Mr Raymond Co (University of California, Berkeley)
We are developing a simple supersymmetric axion theory by extending the MSSM with a gauge singlet axion field and right-handed neutrinos. To our surprise, this simple model has been overlooked in the literature, while models that introduce more singlet fields are intensively studied. In addition to the Peccei-Quinn solution to the strong CP problem, the achievements of our model are as follows. The mu problem in the MSSM is solved by the Kim-Nilles mechanism with an intermediate-scale axion decay constant (10^9-10^11 GeV) generated from dimension transmutation, unlike other axion models’ PQ breaking from the tree level potential minima. From the axion VEV, the right-handed neutrinos obtain a mass suitable for the seesaw mechanism. Dark matter is overproduced by the axino Freeze-In process, where the Higgsinos in the thermal bath decay to the SM Higgs and the axinos with feeble couplings. However, one can obtain the observed dark matter abundance using dilution from large entropy production of late decaying particles, like inflatons or moduli. Interestingly, the aforementioned Higgsino decay also leads to displaced vertices at LHC for a wide range of the parameter space in TeV-scale Supersymmetry.
Prof. Lawrence Hall (University of California, Berkeley)