LHC's Newest Data: A Victory For The Standard Model, Defeat…

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chelle
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LHC's Newest Data: A Victory For The Standard Model, Defeat…

Post by chelle » Sat Dec 03, 2016 6:15 am

LHC's Newest Data: A Victory For The Standard Model, Defeat For New Physics

http://www.forbes.com/sites/startswitha ... 4302c962f5

Looks like it's time to start packing up. :roll:
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chelle
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Re: LHC's Newest Data: A Victory For The Standard Model, Def

Post by chelle » Tue Dec 06, 2016 3:17 pm

And additionally:
It means that colliders aren’t the answer. It means the LHC won’t reveal new physics, and that particle creation, decays and branching ratios won’t shed the light we need them to at reachable energies. But there are always indirect methods to probe new physics. We will have to rely more heavily on those. Indeed, that’s what’s given us our beyond-the-standard-model hints: B and S-factories for CP-violation; neutrino measurements for masses and oscillations; cosmic ray experiments for beyond-collider energies. There is hope, but it doesn’t look like building a giant collider.
Source: http://scienceblogs.com/startswithabang ... ard-model/
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Re: LHC's Newest Data: A Victory For The Standard Model, Def

Post by mfb » Tue Dec 06, 2016 9:50 pm

What a misleading title.

"Oh look at this soccer match! 16 seconds passed and no goal yet! I'm sure the match will end 0:0."
The 16 seconds are not chosen randomly, they are the equivalent ratio the LHC has now with analyzed to future data.
The latest search results at these high energies were just released by the CMS collaboration
The results of one specific search using 2015 data has been released. That's not even 0.1% of the total planned LHC dataset, and it is a single search channel.
This time, with the most data ever at the highest energies, there's not even a hint of anything new.
It is not the most data ever. Various ICHEP results were based on ~10/fb, the new search just uses 2.3/fb.
That the Standard Model might be all our particle colliders can access in our lifetime.
Yes - it might be. That was always considered an option. So what exactly is new? That we didn't find evidence for new particles with the first 0.3% of the dataset (ICHEP)?

A blog comment as source, seriously? Who is this "Anonymous Coward" (sic!) and what makes them so sure about their conclusion?
There are tons of measurements that the LHC didn't even start, because - did I mention it? - we are just at the start of data-taking. And there are interesting deviations from the standard model in B-decays already. The B-factories that "Anonymous Coward" mentioned: the LHC is one of them!

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Re: LHC's Newest Data: A Victory For The Standard Model, Def

Post by chelle » Wed Dec 07, 2016 5:44 am

mfb wrote:A blog comment as source, seriously? Who is this "Anonymous Coward" (sic!) and what makes them so sure about their conclusion?
The comment is related to the first link I posted, if you had followed the link on his name you would have gone there directly, and you would have noticed that his/her(?) blog comment is a comment on a blog-post written by Ethan, and you would have figured out that he is an astrophysics professor. :mrgreen:
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Re: LHC's Newest Data: A Victory For The Standard Model, Def

Post by mfb » Wed Dec 07, 2016 9:20 pm

Ethan collected some comments from others and commented on them. His comment is better than the comment he replied to, but it is still his personal opinion (and not clearly marked as such) - and I'm not even sure about that, he could just explain what it means if the large gap is real.

What exactly makes an astrophysics prof an expert in particle physics, by the way?

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Re: LHC's Newest Data: A Victory For The Standard Model, Def

Post by chelle » Thu Dec 08, 2016 5:59 am

It seems like you're not able to figure out what the comments are about. It leads to his original post and opinion where he wrote:

"What's the takeaway? That the Standard Model might be all our particle colliders can access in our lifetime. It’s not the new, exciting discoveries that are going to get headlines or win Nobel Prizes, but sometimes, it’s what nature gives us. Better to accept the disappointing truth than believe in a sensationalist lie."


Oh, and sure an astrophysicist doesn't know anything about particle physics. :mrgreen:
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Re: LHC's Newest Data: A Victory For The Standard Model, Def

Post by mfb » Sat Dec 10, 2016 12:42 am

Try to find all his LHC-related papers. At arXiv? Maybe at inspire? Nothing. He is working on astrophysics, and while there is some overlap between astrophysics and high-energy physics, he doesn't seem to work in this overlap region.

Concerning the blog comment, I was referring to this:
From Anonymous Coward on the LHC’s failure to turn up anything new: “So we’ve reached the Desert. No new physics from 10^12 eV to 10^25 eV (the grand unification scale), and that’s a long, long way away. No way we’re bridging that gap even if we could build an accelerator that circles the planet.”

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Re: LHC's Newest Data: A Victory For The Standard Model, Def

Post by chelle » Sat Dec 10, 2016 6:39 am

Well of course hardly anyone 'within' the field of high-energy particle physics is going to be critical about their own bread and butter.

… and sure you can keep on looking through the data to find something, just like SETI keeps looking for aliens. It starts to fall in the roam of pseudoscience.

"in light of new findings and insights, it seems appropriate to put excessive euphoria to rest and to take a more down-to-earth view ... We should quietly admit that the early estimates—that there may be a million, a hundred thousand, or ten thousand advanced extraterrestrial civilizations in our galaxy—may no longer be tenable." - https://en.wikipedia.org/wiki/Search_fo ... #Criticism

Sounds familiar doesn't it. :roll:
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Re: LHC's Newest Data: A Victory For The Standard Model, Def

Post by mfb » Sat Dec 10, 2016 1:42 pm

Well of course hardly anyone 'within' the field of high-energy particle physics is going to be critical about their own bread and butter.
That statement is wrong. There are several physicists in high-energy physics with pessimistic outlooks. The difference to Ethan Siegel: they do not rule out the possibility to find something (they just think it is unlikely), and they have actual physics arguments.
It starts to fall in the roam of pseudoscience.
That statement is ridiculously wrong. Even if the LHC doesn't find more fundamental particles (remember that it did find one already), there are so many things about known particles we know the LHC can measure in the future. Discovering particles is not the only thing we do in high-energy physics, measuring the particle properties is by far the largest activity at the LHC.

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Re: LHC's Newest Data: A Victory For The Standard Model, Def

Post by chelle » Sat Dec 10, 2016 3:25 pm

mfb wrote:There are several physicists in high-energy physics with pessimistic outlooks. The difference to Ethan Siegel: they do not rule out the possibility to find something (they just think it is unlikely), and they have actual physics arguments.
Ethan said the same thing, that it is unlikely. His conclusion is that it's better to call it quits.
mfb wrote:
It starts to fall in the roam of pseudoscience.
That statement is ridiculously wrong … Discovering particles is not the only thing we do in high-energy physics, measuring the particle properties is by far the largest activity at the LHC.
So now it has become something more like meteorology … sure that is real science. :mrgreen:
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Re: LHC's Newest Data: A Victory For The Standard Model, Def

Post by mfb » Sat Dec 10, 2016 7:25 pm

chelle wrote:Ethan said the same thing, that it is unlikely. His conclusion is that it's better to call it quits.
His statement is much stronger than that:
Ethan wrote:It means that colliders aren’t the answer. It means the LHC won’t reveal new physics, and that particle creation, decays and branching ratios won’t shed the light we need them to at reachable energies. But there are always indirect methods to probe new physics.
Interesting detail: "Decays and branching ratios" (same thing?) is an indirect method. Anyone familiar with the topic would know that.


I don't see any connection to meteorology.

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Re: LHC's Newest Data: A Victory For The Standard Model, Def

Post by chelle » Sat Dec 10, 2016 7:49 pm

You are right. I was looking at the part where he used the weasel word 'might':
"What's the takeaway? That the Standard Model might be all our particle colliders can access in our lifetime."
Meteorologists measure daily rainfall and sunshine, which is similar to your daily 'measurements of particle properties', at the end of the day it are just fluctuations and variations of the same thing.
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Re: LHC's Newest Data: A Victory For The Standard Model, Def

Post by mfb » Sat Dec 10, 2016 9:35 pm

Meteorologists measure daily rainfall and sunshine, which is similar to your daily 'measurements of particle properties', at the end of the day it are just fluctuations and variations of the same thing.
No, not at all. A property like "the mass the top quark" is a universal constant of nature - the mass is the same tomorrow, in 10 years, and in a billion years, and everywhere in the universe. And we want to know it as precisely as possible. The same applies to all other properties - spin, parity, branching ratios, cross sections, angular correlations, ... - they do not change over time.

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Re: LHC's Newest Data: A Victory For The Standard Model, Def

Post by chelle » Sun Dec 11, 2016 11:23 am

mfb wrote:The same applies to all other properties - spin, parity, branching ratios, cross sections, angular correlations, ... - they do not change over time.
Well at some point (~now) you start ending up with something like the 3 body problem, where you can keep on collecting data but it is no longer adding very much; or like SETI where you keep on listening at signals, without being able do draw any significant conclusions. What's the point of this kind of bookkeeping? :roll:
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Re: LHC's Newest Data: A Victory For The Standard Model, Def

Post by mfb » Sun Dec 11, 2016 1:48 pm

Well at some point (~now) you start ending up with something like the 3 body problem, where you can keep on collecting data but it is no longer adding very much
That point won't be reached within the lifetime of the LHC. Higgs->muons is an example of a decay that will need nearly the full LHC dataset for a discovery, measurements of Higgs self-coupling will profit a lot from it as well. Those are fundamental predictions of the standard model that should get tested. And they are just two examples out of many. 3000/fb will improve the knowledge we gained with 10/fb (published) or 40/fb (collected) massively.

This has absolutely nothing to do with the 3-body problem of gravity.

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