Monday, 14 June 2010

Minos points to neutrinos breaking CPT

One of the most fundamental theorems in quantum field theory, is the CPT theorem, it relates the properties of matter and anti-matter particles, and in particular shows that anti-particles must have the same mass and lifetime as ordinary particles. A recent measurement from MINOS, a accelerator neutrino experiment, has for the first time offered evidence that CPT is broken, it measured the mass difference between electron and muon neutrinos and also electron and muon anti-neutrinos, by watching them oscillate, changing form, in the 735Km between the Fermilab where the neutrinos are created and MINOS neutrino detector.
The first measurement show that the mass difference between electron and muon neutrinos is 40% smaller than for anti-neutrinos. The experimental uncertainty leaves just a 5% chance that the mass difference is the same for both particles. Unless some other effect such as interaction with the background matter along the journey has prevented some of the muon neutrinos oscillating to electron neutrinos, it looks like evidence of CPT violation for the first time. CPT violation also applies violation of Lorentz symmetry, so the effect would be in some way breaking specially relativity. I expect that this measurement may disappear as more data come in, but note that my Axial-force would imply that ordinary matter has a background sea of neutrinos that might interact with the travelling neutrinos (more so that anti-neutrinos), to slow the neutrino oscillation.

Monday, 7 June 2010

Supermassive Black Hole growth limits dark matter

Found an interesting article, at the daily galaxy. About a paper from from Dr. Xavier Hernandez and Dr. William Lee, (sorry, no article citation in the link, and couldn't find them with an ArXiv search), which looks at how the central black hole in the middle of a galaxy, absorbs dark matter. According to the Hernandez and Lee, if the density of dark matter in the centre of the galaxy, is greater than seven hole masses per cubic light year, the central black hole would grow fast than observation of black hole size predict. However ordinary theory of dark matter predict that concentration of dark matter is cuspy, tending to infinity as 1/r square, or so at the centres of galaxy. Thus some mechanism must intervene to prevent dark matter getting to dense. This could be annihilation of dark matter particles in the super-symmetric models, or formation of mirror stars, in the mirror matter model.