Child Benefit and Fiscal Burden in the Endogenous Fertility Setting

This paper analyzes the possibility of improving the efficiency of child benefit programs in an overlapping generations economy that has endogenous fertility and large government debt levels. We derive the conditions for this improvement using Representative-Consumer and Children-for-Representative-Consumers efficiency criteria in the endogenous fertility setting, as proposed by Michel and Wigniolle (2007). We find that the result crucially depends on the relative amount of accumulated government debt in the economy. When the elasticity of interest rates to child benefit is close to zero and there exists a huge amount of accumulated debt in the economy, financing child benefit programs by issuing debt and using lump-sum tax leads to RC-improvements. This finding is likely to hold in the economies of developed countries that have low fertility rates. We finally provide the implications of these findings on the real economy.Endogenous fertility, Pareto-efficiency, child benefit, fiscal burden

Essays on Taxes and Donations.

This dissertation concerns donation and tax issues, significant for current policy making. Chapter I considers cases where fundraisers reflect donors’ preferences for the characteristics of public good. Relying solely on voluntary contributions, public good is always under-provided. Among many countermeasures of this under-provision issue, some fundraisers take into account large donors’ preferences. We formalize such a mechanism and prove that this mechanism enhances private contributions because of additional incentive to donate. Moreover, we find that government direct subsidy may not only crowds-out but also crowds-in private contributions under this mechanism. Crowding-in may occur because the influence of one’s contribution is leveraged by direct subsidy. Crowding-out may occur because direct subsidy decreases marginal utility of public good. We analytically deduce the condition where crowding-in/crowding-out occurs. Chapter II is a collaborated work with Hasegawa, Hoopes and Slemrod. The behavioral response to public disclosure of income tax returns figures prominently in policy debates about its advisability. Although supporters stress that disclosure encourages tax compliance, policy debates proceed in the absence of empirical evidence about this, and any other, claimed behavioral impact. This paper provides the first such evidence by examining the behavioral response to the Japanese tax return public notification system. The analysis suggests that, when there is a threshold for disclosure, a non-trivial number of both individual and corporate taxpayers whose tax liability would otherwise be close to the threshold will under-report so as to avoid disclosure — a response in the opposite direction from that stressed by supporters of disclosure. An analysis of corporations’ financial data offers no evidence that these companies’ taxable income declined after the end of the disclosure system. Chapter III finds factors that associate with donations just after the two disastrous earthquakes in Japan, 2011 Tohoku Earthquake and 1995 Hanshin Earthquake, using household-level monthly panel data. The novel finding is that geographical distance from the disaster epicenter negatively associates with private donations, which may indicate that distance negatively correlates with sympathy. Also, one who donated before the earthquakes tends to donate after the earthquake. Moreover, income, saving and age are found to be positive factors.PHDEconomicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/116678/1/rishida_1.pd

Hierarchy problem, gauge coupling unification at the Planck scale, and vacuum stability

From the point of view of the gauge hierarchy problem, introducing an intermediate scale in addition to TeV scale and the Planck scale ($M_{\rm Pl} = 2.4 \times 10^{18}\,{\rm GeV}$) is unfavorable. In that way, a gauge coupling unification (GCU) is expected to be realized at $M_{\rm Pl}$. We explore possibilities of GCU at $M_{\rm Pl}$ by adding a few extra particles with TeV scale mass into the standard model (SM). When extra particles are fermions and scalars (only fermions) with the same mass, the GCU at $M_{\rm Pl}$ can (not) be realized. On the other hand, when extra fermions have different masses, the GCU can be realized around $\sqrt{8 \pi} M_{\rm Pl}$ without extra scalars. This simple SM extension has two advantages that a vacuum becomes stable up to $M_{\rm Pl}$ ($\sqrt{8 \pi} M_{\rm Pl}$) and a proton lifetime becomes much longer than an experimental bound.Comment: 19 pages, 4 figures. Published version in NPB. Abstract and Introduction are revise

Search for new physics via photon polarization of b→sγb \rightarrow s \gamma

We suggest a discriminant analysis of new physics beyond the standard model through a detection of photon polarization in a radiative B meson decay. This analysis is investigated in SUSY SU(5) GUT with right-handed neutrino and left-right symmetric models. New physics search via CP asymmetry in the same process are also evaluated in each model for comparison. We show that new physics can be found via detecting the photon polarization in a parameter space of TeV energy scale.Comment: 20 pages, 8 figures, v2:references added, v3:published versio

Evolution of Synchrotron X-rays in Supernova Remnants

A systematic study of the synchrotron X-ray emission from supernova remnants (SNRs) has been conducted. We selected a total of 12 SNRs whose synchrotron X-ray spectral parameters are available in the literature with reasonable accuracy, and studied how their luminosities change as a function of radius. It is found that the synchrotron X-ray luminosity tends to drop especially when the SNRs become larger than ~5 pc, despite large scatter. This may be explained by the change of spectral shape caused by the decrease of the synchrotron roll-off energy. A simple evolutionary model of the X-ray luminosity is proposed and is found to reproduce the observed data approximately, with reasonable model parameters. According to the model, the total energy of accelerated electrons is estimated to be 10^(47-48) ergs, which is well below the supernova explosion energy. The maximum energies of accelerated electrons and protons are also discussed.Comment: 6 pages, 2 figures, ApJ, in pres

Dispersion cancellation in high resolution two-photon interference

The dispersion cancellation observed in Hong-Ou-Mandel (HOM) interference between frequency-entangled photon pairs has been the basis of quantum optical coherence tomography and quantum clock synchronization. Here we explore the effect of phase dispersion on ultranarrow HOM dips. We show that the higher-order dispersion, the line width of the pump laser, and the spectral shape of the parametric fluorescence have a strong effect on the dispersion cancellation in the high-resolution regime with several experimental verifications. Perfect dispersion cancellation with a linewidth of 3\mu m is also demonstrated through 25 mm of water.Comment: 6 pages, 6 figure

νR\nu_R dark matter-philic Higgs for 3.5 keV X-ray signal

We suggest a new model of 7 keV right-handed neutrino dark matter inspired by a recent observation of 3.5 keV X-ray line signal in the XMM-Newton observatory. It is difficult to derive the tiny masses with a suitable left-right mixing of the neutrino in a framework of ordinary simple type-I seesaw mechanism. We introduce a new Higgs boson, a dark matter-philic Higgs boson, in which the smallness of its vacuum expectation value can be achieved. We investigate suitable parameter regions where the observed dark matter properties are satisfied. We find that the vacuum expectation value of dark matter-philic Higgs boson should be about 0.17 GeV.Comment: 10 pages, 1 figure, v2:references added, minor changes, v3:published versio