Tuesday, July 03, 2007

No axions: PVLAS back to Earth

In March 2006, this blog and other blogs have informed about surprising results of the PVLAS collaboration:
Optical rotation in magnetic field
The polarization plane seemed to be affected by the presence of a magnetic field - an effect that could be explained by the existence of a new light scalar field called the axion.

However, the theoretical details of a model that would explain the observation didn't seem natural at all because they needed convoluted constructions to avoid astrophysical bounds, as Jacques Distler argued and I somewhat more passively agreed. Not surprisingly, we were right: the signal has disappeared:
Extraordinary statements - and a claim about a new light particle is always extraordinary - require extraordinary evidence and when honest scientists look for such evidence - a stronger signal - the previous weaker signals usually evaporate and the bombshell theories are falsified. This was no exception.

Thanks to Charles Tye!

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