Measurement of the inclusive $$ \textrm{t}\overline{\textrm{t}} $$ cross section in final states with at least one lepton and additional jets with 302 pb−1 of pp collisions at $$ \sqrt{\textrm{s}} $$ = 5.02 TeV
Abstract
A bstract A measurement of the top quark pair ( $$ \textrm{t}\overline{\textrm{t}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>t</mml:mi> <mml:mover> <mml:mi>t</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> ) production cross section in proton-proton collisions at a centre-of-mass energy of 5.02 TeV is presented. The data were collected at the LHC in autumn 2017, in dedicated runs with low-energy and low-intensity conditions with respect to the default configuration, and correspond to an integrated luminosity of 302 pb − 1 . The measurement is performed using events with one electron or muon, and multiple jets, at least one of them being identified as originating from a b quark (b tagged). Events are classified based on the number of all reconstructed jets and of b-tagged jets. Multivariate analysis techniques are used to enhance the separation between the signal and backgrounds. The measured cross section is $$ 62.5\pm 1.6{\left(\textrm{stat}\right)}_{-2.5}^{+2.6}\left(\textrm{syst}\right)\pm 1.2\left(\textrm{lumi}\right) $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mn>62.5</mml:mn> <mml:mo>±</mml:mo> <mml:mn>1.6</mml:mn> <mml:msubsup> <mml:mfenced> <mml:mtext>stat</mml:mtext> </mml:mfenced> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>2.5</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>2.6</mml:mn> </mml:mrow> </mml:msubsup> <mml:mfenced> <mml:mtext>syst</mml:mtext> </mml:mfenced> <mml:mo>±</mml:mo> <mml:mn>1.2</mml:mn> <mml:mfenced> <mml:mtext>lumi</mml:mtext> </mml:mfenced> </mml:math> pb. A combination with the result in the dilepton channel based on the same data set yields a value of 62.3 ± 1.5 (stat) ± 2.4 (syst) ± 1.2 (lumi) pb, to be compared with the standard model prediction of $$ {69.5}_{-3.7}^{+3.5} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mn>69.5</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>3.7</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>3.5</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> pb at next-to-next-to-leading order in perturbative quantum chromodynamics.