Speaker
Description
Recently, the CMS and ATLAS collaborations have reported a ttbar resonance excess near the ttbar threshold with above 5 sigma deviation from the SM pQCD prediction. This excess may be interpreted as a new pseudoscalar particle interacting with the top quark. Alternatively, it can be explained within the SM framework through toponium production—the bound state of a top quark pair, which can enhance the ttbar production cross section near the threshold. In this talk, I will discuss a combined scenario in which both a BSM particle and toponium production exist simultaneously, as would naturally occur if new physics couples to top quarks. In this case, not only does the pure BSM signal contribute to ttbar production, but the interference between the BSM particle and the SM also becomes very important. In particular, the interference can enhance or reduce the total cross section depending on the mass of the BSM particle. I will present how the interference modifies the total cross section and toponium line shape, and demonstrate its significant impact on constraining or reopening the BSM parameter space.