LHC reveals hints of ‘new physics’ in particle decays

Researchers from the Large Hadron Collider have shown off results that may help explain why the Universe is made largely of matter, not antimatter. Particles called D-mesons seem to decay slightly more often into one kind of particle rather than another, LHCb physicist Matthew Charles told the HCP 2011 meeting on Monday. The phenomenon may help explain our matter-dominated Universe. The team stresses that further analysis will be needed to shore up the result.

At the moment, they are claiming a statistical certainty of “3.5 sigma” – suggesting that there less than a 0.5% chance that the result they see is down to chance. The team has nearly double the amount of data that they have analysed so far, so time will tell whether the result reaches the “five-sigma” level that qualifies it for a formal discovery.

  • 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

via LHC reveals hints of ‘new physics’ in particle decays.

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