## Wednesday, July 22, 2009

### Verka Serduchka

The Queen of Over the Top Music Videos is the Ukranian phenom Verka Serduchka. Here are some of my favorites:

### The GSI Anomaly

The GSI anomaly
Recently, an experiment at GSI Darmstadt has observed oscillating decay rates of heavy ions. Several controversial attempts have been made to explain this effect in terms of neutrino mixing. We briefly describe the experimental results, give an overview of the literature, and show that the effect cannot be due to neutrino mixing. If the effect survives, it could, however, be explained by hypothetical internal excitations of the mother ions (~ 10^(-15) eV).

Why a splitting in the final state cannot explain the GSI-Oscillations
In this paper, I give a pedagogical discussion of the GSI anomaly. Using two different formulations, namely the intuitive Quantum Field Theory language of the second quantized picture as well as the language of amplitudes, I clear up the analogies and differences between the GSI anomaly and other processes (the Double Slit experiment using photons, $e^+ e^- \to \mu^+ \mu^-$ scattering, and charged pion decay). In both formulations, the conclusion is reached that the decay rate measured at GSI cannot oscillate if only Standard Model physics is involved and the initial hydrogen-like ion is no coherent superposition of more than one state (in case there is no new, yet unknown, mechanism at work). Furthermore, a discussion of the Quantum Beat phenomenon will be given, which is often assumed to be able to cause the observed oscillations. This is, however, not possible for a splitting in the final state only.

### Do Electrons Oscillate?

Neutrino Oscillation is the theorectical explanation of the Solar Neutrino Problem. All attempts to measure the elusive neutrinos which should theorectically be produced by nuclear fusion in the sun came up short by a factor of three. The explanation is that neutrinos come in three flavors and they oscillate amongst the flavors while they travel.
The three flavors of neutrino correspond to the three flavors of electron, which include the muon and the tau - heavier, unstable particles otherwise very similar to the electron. So then shouldn't the different flavors of electron oscillate just like the neutrino flavors? The answer is they do, but it doesn't come up much in practice - see the post by Carlb in physics forums. Here's a previous blog post on the same topic: lepton oscillation.