Gauge Fields on Tachyon Matter

We study the rolling tachyon including the gauge fields in boundary string field theory. We show that there are no plane wave solutions for the gauge fields for large time. The disappearance of the plane wave solutions indicates that there are no excitations of the gauge fields on the tachyon matter, which is consistent with the Sen's conjecture.Comment: 6 pages, (v2)minor corrections (v3)some modifications, comments and a reference added (v4)some equations refined, to appear in Phys. Lett.

BPS Limit of Multi- D- and DF-strings in Boundary String Field Theory

A BPS limit is systematically derived for straight multi- D- and DF-strings from the D3D3bar system in the context of boundary superstring field theory. The BPS limit is obtained in the limit of thin D(F)-strings, where the Bogomolnyi equation supports singular static multi-D(F)-string solutions. For the BPS multi-string configurations with arbitrary separations, BPS sum rule is fulfilled under a Gaussian type tachyon potential and reproduces exactly the descent relation. For the DF-strings ((p,q)-strings), the distribution of fundamental string charge density coincides with its energy density and the Hamiltonian density takes the BPS formula of square-root form.Comment: 14 pages, 1 figur

On the general action of boundary (super)string field theory

We reconstruct boundary superstring field theory via boundary states. After a minor modification of the fermionic two-form, all the equations needed for Batalin-Vilkovisky formulation are simply represented by closed string oscillators and the proof of gauge invariance is drastically simplified. The general form of the action of boundary superstring field theory is also obtained without any assumption and found to take exactly the same form as the bosonic one. As a special case of this action, we revisit the conjecture that the action is simply given by the disk partition function when matter and ghosts are completely decoupled.Comment: 19 pages, minor correction

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

Remission of Congenital Multi-system Type Langerhans Cell Histiocytosis with Chemotherapy

Patients with multi-system (MS)-type langerhans cell histiocytosis (LCH) show poor outcomes, especially congenital MS LCH cases were shown in high mortality rate. We experienced a congenital case of MS LCH with high risk organs, who needed intensive respiratory support after birth. Even though intensive chemotherapy was discontinued, this patient’s lung LCH lesions gradually became reduced and his respiratory condition recovered; therefore, we restarted and completed maintenance chemotherapy. The patient maintained complete remission for more than 4 years after the end of chemotherapy. Our case suggests that congenital MS LCH even with severe organ involvement can be treated successfully with chemotherapy

Thermal Shock Resistances and the Irradiation Effects ot Graphites and C/C-Composites for Fusion Reactor Devices

Graphites and/or C/C-composites as plasma-facing first wall components for fusion reactor devices are subjected occasionally to plasma disruption. Therefore the thermal shock resistances and fracture toughnesses of these materials must be evaluated to assure appropriate performances. In this study, the thermal shock resistance and fracture toughness of several kinds of graphites and C/C-composites for candidate first wall component tiles are evaluated. The mechanical and fracture mechanics properties for these specimens are also measured. Then, two graphites and three C/C-composites are irradiated with 1.1-1.9×10^n/cm^2 (Energy>29fJ) at 650-1000℃ in a fission reactor (Japan Material Testing Reactor, JMTR) and the degradations in the thermal shock resistances and fracture toughnesses and the changes of mechanical and fracture mechanics properties due to the neutron irradiation are quantitatively studied

Dramatically Accelerated Formation of Graphite Intercalation Compounds Catalyzed by Sodium

Graphite intercalation compounds (GICs) have a variety of functions due to their rich material variations, and thus,innovative methods for their synthesis are desired for practical applications. We have discovered that Na has a catalytic property that dramatically accelerates the formation of GICs. We demonstrate that LiC6n (n = 1, 2), KC8, KC12n (n = 2, 3, 4), and NaCx are synthesized simply by mixing alkali metals and graphite powder with Na at room temperature (~25 {\deg}C), and AEC6 (AE = Ca, Sr, Ba) are synthesized by heating Na-added reagents at 250 {\deg}C only for a few hours. The NaCx, formed by the mixing of C and Na, is understood to act as a reaction intermediate for a catalyst, thereby accelerating the formation of GICs by lowering the activation energy of intercalation. The Na-catalyzed method, which enables the rapid and mass synthesis of homogeneous GIC samples in a significantly simpler manner than conventional methods, is anticipated to stimulate research and development for GIC applications.Comment: 10 pages, 4 figures, 1 tabl

Charge Transport in Ba1−x_{1-x}Rbx_{x}Fe2_{2}As2_{2} Single Crystals

Recent studies in heavily hole-doped iron-based superconductor RbFe$_2$As$_2$ have suggested the emergence of novel electronic nematicity directed along the Fe-As direction, 45$^\circ$ rotated from the usual nematicity ubiquitously found in BaFe$_2$As$_2$ and related materials. This motivates us to study the physical properties of Ba$_{1-x}$Rb$_{x}$Fe$_{2}$As$_{2}$, details of which remain largely unexplored. Here we report on the normal-state charge transport in Ba$_{1-x}$Rb$_{x}$Fe$_{2}$As$_{2}$ superconductors by using high-quality single crystals in the range of Rb concentration $0.14\le x \le 1.00$. From the systematic measurements of the temperature dependence of electrical resistivity $\rho(T)$, we find a signature of a deviation from the Fermi liquid behavior around the optimal composition, which does not seem related to the antiferromagnetic quantum criticality but has a potential link to hidden nematic quantum criticality. In addition, electron correlations derived from the coefficient of $T^2$ resistivity show a marked increase with Rb content near the heavily hole-doped end, consistent with the putative Mott physics near the $3d^5$ electron configuration in iron-based superconductors.Comment: 6 pages, 4 figure