35.9 fb - 1 . The double-differential $$\hbox {t}{\bar{\hbox {t}}}$$ t t ¯ cross section is measured as a function of the kinematic properties of the top quark and of the $$\hbox {t}{\bar{\hbox {t}}}$$ t t ¯ system at parton level in the full phase space. A triple-differential measurement is performed as a function of the invariant mass and rapidity of the $$\hbox {t}{\bar{\hbox {t}}}$$ t t ¯ system and the multiplicity of additional jets at particle level. The data are compared to predictions of Monte Carlo event generators that complement next-to-leading-order (NLO) quantum chromodynamics (QCD) calculations with parton showers. Together with a fixed-order NLO QCD calculation, the triple-differential measurement is used to extract values of the strong coupling strength $$\alpha _{S}$$ α S and the top quark pole mass ( $$m_{{\text {t}}}^{{\text {pole}}}$$ m t pole ) using several sets of parton distribution functions (PDFs). The measurement of $$m_{{\text {t}}}^{{\text {pole}}}$$ m t pole exploits the sensitivity of the $$\hbox {t}{\bar{\hbox {t}}}$$ t t ¯ invariant mass distribution to $$m_{{\text {t}}}^{{\text {pole}}}$$ m t pole near the production threshold. Furthermore, a simultaneous fit of the PDFs, $$\alpha _{S}$$ α S , and $$m_{{\text {t}}}^{{\text {pole}}}$$ m t pole is performed at NLO, demonstrating that the new data have significant impact on the gluon PDF, and at the same time allow an accurate determination of $$\alpha _{S}$$ α S and $$m_{{\text {t}}}^{{\text {pole}}}$$ m t pole . The values $$\alpha _{S}(m_{{\text {Z}}}) = 0.1135{}^{+0.0021}_{-0.0017}$$ α S ( m Z ) = 0.1135 - 0.0017 + 0.0021 and $$m_{{\text {t}}}^{{\text {pole}}} = 170.5 \pm 0.8 \,{\text {GeV}} $$ m t pole = 170.5 ± 0.8 GeV are extracted, which account for experimental and theoretical uncertainties, the latter being estimated from NLO scale variations. Possible effects from Coulomb and soft-gluon resummation near the $$\hbox {t}{\bar{\hbox {t}}}$$ t t ¯ production threshold are neglected in these parameter extractions. A rough estimate of these effects indicates an expected correction of $$m_{{\text {t}}}^{{\text {pole}}}$$ m t pole of the order of $$+1 \,{\text {GeV}} $$ + 1 GeV , which can be regarded as additional theoretical uncertainty in the current $$m_{{\text {t}}}^{{\text {pole}}}$$ m t pole extraction.
Type of Medium:
Online Resource
ISSN:
1434-6044
,
1434-6052
DOI:
10.1140/epjc/s10052-020-7917-7
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2020
detail.hit.zdb_id:
1397769-6
detail.hit.zdb_id:
1459069-4
