Equity Price Dynamics Before and After the Introduction of the Euro

Daily data from the German and U.S. equity markets before and after the introduction of the Euro are used to study the effect of exchange rate regime choices on equity markets. It is found that, since the introduction of the Euro, the volatility and the persistence of the German stock index have fallen significantly relative to those of the U.S. index. However, the switch in exchange rate arrangement appears to have no significant implication for the causal relationships - both the mean and varianc causalities - between the two equity markets

Output Dynamics of the G7 Countries - Stochastic Trends and Cyclical Movements

Using a time series framework, the paper studies the interac tions of the annual real per capita GDP data of the G7 countries. We find evidence of six common nonstationary processes behind the international output dynamics. In addition, there is evidence for the existence of a common business cycle among these coun t ries. The trend and cycle components of each output series are obtained with a procedure that accounts for the presence of both the common nonstationary and cyclical factors. It is found that the relative variability and the correlation of the trend and cycle components are not similar across the G7 countries.

Equity Price Dynamics Before and After the Introduction of the Euro: A Note

Daily data from the German and U.S. equity markets before and after the introduction of the Euro are used to study the effect of exchange rate regime choices on equity markets. It is found that, since the introduction of the Euro, the volatility and the persistence of the German stock index have fallen significantly relative to those of the U.S. index. However, the switch in exchange rate arrangement appears to have no significant implication for the causal relationships – both the mean and variance causalities – between the two equity markets.

Stability of the spin-1/21/2 kagome ground state with breathing anisotropy

We numerically study the spin-$1/2$ breathing kagome lattice. In this variation of the kagome Heisenberg antiferromagnet, the spins belonging to upward and downward facing triangles have different coupling strengths. Using the density matrix renormalization group (DMRG) method and exact diagonalization, we show that the kagome antiferromagnet spin liquid is extremely robust to this anisotropy. Materials featuring this anisotropy -- and especially the recently studied vanadium compound $[{\mathrm{NH}}_{4}{]}_{2}[{\mathbf{C}}_{7}{\mathbf{H}}_{14}\mathbf{N}][{\mathbf{V}}_{7}{\mathbf{O}}_{6}{\mathbf{F}}_{18}]$ (DQVOF) -- may thus be very good candidates to realize the much studied kagome spin liquid. Further, we closely examine the limit of strong breathing anisotropy and find indications of a transition to a nematic phase.Comment: 12 pages, 15 figure

Equity Price Dynamics Before and After the Introduction of the Euro

Daily data from the German and U.S. equity markets before and after the introduction of the Euro are used to study the effect of exchange rate regime choices on equity markets. It is found that, since the introduction of the Euro, the volatility and the persistence of the German stock index have fallen significantly relative to those of the U.S. index. However, the switch in exchange rate arrangement appears to have no significant implication for the causal relationships - both the mean and varianc causalities - between the two equity markets.

Sectoral Trends and Cycles in Germany

We examine the comovements between the output indexes of three German sectors (manufacturing, mining, and agriculture) and the three corresponding sectoral stock market indexes. It is found that data with and without seasonal adjustment give mixed results on the long-run interaction between the sectoral indexes. Compared with data that are non-seasonally adjusted, the adjusted data offer a weaker evidence on the cointegration relationship between a) the sectoral output indexes, b) sectoral stock indexes, and c) individual pairs of real and financial indexes. On short-run comovement, seasonally adjusted data offer stronger evidence on the presence of common synchronized and non-synchronized cyclical components.

Bosonic Integer Quantum Hall effect in an interacting lattice model

We study a bosonic model with correlated hopping on a honeycomb lattice, and show that its ground state is a bosonic integer quantum Hall (BIQH) phase, a prominent example of a symmetry protected topological (SPT) phase. By using the infinite density matrix renormalization group method, we establish the existence of the BIQH phase by providing clear numerical evidence: (i) a quantized Hall conductance with $|\sigma_{xy}|= 2$ (ii) two counter propagating gapless edge modes. Our simple model is an example of a novel class of systems that can stabilize SPT phases protected by a continuous symmetry on lattices and opens up new possibilities for the experimental realization of these exotic phases.Comment: 7 pages, 6 figure

Kagome chiral spin liquid as a gauged U(1) symmetry protected topological phase

While the existence of a chiral spin liquid (CSL) on a class of spin-1/2 kagome antiferromagnets is by now well-established numerically, a controlled theoretical path from the lattice model leading to a low energy topological field theory is still lacking. This we provide via an explicit construction, starting from reformulating a microscopic model for a CSL as a lattice gauge theory, and deriving the low-energy form of its continuum limit. A crucial ingredient is the realisation that the bosonic spinons of the gauge theory exhibit a $U(1)$ symmetry-protected topological (SPT) phase, which upon promoting its $U(1)$ global symmetry to a local gauge structure ("gauging") yields the CSL. We suggest that such an explicit lattice-based construction involving gauging of an SPT phase can be applied more generally to understand topological spin liquids.Comment: 5+3 pages, 3+4 figure

Signatures of Dirac cones in a DMRG study of the Kagome Heisenberg model

The antiferromagnetic spin-$1/2$ Heisenberg model on a kagome lattice is one of the most paradigmatic models in the context of spin liquids, yet the precise nature of its ground state is not understood. We use large scale density matrix normalization group simulations (DMRG) on infinitely long cylinders and find indications for the formation of a gapless Dirac spin liquid. First, we use adiabatic flux insertion to demonstrate that the spin gap is much smaller than estimated from previous DMRG simulation. Second, we find that the momentum dependent excitation spectrum, as extracted from the DMRG transfer matrix, exhibits Dirac cones that match those of a $\pi$-flux free fermion model (the parton mean-field ansatz of a $U(1)$ Dirac spin liquid)Comment: 15 pages, 16 figure