Joint Theory Seminar
Speaker: Da Huang and Wei-Ping Pan
Title: (Talk 1) Cosmic Ray Excesses from Multi-component Dark Matter Decays
Host: Yuhsin Tsai
Room: 432
Abstract: (Talk 1)Last year AMS-02 collaboration published their measurement on the positron fraction in the cosmic rays, confirming the excesses by PAMELA. Also, the Fermi-LAT data on the total e^+ + e^- flux also showed excess above 20 GeV. In this talk, I shall show that the multi-component decaying dark matter (DM) scenario can naturally explain these two anomalies. By performing the chi-square fits, we find that two DM components are already enough to give a reasonable fit of both AMS-02 and Fermi-LAT data. As a byproduct, the fine structure around 100 GeV observed by AMS-02 and Fermi-LAT can be naturally explained by the dropping due to the lighter DM component. With the obtained model parameters by the fitting, we calculate the diffuse gamma-ray emission spectrum in this two-component DM scenario, and find that it is consistent with the data measured by Fermi-LAT. Finally, a microscopic particle DM model is constructed to naturally realize the two-component DM scenario, which points out an interesting neutrino signal which is possible to be measured in the near future by IceCube.
Title: (Talk 2) An effective gauge-Higgs operators analysis of new physics associated with the Higgs
Host: Yuhsin Tsai
Abstract: (Talk 2) We study the new physics(NP) related to the recent discovered 125 GeV Higgs by employing an important subset of the standard model(SM) gauge invariant dimension-six operators constructed by the the SM Higgs and gauge fields. Explicitly, we perform a model-independent study on the production and decays of the Higgs, the electric dipole moments(EDM) of the neutron and the electron, and we take into account the anomalous magnetic dipole moments of muon and electron as well.
We find that, even all Higgs decay channels agree with the SM predictions, the SM theoretical uncertainties provide a lot of room to host NP associated with the 125 GeV boson. A linear relation is revealed in our numerical study that muZZ~=muWW and 0.6=<muZZ,WW=<1.4 at 95% CL with or without the EDM's constraints. The neutron and electron EDM's severely constrain the relevant Wilson coefficients. Therefore the CP violating components in the h to WW,ZZ channels are too small, O(10^-5), to be detected at LHC. However, we point out that even the parity of the 125GeV boson has been largely determined to be even in the h to ZZ channel, one should pay special attention to the potentially large CP violation in the h to gamma gamma; and h to gamma Z channels. This should be seriously checked in the future spin correlation experiments.
Hiroshima Day