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The article offers information on the high energy physics research being conducted at the High Energy Accelerator Research Organization (KEK) in Japan. Topics cited include the formation of the organization as the National Laboratory for High Energy Physics in 1971, development of 12GeV proton synchrotron, organization's dedicated rings for photon science, and creation of neutron and muon beam lines.

This work provides an overview on the current status of phenomenology and searches for heavy vector-like quarks, which are predicted in many models of new physics beyond the Standard Model. Searches at Tevatron and at the LHC, here listed and shortly described, have not found any evidence for new heavy fermionic states (either chiral or vector-like) and have therefore posed strong bounds on their masses: depending on specific assumptions on the interactions and on the observed final state, vector-like quarks with masses up to roughly 400-600GeV have been excluded by all experiments. In order to be as simple and model independent as possible, the chosen framework for the phenomenological analysis is an effective model with the addition of a vector-like quark representation (singlet, doublet, or triplet under SU(2)L) which couples through Yukawa interactions with all SM families. The relevance of different observables for the determination of bounds on mixing parameters is then discussed and a complete overview of possible two body final states for every vector-like quark is provided, including their subsequent decay into SM particles. A list and short description of phenomenological analyses present in the literature are also provided for reference purposes. [ABSTRACT FROM AUTHOR]

This paper presents a newly developed compact model HiSIM-GaN [Hiroshima University STARC IGFET Model for GaN high electron mobility transistors (HEMTs)]. The developed model includes two specific features of GaN-HEMT to reproduce the power efficiency accurately. One is the two-dimensional electron gas induced at the heterojunction, which is modeled by considering the potential distribution across the junction including the trap density contribution. The second feature is the field plate, which is introduced to delocalize the electric-field peak that occurs at the electrode edge. Using HiSIM-GaN, device characteristics have been simulated. It is demonstrated that measured DC/AC characteristics are well reproduced with the developed model. The model has also been applied to analyze circuit characteristics of a boost converter. It is shown that the waveform is well reproduced by considering one half of the trap density extracted with measured DC characteristics due to the time constant of trap events. Furthermore, it is verified that the power efficiency as a function of the load current is predicted within an accuracy of 1%. Influence of the trap density and the field plate on circuit performances is also discussed. [ABSTRACT FROM AUTHOR]