Novel and Unique Expression for the Radiation Reaction Force, Relevance of Newton's Third Law and Tunneling

We derive the radiation reaction by taking into account that the acceleration of the charge is caused by the interaction with some heavy source particle. In the non relativistic case this leads, in contrast to the usual approach, immediately to a result which is Galilei invariant. Simple examples show that there can be small regions of extremely low velocity where the energy requirements cannot be fulfilled, and which the charged particle can only cross by quantum mechanical tunneling. We also give the relativistic generalization which appears unique. The force is a four-vector, but only if the presence of the source is taken into account as well. It contains no third derivatives of the position as the Lorentz-Abraham-Dirac equation, and consequently no run away solutions. All examples considered so far give reasonable results.Comment: 9 page

Baryon Acoustic Oscillations and Dynamical Dark Energy

We compute the impact of dark energy at last scattering on measurements of baryon acoustic oscillations (BAOs). We show that an early dark energy component can contribute a systematic uncertainty to BAO measurements of up to 2.5%. Whilst this effect turns out to only slightly affect current BAO surveys, the results of future BAO surveys might become biased. We find that BAO surveys alone appear unable to resolve this systematic uncertainty, so supplementary measurements are necessary.Comment: 4 pages, added sections and references, matches published versio