2015/06/30 by Gang Li, Haoran Wang, Hao-Ran Wang +1
Physics and Astronomy · #Combinatorics #Coupling (piping) #Crystallography #Energy (signal processing) #Luminosity #Neutrino Physics Research #Particle Detector Development and Performance #Particle physics #Particle physics theoretical and experimental studies #Physics #Quantum mechanics #hep-ex #hep-ph
paper · pdf · doi:10.1103/physrevd.93.055038
published as Phys. Rev. D 93, 055038 (2016) · Published version. 19 pages, 11 figures, 3 tables. Discussion on the forward-backward asymmetry is added
openalex publication_date 2016/03/25 · arxiv created 2016/04/05 · arxiv updated 2016/04/06 · openalex created_date 2019/12/26 · openalex updated_date 2026/08/05
We investigate the possibility of probing the CP-violating htt coupling in the process e+e^\ensuremath-\ensuremath→h\ensuremathγ at the future high luminosity e+e^\ensuremath- colliders. Our numerical results show that the cross section for this process can be significantly increased for the allowed CP phase \ensuremathξ and center of mass energy. For example, the cross section is about 10 times that in the standard model (SM) for √(s)=350 GeV and \ensuremathξ=3\ensuremathπ/5 (see text for \ensuremathξ definition). The simulation for the signal process e+e^\ensuremath-\ensuremath→h\ensuremathγ\ensuremath→bb\ensuremathγ and its backgrounds shows that the signal significance can reach about 5\ensuremathσ and more than 2.1\ensuremathσ for √(s)=350 GeV and 500 GeV, respectively, with the integrated luminosity L=3 ab^\ensuremath-1 and \ensuremathξ\ensuremath∈[\ensuremathπ/2,3\ensuremathπ/5]. For L=10 ab^\ensuremath-1, the signal significance can be greater than 5\ensuremathσ for √(s)=350 GeV and about 4\ensuremathσ for √(s)=500 GeV with the CP phase \ensuremathξ\ensuremath∈[\ensuremathπ/2,3\ensuremathπ/5]. Besides the cross section enhancement, the CP-violating htt coupling will induce a forward-backward asymmetry AFB which is absent in the SM and is a clear signal of new CP violation. Compared with the AFB in the Higgs decay h\ensuremath→l+l^\ensuremath-\ensuremathγ, the AFB can be greatly enhanced in the production process. For example, AFB can reach \ensuremath-0.55 for \ensuremathξ=\ensuremathπ/4 and √(s)=500 GeV. Because of the large backgrounds, the significance of the expected AFB can be observed only at 1.68\ensuremathσ with L=10 ab^\ensuremath-1 and √(s)=500 GeV. It is essential to trigger the single photon in the final state to separate the bottom jets arising from scalar or vector bosons, in order to isolate the signal from the backgrounds more efficiently.