Magnetic order and moment distribution in doped spin-chain systems

We consider the effect of doping on the magnetic order in quasi one-dimensional (1D) antiferromagnets. First the detailed magnetic response of finite spin-1/2 chains in the presence of a staggered field is determined, which by itself shows an interesting crossover as function of length and field strength. We can then understand the ordering by including an effective coupling between the chains, which results in a Neel ordered phase at low temperatures, but with a broad distribution of magnetic moments that has to be determined self-consistently.Comment: 2 pages, 1 figure. Latest pdf-file is available at http://www.physik.uni-kl.de/eggert/papers/magorder.pd

Reply to the "Comment on 'Phase diagram of an impurity in the spin-1/2 chain: two channel Kondo effect versus Curie law'"

In a comment by A.A. Zvyagin the phase diagram in our Letter [Phys. Rev. Lett. 86, 516 (2001)] was critisized of being incomplete and a new fixed point was suggested. We show that this point is in fact not a fixed point and that the phase diagram is correct as presented.Comment: Reply to a comment by A.A. Zvyagin. 1 page, 1 figure. The latest version in PDF format is available from http://fy.chalmers.se/~eggert/papers/reply.pd

Recursive Method for the Density of States in One Dimension

We derive a powerful yet simple method for analyzing the local density of states in gapless one dimensional fermionic systems, including extensions such as momentum dependent interaction parameters and hard-wall boundaries. We study the crossover of the local DOS from individual density waves to the well-known asymptotic powerlaws and identify characteristic signs of spin charge separation in possible STM experiments. For semi-infinite systems a closed analytic expression is found in terms of hypergeometric functions.Comment: 5 pages and 3 figures. The latest version can be found at http://www.physik.uni-kl.de/eggert/papers/index.htm

A two-channel Kondo impurity in the spin-1/2 chain: Consequences for Knight shift experiments

A magnetic impurity in the spin-1/2 chain is a simple realization of the two-channel Kondo problem since the field theoretical descriptions in the spin-sector are identical. The correlation functions near the impurity can be calculated. Using a modified version of the numerical transfer matrix DMRG, we are able to accurately determine local properties close to the impurity in the thermodynamic limit. The local susceptibilities (Knight-shifts) show an interesting behavior in a large range around the impurities. We are able to make quantitative experimental predictions which would allow to observe two-channel Kondo physics for the first time directly by doping of spin-1/2 chain compounds.Comment: 2 pages in revtex format including 2 embedded figures (using epsf

Violence and Silence: The Prison Rape Elimination Act and Beyond

Connecting the #MeToo movement to sexual abuse in prisons, this paper analyzes the flaws of the Prison Rape Elimination Act of 2003. Examining the genesis behind PREA, the lack of enforcement and accountability, and the remaining unresolved issues, I argue that the law fails to meaningfully combat the pervasive and multifaceted problem of sexual abuse in US prisons. The racist, sexist, and homophobic ideologies that gave rise to PREA, as well as its focus on prison efficiency rather than prisoners’ lives, only serve to further entrench harmful biases within United States prisons and broader society

International Percussions of Direct Taxes

This paper anlyzes the impact of tax competition between two countries of un- equal per-capita capital endownments on tax rates and efficiency when distorting wage, residence-based and source-based capital taxes (or any combination of two instruments) are available for governments. The national welfare costs and benefits of tax rate variations are shown to be ambiguous in the asymmetric Nash equilibrium due to the existence of tax base and terms of trade effects. Moreover, numerical simulation results indicate that non-cooperative equilibria in Nash strategies are inefficient from an international perspective, even if residence-based capital taxes are in the set of tax instruments available to fiscal authorities.

International Percussions of Direct Taxes

This peper anlyzes the impact of tax competition between two countries of un- equal per-capita capital endownments on tax rates and efficiency when distorting wage, residence-based and source-based capital taxes (or any combination of two instruments) are available for governments. The national welfare costs and benefits of tax rate varia- tions are shown to be ambiguous in the asymmetric Nash equilibrium due to the existence of tax base and terms of trade effects. Moreover, numerical simulation results indicate that non-cooperative equilibria in Nash strategies are inefficient from an international perspective, even if residence-based capital taxes are in the set of tax instruments available to fiscal authorities.

Company tax coordination cum tax rate competition in the European Union

This paper reviews the recent theoretical literature that analyses the European Union's policy to eliminate preferential corporate tax regimes and the proposal to introduce a consolidated EU tax base with formula apportionment for the taxation of multinational firms. Since neither proposal includes a harmonisation of corporate tax rates, a core issue is how tax competition between member states will be affected by these partial coordination measures. The conclusions from our review are supportive of the EU's ban on preferential tax regimes, but the economic incentive effects of a switch to formula apportionment are found to be ambiguous

Double Taxation, Tax Credits and the Information Exchange Puzzle

This paper analyzes the choice of taxes and international information exchange by governments in a capital tax competition model. We explain situations where countries can choose tax rates on tax savings income and exchange information about the domestic savings of foreigners, implying that the decentralized equilibrium is efficient. However, we also identify situations with adverse welfare properties in which information exchange is compatible with zero taxes on capital income. The model helps to identify the linkage between voluntary information exchange and the choice of tax rates. It is shown that the recent development in information exchange treaties may not be useful to overcome the inefficiencies caused by decentralized tax setting.withholding tax, tax credit, international tax competition, information exchange