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arivero
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What do you think of Moriond results? had they really got 5 sigma and chickened out? What could the particle be, if it is real?
arivero said:had they really got 5 sigma and chickened out?
Buzz Bloom said:Would you please cite a reference?
Misconduct? I never suggested it.Vanadium 50 said:Do you have any evidence that the experiments indulged in the sort of scientific misconduct that you suggest?
Based on rumors, not on actual physics. Even worse if you need a second rumor to explain the lack of evidence for the first rumor.arivero said:Strasttler and Motl commented the friday that ATLAS was expected to claim "almost 5" in the friday conference but surely they were not still convinced of their own analysis.
arivero said:Misconduct? I never suggested it.
nolxiii said:so how safe is it to say at this point that, whatever does or doesn't come out of this, it will be the only really new/unexpected thing that the LHC will see?
nolxiii said:so how safe is it to say at this point that, whatever does or doesn't come out of this, it will be the only really new/unexpected thing that the LHC will see?
Valid enough. Let me to point out also Resonaances entry "the loose-cuts analysis was not approved in time by the collaboration",Vanadium 50 said:If Lubos told me my mother loved me, I would check it out.
mfb said:We had a longer discussion in December.
vanhees71 said:Another example were the faster-than-light neutrinos with a big media hype followed by a big spaming of all kinds of wanna-be-theory papers "explaining" possible "effects". For anybody a bit used to the physics underlying the Standard Model it was quite clear how extremely unlikely a tachyonic nature of neutrinos is, and it was no surprise at all that afterwards the technical problems with some glass fiber and a time-keeping oscillator was figured out.
Yes, assuming it is a particle that decays to two photons. There are also models where the particle decays to a photon plus a very light pion-like particle that decays to two (very collimated) photons that appear like a single photon. In that case it could have spin 1.Lord Crc said:In this[1] page about the Higgs, it's mentioned that the diphoton signal implies the particle is a boson and that it cannot be spin 1. Does the same apply if in this case, assuming it is a particle?
[1]: http://cms.web.cern.ch/news/observation-new-particle-mass-125-gev
"Spin 2" has a slightly lower significance, but the difference is small. The additional plots about jet distributions and so on are interesting, and we'll see how they get accounted for in upcoming theory papers.arivero said:Hmm, really, we had not. Models were not touched, and the discussion of significance can have evolved given the new analysis of ATLAS and the magic of CMS that incorporates new data from the days where the magnet was off. Model-wise, it seems that spin-2 loses weight.
I don't see disagreement. In ATLAS the peak looks a bit wider, in CMS it does not. All that is at the level of statistical fluctuations you would expect with such an excess.arivero said:I am also a bit puzzled by the debate between wide vs narrow resonance. It amuses me that both experiments can disagree on this.
Well, the popular press uses the most dramatic headlines it can get away with. With the given status of the OPERA analysis at that time, what else would you have suggested? They did not understand the problem, even after checking everything for months, so they asked experts outside for help. In terms of science, 6 sigma slower than light neutrinos would have been equally surprising, but then the headlines would have been much weaker.vanhees71 said:Of course, nobody believed in really having found faster-than light neutrinos. It was, however, written in the popular press as if, and that's very bad for science in the sense, I've written above.
Thanks, that was exactly the kind of exceptions I was curious of.mfb said:Yes, assuming it is a particle that decays to two photons. There are also models where the particle decays to a photon plus a very light pion-like particle that decays to two (very collimated) photons that appear like a single photon. In that case it could have spin 1.
mfb said:I don't see disagreement. In ATLAS the peak looks a bit wider, in CMS it does not. All that is at the level of statistical fluctuations you would expect with such an excess
arivero said:Let me to point out also Resonaances entry "the loose-cuts analysis was not approved in time by the collaboration"
Don't take the LEE twice. This statement would be a proper description if ATLAS would have the excess at 750 GeV and CMS at 1 TeV. I don't think it would have triggered so many theory papers then. The masses are not exactly the same (how could they?), but very close and the yield comparison depends on your favorite theory model as the selection is different. CMS 8+13 TeV quotes 750 GeV, ATLAS quotes 750 GeV, CMS 13 TeV quotes 760 GeV, it looks like all values are rounded to multiples of 10.Vanadium 50 said:The significances are very low. One and two sigma are nowhere near five.
The narrow width gives a fine fit for ATLAS, so does a slightly larger width for CMS. That difference is way less significant than the excesses.Vanadium 50 said:ATLAS and CMS see rather different widths.
There is a slight excess, not significant on its own but compatible with gg production.Vanadium 50 said:The 8 TeV data does not confirm the 13 TeV data.
The interpretation depends on your favorite theory model.Vanadium 50 said:CMS doesn't see the signal in all parts of their detector.
To figure out what it is (if it is real): sure. To get highly confident that something is there: I don't think so. If the ~3.5 local significance is the expected strength of an actual signal, twice that data with the same conditions will give an expected local significance of ~4.9 sigma. But you can do better. You can check the various theory papers to improve the selection, you can improve the background suppression and estimation and so on. Pileup will increase a bit, but that should be manageable.Vanadium 50 said:Finally, even if it's real, you won't settle things with twice as much data. You need ten times as much data.
I assume there is some experimental reason, but I was also thinking that if the resonance pole is at M - i Γ with Γ = M then its square is in (M^2 - Γ^2) - 2 i M Γ the pure imaginary line, and that could be theoretically relevant. Also, perhaps the indeterminacy principle in energy-time has some say here, as Γ is inverse lifetime.mfb said:
Can you tell me what R-D gravitons refers to?arivero said:Please note also that I started the thread in the Lounge in order to allow for wide discussion. Of course, with more that 750 papers in the arxiv, almost everybody can quote its favorite model from some arxiv paper :-) I am particularly surprised that R-D gravitons are considered as a major possibility
The 750 GeV diphoton excess refers to a potential signal observed in the data from the Large Hadron Collider (LHC) in 2015. This signal appeared as an excess of photon pairs with a combined energy of 750 GeV, which could potentially indicate the presence of a new particle.
There are multiple theories about what could be causing the 750 GeV diphoton excess. One possibility is the existence of a new particle, such as a heavy scalar or pseudoscalar boson. Another possibility is that the excess is a statistical fluctuation or error in the data.
No, the 750 GeV diphoton excess has not been confirmed. While the initial data from the LHC showed a potential signal, further analysis and experiments have not been able to reproduce the same results. This means that the existence of the excess is still uncertain.
If the 750 GeV diphoton excess is confirmed, it could potentially lead to a major breakthrough in particle physics. The discovery of a new particle could help us better understand the fundamental building blocks of the universe and potentially open up new avenues for scientific research and technological advancements.
Scientists are conducting further experiments and analyses to try and confirm or disprove the existence of the 750 GeV diphoton excess. This includes collecting more data from the LHC and using other experiments and techniques to search for the potential new particle. Additionally, scientists are also exploring alternative explanations for the excess and working to improve our understanding of the data and potential sources of error.