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Seminars

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  • Title:Polarization effects in the search for a dark vector boson at e^+ e^− colliders
  • Start Date/Time:2021-03-18 / 12:30
  • End Date/Time :2021-03-18 / 13:30
    • Speaker:Prof. Guey-Lin Lin (National Yang Ming Chiao Tung University)
    • Place:R521, 5F, 2nd General Building, Nat'l Tsing Hua Univ.
    • Host:Prof. Kingman Cheung (NTHU)
    • Abstract:We argue that the search for dark vector boson through e^+e^− → Z_d γ can determine the Lorentz structure of Z_d l^+ l^− couplings with the detection of leptonic decays Z_d → l^+l^-. We assume a general framework that the dark vector boson interacts with ordinary fermions through vector and axial-vector couplings. As a consequence of Ward-Takahashi identity, Z_d is transversely polarized in the limit m_Zd ≪ sqrt{s}. On the other hand, the fraction of longitudinal Z_d is non-negligible for m_Zd comparable to sqrt{s}. Such polarization effects can be analyzed through angular distributions of final-state particles in Z_d decays. Taking l ≡ μ, we study the correlation between Z_d angle relative to e^− beam direction in e^+e^- center of momentum frame and μ− angle relative to the boost direction of Z_d in Z_d rest frame. This correlation is shown to be useful for probing the Lorentz structure of Z_d l^+ l^− couplings. We discuss the measurement of such correlation in Belle II detector, taking into account the detector acceptance and energy resolution.


      [List of Attendees Registered for the Lunchboxes] 


      [Lunchbox Registration]
      If you will attend the seminar and would like to have a lunchbox on that day, please fill out the online registration form below by 10:00AM Mar. 17th (Wednesday morning). Late registration will not be accepted.
      *Note:
      1. The lunchboxes will only be prepared for the participation of professors and postdoctoral researchers.

      2. In order to prevent the potential spread of COVID-19, we suggest that you bring your own face mask and wear it while attending the seminar.
      3. You may check this web page again later after you have completed the online registration. The data for the list of registered attendees will be updated every 5 minutes and shown at the page. 


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