ATLAS Results: One Higgs Or Two? 73
TaeKwonDood writes with news from CERN about more results in the search for the Higgs Boson, this time from the ATLAS experiment. Researchers report peaks in the data in accordance with what they'd expect from the Higgs. The curiosity is that the peaks are a couple GeV away from each other. "The ATLAS analyses in these channels return the best fit Higgs masses that differ by more than 3 GeV: 123.5 GeV for ZZ and 126.6 GeV for gamma-gamma, which is much more than the estimated resolution of about 1 GeV. The tension between these 2 results is estimated to be 2.7sigma. Apparently, ATLAS used this last month to search for the systematic errors that might be responsible for the discrepancy but, having found nothing, they decided to go public." Scientific American has a more layman-friendly explanation available. As this work undergoes review, physicists hope more eyes and more data will shed some light on this incongruity. Tommaso Dorigo, a particle physicist working at the CMS experiment at CERN, writes, "Another idea is that the gamma-gamma signal contains some unexpected background which somehow shifts the best-fit mass to higher values, also contributing to the anomalously high signal rate. However, this also does not hold much water — if you look at the various mass histograms produced by ATLAS (there is a bunch here) you do not see anything striking as suspicious in the background distributions. Then there is the possibility of a statistical fluctuation. I think this is the most likely explanation." Matt Strassler provides a broader update to the work proceeding on nailing down the Higgs boson.
Re:The most wonderful exclamation in science (Score:5, Interesting)
I agree. I was actually annoyed that they found the Higgs where they predicted it to be. That meant that the Standard Model was all wrapped up, but without any sort of loose threads which we could pull to work out wtf was up with quantum gravity, or dark matter and dark energy. (Like the way the photoelectric effect and the ultraviolet paradox were the loose threads that lead to quantum mechanics.)
It would be really exciting if this result was real, and there's something funky about the Higgs which means the different experiements are detecting it at different masses. It might give us the kick in the pants we need to better understand the universe.
That said, it's probably going to be something banal like a miscalibrated detector shim, or an unaccounted-for term in one of the equations ... but a geek can hope.
Made me think of my Prof. (Score:5, Interesting)
So, I'm working on a cutesy undergraduate project with a physicist who works at the LHC (he is involved in a group searching for supersymmetry, so his primary work isn't the Higgs, but yeah). The project is a prototype for a new photo-detector.
In any case, I finally got the data acquisition working just a few days ago, (it uses a maple, a sort of a faster arduino. I just use the usb serial thingy, and 'cat' and file redirection, lol) so I ran and took some data counting hits from cosmic rays and with some easy python scripting to parse the output, I had a nice rough estimate of cosmic ray flux over my detector. I did a quick wiki search, and found a rate that was within the order of my result, so I typed up a mini report and emailed him my quick and dirty results while noting they were just that, quick and dirty. I was actually kind of proud of myself.
But, then he sent back this email, if I may quote him:
Thanks for the update. The approach of checking whether the coincident rate makes sense is a good step, but you need more information. Imagine, for example, that no one had every measured this before. Then, instead of checking if your answer is compatible with Wikipedia, we would be preparing to publish the measurement, and staking our reputation on its validity. In that case, we'd want to do a variety of things to be convinced that it is correct. I can imagine a couple of things to do[...]
And he listed a number of things try so I can be really sure of my measurements.
Think about this, the ATLAS guys could have announced the possibility of two peaks in their data and blown our frickin heads off into outer space after having already blown them off our shoulders with the Higgs, but they didn't because it wasn't a sure bet, as TFAs say...it could be background, it could be statistical fluctuations... In any case, there is something very wise about physicists and scientists in general who are often very cautious and untrusting about their measurements and are more than willing for you to double check their measurements and prove them wrong. Well, it could just be for reputation's sake. Whatever the motivation, I think this is one of the strengths of the scientific method and thus, one of the reasons for its success: we aren't quick to publishing until it is just right, and therefore, perhaps our best approximation of the "truth" we can muster.
This is not to take away from the times when certain people forget to tighten their fiber optic cables...but actually, that works wonderfully for my point...I sometimes feel impatient when I hear, "we're not quite sure yet" or ,"it's only preliminary" from some of these reports and I imagine some of you might too. Nonetheless, science isn't really star trek where you make a discovery, get locked into a phaser fight with it, and make peace in an hour time frame. It is a slow, careful process that at the end, as we see, yields good results in technology and the advances we have today. Therefore, it's worth the wait. So, have some patience, my reputation is on the line.
Re:The most wonderful exclamation in science (Score:5, Interesting)
But there's still hope in the TeV-per-parton scale the upgraded LHC will be able to reach in terms of finding what keeps the Top mass in check. Plus, dark matter's got to be made of something goddamnit, and it's hopefully not just cold neutrinos.
And of course, there may be new shit that we haven't even considered yet!
Re:The most wonderful exclamation in science (Score:3, Interesting)
I think with "ultraviolet paradox" he meant the problem Max Planck solved, that with classical physics you'd calculate the intensity of thermal (black body) radiation to always grow with growing frequency, giving rise to infinite total thermal radiation. Planck solved that problem by introducing the quantum hypothesis, that radiation energy can only be emitted in fixed portions proportional to the frequency.
The problem I think you are referring to is a problem in quantum field theory where certain integrals diverge, and which is solved using renormalization.
Re:Accuracy (Score:5, Interesting)
I'm pretty sure their huge device is just not accurate enough.
Of course! This would surely not have occurred to the particle physicists who built and operate the machine and published these results. It's a good job there are people like you who read about things on the internet and therefore know more than they do.
Two separate measurements can give different results based on how they configured the device.
I think they did a few more than two measurements, and I doubt they're dumb enough to go fiddling with the detector in the middle of a run.
Damn floccinaucinihilipilificationists...