dukwon

10 ms·

61.
by dukwon 8y ago
> LHCb for example does not use simulated background. That depends on the analysis. If you're looking at a partially-reconstructed decay (common in semileptonics) then you can't rely on the regular trick of choosing a sideband
62.
by dukwon 8y ago
This is already what happens. The problem is that forming tracks and vertices becomes much harder as the number increases.
63.
by dukwon 8y ago
In general, simulation doesn't agree with data perfectly. The more the variables (and their correlations) aren't reproduced faithfully, the more the efficiency determined from simulation is likely to depart from the truth. It&#x27
64.
by dukwon 8y ago
From what I've heard, the amount of pile-up ATLAS and CMS can handle is limited by the CPU time it takes to reconstruct events, which can be alleviated by throwing more resources at it, but it is much better to develop quicker recons
65.
by dukwon 8y ago
> Is the news that they want to use ML in the trigger selection now? Not quite (and that wouldn't be news). It's using ML for track reconstruction. Not even LHCb does this.
66.
by dukwon 8y ago
Raw event sizes in modern collider experiments are typically 100s of kB to a few MB. The trigger rate at Belle II is about 30 kHz. It's comparable to an LHC experiment in terms of data output, but it has the advantage of lower particle
67.
by dukwon 9y ago
Meanwhile, in real physics, there's a well-defined difference between the norm of a vector and one of its components. Mass is Lorentz-invariant, energy is not.
68.
by dukwon 9y ago
> No physicist is going to say "oh the universe shouldn't exist" Read the quote from Christian Smorra in the 4th paragraph > This is probably getting some physicists very excited, it means there may be entirely new phys
69.
by dukwon 9y ago
Don't you think that's exactly what the headline is trying to convey?
70.
by dukwon 9y ago
So is LHCb. The two experiments may share a data centre on the Prevessin site.
71.
by dukwon 9y ago
Good thing science isn't done for your entertainment. What's the point of your comments other than to imply that physicists somehow aren't doing a good enough job?
72.
by dukwon 9y ago
++ means a charge of +2, cc means two charm quarks (doubly-charmed) A triply-charmed baryon would be the Ωccc++
73.
Happy 5th anniversary, Higgs boson(home.cern)
1 points by dukwon 9y ago|0 comments
74.
by dukwon 9y ago
> Has neutrino-based signalling been achieved or is it still a research topic? An accelerator- or reactor-based neutrino experiment can detect whether the source is on or off, so in principle you can send binary information. This has bee
75.
by dukwon 9y ago
> I do not think we are anywhere close to a DIY subatomic particle detector You've probably got one in your pocket already https://arxiv.org/abs/1410.2895
76.
by dukwon 9y ago
There are several independent anomalous results in measurements of b-quark decays which all seem to point to a violation of lepton flavour universality. Specifically a reduced coupling to muons.
77.
by dukwon 9y ago
Well, that's the story at the moment. The question is what will it turn out to be once the analyses are repeated with more data.
78.
by dukwon 9y ago
As it happens, it was students, but they weren't enrolled in any sort of CERN student programme.
79.
by dukwon 9y ago
> Has anyone heard any more about why scientists performed a mock ritual like that? Because it seemed like a funny idea at the time, they didn't think they would get caught, and they didn't think it would receive as much media
80.
by dukwon 10y ago
It's common in particle physics to express base-10 order of magnitude using this notation. I'm unfamiliar with how it's used elsewhere.
81.
by dukwon 10y ago
You're jumping the gun a bit there. The general purpose experiments have only collected O(1%) of their eventual datasets.
82.
by dukwon 10y ago
The theory uncertainties are large. Any measurements within a broad range would also agree with some calculated masses. That doesn't tell you much. See e.g. https://arxiv.org/abs/1311.4806
83.
by dukwon 10y ago
Since QCD can't be calculated perturbatively at low energy, there are unsolved problems with how to get those predictions in the first place.
84.
by dukwon 10y ago
More recent news http://www.nature.com/news/lhc-scientists-bring-conference-t...
85.
by dukwon 10y ago
1. It's only fair that the collaborations get first dibs on producing results out of their blood, sweat and tears. 2. The collaborations don't want to waste time shooting down the large number of false claims that would inevitably
86.
by dukwon 11y ago
> Presumably this was a result of the LHC's power upgrade to 13 TeV Eh... despite what the other guy is saying, you can't really say this for sure. These bumps appear in a region that was accessible during Run 1 at 7 and 8 TeV.
87.
by dukwon 11y ago
Let's put it this way: the LHC has on the order 2000 results so far, assuming the null hypothesis, you expect about 100 >2σ deviations and about 5 that are >3σ. The combined significance from ATLAS and CMS will be higher, but it&
88.
by dukwon 11y ago
The look-elsewhere effect is already taken into account. This is what is meant by "global".
89.
by dukwon 11y ago
CMS observes the peak with a global significance of 1.2σ http://cds.cern.ch/record/2114808 ATLAS observes the peak with a global significance of 2σ http://cds.cern.ch/record/2114853 5σ is the gold
90.
by dukwon 11y ago
> The tau neutrino was discovered without any prior reason to believe it existed. We knew of neutrinos and they seemed to fill the only related gaps we had. It wasn't until the tau neutrino was experimentally detected that we even r

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