Decaying Cosmological Constant of the Inflating Branes in the Randall-Sundrum -Oda Model

We examine the issue of the cosmological constant in the $many$ $inflating$ branes scenario, extending on two recent models by I.Oda and Randall-Sundrum. The exact solution in a closed form is found in the slow roll approximation of the radion. Defining an effective expansion rate, which depends on the location of each brane in the fifth dimension and demanding stability for this case we show that each positive tension brane has a localized, decaying cosmological constant (the opposite process applies to the negative energy branes [4]) . The reason is that the square of the effective expansion rate enters as a source term in the Einstein equations for the branes.Thus the brane has two scale factors depending on time and the fifth dimnesion respectively .The brane will roll along the fifth dimension in order to readjust its effective expansion rate in such a way that it compensates for its internal energy changes due to inflation and possible phase transitions.Comment: 9 pages, comments and ref.added, solution replaced with the exact one, submitted to PR

Soliton Solutions of M-theory on an Orbifold

We explicitly construct soliton solutions in the low energy description of M-theory on S^1/Z_2. It is shown that the 11-dimensional membrane is a BPS solution of this theory if stretched between the Z_2 hyperplanes. A similar statement holds for the 11-dimensional 5--brane oriented parallel to the hyperplanes. The parallel membrane and the orthogonal 5-brane, though solutions, break all supersymmetries. Furthermore, we construct the analog of the gauge 5-brane with gauge instantons on the hyperplanes. This solution varies nontrivially along the orbifold direction due to the gauge anomalies located on the orbifold hyperplanes. Its zero mode part is identical to the weakly coupled 10-dimensional gauge 5-brane.Comment: 19 pages, 1 figure, Latex, uses epsf.st

On the Friedmann Equation in Brane-World Scenarios

The Friedmann law on the brane generically depends quadratically on the brane energy density and involves a ``dark radiation'' term due to the bulk Weyl tensor. Despite its unfamiliar form, we show how it can be derived from a standard four-dimensional Brans-Dicke theory at low energy. In particular, the dark radiation term is found to depend linearly on the brane energy densities. For any equation of state on the branes, the radion evolves such as to generate radiation-dominated cosmology. The radiation-dominated era is conventional and consistent with nucleosynthesis.Comment: 4 pages. v2,v3: discussion on BBN extended, minor correction

Towards supersymmetric cosmology in M theory

We present a new solution in the heterotic M-theory in which the metric depends on (cosmic) time. The solution preserves N=1 supersymmetry in 4 dimensions in the leading order of the $\kappa^{2/3}$ expansion. It is the first example of the time-dependent supersymmetric solution in M-theory on $S^1/Z_2$. It describes expanding 4-dimensional space-time with shrinking orientifold interval and static Calabi-Yau internal space.Comment: latex, 12 page

One loop effective potential in heterotic M-theory

We have calculated the one loop effective potential of the vector multiplets arising from the compactification to five dimensions of heterotic M-theory on a Calabi-Yau manifold with h^{1,1}>1. We find that extensive cancellations between the fermionic and bosonic sectors of the theory cause the effective potential to vanish, with the exception of a higher order curvature term of the type which might arise from string corrections.Comment: Latex, 28 pages, 1 figur

Reactor Searches for Neutrino Magnetic Moment as a Probe of Extra Dimensions

We present calculations of the magnetic moment contribution to neutrino electron scattering in large extra dimension brane-bulk models (LED) with three bulk neutrinos. We discuss the cases with two and three large extra dimensions of sizes $R$. The calculations are done using reactor flux from Uranium, $^{235}U$ as the neutrino source. We find that if the electron neutrino mass is chosen to be in the range of one eV, the differential cross section for $\bar{\nu}-e$ scattering for low electron recoil energy can be of the same order as the presently explored values in reactor experiments. Furthermore the spectral shape for the LED models is different from the four dimensional case. Future higher precision reactor experiments can therefore be used to provide new constraints on a class of large extra dimension theories.Comment: 8 pages; 3 figure

Contributions of organic farming to a sustainable environment

Summary and Conclusions For each indicator organic farming is ranked at least equal to conventional farming, while in the majority of environmental indicators organic farming performs better or much better. In two cases, the subjective confidence interval could allow conventional farming to appear as the preferable system (partly due to the lack of evident data). However, when considering the aggregation level of the indicator categories, the analysis becomes more uniform. With the exception of climate and air, organic farming performs better than conventional farming in all categories. None of the indicator categories showed that organic farming performed worse. A summary assessment of all indicator categories was not carried out in the table, however, the result is clear: organic farming is, in an area-related comparison, more environmentally friendly than conventional farming. This result confirms one of the basic assumptions of the political support for organic farming, as mentioned in the introduction. On the one hand, the environmental performance of farms depends on the farming intensity, while on the other hand it depends on bio-tope management of nonproductive areas. The combination of organic farming with the conservation of semi-natural habitats and valuable field margins offers a real option to meet many environmental goals, especially biodiversity, on agricultural land