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ATLAS released 10 papers today

Update: Wow, by the end of the day, there would be 15 new papers posted but the extra five are on lead-lead collisions and will be ignored below.

The ATLAS collaboration at the LHC released ten papers today:

ATLAS Conf Notes
Six of them are based on the \(7\TeV\) data from 2011; four of them already use the \(8\TeV\) data collected in 2012.

But before you buy the cherished libertarian book with "ATLAS" in the name (one that happens to have stunning 2,651 reviews at amazon.com), you are surely interested in the results of these studies. Have they found something surprising?




No significant deviation from the Standard Model was seen anywhere in the papers and I decided that the smaller deviations were small enough and don't deserve a detailed discussion at this moment. On the contrary, I have the feeling that some of the new papers show that some previous excesses, e.g. those with very many jets and MET, have probably been flukes. I haven't checked that it's exactly the same data that Nanopoulos and others were building their excitement upon but I do think that their excitement will diminish.

The papers are full of excellent work which brings us results that confirm the integrity and legality of Nature – and the power of the human brain, especially the human brain that worked hard sometimes by the 1960s and early 1970s ;-) but many unusually competent contemporary people (and their state-of-the-art computers with sometimes new software) had to work hard to calculate the right predictions of the Standard Model for many detailed situations. The agreement between the theory and the experiment is truly impressive.

It is misleading to describe the searches by saying that "those 3,000 folks have found nothing". It's more accurate to say that they're mostly searching for platinum, titanium, and perhaps also an elixir of life but during their search, they have found and collected tons of gold, silver, and other metals at places that were exactly predicted by the geologists – I mean particle theorists, of course. ;-)



Given the bias and desire of most people to see hints that the brains in the 1960s and 1970s were inadequate, it's likely that the people feel disappointed. I wonder how many people read all the papers in detail. What percentage of the authors has read the full papers? What about the rest of ATLAS and the competitors at CMS? How many people outside the LHC Collaborations does so? Wouldn't it be a good idea to make the formatting of these papers more concise and unified so that they're viewed as aspects of one "megapaper" that could be presented via a universal user interface on the web?

You may see that the LHC is still mostly releasing the data accumulated in 2011. It will take quite some time to evaluate the 2012 data. And there may still be many papers based on the 2011 data that are being completed – and waiting to be published. Of course, there may even be papers with exciting results based on the 2011 data.

Every time the LHC quadruples the total number of collisions, the statistical significance of the signals of new physics has a chance to double. The signals (in the units of one standard deviation) may more than double or less than double (because the changes contain a random component) but the doubling of signals is the neutral expectation coming from the quadrupling of the data. So if you want a 5-sigma discovery based on the 2012 data, it's rather likely that the dataset based on the 2011 only data in the same channel should already show at least a 2-sigma deviation from the Standard Model. Or if I use the inverse language: if there's no 2-sigma deviation seen in the 2011 data, it is rather likely that there won't be any 5-sigma discovery in the 2012 data. But as I have mentioned, none of these two statements has been established yet.

The counting will change after the 2013 break. In 2014, the LHC will start collisions at the center-of-mass energy \(13\TeV\). Even one inverse femtobarn of those higher-energy data will have the potential to see many hypothetical new effects that will have been invisible in dozens of inverse femtobarns of the \(7\TeV\) or \(8\TeV\) data. In other words, the extrapolation of "no signal seen through 2012 and therefore no signal will be seen in 2014" will be pretty much indefensible because the new data will be independent of the old ones. Of course, the LHC may very well refuse to see any hint of physics beyond the Standard Model in the \(13\TeV\) data, too, but there exists no truly convincing, scientific, or logical argument that would imply that it has to be so.

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reader Pepa said...

Salut Lubos,
As I glanced at one paper - 104 -
A search with the Atlas detector for Susy in final stages containing at least 4 hard jets, one isolated lepton (electron or muon) and missing transverse energy, 5.8 inverse femtobarns of data collected at centre-of mass energy of 8 TeV - "no excess above SM background expectation" is observed, in MSUGRA/CMSSM model, results in this signal region alone exclude squarks and gluino masses of 1.24 TeV. , etc
now I'll go back to my vacation... :-)


reader Luboš Motl said...

Hi Pepo, nice, just be careful on the vacations. ;-) CMSSM/MSUGRA is still a very thin slice through the parameter space in which all the superpartners with the same spin are essentially assumed to be equally heavy - so the strong constraints on these models that have emerged pretty much say that "it it not possible that all superpartners are extremely light". However, it doesn't have to be the case that all the superpartners are equally heavy at all and there may still be lots of superpartners that are as light as 200 GeV or even less.


reader George Christodoulides said...

they don't have to buy Atlas Shrugged, i give it for free with 2 video games!


reader Luke Lea said...

"It is misleading to describe the searches by saying that "those 3,000 folks have found nothing". It's more accurate to say that they're mostly searching for platinum, titanium, and perhaps also an elixir of life but during their search, they have found and collected tons of gold, silver, and other metals at places that were exactly predicted by the geologists – I mean particle theorists, of course. ;-)"

You could have been a writer! Very nice.


reader CIP said...
This comment has been removed by a blog administrator.

reader Casper said...

But the redoubtable Ms Rand was half-Russian and therefore possibly mad.

Readers who crave even more dystopian fantasy should look no further than 'Clusterfuck Nation', a blog that combines modern doomer philosophy with the finest of American humour.


reader anna v said...

My experience with large groups and research is that if they have found something new and possibly exciting they will not tell us until they have combed it through umpteen times for mistakes and biases and will then come out with the most conservative option on the paper.

It is unfortunate that the supeluminal neutrino happening came so close in time with the LHC analysis. People become doubly conservative and cautious when they see another one stumbling.

Back in the late seventies I was in a neutrino BEBC group and on a sabbatical at CERN for a year. We had the misfortune of a fellow stumbling on a mu-pi 4 sigma resonance, which got everyone so excited they became incautious and publicized it :history shows that the other experiments found no such thing and the story fizzled. ( the look elsewhere effect was just being learned the hard way: too many cuts). As a result the collaboration became ultra cautious and only allowed platitudes to go to publication for some time.


reader George Christodoulides said...

do you actually have any actual arguments against the philosophy of the book? if you don't get the theory check which people happen to be libertarians.


reader SHOAIB JI said...

The ATLAS collaboration at the LHC released ten papers today:

Six of them are based on the \(7\TeV\) data from 2011; four of them already use the \(8\TeV\) data collected in 2012.
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