Scientists may have found Higgs boson. What next?
Physicists working at CERN's Large Hadron Collider say it's possible they've discovered the long-sought 'God particle'. The Higgs boson could lead to 'new physics', they add.
(Page 2 of 2)
The standard model holds up very well at the low energies in today's universe and for most particle interactions, says University of Wisconsin physicist Wesley Smith, a member of one of the two teams. But when physicists try to crunch the numbers for the standard model at higher energy levels, they get pencil-snapping results – infinities.Skip to next paragraph
In Pictures Discovery of the 'God Particle'
Subscribe Today to the Monitor
That means that at higher energy levels, the standard model "must be wrong," he says.
One solution theorists have proposed to eliminate the nasty infinities is the existence of what Dr. Smith calls much more massive "shadow world" counterparts to the electrons, quarks, and other fundamental particles that standard model describes. These so-called supersymmetry theories in effect cancel out the infinities, making everyone happy.
But no one has found any supersymmetric particles.
"If the Higgs turns out to have some unusual properties, it might indicate that maybe it's not quite the standard-model Higgs, but it's a Higgs you might expect in a supersymmetric model," he says.
In addition to exploring the potential for new physics beyond the standard model, today's discovery – if it's a Higgs particle – would be the first detection of what physicists call a scalar boson.
Bosons are so-called force carriers, associated with the four forces of nature – electromagnetism, the strong force (which binds particles in an atom's nucleus), the weak force (which governs radioactive decay), and gravity. No particle has yet been found for gravity, although one has been proposed: the graviton. The other three – photons, gluons, and the W and Z bosons – have a property known as spin. The graviton is predicted to have spin as well. The Higgs boson is predicted to be the only spinless force carrier.
The Large Hadron Collider (LHC) accelerates two beams of protons traveling in opposite directions until the beams reach the desired collision-energy level. By then, they are traveling within a whisker of the speed of light. Magnets steer the beams through the underground beam lines, then focus them into hair-thin lines in anticipation of looming collisions.
These collisions take place in the hearts of two massive detectors – one for each team, and each with a unique design. This way, if both teams see the same results using independent approaches, both will have more confidence in the outcome.
The energy at the collision point crates new particles, which quickly decay into other particles that the collider's two massive detectors track. By analyzing the types of decay particles, their energies, and their paths through the detectors, researchers can determine the nature of the particle they fleetingly created.
One surprise for the teams came in discovering the particle when the LHC was running at slightly more than half its rated collision energy of 14 trillion electron-volts. The detections were made possible by the sheer number of protons in the beams during the accelerator's 2011 and especially its 2012 runs. Five hundred trillion protons were sacrificed in the production of these results. They yielded only a few tens or dozens of Higgs-like events, says Dr. Icandela.
And every one of those sacrificial protons came from a single, one-liter bottle of hydrogen gas, Dr. Smith adds.
Both teams give essentially the same mass estimate for the Higgs-like particle. Researchers with the CMS detector put the particle's mass at 125.3 billion electron-volts. The group associated with the second detector, dubbed ATLAS, put it at 126.5 billion electron-volts – essentially the same result, given the uncertainties in the data. In addition, both found that when the Higgs-like particles they created decayed, the decay produced at least two of the five combinations of decay particles that theories predict for a standard-model Higgs. Those decay "channels" also turned out to be the best ones to use to reconstruct the Higgs-like particle's mass.
The results – and answer to some of the remaining questions about the particle – should become clearer over the next several months. On Tuesday, CERN officials decided to run the collider for another three months, instead of shutting it down for a long-planned maintenance and upgrade outage. When the collider resumes operation at the end of the outage, engineers say it will be ready to run at its full collision energy.