The N=8 Supergravity Hamiltonian as a Quadratic Form

We conjecture that the light-cone Hamiltonian of N=8 Supergravity can be expressed as a quadratic form. We explain why this rewriting is unique to maximally supersymmetric theories. The N=8 quartic interaction vertex is constructed and used to verify that this conjecture holds to second order in the coupling constant.Comment: 23 pages, minor corrections in appendix

Comparison between predicted and observed sand waves and sand banks in the North Sea

For the first time a prediction model of regular morphological patterns on the seabed was tested against observations of sand wave and sand bank occurrence in the entire North Sea. The model, which originates from first physical principles, predicts this occurrence via two dimensionless parameters on the basis of the water depth, the tidal velocity amplitude, the level of zero intercept above the seabed (z0), and a viscosity variation parameter alt epsilon. The latter two quantities were varied in a number of predictions for the entire North Sea, whereas for the first two, local values were used. The range of realistic values of alt epsilon and z0 was large enough to let these two parameters distinguish between the possible (combinations of) bed forms, as is shown in the shallower southern bight of the North Sea. The results were more sensitive to variations in z0 than in alt epsilon. A slightly more detailed approach focused on sand waves only in the southern North Sea and estimated local values for z0 using depth information. Quantification of the results showed that the model was able to predict the contours of the sand wave patches, but it could not account for the absence of the bed features within this area. The type of bed deposit partly explains the smaller-scale variation. The work confirms the validity of the theoretical bed form prediction model and verifies the hypothesis that the large-scale seabed features are formed as free instabilities of tide-topography interactions

Non conventional screening of the Coulomb interaction in low dimensional and finite size system

We study the screening of the Coulomb interaction in non polar systems by polarizable atoms. We show that in low dimensions and small finite size systems this screening deviates strongly from that conventionally assumed. In fact in one dimension the short range interaction is strongly screened and the long range interaction is anti-screened thereby strongly reducing the gradient of the Coulomb interaction and therefore the correlation effects. We argue that this effect explains the success of mean field single particle theories for large molecules.Comment: 4 pages, 5 figure

Coloumb interaction and instability of CE-structure in half doped manganites

In their Letter (Phys. Rev. Lett. 83, 5118 (1999)), den Brink, Khaliullin, and Khomskii proposed theoretically that the one-dimensional ferromagnetic zigzag chains in CE phase in half-doped manganites play an essential role in forming the orbital ordering, and, more surprisingly, the on-site Coulomb interaction U between electrons with different orbitals leads to experimentally observed charge ordering. In this Comment, I point out that the strong U will destroy the stability of CE-type phase, which is stable in a very narrow regime in the parameter space for electronic model.To solve this issue finally, we have to take into account other interactions, such as the long-range Coulomb interaction, Jahn-Teller distortion, and physics of topological berry phase. For example, the effect of finite large J$_{H}$ leads to an attractive particle-hole interaction, which favors to stabilize the charge ordering.Comment: 1 page, 1 figure, To appear in Phys. Rev. Let

10^{10}Li spectrum from 11^{11}Li fragmentation

A recently developed time dependent model for the excitation of a nucleon from a bound state to a continuum resonant state in the system n+core is applied to the study of the population of the low energy continuum of the unbound $^{10}$Li system obtained from $^{11}$Li fragmentation. Comparison of the model results to new data from the GSI laboratory suggests that the reaction mechanism is dominated by final state effects rather than by the sudden process, but for the population of the l=0 virtual state, in which case the two mechanisms give almost identical results. There is also, for the first time, a clear evidence for the population of a d$_{5/2}$ resonance in $^{10}$Li.Comment: 15 pages, 4 figures, 3 tables. Accepted for publication in Nucl.Phys.

Games with permission structures: The conjunctive approach

Game Theory;econometrics

A Class of Consistent Share Functions For Games in Coalition Structure

A cooperative game with transferable utility -or simply a TU-game- describes a situation in which players can obtain certain payoffs by cooperation.A value function for these games is a function which assigns to every such a game a distribution of the payoffs over the players in the game.An alternative type of solutions are share functions which assign to every player in a TU-game its share in the payoffs to be distributed.In this paper we consider cooperative games in which the players are organized into an a priori coalition structure being a finite partition of the set of players.We introduce a general method for defining a class of share functions for such games in coalition structure using a multiplication property that states that the share of player i in the total payoff is equal to the share of player i in some internal game within i 's a priori coalition, multiplied by the share of this coalition in an external game between the a priori given coalitions.We show that these coalition structure share functions satisfy certain consistency properties.We provide axiomatizations of this class of coalition structure share functions using these consistency and multiplication properties.game theory

Games with permission structures: The conjunctive approach

Game Theory