Archive by Author | profalanbarr

Higgs boson flies off top quarks

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Image: Wikipedia

The top is special. It is the heaviest quark by far – more than thirty times heavier than any of the other quarks.

According to the Standard Model, the monsterously heavy top quark should acquire all this mass through its interaction with the Higgs field. The theory tells us that the top is so heavy precisely because it feels the Higgs field more strongly than any other particle.

We can test the theory by making an experimental measurement of the strength of the relationship between the top quark and the Higgs field. To do so we must look at how often a Higgs boson gets spat out when top quarks are produced. This is known as “associated ttH production”, and it has just been measured by the ATLAS experiment at the LHC.

The early results are in and are consistent with expectations – so far. But the uncertainties are very large – about 60% – so there’s plenty of room for something odd to be going on. Any deviations would be very interesting. They might tell us that part of the mass of the top quark came from another source, such as the additional Higgs bosons required by many extensions to the Standard Model.

With more data pouring in all the time, this is a measurement worth keeping an eye on in the future…

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What are you talking about?

While the clicks are gathering, and while various people, including schools working with IRIS, are analysing the resulting data, I’ve been starting a study of what’s being discussed on the Talk forum. A wordcloud of the content of the comments already tells us quite a lot…

WordCloud from HiggsHunter talk

Unsurprisingly #ocv is the top-ranked hashtag as people indicate they’ve found an off-centre vertex.

As we might expect, citizen scientists use descriptors like “blue” or “white” to describe objects in the images, and then there’s also a good deal of further analysis, with words like “branches”, “center” and “detector”. Clearly some images are hard to interpret as they’re #messy, or otherwise generally a #toughie. Fortunately at least some are “interesting”!

It is great that there’s plenty of particle physics technical talk of “muon”, “quark”.  I love even more that the hashtag “#bundle” has developed its own meaning within the HiggsHunters community, even though it’s not one used in the generaly particle physics jargon. Clearly the Zooniverse’s citizen scientists are developing their own technical vocabulary for the images.

So my next job is to go out and understand those new terms…!

 

Schools start HiggsHunting

Discussions of the HiggsHunters team with Prof Peter Higgs at the schools launch in Edinburgh

Discussions of the Zooniverse team with Prof Peter Higgs at the HiggsHunters schools launch in Edinburgh

As part of the legacy of the HiggsHunters project, school children in the UK and around the world are being given the chance to search in the HiggsHunters data for new particles.

Getting schools doing cutting-edge research is the brainchild of the amazing school teacher Prof Becky Parker, who has set up the Institute for Research in Schools to bring real search from NASA, CERN and elsewhere to schools.
students2.pngPupils at the HiggsHunters schools launch

We launched the project to an audience of Scottish school kids and their teachers at the Royal Society of Edinburgh on 16th September. The expert panel answering their questions contained one particularly famous face in the field – Prof Peter Higgs himself.