Random matrix theory of unquenched two-colour QCD with nonzero chemical potential

We solve a random two-matrix model with two real asymmetric matrices whose primary purpose is to describe certain aspects of quantum chromodynamics with two colours and dynamical fermions at nonzero quark chemical potential mu. In this symmetry class the determinant of the Dirac operator is real but not necessarily positive. Despite this sign problem the unquenched matrix model remains completely solvable and provides detailed predictions for the Dirac operator spectrum in two different physical scenarios/limits: (i) the epsilon-regime of chiral perturbation theory at small mu, where mu^2 multiplied by the volume remains fixed in the infinite-volume limit and (ii) the high-density regime where a BCS gap is formed and mu is unscaled. We give explicit examples for the complex, real, and imaginary eigenvalue densities including Nf=2 non-degenerate flavours. Whilst the limit of two degenerate masses has no sign problem and can be tested with standard lattice techniques, we analyse the severity of the sign problem for non-degenerate masses as a function of the mass split and of mu. On the mathematical side our new results include an analytical formula for the spectral density of real Wishart eigenvalues in the limit (i) of weak non-Hermiticity, thus completing the previous solution of the corresponding quenched model of two real asymmetric Wishart matrices.Comment: 45 pages, 31 figures; references added, as published in JHE

Cosmological perturbation theory

This is a review on cosmological perturbation theory. After an introduction, it presents the problem of gauge transformation. Gauge invariant variables are introduced and the Einstein and conservation equations are written in terms of these variables. Some examples, especially perfect fluids and scalar fields are presented in detail. The generation of perturbations during inflation is studied. Lightlike geodesics and their relevance for CMB anisotropies are briefly discussed. Perturbation theory in braneworlds is also introduced.Comment: my course at the Second Aegean Summerschool on the Early Universe, 39 pages (I have corrected some typos

A small and light weight heat exchanger for on-board helium refrigerator

A small and light weight heat exchanger used for small helium refrigerator has been developed by Sumitomo Heavy Industries, Ltd. This heat exchanger is a laminated metal heat exchanger which consists of perforated aluminum metal plates and glassfiber reinforced plastic separators. The size is from 100 mm to 28 mm in diameter and about 300 mm in length. The weight is from 2.5 kg to 0.6 kg. Also it can be used between room temperature and liquid helium temperature. The thermal efficiency obtained has been more than 96%. The heat exchanger has been practically used for on-board helium refrigerator in Japanese National Railways' superconducting magnetic levitated trains

Double inflation in supergravity and the primordial black hole formation

We study a double inflation model (a hybrid inflation + a new inflation) in supergravity and discuss the formation of primordial black holes (PBHs) with mass \sim 10^{-20}-10^{5}M_{\odot}. We find that in a wide range of parameter space, we obtain PBHs which amount to \Omega \simeq 1, i.e., PBH dark matter. Also, we find a set of inflation parameters which produces PBHs evaporating now. Those PBHs may be responsible for antiproton fluxes observed by the BESS experiment.Comment: 14 pages, 2 figures (RevTeX file

Politics and eminent domain: Evidence from the 1879 California Constitution

This paper explores the politics of eminent domain, using a specific historical episode: the enactment of the new California constitution in 1879. It presents evidence that the failure of a constitutional provision that would have codified eminent domain powers for water development resulted from a complex interchange of economic interests among farmers, miners, and urban residents. This evidence was manifested in delegate behavior on the floor of the constitutional convention in 1878, including various roll-call votes, which are subjected to an econometric analysis. The results have implications for the interpretation of legislative eminent domain decisions, and the degree to which economic development processes are shaped by the institutional environment in which they occur

Judicial Deference and the Efficiency of the Common Law

Economists and legal scholars in the law-and-economics tradition have long been occupied with the question of whether, and the extent to which, the common law is efficient. There have been two main approaches taken in the scholarly literature. One approach has been to focus on judges, who are modeled having various motivations including, but not necessarily confined to, concern for efficient allocation of resources.1 However, to the extent they are concerned with efficiency, this attitude will be reflected in their opinions.2 This argument has been subject to criticism by scholars on various grounds, including questioning the assumption that judges are principally interested in promoting efficient resource use, at the expense of other arguments in their utility function such as ideology, fairness, and professional reputation and status

Transaction Costs in Water Transfers: The issue of local control

As water becomes increasingly scarce relative to demand, it becomes increasingly important to maximize the value that we derive from it. For years, economists have been advocating increased reliance on water markets as a means of rationalizing water use, the objective being to facilitate the allocation of water to its highest-value uses.1 Yet in many parts of the arid West, water markets have been surprisingly slow to take hold. Despite some recent progress, perhaps nowhere is this truer than in California.2 The conditions of extreme drought recently experienced by the state make it even more incumbent to better understand why water markets have been so slow to emerge