SoylentNews is people
SoylentNews
Two of the Large Hadron Collider (LHC) detectors, CMS and ATLAS, have seen excess photon pairs that hint at the existence of a previously unknown boson with a mass of about 1500 GeV [gigaelectronvolt], which is about 12 times larger than the mass of the Higgs boson. The excess photons turned up while searching through data looking for gravitons. By themselves the data are not very significant and would not have garnered much interest, but this becomes more interesting since both experiments saw these statistical bumps in the same place. The next round of data taking in March will be able to determine whether this particle really exists.
In addition to what they might have found, also of interest is what they haven't found:
Meanwhile, searches for particles predicted by supersymmetry, physicists' favourite extension of the standard model, continue to come up empty-handed. To theoretical physicist Michael Peskin of the SLAC National Accelerator Laboratory in Menlo Park, California, the most relevant part of the talks concerned the failure to find a supersymmetric particle called the gluino in the range of possible masses up to 1,600 GeV (much farther than the 1,300-GeV limit of Run 1). This pushes supersymmetry closer to the point where many physicists might give up on it, Peskin says.
(Score: 2) by Covalent on Wednesday December 16 2015, @04:57PM
I'm assuming from the article / summary that this isn't a gluino (correct me if I'm wrong).
If so, then what is it? Does the standard model predict anything this heavy / energetic? If not, then does that indicate a crack in the standard model?
Facts people...I need some.
You can't rationally argue somebody out of a position they didn't rationally get into.
(Score: 3, Informative) by Anonymous Coward on Wednesday December 16 2015, @05:08PM
An unknown particle. Or maybe just a statistical anomaly without any meaning. That's what they want to find out next year.
No. The Higgs particle was the last standard model particle to be found. You can say for sure that any new particle they may find is not predicted by the standard model.
What is "a crack in the standard model"? It certainly indicates physics beyond the standard model. But that doesn't imply that the standard model is wrong, just incomplete.
(Score: 1, Informative) by Anonymous Coward on Wednesday December 16 2015, @06:00PM
short answer: they suspect it could be the graviton.
long answer: they don't know yet and they don't even know that there *is* something, there is just some discrepancy in their data (a bump as they call it) which could be explained as well by a new particle or by statistical noise. However, the Higgs boson was detected just that way in the beginning: it was but a bump in the data that could have disappeared as more experiments went on. Instead it was confirmed to be there. Nobel prize ensues. So, for now, they are collecting more date about that new bump before they can tell anything about it. And at these levels of energy, it will take a while.
Ars has a good article on all this: http://arstechnica.com/science/2015/12/first-high-energy-lhc-results-supersymmetry-still-dead-watch-for-gravitons/ [arstechnica.com]
(Score: 2) by Covalent on Thursday December 17 2015, @04:06AM
Thank you! Much more informative.
Graviton discovery would be a big deal! We are plumbing the depths here.
I thought it was interesting that there was no sign of dark matter here. If dark matter is a real thing (which it certainly seems to be), then it must be truly unusual if the LHC is not seeing any hints and all of the experiments searching for it are coming up blank.
Also it seems that dark matter occurs in places that are not exotic or high energy (like empty space) and despite this fact we still are nearly clueless as to its nature.
I hope I live long enough to see this but cracked. :)
You can't rationally argue somebody out of a position they didn't rationally get into.
(Score: 2) by sjames on Thursday December 17 2015, @06:13AM
Even if LHC is creating dark matter particles (if such a thing exists), it would be hard to tell. Since the only interaction would be gravity and the gravitational force of a single particle would be minuscule, they could only detect it by adding up the energy of all particles from a collision and seeing what's missing. Then they'd have to make sure it isn't neutrinos (which are hard to detect themselves).
(Score: 0) by Anonymous Coward on Thursday December 17 2015, @04:54PM
It's not a graviton. The graviton is expected to be a spin 2 massless particle. If it did have mass, then the range of effect of gravity should be short (like weak and strong forces, which have massive force carrier particles), whereas only gravity and photons (electromagnetic) have long distance effects.
https://en.wikipedia.org/wiki/Graviton [wikipedia.org]
(Score: 2) by seeprime on Wednesday December 16 2015, @10:20PM
It's a statistical anomaly. It's not real. Yet.
(Score: 0) by Anonymous Coward on Thursday December 17 2015, @11:02AM
Disagree. We don't know yet whether it is real or just a statistical anomaly. But if we later find it to be real, it means it was real even before we found out (unless you believe the universe is not yet finished, and God makes up new particles on the fly when we start looking for them).
(Score: 2) by Immerman on Thursday December 17 2015, @08:45PM
That line certainly seems to suggest that this particle is not a gluino, but can anybody offer an explanation as to why that is the assumption? Or was the statement possibly taken from before the new particle was detected?
It seems to me that "We just found some evidence suggesting there may be an unknown particle at 1500GeV" and "We haven't found any evidence for a super-massive particle whose mass could be up to 1,600Gev" are a bit mutually exclusive without some further information.
(Score: 2) by maxwell demon on Thursday December 17 2015, @11:28PM
The gluino would be a fermion, not a boson.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by Immerman on Friday December 18 2015, @07:23PM
Okay, fair enough. So, any idea how you determine whether a particle that has only *maybe* been detected a couple times, with a confidence level low enough to put it's very existence in serious doubt, can be conclusively categorized as one or the other? I assume it has to do with the ratio of decay products, but if you're barely getting a suggestion that it exists in the first place, how can you conclusively categorize its decay products distinct from the noise?
(Score: 2) by maxwell demon on Friday December 18 2015, @07:54PM
I'm not a high-energy physicist, so I cannot tell for sure, but one possibility would be that the anomaly is only seen in bosons; any particle that decays only into bosons must be a boson itself (you cannot add up integers to obtain a half-integer).
The Tao of math: The numbers you can count are not the real numbers.