LHC Discovers New Particle That Looks Like the Higgs Boson 396
The wait is over: new submitter Roger W Moore (among many, many other submitters) writes "The ATLAS and CMS experiments at CERN have just announced the discovery of a new particle which is consistent with a Standard Model Higgs boson. There is still a lot of work to do to confirm whether this really is the Higgs, and if so whether it is a Standard Model Higgs, but this is a major result."
Re:Dr. Higgs himself said it best... (Score:5, Interesting)
Well it's not that much good luck really. CMS showed the expected significance of a SM Higgs boson for the full 5 channel combination to be ~6 sigma for 125 GeV. So seeing 4.9 sigma is actually a downward fluctuation (or in other words unlucky) or it's not Higgs.
Also, it's odd to see how much worse ATLAS was. They got 10% more statistics, yet see about the same significance as CMS. They also presented only 2 channels (true, the most sensitive ones) and didn't even attempt to fit the mass of the new particle (while CMS gave 125.3 +- 0.6 GeV, a precision of 0.5%!!!) nor did they look at the other supporting channels that could indicate if this is SM Higgs or some other particle. CMS as an example sees some tension in the 2tau final state where there is actually a downward fluctuation and almost exclusion of SM Higgs. CMS also showed first fits of couplings to fermions and bosons and that was very interesting result. ATLAS just claimed the 5 sigma and approximate mass. Really expected more of them...
Worth the waking hours (Score:5, Interesting)
And let it now please NOT be a standard-model Higgs boson, but something a little more intriguing!
Re:Careful Announcement (Score:4, Interesting)
And there are plenty of smart people in Batavia sitting atop the dormant tevatron (literally), in their little glass box linked to CERN, working on this. It looks like a mini NORAD in there.
It's not a football game. It's a scientific pursuit.
Re:Found at 125 GeV (Score:5, Interesting)
Photon propagation is affected by gravity, though.
But the Higgs mechanism isn't there to explain gravity. It's there to explain why some particles have rest masses at all. AIUI, a large part of the mass of a proton or neutron is explained by the energy stored in the Strong Nuclear binding field that couples the component quarks, but the Higgs mechanism is there to explain the rest.
Re:huh (Score:4, Interesting)
So... Now what? (Score:5, Interesting)
But honestly? I would have preferred we didn't find it. However deep we look, the universe appears to fit the standard model flawlessly, just a matter of adding more decimal places to our store of knowledge. So, we found it, the standard model prevails yet again - Where does that leave gravity and QCD? What do we look for now?
Or perhaps more to the point, does finding the Higgs, that everyone fully expected to find roughly where they found it, really answer anything? At the risk of sounding like I would ascribe some sense of agency to the question (I do not mean to - consider me an agnostic in the strictest epistemological sense), this just barely answers the "what"; Yet with billions of dollars and millions of man-hours and the highest tech known to Man, we haven't even come close to answering the "why". We have a handful of nice tidy self-contained islands that make up the fabric of the universe, with no better idea of why they exist or how they interact (in the mechanism sense, not the phenomenal sense) than we did a decade and many billions of dollars ago.
Re:So... Now what? (Score:3, Interesting)
http://en.wikipedia.org/wiki/Hierarchy_problem
So except for measuring all the particles' properties, which especially in case of the self-coupling will take many years, we will have to find an answer to the hierarchy problem. Hopefully that can come in the form of new physics, which is likely to also influence the Higgs boson properties like production and decay rates.
Re:Massive (Score:5, Interesting)
That's what she said.
You are oddly correct. Fabiola Gianotti [wikipedia.org] is in charge of the ATLAS detector.
Re:No, not really (Score:5, Interesting)
The Higgs field gives particles mass, and gravity acts on mass. Therefore, the Higgs field, while not binding the universe together, is vital for gravity to do so.
it's probably over-simplified (there's no quantum weirdness described), but I think it sums up the link well enough.
A thought occurs - if the Higgs is confirmed, and we find a way to cancel its effect out, hello anti-grav and inertia-free travel!
Maybe we've found the Force after all... :)
Re:Rest mass versus relativistic mass (Score:4, Interesting)
The E in E =mc^2 refers to the rest energy, which is indeed zero for a photon. There's also a component related to motion, and it can be shown from relativity that the total energy is given by E^2 = p^2c^2 + m^2c^4. For a photon of course, this means that E=pc.
Relativistic mass is a rather useless concept, since it doesn't behave as we'd intuitively think that mass would, and is in any case equivalent to the total energy mentioned above. Best to stick to rest mass, which has the useful feature of being independent of frame of reference.