Phase structure of NJL model with finite quark mass and QED correction

We study QED corrections to the chiral symmetry breaking in Nambu-Jona-Lasinio (NJL) model with two flavors of quarks. In the model the isospin symmetry is broken by differences of the current quark masses and the electromagnetic charges between up and down quarks. In the leading order of the 1/N expansion we calculate the effective potential of the model with one-loop QED corrections. Evaluating the effective potential, we study an influence of the isospin symmetry breaking on the orientation of chiral symmetry breaking. The current quark mass has an important contribution for the orientation of chiral symmetry breaking.Comment: 7 pages, 8 figures, To appear in the proceedings of the Workshop on Origin of Mass and Strong Coupling Gauge Theories, Nagoya, Japan, 21-24 November 200

Stochastic Gravitational Wave Background originating from Halo Mergers

The stochastic gravitational wave background (GWB) from halo mergers is investigated by a quasi-analytic method. The method we employ consists of two steps. The first step is to construct a merger tree by using the Extended Press-Schechter formalism or the Sheth & Tormen formalism, with Monte-Carlo realizations. This merger tree provides evolution of halo masses. From $N$-body simulation of two-halo mergers, we can estimate the amount of gravitational wave emission induced by the individual merger process. Therefore the second step is to combine this gravitaional wave emission to the merger tree and obtain the amplitude of GWB. We find $\Omega_{GW}\sim 10^{-19}$ for $f\sim 10^{-17}-10^{-16}$ Hz, where $\Omega_{GW}$ is the energy density of the GWB. It turns out that most of the contribution on the GWB comes from halos with masses below $10^{15} M_\odot$ and mergers at low redshift, i.e., $0<z<0.8$.Comment: 5 pages, 8 figures. Accepted for publication in Physical Review

Influence of QED Corrections on the Orientation of Chiral Symmetry Breaking in the NJL model

We study QED corrections to chiral symmetry breaking in the Nambu--Jona-Lasinio (NJL) model with two flavors of quarks. In this model, the isospin symmetry is broken by the differences between the current quark masses and the electromagnetic charges of the up and down quarks. To leading order in the 1/N expansion, we calculate the effective potential of the model with one-loop QED corrections at finite temperature. Evaluating the effective potential, we study the influence of the isospin symmetry breaking on the orientation of chiral symmetry breaking. The current quark mass plays an essential role in maintaining the orientation of the chiral symmetry breaking. If the average of the up and down quark masses is small enough, we find a phase in which the pion field has non-vanishing expectation value and dynamical CP violation takes place.Comment: 22 pages, 13 figures; added discussion about pion mass differenc

Composition and Antioxidant Activity of Rice Fermented with Saccharifying Organisms from Asian Countries

In recent years, more effective use of rice has become important because of an annual increase in surplus rice. We fermented rice in pure cultures of eight organisms (Aspergillus oryzae, Monaseus pilosus, Absidia corymbifera, Mucor circinelloides, Mucor racemosus, Rhizopus oligosporus, Rhizopus oryzae, and Saccharomycopsis fibuligera), which were isolated from molded rice and soybean products in Asian countries, and evaluated the composition and antioxidant activity of the products. Rice fermented with the two Rhizopus species had a high methanol extract yield, implying good fermentation properties. High saccharification and increased levels of total amino acids and total polyphenols were also found in Rhizopus-fermented rice samples. Ethyl acetate extracts of rice fermented with Ab. corymbifera and Mu. circinelloides had enhanced antioxidant activity compared to unfermented rice, and some fractions obtained from the extracts by high performance liquid chromatography exhibited high antioxidant activity. Based on these results, Ab. corymbifera, Mu. circinelloides, R. oligosporus, and R. oryzae are promising starter organisms for the development of new fermented rice products.ArticleFOOD SCIENCE AND TECHNOLOGY RESEARCH. 19(5):893-899 (2013)journal articl

Synchronously-pumped OPO coherent Ising machine: benchmarking and prospects

The coherent Ising machine (CIM) is a network of optical parametric oscillators (OPOs) that solves for the ground state of Ising problems through OPO bifurcation dynamics. Here, we present experimental results comparing the performance of the CIM to quantum annealers (QAs) on two classes of NP-hard optimization problems: ground state calculation of the Sherrington-Kirkpatrick (SK) model and MAX-CUT. While the two machines perform comparably on sparsely-connected problems such as cubic MAX-CUT, on problems with dense connectivity, the QA shows an exponential performance penalty relative to CIMs. We attribute this to the embedding overhead required to map dense problems onto the sparse hardware architecture of the QA, a problem that can be overcome in photonic architectures such as the CIM

A low vibration type compressor for refrigerators using a Self-standing support method

In household refrigerators, the rotational speed of a reciprocating compressor can be appropriately adjusted according to the temperature inside of the refrigerator. The lower rotational speed reduces the power consumption of the compressor. However, several natural frequencies of the compressor exist in the low rotation region, and besides, the unbalance force arising from the piston motion acts on the internal drive unit. Thereby the vibrations of the compressor are likely to be larger due to the resonance in the low rotation region. Although the compressor on the refrigerator is supported by vibration-proofing materials, such as rubber bushes, it is difficult to fully suppress the vibration transmission from the compressor to the refrigerator. In this study, therefore, a method for supporting the drive unit inside the shell, which is called “the self-standing support” is newly proposed in order to reduce the vibration of the compressor drastically. In the proposed method, a spherical support element is utilized instead of coil springs to support the drive unit. And the drive unit can maintain a stable self-standing state by acting restoring moment due to the gravity while it is directly placed on the shell. The natural frequencies of the compressor can be greatly reduced by decreasing the support stiffness for the drive unit in comparison with the support method using coil springs. Furthermore, in designing the drive unit, the application point of the exciting force is matched with the center of percussion to the contact point on the spherical support. As a consequence, the periodic restraining force acting on the contact point can be minimized. By these two features, it is possible to considerably reduce the vibration transmission from the drive unit to the shell. In the present study, a simplified model for a reciprocating compressor is treated, and the effectiveness of the self-standing support is investigated analytically and experimentally