Friday, September 23, 2011

Faster than light?

An experiment where a beam of neutrinos was fired from Geneva (CERN), to Gran Sasso, Italy, a distance of 730 kilometers, claims that the neutrinos reached their target 60 nanoseconds faster than a light beam would have, thereby violating a fundamental principle of special relativity, viz. nothing can travel faster than light.

Physics would undergo a stupendous change if it were true. The scientists who analysed the data said, "Although our measurements have low systematic uncertainty and high statistical accuracy, and we place great confidence in our results, we're looking forward to comparing them with those from other experiments". However, no one seriously believes this one; earlier claims of neutrinos that travel faster than light have not stood up to scrutiny. Still, this news item will have its moment of fame, so here is its blog post!

For a very clear discussion of the details of the experiment, see this link.

Tailpiece: A battered photon totters into a police station and tells a cop, "A bunch of neutrinos just beat me". The cop says: "Did you get a good look at them?" The photon says: "Heck, no, it all happened so fast!"

This blog post is by Neelima Gupte and Sumathi Rao.

Sunday, September 4, 2011

The case of the missing Higgs

As physicists, and those who follow physics, know, the Higgs boson is the most sought after particle in physics. The fanciful have even called it "the God particle". They also know that it is proving to be even more elusive than the snark.

The hunters had turned hopeful last month, when data from the Large Hadron Collider at CERN showed a flurry of events that were consistent with the Higgs. Two independent detectors, the ATLAS and the CMS (Compact Muon Solenoid) saw an excess of W bosons, an event considered to be a precursor of the Higgs, in the neighbourhood of 144 GeV. It was hoped that the signal would strengthen, and that the Lepton Photon meeting held in Mumbai in August would announce the discovery of the Higgs. Unfortunately, the latest results which use about twice the data show that the confidence levels in the data have fallen from 2.8 sigma to 2 sigma, i.e. from 99 percent to 95 percent, as researchers have included the effects of other processes that could give an excess of W bosons. (Followers of this blog will remember that 5 sigma results are required before a particle is declared as being discovered). What has been stated with confidence are the energy ranges where the Higgs is not, viz. between 145 and 400 GeV, and patches between 146 and 466 GeV. The Higgs might actually lurk at the lower ends of the energy spectrum viz. between 120 and 140 GeV. More data is awaited, and maybe a result by 2012.

Tailpiece: Why is the Higgs so eagerly awaited? The following hoary chestnut tells it all (thanks, Ashutosh): A Higgs boson walks into a church. The priest says, "We don't allow Higgs bosons in here." The Higgs boson says huffily, "But without me how can you have mass?"

This blog post is by Neelima Gupte and Sumathi Rao.