A family of Higgs particles is predicted by many versions of a theory called supersymmetry, which says that all the known kinds of particles in nature have heavy, invisible twins that have yet to be discovered. So far at the LHC, there is no sign of supersymmetric particles, which have names such as "squarks" and "stops" and "gluinos". One of the great attractions of supersymmetry is that it shows how three of the four forces of nature were one in the early universe and separated later, leaving only gravity unaccounted for. Some particles predicted by supersymmetry are prime candidates to make up dark matter.
To produce a Higgs particle, the LHC smashes protons together about a billion times every second, producing something like one Higgs particle every 10bn collisions. Almost as soon as it is created the Higgs undergoes a radioactive decay into other particles and these are what the giant detectors see. Sometimes a dying Higgs converts into a pair of photons (particles of light), other times it converts into a pair of quarks and so on. We want to know not only how often Higgs particles are created but also how often they convert into the different types of particle. The data from Cern is quite consistent with the plain vanilla Higgs particle predicted in the simplest model but there are already hints that things may not be so straightforward and that really whets the appetite for the future.
However, more work needs to be done to figure out if this is indeed a Higgs boson or some unexpected renegade particle that just acts like the Higgs (although the latter is highly unlikely). Also, if it is a Higgs boson, is it a part of a larger Higgs family of particles?
In this high-stakes game of quantum mechanics, statistics and landmark particle discoveries, it can be hard to pronounce a definitive discovery of any subatomic particle, especially if it happens to be a particle that underpins the Universe's very existence.
"It's mind-boggling," said one. "Amazing," said another, and everyone in the close-knit physics community here was willing to liken its importance to the discovery of the DNA sequence in the human body.
The long-sought particle called the Higgs boson - if it's real - is what gives protons, electrons, neutrons and all the other particles inside atoms their mass, and was probably responsible for creating all the particles that first formed in the Big Bang, when the universe began.
Peter Higgs, the shy, soft-spoken Briton who in 1964 published the conceptual groundwork for the particle and whose name became associated with it, expressed delight.
“I never expected this to happen in my lifetime and shall be asking my family to put some champagne in the fridge,” the 83-year-old said in a statement.
The CMS team claimed they had seen a "bump" in their data corresponding to a particle weighing in at 125.3 gigaelectronvolts (GeV) - about 133 times heavier than the protons that lie at the heart of every atom.
They claimed that by combining two data sets, they had attained a confidence level just at the "five-sigma" point - about a one-in-3.5 million chance that the signal they see would appear if there were no Higgs particle.
However, a full combination of the CMS data brings that number just back to 4.9 sigma - a one-in-two million chance.
The Higgs boson appears in a theory first fleshed out in 1964 by Peter Higgs at Edinburgh University and five other physicists. Finding the particle proves there is an energy field that fills the vacuum of the observable universe. It plays the crucial role of giving mass to certain subatomic particles that are the building blocks of matter.
One peculiar aspect of this is that this Higgs field that permeates throughout all space is part of what we call empty space or the vacuum. It is only its impact on the particles that travel through it and the Higgs boson that we can observe in the laboratory. The Higgs boson lives for a very short amount of time so we don't observe it directly but rather we observe the particles it decays into and have to infer its existence from that.
According to the Standard Model, the Higgs boson is the only manifestation of an invisible force field, a cosmic molasses that permeates space and imbues elementary particles with mass. Particles wading through the field gain heft the way a bill going through Congress attracts riders and amendments, becoming ever more ponderous.
Without the Higgs field, as it is known, or something like it, all elementary forms of matter would zoom around at the speed of light, flowing through our hands like moonlight. There would be neither atoms nor life.
What is the Higgs boson?
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