Wednesday, March 25, 2015 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

CMS: a 2.9-sigma \(WH\) hint at \(1850\GeV\)



Unfortunately, due to a short circuit somewhere at the LHC, a small metallic piece will have to be removed – which takes a week (it's so slow because CERN employs LEGO men to do the job) – and the 2015 LHC physics run may be postponed by up to 5 weeks because of that.

Wolfram: You have the last week to buy Mathematica at a 25% discount (a "pi day" celebration; student edition). Edward Measure has already happily bought it.
Meanwhile, ATLAS and CMS have flooded their web pages with new papers resulting from the 2012 run. In most of these papers, the Standard Model gets an "A".




It is not really the case of the CMS' note
Search for massive \(WH\) resonances decaying to \(\ell\nu b\bar b\) final state in the boosted regime at \(\sqrt{s}=8\TeV\)
because a local 2.9-sigma excess is seen in the muon subchannel – see Figures 5, 6b, and 7 – for the mass of a new hypothetical charged particle \(1.8\TeV\leq m_{W'} \leq 1.9 \TeV\).




It's a small excess – the confidence level gets reduced to about 2 sigma with the look-elsewhere correction – but this new hypothetical charged particle could be interpreted within the Littlest Higgs model (theory) or a Heavy Vector Triplet model, among other, perhaps more likely ones.

In the (now) long list of LHC anomalies mentioned at this blog, some of them could look similar, especially the \(2.1 \TeV\) right-handed \(W_R^\pm\)-boson (CMS July 2014) and and the strange effective-mass \(1.65\TeV\) events (ATLAS March 2012).

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reader BobSykes said...

Once again, all the geniuses at CERN are unable to do undergraduate 19th Century electrical engineering. The Three Stooges were better physicists.


reader Luboš Motl said...

LOL, Bob, I don't think that the short circuit is due to someone's deliberately inserting wires at wrong places. It's probably due to some sensitive wiring that makes a short circuit by accident, after a small deformation, or something like that. But maybe I am wrong.


reader Bob said...

A short in a superconducting magnet? With a super-duperconductor?


reader lukelea said...

Maybe an enemy of physics did a little sabotage?


reader Ralph Hartley said...

Also, some electrical components (e.g. diodes) often become shorts when they fail.


reader cynholt said...

Yes, what the Starship CERN needs is an engineer of Scotty's caliber to prevent an electrical mishap of this kind from happening in the first place!

https://www.youtube.com/watch?v=oXZa89Hv8Bo


reader Gene Day said...

Temperature cycling, i.e., heating to ambient temperature and back, is a very lengthy process for such a huge machine. For this reason extreme care must be taken to insure that no bits of ferromagnetic material are left behind because they can be accelerated to high velocity in the physically huge magnetic fields of the LHC.
I am personally surprised that there have been so few “glitches” in the LHC. This is a credit to the extreme care being exercised but occasional mistakes are inevitable, nonetheless.


reader Rehbock said...

The Indico.cern.ch site shows they believe the problem is an intermittent fault to ground in the diode box. I am guessing that means the big diodes that are part of quenching mechanism. That means warming and recooling but that is what competent technicians do. Too bad we don't have much more ability to recool it quicker but I am glad that CERN is funded and operating well enough that these things are planned for.


reader Liam said...

Not to worry, I phoned them and told Bob Sykes is the on the way, and will show them how to fix everything...

They were all like "Bob Sykes? No waaay, we'll be up and running in no time!" ;-)


reader Steve R said...

Due to the high internal resistance of a 9v battery, it is perfectly safe to short it.


reader kashyap vasavada said...

Well. This proves that even those of us who understand physics, do not appreciate the full immense technology of LHC. That is why, I suggested in a previous post that it would be nice to have a blog on technology of LHC. Of course, this would not make any of us experts so we could rush to CERN and fix the machine!!!


reader David Nataf said...

It must be terribly intimidating to be a particle physics theory postdoc right now. Your job prospects and future citation counts will partly depend on nature's whims, whether the next energy scale to matter is at 13 TeV or 130 TeV.


reader Luboš Motl said...

I think if this dependence were real, it would be wrong.


Science never knew the answers "in advance". New phenomena may have always been "closer" or "further", new theories to be discovered could be more radical or more conservative, easier or simpler, and it was never known in advance.


People in any scientific discipline write papers - with some expected number of papers per researcher per year, independently of the scale of new physics, and the citations are being distributed by the relative quality, not by absolute excitement.


Experiments are measuring and their papers are valuable when they invent new physics as well as when they impose new bounds etc. Phenomenologists and theorists are studying new physics models which may be easier to test or harder to test, depending on Nature's will, but that must still be taken into account and evaluated by others.


reader QsaTheory said...

I don't know if this has been posted before, Davis gross lectures are very good at summarizing the mainstream(or semi) concepts in physics

https://www.youtube.com/watch?v=AM7SnUlw-DU


reader Luboš Motl said...

Yes, this talk was posted and discussed before, namely over 7 years ago because it's this old.

http://motls.blogspot.com/2007/10/david-gross-coming-revolutions-in.html?m=1


reader QsaTheory said...

But this guy is something else

https://www.youtube.com/watch?v=Vci3C6yAzRE