LHC glimpses hint of new physics | Hacker News Reader

LHC glimpses hint of new physics

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99 pointsaethertap7 comments

Please note that this is still an analysis of "LHC Run 1" data. Fore more details you can visit Jesters blog:

http://resonaances.blogspot.de/2015/03/lhcb-b-meson-anomaly-...

"So how excited should we be? One thing we learned today is that the anomaly is unlikely to be a statistical fluctuation. However, the observable is not of the clean kind, as the measured angular distributions are susceptible to poorly known QCD effects. The significance depends a lot on what is assumed about these uncertainties, and experts wage ferocious battles about the numbers."

Conclusively: "Therefore, the deviation from the standard model is not yet convincing at this point."

And these kinds of discoveries come and go a lot.

Of course eventually one of them really needs to pan out in order to explain dark matter and dark energy. But the default attitude to any of these results should be a good dose of healthy skepticism.

Wow. I was a CERN summer student in 1995 and me and another student worked on the tagging of B-meson decays in ATLAS. Hers was exactly the B->K mu+mu- decay. So 20 years later, it's observed... ;-)

(Incidentally, the particle physics publication system is beyond screwed up. We, who did the actual work, weren't even allowed to be authors on the paper where the results were described, because we weren't "members of the ATLAS collaboration". We merely got an acknowledgement.)

What did tagging B-meson decay involve? I almost understand some of those words, so be gentle :)

I barely remember... ;-)

The idea is that you need to quickly identify ("tag") interesting reactions out of the millions happening, so there are a set of increasingly stringent but slower filters that select events. Muons are good because they are easy to identify, then you look back at where they came from and see what other things were created. Typically mesons (and other hadrons) create a "shower" of particles and by adding upp all their energies you can estimate what particle they came from.

But all that stuff is mostly repressed from my memory. I decided that particle physics wasn't for me after that summer... ;-)

Whenever I read something like this I'm reminded of this Douglas Adams quote:

  “There is a theory which states that if ever anyone
  discovers exactly what the Universe is for and why it is
  here, it will instantly disappear and be replaced by
  something even more bizarre and inexplicable.

  There is another theory which states that this has
  already happened.”

It look like run1 recorded about 10^13 interesting collision events on the b-detector, each on several thousand sensors. If you wish to scan for a new type of particle you potsulate various decay sequence sensor geometries and intensities, scan all the events and cross your fingers. ANd hope you avoid false positives. Will keep grad students busy for decades mining all this data.

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