Can Cross-Border Financial Markets Create Endogenously Good Collateral in a Crisis?

In this paper, we explore whether markets can create endogenously good collateral in a crisis by analyzing a simple exchange economy where a country-specific catastrophic shock is shared between two countries. To see this possibility, we examine whether the equilibrium achieved by the time-0 complete markets with solvency constraints can be recovered in the dynamically complete markets with collateral constraints. This paper demonstrates that it is possible to recover the time-0 equilibrium outcome in a sequential manner when pricing errors occur randomly in evaluating Lucas trees at a catastrophic event. Such stochastic components may be interpreted as a policy initiative to create good collateral and yield constrained efficient outcomes at crisis periods.Solvency Constraints, Collateral Constraints, Dynamic Optimal Contract, Catastrophic Shocks

Hidden photon CDM search at Tokyo

We report on a search for hidden photon cold dark matter (HP CDM) using a novel technique with a dish antenna. We constructed two independent apparatus: one is aiming at the detection of the HP with a mass of $\sim\,\rm{eV}$ which employs optical instruments, and the other is for a mass of $\sim5\times10^{-5}\, \rm{eV}$ utilizing a commercially available parabolic antenna facing on a plane reflector. From the result of the measurements, we found no evidence for the existence of HP CDM and set upper limits on the photon-HP mixing parameter $\chi$.Comment: Contributed to the 11th Patras Workshop on Axions, WIMPs and WISPs, Zaragoza, June 22 to 26, 201

The Evolution of High Temperature Plasma in Magnetar Magnetospheres and its Implications for Giant Flares

In this paper we propose a new mechanism describing the initial spike of giant flares in the framework of the starquake model. We investigate the evolution of a plasma on a closed magnetic flux tube in the magnetosphere of a magnetar in the case of a sudden energy release and discuss the relationship with observations of giant flares. We perform one-dimensional numerical simulations of the relativistic magnetohydrodynamics in Schwarzschild geometry. We assume energy is injected at the footpoints of the loop by a hot star surface containing random perturbations of the transverse velocity. Alfv\'en waves are generated and propagate upward, accompanying very hot plasma that is also continuously heated by nonlinearly generated compressive waves. We find that the front edges of the fireball regions collide at the top of the tube with their symmetrically launched counterparts. This collision results in an energy release which can describe the light curve of initial spikes of giant flares.Comment: 13 pages, 11 figures, accepted for publication in Ap

Hadronic Paschen-Back effect

We find a novel phenomenon induced by the interplay between a strong magnetic field and finite orbital angular momenta in hadronic systems, which is analogous to the Paschen-Back effect observed in the field of atomic physics. This effect allows the wave functions to drastically deform. We discuss anisotropic decay from the deformation as a possibility to measure the strength of the magnetic field in heavy-ion collision at LHC, RHIC and SPS, which has not experimentally been measured. As an example we investigate charmonia with a finite orbital angular momentum in a strong magnetic field. We calculate the mass spectra and mixing rates. To obtain anisotropic wave functions, we apply the cylindrical Gaussian expansion method, where the Gaussian bases to expand the wave functions have different widths along transverse and longitudinal directions in the cylindrical coordinate.Comment: 8 pages, 8 figures, v3: updated to the published style on PL

Charmonium ground and excited states at finite temperature from complex Borel sum rules

Charmonium spectral functions in vector and pseudoscalar channels at finite temperature are investigated through the complex Borel sum rules and the maximum entropy method. Our approach enables us to extract the peaks corresponding to the excited charmonia, $\psi^\prime$ and $\eta_c^\prime$, as well as those of the ground states, $J/\psi$ and $\eta_c$, which has never been achieved in usual QCD sum rule analyses. We show the spectral functions in vacuum and their thermal modification around the critical temperature, which leads to the almost simultaneous melting (or peak disappearance) of the ground and excited states.Comment: 6 pages, 4 figures; published versio