Light wino dark matter in brane world cosmology

The thermal relic density of the wino-like neutralino dark matter in the brane world cosmology is studied. The expansion law at a high energy regime in the brane world cosmology is modified from the one in the standard cosmology, and the resultant relic density can be enhanced if the five dimensional Planck mass $M_5$ is low enough. We calculate the wino-like neutralino relic density in the anomaly mediated supersymmetry breaking scenario and show that the allowed region is dramatically modified from the one in the standard cosmology and the wino-like neutralino with mass of order 100 GeV can be a good candidate for the dark matter. Since the allowed region disappears eventually as $M_5$ is decreasing, we can find a lower bound on $M_5 \gtrsim 100$ TeV according to the neutralino dark matter hypothesis, namely the lower bound in order for the allowed region of the neutralino dark matter to exist.Comment: 16 pages, 9 figures, final versio

Neutralino dark matter in brane world cosmology

The thermal relic density of the neutralino dark matter in the brane world cosmology is studied. Since the expansion law at a high energy regime in the brane world cosmology is modified from the one in the standard cosmology, the resultant relic density can be altered. It has been found that, if the five dimensional Planck mass $M_5$ is lower than $10^4$ TeV, the brane world cosmological effect is significant at the decoupling time and the resultant relic density is enhanced. We calculate the neutralino relic density in the Constrained Minimal Supersymmetric Standard Model (CMSSM) and show that the allowed region is dramatically modified from the one in the standard cosmology and eventually disappears as $M_5$ is decreasing. We also find a new lower bound on $M_5 \gtrsim 600$ TeV based on the neutralino dark matter hypothesis, namely the lower bound in order for the allowed region of the neutralino dark matter to exist.Comment: 12 pages, 8 figure

Can only flavor-nonsinglet H dibaryons be stable against strong decays?

Using the QCD sum rule approach, we show that the flavor-nonsinglet $H$ dibaryon states with J$^{\pi} = 1^+$, J$^{\pi} = 0^+$, I=1 (27plet) are nearly degenerate with the J$^{\pi} = 0^+$, I=0 singlet $H_0$ dibaryon, which has been predicted to be stable against strong decay, but has not been observed. Our calculation, which does not require an instanton correction, suggests that the $H_0$ is slightly heavier than these flavor-nonsinglet $H$s over a wide range of the parameter space. If the singlet $H_0$ mass lies above the $\Lambda \Lambda$ threshold (2231~MeV), then the strong interaction breakup to $\Lambda \Lambda$ would produce a very broad resonance in the $\Lambda \Lambda$ invariant mass spectrum which would be very difficult to observe. On the other hand, if these flavor-nonsinglet J=0 and 1 $H$ dibaryons are also above the $\Lambda \Lambda$ threshold, but below the $\Xi^0n$ breakup threshold (2254 MeV), then because the direct, strong interaction decay to the $\Lambda \Lambda$ channel is forbidden, these flavor-nonsinglet states might be more amenable to experimental observation. The present results allow a possible reconciliation between the reported observation of $\Lambda \Lambda$ hypernuclei, which argue against a stable $H_0$, and the possible existence of $H$ dibaryons in general.Comment: 10 pages, 2 figure

How Do The Trans-Pacific Economies Affect the USA? An Industrial Sector Approach

This paper studies how the Trans-Pacific region affects the US economy in terms of business cycle transmission. We use a large data set consisting of disaggregated sectoral industrial production indexes from selected countries in the region and employ a factor-augmented vector autoregression (FAVAR) approach to analyze the transmission of shocks in different industries. We find that a positive output shock in the entire Trans-Pacific region has positive effects on the majority of US manufacturing sectors. We also find that sectoral shocks in five sectors of the Trans-Pacific region have a large impact on the overall US economy. Three of the five sectors displayed strong same-sector responses relative to the overall response, suggesting that vertical production linkages might play a key role in the transmission of shocks. Our results highlight the importance of examining industrial sectors in studying the transmission of shocks in the Trans-Pacific region

Discrete R-symmetry anomalies in heterotic orbifold models

Anomalies of discrete R-symmetries appearing in heterotic orbifold models are studied. We find that the mixed anomalies for different gauge groups satisfy the universal Green-Schwarz (GS) condition, indicating that these anomalies are canceled by the GS mechanism. An exact relation between the anomaly coefficients of the discrete R-symmetries and one-loop beta-function coefficients is obtained. We also find that the discrete R-symmetries have a good chance to be unbroken down to the supersymmetry breaking scale. Even below this scale a $Z_2$ subgroup is unbroken, which may be an origin of the R-parity of the minimal supersymmetric standard model. Relations between the R-symmetry anomalies and T-duality anomalies are also investigated.Comment: 19 pages, no figur

Examining Industrial Interdependence Between Japan and South Korea: A FAVAR Approach

This paper investigates the economic relationship between Japan and South Korea by incorporating disaggregated output measures. Using a factor-augmented vector autoregression (FAVAR) model, we conduct several experiments to test the nature of the interdependence, both in the aggregate and by sector. We find that South Korean output shocks affect the Japanese economy in a significant manner, whereas Japanese output shocks have a limited effect on South Korea. By further examining the transmission mechanism of sectoral output shocks and comparing them with the direction of sectoral trade, we find evidence of cross-border production sharing, which explains the asymmetric results seen in the aggregate output

Evidence for competition between the superconducting and the pseudogap state in (BiPb)_2(SrLa)_2CuO_{6+\delta} from muon-spin rotation experiments

The in-plane magnetic penetration depth \lambda_{ab} in optimally doped (BiPb)_2(SrLa)_2CuO_{6+\delta} (OP Bi2201) was studied by means of muon-spin rotation. The measurements of \lambda_{ab}^{-2}(T) are inconsistent with a simple model of a d-wave order parameter and a uniform quasiparticle weight around the Fermi surface. The data are well described assuming the angular gap symmetry obtained in ARPES experiments [Phys. Rev. Lett {\bf 98}, 267004 (2007)], where it was shown that the superconducting gap in OP Bi2201 exists only in segments of the Fermi surface near the nodes. We find that the remaining parts of the Fermi surface, which are strongly affected by the pseudogap state, do not contribute significantly to the superconducting condensate. Our data provide evidence that high temperature superconductivity and pseudogap behavior in cuprates are competing phenomena.Comment: 5 pages, 3 figure

Is Cognitive Science Truly Interdisciplinary?: The Case of Interdisciplinary Collaborations

The field of cognitive science is inherently multi?disciplinary. However, it is unclear to what extent truly interdisciplinary work occurs in cognitive science. That is, is cognitive science merely a collection of researchers from different disciplines working separately on commo n problems? Data gathered from a recent cognitive science conference are presented. Interestingly, a significant proportion of interdisciplinary collaborations were found. Analyses were also conducted on the impact of same vs. different backgrounds on the structure of collaborations, and It was found that interdisciplinary collaborations involved more equally distributed contributions among the authors than did intradisciplinary collaborations