Higgs hunt narrows


Pete Wilton | 13 Dec 11

Atlas Higgs LHC

Today scientists at the Large Hadron Collider announced tantalising news about the biggest piece missing from the physics jigsaw.

The Higgs boson is a hypothetical particle used to explain why many of the fundamental particles in the Standard Model of particle physics have mass.

Proving if it exists is tricky because the model doesn't predict its exact mass.

Now results from the Large Hadron Collider (LHC) suggest that, if it exists, the Higgs is most likely to have a mass between 116-130 gigaelectronvolts (GeV), according to the ATLAS experiment, and 115-127 GeV according to CMS.

Both experiments saw a ‘spike’ in their data around 124-125 GeV - this might be a random fluctuation or, as BBC News Online reports, it could just be a first glimpse of the Higgs.

Reacting to these early results Alan Barr of Oxford University’s Department of Physics, ATLAS UK physics coordinator, commented:

‘It is a testament to the superb performance of the LHC that we are already finding hints that might be indicative of Higgs bosons so early in the machine’s lifetime.

'The results are not yet conclusive, but during the next year we will know whether the Higgs boson exists in the form predicted by the “Standard Model” of particle physics. The analysis has to be done very carefully, since in scientific research the most interesting results are often found in unexpected places.

'We must bear in mind that the Standard Model is known to be incomplete, since it describes only that 5% of the universe that is made of atoms. What the LHC will tell us about the other 95% of the universe is likely to be an open question for many years to come.'

Chris Hays of Oxford University’s Department of Physics, another member of the ATLAS team, told me:

‘We have seen the first tantalizing hints of the Higgs boson after many years of pursuit. The concurrent signals in several different decay channels are suggestive.

‘Nonetheless the signals are still weak and more data are needed to determine if we are truly seeing the Higgs boson.’

UPDATE: Tony Weidberg, of Oxford University’s Department of Physics, also from the ATLAS team, comments:

'Science is a never ending frontier because as soon as one question is answered, more questions open up. If the hints of a standard model Higgs particle are confirmed next year, then the internal problems with the theory require the existence of new physics in the LHC energy regime.

'So this discovery would be the start of a new adventure. However, if we can exclude the existence of a Standard Model Higgs boson, then it raises the exciting question of just how particles like electrons do acquire mass. Again the LHC would be ideally placed to probe these questions.' 

Image: An event with four identified muons from a proton-proton collision in ATLAS. It could contain the signature of the Higgs boson.