Physicists shrink their next big accelerator

Because of high costs and a refocus in research goals, physicists have reduced the size of their proposed next big particle accelerator, which they hope will be built in Japan.

On 7 November, the International Committee for Future Accelerators (ICFA), which oversees work on the ILC, endorsed halving the machine’s planned energy from 500 to 250 gigaelectronvolts (GeV), and shortening its proposed 33.5-kilometre-long tunnel by as much as 13 kilometres. The scaled-down version would have to forego some of its planned research such as studies of the ‘top’ flavour of quark, which is produced only at higher energies.

Instead, the collider would focus on studying the particle that endows all others with mass — the Higgs boson, which was detected in 2012 by the Large Hadron Collider (LHC) at CERN, Europe’s particle-physics lab near Geneva, Switzerland.

Part of the reason for these changes is that the Large Hadron Collider has not discovered any new particles, other than the Higgs Boson. The cost to discover any remaining theorized particles was judged as simply too high. Better to focus on studying the Higgs Boson itself.

The Higgs boson has once again been confirmed with new data, and the scientists are disappointed!

The Higgs boson has once again been confirmed with new data, and the scientists are disappointed!

Alas, most of the Higgs results being presented this week at the Hadron Collider Physics symposium in Kyoto, Japan, have been well within our standard understanding. Physicists at ATLAS and CMS, the two largest particle detectors at the LHC, have about double the amount of data they did in July; this new data hasn’t dramatically changed the tentative conclusion that the LHC is seeing a plain-old Standard Model Higgs.

In other words, the theories are proving to be just about exactly right. No big surprises, which means no new mysteries to solve.

How the Higgs boson explains the universe.

How the Higgs boson explains the universe.

And what it can’t explain:

The discovery [by the existence of the Higgs boson] that nature is beautifully symmetric means we have very little choice in how the elementary particles do their dance – the rules simply “come for free”. Why the universe should be built in such an elegant fashion is not understood yet, but it leaves us with a sense of awe and wonder that we should be privileged to live in such a place.

Science discovers how the universe operates. Philosophy and religion try to explain why. Thus, it is perfectly reasonable in a rational world to consider the existence of God, and why musings about the possibility of intelligent design do not contradict pure science.

And I speak not as a religious person, but as a secular humanist.

From CERN: The experiments have observed a “particle consistent with long-sought Higgs boson.”

From CERN: The experiments there have now observed a “particle consistent with long-sought Higgs boson.”

The press release also emphasizes repeatedly the preliminary nature of this result. More details in this article, including this not unexpected punchline if you know science:

Already, the new boson seems to be decaying slightly more often into pairs of gamma rays than was predicted by theories, says Bill Murray, a physicist on ATLAS, the other experiment involved in making the discovery.

A rehash of the available data has narrowed the search for the Higgs particle.

A rehash of the available data has narrowed the search for the Higgs particle.

Taken together with data from the other detector, ATLAS, Higgs overall signal now unofficially stands at about 4.3σ. In other words, if statistics are to be believed, then this signal has about a 99.996% chance of being right.

It all sounds very convincing, but don’t get too excited, because the fact is that statistical coincidences happen every day. Over at Cosmic Variance, Sean Carroll points out that there is a 3.8σ signal in the Super Bowl coin toss.

CERN announces an update on the search for the Higgs Boson

Not there yet: CERN announces an update on the search for the Higgs Boson.

The main conclusion is that the Standard Model Higgs boson, if it exists, is most likely to have a mass constrained to the range 116-130 GeV by the ATLAS experiment, and 115-127 GeV by CMS. Tantalising hints have been seen by both experiments in this mass region, but these are not yet strong enough to claim a discovery.

LHC’s first year’s hunt for the Higgs is ending

The first year’s hunt by the Large Hadron Collider for the Higgs particle is ending.

Vivek Sharma of the University of California, San Diego, who heads the search for the Higgs at [one experiment], points out that results . . . have already ruled out, with a confidence of 2 sigma, a Higgs mass of between about 145 and 400 gigaelectronvolts, and that the LHC’s predecessor, the Large Electron Positron collider, ruled out a Higgs mass below about 114 gigaelectronvolts. So the Higgs, if it exists, almost certainly lies in the gap between the two. According to Sharma, the extra data to be collected in 2012 once proton-proton collisions resume in March will allow the CERN scientists to “either find the Higgs in this mass range, or wipe it out”.

If the Higgs particle turns out not to exist, it will mean that physicists will have to go back to the drawing board to explain all the phenomenon seen in the subatomic world.