Sneutrino Inflation with Asymmetric Dark Matter

The asymmetric dark matter scenario is known to give an interesting solution for the cosmic coincidence problem between baryon and dark matter densities. In the scenario, the dark matter asymmetry, which is translated to the dark matter density in the present universe, is transferred from the B-L asymmetry generated in the early universe. On the other hand, the generation of the B-L asymmetry is simply assumed, though many mechanisms for the generation are expected to be consistent with the scenario. We show that the generation of the asymmetry in the sneutrino inflation scenario works similarly to the asymmetric dark matter scenario, because the non-renormalizable operator which translates the B-L asymmetry to the dark matter asymmetry is naturally obtained by integrating right-handed neutrinos out. As a result, important issues concerning cosmology (inflation, the mass density of dark matter, and the baryon asymmetry of the universe) as well as neutrino masses and mixing have a unified origin, namely, the right-handed neutrinos.Comment: 11 pages, 4 figures; v2: reference added, Fig. 3 changed and explanation added; v3: version accepted for publication in PR

無血清培養系を用いた口腔癌由来細胞株の樹立ならびに機能解析

広島大学(Hiroshima University)博士(歯学)Doctor of Philosophy in Dental Sciencedoctora

Detecting Android Malware by Analyzing Manifest Files

The threat of Android malware has increased owing to the increasingpopularity of smartphones. Once an Android smartphone is infected with malware, theuser suffers from various damages, such as the theft of personal information stored in thesmartphones, the unintentional sending of short messages to premium-rate numberswithout the user’s knowledge, and the ability for the infected smartphones to be remotelyoperated and used for other malicious attacks. However, there are currently insufficientdefense mechanisms against Android malware. This study proposes a new method todetect Android malware. The new method analyzes only manifest files that are required inAndroid applications. It realizes a lightweight approach for detection, and its effectivenessis experimentally confirmed by employing real samples of Android malware. The resultshows that the new method can effectively detect Android malware, even when thesample is unknown

Solving cosmological problem in universal extra dimension models by introducing Dirac neutrino

Universal extra dimension (UED) models with right-handed neutrinos are studied. The introduction of the neutrinos makes us possible not only to describe Dirac neutrino masses but also to solve the cosmological problem called the KK graviton problem. This problem is essentially caused by the late time decay of a KK photon into a KK graviton and a photon, and it distorts the spectrum of the cosmic microwave background or the diffuse photon. We point out that, once we introduce right-handed neutrinos to UED models, the KK photon decays dominantly into neutrinos and does not emit a photon. We also discuss sub-dominant modes with a photon in the decay quantitatively, and show that their branching ratios are so small that the spectra are not distorted.Comment: Some discussions are added