Analysis of equi-intensity curves and NU distribution of EAS

The distribution of the number of muons in extensive air showers (EAS) and the equi-intensity curves of EAS are analyzed on the basis of Monte Carlo simulation of various cosmic ray composition and the interaction models. Problems in the two best combined models are discussed

Floating Black Hole in the Karch-Randall Model and its Holographic Dual

To investigate the holography in the Karch-Randall (KR) braneworld model, we construct time-symmetric initial data of black holes floating in the bulk, and compare it with its holographic dual, which is described by four-dimensional self-gravitating quantum field theory in asymptotically AdS_4 spacetime. We also give a definition and an explicit formula of mass in the KR model extending the definition by Abbott and Deser for asymptotically AdS spacetime. We obtain supporting evidence for the holography in the KR model such as good agreements of phase structures and characteristic values between the two theories, and find clues that the Hawking-Page transition of the four-dimensional quantum theory in a microcanonical ensemble is holographically dual to a transition in the bulk black hole configuration.Comment: 24 pages, 11 figure

Exact black hole solutions in shift symmetric scalar-tensor theories

We derive a variety of exact black hole solutions in a subclass of Horndeski's scalar-tensor theory possessing shift symmetry, $\phi\to\phi+c$, and reflection symmetry, $\phi\to-\phi$. The theory admits two arbitrary functions of $X:=-(\partial\phi)^2/2$, and our solutions are constructed without specifying the concrete form of the two functions, implying that black hole solutions in specific scalar-tensor theories found in the literature can be extended to a more general class of theories with shift symmetry. Our solutions include a black hole in the presence of an effective cosmological constant, the Nariai spacetime, the Lifshitz black hole, and other nontrivial solutions, all of which exhibit nonconstant scalar-field profile.Comment: 10 pages. v2: Corrected an erroneous statement in the first version. Matches version accepted by PTE

Angular momentum at null infinity in five dimensions

In this paper, using the Bondi coordinates, we discuss the angular momentum at null infinity in five dimensions and address the Poincare covariance of the Bondi mass and angular momentum. We also show the angular momentum loss/gain law due to gravitational waves. In four dimensions, the angular momentum at null infinity has the supertranslational ambiguity and then it is known that we cannot construct well-defined angular momentum there. On the other hand, we would stress that we can define angular momentum at null infinity without any ambiguity in higher dimensions. This is because of the non-existence of supertranslations in higher dimensions.Comment: 15 pages, published version in JM