Superpotentials of N=1 Supersymmetric Gauge Theories from M-theory

We consider brane configurations in M-theory describing N=1 supersymmetric gauge theories and using the parametric representation of the brane configurations, we calculate the superpotentials for various cases including multiple gauge groups or fermions. For SU(n) N=1 SQCD with $N_f$ fermion case ($N_f < N_c)$, we find that the superpotential from M-theory and the gauge theory agree precisely. This gives a direct evidence of the validity of Witten's M-theory method for calculating the super potential.Comment: 15pages, latex, typos corrected, a line regarding M\"obius transformation in page 4 and angle dependence in page 12 correcte

Can a "credit crunch" be efficient?

Two observations have sometimes been viewed as evidence that the equilibrium allocations of intermediated credit markets are inefficient. First, low-income households' marginal propensity to consume is close to unity. Second, even high-income households seem to face nonprice constraints during recessions. This paper presents a model that possesses both of these features. (A recession is modeled as an economy in which the equilibrium level of investment is at its lowest possible level.) However, contrary to the conventional view, the equilibrium of this model is ex ante efficient. The model also sheds light on some historical episodes of credit restraint.Credit

A Single-Stage Low-Power Double-Balanced Mixer Merged with LNA and VCO

This paper proposes three types of single stage low-power RF front-end, called double-balanced LMVs, by merging LNA, mixer, and voltage-controlled oscillator (VCO) exploiting a series LC (SLC) network. The low intermediate frequency (IF) or baseband signal can be directly sensed at the drain nodes of the VCO switching transistors by adding a simple resistor-capacitor (RC) low-pass filter (LPF). By adopting a double-balanced mixer topology, the strong leakage of the local oscillator (LO) at the IF output is effectively suppressed. Using a 65 nm CMOS technology, the proposed double-balanced LMVs (DB-LMVs) are designed. Oscillating at around 2.4 GHz ISM band, the phase noise of the proposed three DB-LMVs is −111 dBc/Hz at 1 MHz offset frequency. The simulated voltage conversion gain is larger than 36 dB and the double-side band (DSB) noise figure (NF) is less than 7.7 dB. The DB-LMVs consume only 0.2 mW dc power from 1-V supply voltage

K*{\Lambda}(1116) photoproduction and nucleon resonances

In this presentation, we report our recent studies on the $K^*\Lambda(1116)$ photoproduction off the proton target, using the tree-level Born approximation, via the effective Lagrangian approach. In addition, we include the nine (three- or four-star confirmed) nucleon resonances below the threshold $\sqrt{s}_\mathrm{th}\approx2008$ MeV, to interpret the discrepancy between the experiment and previous theoretical studies, in the vicinity of the threshold region. From the numerical studies, we observe that the $S_{11}(1535)$ and $S_{11}(1650)$ play an important role for the cross-section enhancement near the $\sqrt{s}_\mathrm{th}$. It also turns out that, in order to reproduce the data, we have the vector coupling constants $g_{K^*S_{11}(1535)\Lambda}=(7.0\sim9.0)$ and $g_{K^*S_{11}(1650)\Lambda}=(5.0\sim6.0)$.Comment: 2 pages, 2 figures, talk given at International Conference on the structure of baryons, BARYONS'10, Dec. 7-11, 2010, Osaka, Japa

Determination of the parity of the pentaquark baryons : Theta^+ and Xi_5

We study determination of the parity of the pentaquark baryons in two different processes. First, we investigate the Theta^+ production via the vec{p} vec{p} -> Sigma^+ Theta^+ reaction process which was proposed to determine unambiguously the parity of Theta^+. We observe the clear differences in the total cross sections and the spin observable A_{xx}. As for the Xi_5 in the bar{K} N -> K Xi_5 reaction process, the total cross section for the positive parity presents about one hundred times lager than that of the negative one due to the huge destructive interference.Comment: 5 pages, 8 figures, Talk given at International Workshop on BARYONS04, Ecole polytechnique, Paris, France, 25-29 Oct 200