Scientists a step closer to finding Higgs boson

Published in The Hindu on December 15, 2011


The results announced from CERN on December 13 by the two teams — ATLAS and CMC — do not provide definite and conclusive evidence of the presence of the elusive Higgs boson, but they have collected sufficient data that is consistent with the possible appearance of the God particle.

According to theorists some subatomic particles gain mass by interacting with the Higgs boson. The Higgs boson is the only undiscovered part of the Standard Model of physics, which describes the basic building blocks of matter and their interactions.

The combined results presented last month by the two teams provided no room for the Higgs boson to hide in. The results had narrowed down the mass region where the Higgs particle is most likely to be — between 114 GeV and 141 GeV (gigaelectoron volt).

The latest results have further narrowed the mass range — 115-130 GeV range in the case of ATLAS, and 117-127 GeV by CMC. “We have not collected enough evidence for a discovery. There is an excess of events compatible with the hypothesis that it could be a Higgs,” Guido Tonelli, spokesman for CMC was quoted as saying in Nature . But more confirmatory data is required before its presence can be proved.

Possible mass

According to the journal, if supported by further data, the results suggest a Higgs particle with a mass of about 125 GeV.

This is because the ATLAS results are “consistent with a 125-126 GeV Higgs at a statistical level of at most 3.6 standard deviation, while the CMC team found 124 GeV signal of at most 2.6 standard deviation,” Nature states.

The ATLAS results are well above a standard deviation of 3 which is considered as evidence that a particular particle may exist.

A statistical significance of 5 standard deviations is considered as proof of a particle’s existence.

The results are based on nearly 500 trillion high energy proton-proton collisions inside the Large Hadron Collider at CERN.

So, by the end of 2012, nearly four times the current data will have been generated. Hence definite answers should be available in a year’s time.

But for now there is cautious optimism, and the search for the elusive particle has gained greater momentum.