Screening in two-dimensional gauge theories

We analyze the problem of screening in 1+1 dimensional gauge theories. Using QED2 as a warm-up for the non-abelian models we show the mechanism of the string breaking, in particular the vanishing overlap of the Wilson loops to the broken-string ground state that has been conjectured in higher-dimensional analyses. We attempt to extend our analysis to non-integer charges in the quenched and unquenched cases, in pursuit of the numerical check of a renowned result for the string tension between arbitrarily-charged fermions in the massive Schwinger model.Comment: 7 pages, 4 figures, proceedings of the XXX International Symposium on Lattice Field Theory, Cairns, Australi

The law of two prices: trade costs and relative price variability

The paper investigates whether deviations from the law of one price can attributed to real factors, such as transportation and distribution costs. Even if trade is costly, the prices of a good at di.erent locations will be linked as long as the good is traded. Instead of the usual iceberg assumption, I model costly trade as a transportation sector that uses real resources with potentially different factor intensities than the production of the good. First I use a latent factor model to see if distance specific ("transportation") and location specific ("retailing") factors can explain deviations from the law of one price across U.S. cities. For many products, these two factors explain 10-20% of all the variation in prices. The estimated transportation factor tends to move together with oil prices. Next I derive the variance of relative prices at di.erent locations when the price of transportation is determined in general equilibrium. This variance is high if (i) the good is costly to transport and (ii) it is produced with different factor intensities than transportation. Preliminary empirical results suggest that goods similar to transportation in terms of factor intensity have indeed lower relative price variability. As these goods tend to be costly to ship, this helps resolve the puzzling finding of Engel and Rogers (2001) that less tradable goods have less volatile relative prices.

Survey of free speeds on roads outside built-up areas with elevated speed limits in Hungary

In Hungary since 2008 some roads operate with posted speed limits which are higher than the general 90 kmph outside urban areas. The goal of the current study was to explore how well road users can recognize various types of roads. An on-line picture-show survey was made about the speed choices of 170 drivers at 35 different road scenes. The comparison with existing speed measurements showed a quite good match. Therefore the survey method is appropriate to estimate the drivers’ speed behaviour. The results show on one hand that on the usual road categories like motorways and normal two-lane primary roads the speed choice is clear for road users, i.e. these roads are self-explaining. On the other hand, there are also road categories, which are not self-explaining and therefore road users have difficulties to choose the appropriate speeds

Preliminary study of two-dimensional SU(N) Yang-Mills theory with adjoint matter by Hybrid Monte Carlo approach

Two-dimensional non-abelian quantum field models provide a useful laboratory for analytic and numerical investigations of quantum theories with gauge symmetry. They can exhibit various features, such as charge confinement, which are known from D=4 theories like QCD. Several analytic predictions concerning the spectra of two-dimensional systems with adjoint matter were postulated and numerical results were obtained using Discrete Light Cone Quantization techniques, however none of them has been checked via Monte Carlo simulations. In this Letter we present two such models which are particularly interesting from the physical point of view and discuss first numerical results.Comment: 7 pages, proceedings of The XXIX International Symposium on Lattice Field Theory, Squaw Valley, Lake Tahoe, Californi