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SUMMARY:Twists in Top: Searching for (pseudo)scalar ttbar production
DTSTART:20250228T100000Z
DTEND:20250228T110000Z
DTSTAMP:20260815T222800Z
UID:indico-event-7795@indico.global
DESCRIPTION:Speakers: Alexander Grohsjean (Hamburg University (DE))\n\nIn 
 this seminar\, a search for heavy pseudoscalar or scalar bosons decaying t
 o a top quark pair (ttbar) in final states with one or two charged leptons
  will be presented. The resuls are based on 138 fb⁻¹ of proton-proton c
 ollisions at √s = 13 TeV recorded by the CMS experiment between 2016 and
  2018. The invariant mass of the reconstructed t̄t system\, along with va
 riables sensitive to its spin state\, are used to discriminate against the
  standard model t̄t background and infer properties of the spin quantum n
 umbers. An excess is observed in the data above the background prediction\
 , modeled using perturbative quantum chromodynamics (QCD) alone\, with a s
 ignificance exceeding five standard deviations.\nThree possible hypotheses
  to interpret the excess\, which is located near the t̄t production thres
 hold\, will be discussed: scalar production\, pseudoscalar production\, or
  the existence of a color-singlet pseudoscalar \\ttbar quasi-bound state\,
  as predicted in a simplified model of nonrelativistic QCD. For the first 
 two hypotheses\, upper limits on the coupling of pseudoscalar or scalar bo
 sons to top quarks will be presented in a mass range of 365–1000 GeV and
  relative widths of 0.5–25%. For the third scenario\, first cross-sectio
 n estimates will be shown\, and the stability of the result against altern
 ative background predictions will be discussed.\nGoogle Meet ROOM\n\n\nhtt
 ps://indico.global/event/7795/
LOCATION:Aula U2-01
URL:https://indico.global/event/7795/
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