2025/07/07 by The CMS Collaboration, The Cms Collaboration, CMS Collaboration · 2 voices · 15 citations
Physics and Astronomy · #hep-ex
paper · pdf · doi:10.48550/arxiv.2507.05119
A search for pseudoscalar or scalar bosons decaying to a top quark pair (\mathrmtt) in final states with one or two charged leptons is presented. The analyzed proton-proton collision data was recorded at √(s) = 13 TeV by the CMS experiment at the CERN LHC and corresponds to an integrated luminosity of 138 fb-1. The invariant mass m_\mathrmtt of the reconstructed \mathrmtt system and variables sensitive to its spin and parity are used to discriminate against the standard model \mathrmtt background. Interference between pseudoscalar or scalar boson production and the standard model \mathrmtt continuum is included, leading to peak-dip structures in the m_\mathrmtt distribution. An excess of the data above the background prediction, based on perturbative quantum chromodynamics (QCD) calculations, is observed near the kinematic \mathrmtt production threshold, while good agreement is found for high m_\mathrmtt. The data are consistent with the background prediction if the contribution from the production of a color-singlet 1S0[1] \mathrmtt quasi-bound state ηt, predicted by nonrelativistic QCD, is added. Upper limits at 95% confidence level are set on the coupling between the pseudoscalar or scalar bosons and the top quark for boson masses in the range 365-1000 GeV, relative widths between 0.5 and 25%, and two background scenarios with or without ηt contribution.