Large N Expansion and Softly Broken Supersymmetry

We examine the supersymmetric non-linear O(N) sigma model with a soft breaking term. In two dimensions, we found that the mass difference between supersymmetric partner fields vanishes accidentally. In three dimensions, the mass difference is observed but O(N) symmetry is always broken also in the strong coupling region.Comment: Plain Latex(8pages), No Figur

Q ball inflation

We show that inflation can occur in the core of a Q-ball.Comment: 11 pages, latex2e, no figure, references added, final version to appear in PR

String production after angled brane inflation

We describe string production after angled brane inflation. First, we point out that there was a discrepancy in previous discussions. The expected tension of the cosmic string calculated from the four-dimensional effective Lagrangian did not match the one obtained in the brane analysis. In the previous analysis, the cosmic string is assumed to correspond to the lower-dimensional daughter brane, which wraps the same compactified space as the original mother brane. In this case, however, the tension of the daughter brane cannot depend on the angle (\theta). On the other hand, from the analysis of the effective Lagrangian for tachyon condensation, it is easy to see that the tension of the cosmic string must be proportional to \theta, when \theta << 1. This is an obvious discrepancy that must be explained by consideration of the explicit brane dynamics. In this paper, we will solve this problem by introducing a simple idea. We calculate the tension of the string in the two cases, which matches precisely. The cosmological constraint for angled inflation is relaxed, because the expected tension of the cosmic string becomes smaller than the one obtained in previous arguments, by a factor of \theta.Comment: 13pages, 3 figures, typos correcte

Hybridized Affleck-Dine baryogenesis

We propose a novel scenario for Affleck-Dine baryogenesis in the braneworld, considering the hybrid potential for the Affleck-Dine field. Destabilization of the flat direction is not due to the Hubble parameter, but is induced by a trigger field. The moduli for the brane distance plays the role of the trigger field. Q-balls are unstable in models with large extra dimensions.Comment: 10pages, plain latex2e, references added, to appear in PR

Evolution of Paramagnetic Quasiparticle Excitations Emerged in the High-Field Superconducting Phase of CeCoIn5

We present In NMR measurements in a novel thermodynamic phase of CeCoIn5 in high magnetic field, where exotic superconductivity coexists with the incommensurate spin-density wave order. We show that the NMR spectra in this phase provide direct evidence for the emergence of the spatially distributed normal quasiparticle regions. The quantitative analysis for the field evolution of the paramagnetic magnetization and newly-emerged low-energy quasiparticle density of states is consistent with the nodal plane formation, which is characterized by an order parameter in the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state. The NMR spectra also suggest that the spatially uniform spin-density wave is induced in the FFLO phase.Comment: 4 pages, 4 figures, accepted for publication in Phys. Rev. Let

Doping evolution of the electronic specific heat coefficient in slightly-doped La2-xSrxCuO4 single crystals

Detailed doping dependence of the electronic specific heat coefficient gamma is studied for La2-xSrxCuO4 (LSCO) single crystals in the slightly-doped regime. We find that gamma systematically increases with doping, and furthermore, even for the samples in the antiferromagnetic (AF) regime, gamma already acquires finite value and grows with x. This suggests that finite electronic density of states (DOS) is created in the AF regime where the transport shows strong localization at low temperatures, and this means the system is not a real insulator with a clear gap even though it still keeps long range AF order.Comment: 4 pages, 4 figures, accepted for publication in Journal of Physics: Conference Series (LT25 proceeding

Magnetic measurements at pressures above 10 GPa in a miniature ceramic anvil cell for a superconducting quantum interference device magnetometer

A miniature ceramic anvil high pressure cell (mCAC) was earlier designed by us for magnetic measurements at pressures up to 7.6 GPa in a commercial superconducting quantum interference (SQUID) magnetometer [N. Tateiwa et al., Rev. Sci. Instrum. 82, 053906 (2011)]. Here, we describe methods to generate pressures above 10 GPa in the mCAC. The efficiency of the pressure generation is sharply improved when the Cu-Be gasket is sufficiently preindented. The maximum pressure for the 0.6 mm culet anvils is 12.6 GPa when the Cu-Be gasket is preindented from the initial thickness of 0.30 to 0.06 mm. The 0.5 mm culet anvils were also tested with a rhenium gasket. The maximum pressure attainable in the mCAC is about 13 GPa. The present cell was used to study YbCu2Si2 which shows a pressure induced transition from the non-magnetic to magnetic phases at 8 GPa. We confirm a ferromagnetic transition from the dc magnetization measurement at high pressure. The mCAC can detect the ferromagnetic ordered state whose spontaneous magnetic moment is smaller than 1 mB per unit cell. The high sensitivity for magnetic measurements in the mCAC may result from the the simplicity of cell structure. The present study shows the availability of the mCAC for precise magnetic measurements at pressures above 10 GPa

Superconducting Plasma Excitation at Microwave Frequencies in Parallel Magnetic Fields in Bi2Sr2CaCu2O8+δ\mathrm{\mathbf{Bi_2Sr_2CaCu_2O_{8+\delta}}}

Josephson plasma resonance has been studied in a wide microwave frequency range between 10 and 52 GHz in a magnetic field parallel to the $ab$-plane in under-doped \BI. Above about 30 GHz two resonance modes were observed: one (LT mode) appears at low temperatures and another (HT mode) at higher temperatures, leaving a temperature gap between two regions. These two resonance modes exhibit a sharp contrast each other both on temperture and magnetic field dependences and show distinct characters different entirely from the c-axis Josephson plasma resonance. From temperature and field scan experiments at various frequencies it is suggested that the LT mode can be attributed to the coupled Josephson plasma mode with Josephson vortices, while the HT mode is a new plasma mode associated possibly with the periodic array of Josephson vortices.Comment: submitted to Physica C (Prceedings of Plasma2000, Sendai