First measurement of the cross section for top quark pair production with additional charm jets using dileptonic final states in pp collisions at s=13TeV

Bethani, Agni;Bruno, Giacomo;Bury, Florian;Caputo, Claudio;Wuyckens, Sophie;et.al.
(2021) Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics — Vol. 820 (2021)

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Authors
  • Bethani, Agniorcid-logoUCLouvain
    Author
  • Bruno, GiacomoUCLouvain
    Author
  • Bury, FlorianUCLouvain
    Author
  • Caputo, ClaudioUCLouvain
    Author
  • David, PieterUCLouvain
    Author
  • Delaere, Christopheorcid-logoUCLouvain
    Author
  • Delcourt, MartinUCLouvain
    Author
  • Donertas, Izzeddin SuatUCLouvain
    Author
  • Giammanco, Andreaorcid-logoUCLouvain
    Author
  • Lemaitre, VincentUCLouvain
    Author
  • Mondal, KuntalUCLouvain
    Author
  • Prisciandaro, JessicaUCLouvain
    Author
  • Taliercio, AngelaUCLouvain
    Author
  • Teklishyn, MaksymUCLouvain
    Author
  • Vischia, PietroUCLouvain
    Author
  • Wertz, SébastienUCLouvain
    Author
  • Wuyckens, SophieUCLouvain
    Author
  • et. al.
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Abstract
The first measurement of the inclusive cross section for top quark pairs (<math altimg="si2.svg"><mi mathvariant="normal">t</mi><mover accent="true"><mrow><mi mathvariant="normal">t</mi></mrow><mo>‾</mo></mover></math>) produced in association with two additional charm jets is presented. The analysis uses the dileptonic final states of <math altimg="si2.svg"><mi mathvariant="normal">t</mi><mover accent="true"><mrow><mi mathvariant="normal">t</mi></mrow><mo>‾</mo></mover></math> events produced in proton-proton collisions at a centre-of-mass energy of 13 TeV. The data correspond to an integrated luminosity of <math altimg="si3.svg"><mn>41.5</mn><mspace width="0.25em"/><msup><mrow><mtext>fb</mtext></mrow><mrow><mo linebreak="badbreak" linebreakstyle="after">−</mo><mn>1</mn></mrow></msup></math>, marc:recorded by the CMS experiment at the LHC. A new charm jet identification algorithm provides input to a neural network that is trained to distinguish among <math altimg="si2.svg"><mi mathvariant="normal">t</mi><mover accent="true"><mrow><mi mathvariant="normal">t</mi></mrow><mo>‾</mo></mover></math> events with two additional charm (<math altimg="si18.svg"><mi mathvariant="normal">t</mi><mover accent="true"><mrow><mi mathvariant="normal">t</mi></mrow><mo>‾</mo></mover><mi mathvariant="normal">c</mi><mover accent="true"><mrow><mi mathvariant="normal">c</mi></mrow><mo>‾</mo></mover></math>), bottom (<math altimg="si11.svg"><mi mathvariant="normal">t</mi><mover accent="true"><mrow><mi mathvariant="normal">t</mi></mrow><mo>‾</mo></mover><mi mathvariant="normal">b</mi><mover accent="true"><mrow><mi mathvariant="normal">b</mi></mrow><mo>‾</mo></mover></math>), and light-flavour or gluon (<math altimg="si125.svg"><mi mathvariant="normal">t</mi><mover accent="true"><mrow><mi mathvariant="normal">t</mi></mrow><mo>‾</mo></mover><mtext>LL</mtext></math>) jets. By means of a template fitting procedure, the inclusive <math altimg="si18.svg"><mi mathvariant="normal">t</mi><mover accent="true"><mrow><mi mathvariant="normal">t</mi></mrow><mo>‾</mo></mover><mi mathvariant="normal">c</mi><mover accent="true"><mrow><mi mathvariant="normal">c</mi></mrow><mo>‾</mo></mover></math>, <math altimg="si11.svg"><mi mathvariant="normal">t</mi><mover accent="true"><mrow><mi mathvariant="normal">t</mi></mrow><mo>‾</mo></mover><mi mathvariant="normal">b</mi><mover accent="true"><mrow><mi mathvariant="normal">b</mi></mrow><mo>‾</mo></mover></math>, and <math altimg="si125.svg"><mi mathvariant="normal">t</mi><mover accent="true"><mrow><mi mathvariant="normal">t</mi></mrow><mo>‾</mo></mover><mtext>LL</mtext></math> cross sections are simultaneously measured, together with their ratios to the inclusive <math altimg="si2.svg"><mi mathvariant="normal">t</mi><mover accent="true"><mrow><mi mathvariant="normal">t</mi></mrow><mo>‾</mo></mover></math> + two jets cross section. This provides measurements of the <math altimg="si18.svg"><mi mathvariant="normal">t</mi><mover accent="true"><mrow><mi mathvariant="normal">t</mi></mrow><mo>‾</mo></mover><mi mathvariant="normal">c</mi><mover accent="true"><mrow><mi mathvariant="normal">c</mi></mrow><mo>‾</mo></mover></math> and <math altimg="si11.svg"><mi mathvariant="normal">t</mi><mover accent="true"><mrow><mi mathvariant="normal">t</mi></mrow><mo>‾</mo></mover><mi mathvariant="normal">b</mi><mover accent="true"><mrow><mi mathvariant="normal">b</mi></mrow><mo>‾</mo></mover></math> cross sections of <math altimg="si127.svg"><mn>10.1</mn><mo>±</mo><mn>1.2</mn><mspace width="0.25em"/><mtext>(stat)</mtext><mo>±</mo><mn>1.4</mn><mspace width="0.25em"/><mtext>(syst)</mtext><mspace width="0.2em"/><mtext>pb</mtext></math> and <math altimg="si8.svg"><mn>4.54</mn><mo>±</mo><mn>0.35</mn><mspace width="0.25em"/><mtext>(stat)</mtext><mo>±</mo><mn>0.56</mn><mspace width="0.25em"/><mtext>(syst)</mtext><mspace width="0.2em"/><mtext>pb</mtext></math>, respectively, in the full phase space. The results are compared and found to be consistent with predictions from two different matrix element generators with next-to-leading order accuracy in quantum chromodynamics, interfaced with a parton shower simulation.
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Bethani, A., Bruno, G., Bury, F., Caputo, C., David, P., Delaere, C., Delcourt, M., Donertas, I. S., Giammanco, A., Lemaitre, V., Mondal, K., Prisciandaro, J., Taliercio, A., Teklishyn, M., Vischia, P., Wertz, S., Wuyckens, S., & et al. (2021). First measurement of the cross section for top quark pair production with additional charm jets using dileptonic final states in pp collisions at s=13TeV. Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 820. https://doi.org/10.1016/j.physletb.2021.136565 (Original work published 2021)