Pippa Wells
speaker
13 appearances
1 recordings
1 series
first heard Dec 2012
last heard Dec 2012
Pippa Wells’s voice in public audio — every appearance, attributed to the second.
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Appearances
My name is Pippa Wells, and I'm a physicist working at CERN in Geneva.
At the end of last year, we had a tantalising hint that there might be a new signal emerging in the data we'd been recording at the Large Hadron Collider.
And we're trying to answer various questions about how matter works.
Why do elementary particles have mass?
In the 1960s, several theorists proposed a mechanism to give mass to fundamental particles, and Peter Higgs realised that this new field that they needed would actually produce itself a new particle, the Higgs boson.
Over the last decades, people have been searching for the Higgs boson, and we were really hoping that this year we'd confirm it and be able to announce the discovery of the Higgs boson.
So my number for this year was five.
That's the significance we had to reach in order to be able to say that we'd really found something.
If you make a measurement, the data tends to spread around the central value, and the width of that spread is characterised by the standard deviation, which we call sigma, the Greek letter sigma.
About two-thirds of the data will be within one sigma of the central value, but we need to get five sigma away from the central value to be able to say we've actually made a significant discovery.
This means that the events we're seeing from well-known processes could not have fluctuated up to give a fake signal with a probability of more than one in 3.5 million.
To everyone's astonishment, both experiments had reached the five-sigma level, and both with the same mass for the Higgs boson of around 125 GV, so that's about 125 times heavier than a hydrogen atom.
So the fact both experiments had seen it, and what's more, with consistent mass in the two experiments, we were absolutely confident that we'd found something new.
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