Update: The spokespeople of the two major Higgs-hunting detectors have now confirmed that . 鈥淭he preliminary results with the full 2012 dataset are magnificent and to me it is clear that we are dealing with a Higgs boson,鈥� says CMS spokesperson Joe Incandela.
Original article, posted 12 March 2013
Say hello to Higgs. New data confirms that the unsatisfyingly named 鈥淗iggs-like particle鈥� announced at CERN last year really is a Higgs boson.
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Back then, the particle鈥檚 discoverers were sure it was a boson, one of two types of elementary particle, and that its mass was about 126 GeV. But their data couldn鈥檛 reveal all its properties.
Theory dictates that a Higgs boson must have a value of zero for a quantum mechanical property called spin, and positive 鈥減arity鈥�, which can be thought of as looking the same when reflected in a mirror. Data reported at the in La Thuile, Italy, last week all but nailed these two qualities.
Most importantly, though, a Higgs boson needs to have the role it was dreamed up to perform. Peter Higgs suggested that a mass-giving Higgs field pervades all space, in order to explain why the W and Z bosons have mass but the photon, another boson, doesn鈥檛. Photons zip through the field, others are slowed to different degrees corresponding to mass and the Higgs boson is a ripple in the field.
W decay
So the real clincher came when data presented at Moriond showed the first strong sign that the new particle decays into W bosons. A Higgs boson must decay into particles its field gives mass to. There was plenty of evidence that the particle decayed into Zs, but until Moriond, no good evidence that it decayed into Ws. The Moriond result prompted Adam Falkowski of CERN and colleagues to post the analysis .
There鈥檚 still an important distinction, though. 鈥淚t is legitimate to call this beastie 鈥榓鈥� Higgs boson,鈥� says Raymond Volkas, of the University of Melbourne in Australia, but not 鈥渢he Higgs鈥�.
While 鈥渁鈥� Higgs must at least give mass to the W and Z bosons, the leading standard model of particle physics assumes the boson gives mass to other elementary particles too, called fermions. This 鈥渟tandard model Higgs鈥� is 鈥渢he鈥� Higgs: testing for this involves measuring its rate of decay into fermions.
Though measurements so far indicate the new particle explains some of the mass of fermions, huge numbers of decays would need to be gathered to confirm it explains all of it 鈥� something the Large Hadron Collider at CERN may never be able to do.
Time to drop 鈥淗iggs-like boson鈥�? Falkowski thinks so: 鈥淎t this point, 鈥榣ike鈥� sounds silly.鈥�
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