First Post of the Year – First New Science from the LHC

The Large Hadron Collider has been running for over a year now and scientists have a massive amount of data to go through.

So far they have been looking for things we already know about, just to check the thing is working properly.

Now they have started looking for new Physics – in this case trying to work out why the antimatter and matter created at the Big Bang did not cancel each other out. 1 particle in billions of billions got left behind.

LHCb, the detector looking for the beauty quark has noticed that the matter and antimatter quarks are decaying in different ways.

You can see the red curve is different for matter B particles (left graph) and antimatter B particles (right graph). This extra time might be the reason why more matter existed than antimatter after the universe had started expanding.

At the moment the data is mostly certain (sigma 3.5) – we need a sigma of 5 for a formal discovery to be published. Sigma is a measure  standard deviation, the likelihood of the results being by chance.

  • Particle physics has an accepted definition for a “discovery”: a five-sigma level of certainty
  • The number of standard deviations, or sigmas, is a measure of how unlikely it is that an experimental result is simply down to chance rather than a real effect
  • Similarly, tossing a coin and getting a number of heads in a row may just be chance, rather than a sign of a “loaded” coin
  • The “three sigma” level represents about the same likelihood of tossing more than eight heads in a row
  • Five sigma, on the other hand, would correspond to tossing more than 20 in a row
  • A five-sigma result is highly unlikely to happen by chance, and thus an experimental result becomes an accepted discovery
Mr G
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