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LHC - New Force... Z-prime... Leptoquarks?


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1 hour ago, Macavity said:

Three sigma results...

Yes!,
I noted that also when I read it on the CERN site.
There are from time to time many ",,, is this maybe new that points to beyond the Standard Model ,,,,"  at 3sig this one may stand out from the herd ? :)

Guess what , I was amazed when swmbo came in saying "did you know about,, ", as I was typing the above bit,
(she watches TV !)  and so it has made it onto the Beeb news !
https://www.bbc.co.uk/news/science-environment-56491033

 

Edited by Corncrake
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5 hours ago, Corncrake said:

Yes!,
I noted that also when I read it on the CERN site.
There are from time to time many ",,, is this maybe new that points to beyond the Standard Model ,,,,"  at 3sig this one may stand out from the herd ? :)

Guess what , I was amazed when swmbo came in saying "did you know about,, ", as I was typing the above bit,
(she watches TV !)  and so it has made it onto the Beeb news !
https://www.bbc.co.uk/news/science-environment-56491033

 

Exciting stuff.  Curious how the reporter styled it "Physicists have uncovered a potential flaw in a theory that explains how the building blocks of the Universe behave."

Why is it a "flaw" and not "an previously unknown level of detail"  because that what it truly is.  Theories by their nature do not describe nature - they describe our present understanding of nature and as our understanding improves the theory advances. Grrr Arghhhh . :) 

 

Jim 

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So Sigma 3 is the confidence level am I right .  Does anybody know off the  top of their head exactly what that means in terms of successful coin tosses.  Also what confidence level did they declare for the Higgs Bozon - was it 6  - I  can't remember . 🙄 

 

Jim 

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40 minutes ago, saac said:

So Sigma 3 is the confidence level am I right .  Does anybody know off the  top of their head exactly what that means in terms of successful coin tosses.  Also what confidence level did they declare for the Higgs Bozon - was it 6  - I  can't remember . 🙄

Yes.

Higgs :- dont quote me but I think when Higgs got to 3 'they' said they were getting excited (or was it quietly confident :) ?) but it took a while longer to get to 5 and declare it.

EDIT  From CERN :-

https://home.cern/news/news/physics/intriguing-new-result-lhcb-experiment-cern
"The new result  [,,,,]  the statistical significance of the result is 3.1 standard deviations, which implies a probability of around 0.1% that the data is compatible with the Standard Model predictions."

Edited by Corncrake
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37 minutes ago, saac said:

Also what confidence level did they

I edited the CERN, 3.1, quote (and link) about confidence of this one, into my previous.

5 sigma is the going rate for 'certainty' in science I think, note the  ' '  !!!

I should of course say 5 is considered "beyond reasonable doubt" :)

 

Edited by Corncrake
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Tx corncrake, Level 5 seems to ring a bell - I remember reading an explanation in a book somewhere what it actually translated to in terms of getting the same result in successive coin tosses. Some googling required I think.  :) 

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24 minutes ago, saac said:

Tx corncrake, Level 5 seems to ring a bell - I remember reading an explanation in a book somewhere what it actually translated to in terms of getting the same result in successive coin tosses. Some googling required I think.  :) 

Coin tossing is very similar to the LHC experiment as the standard model predicts equal numbers of muons and electrons from the decay!

However, tossing coins is a lot cheaper but less fundamental. 

Regards Andrew 

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Posted (edited)

If we are allowed a few personal (lighthearted) gripes re. the internet effect on science?

I sometimes miss times when 3-sigma results carried informal (but "99.999"% respected?):
Rubber Stamps -- "[Emperiment Name] Preliminary Data - For internal distribution only".
Collaborations are an order of magnitude bigger... Scientists speak directly to fans? 🥳

Such blips in data can become significant when "under different experimental conditions".
Examine many plots and you WILL see 3-SD effects. Some have lesser backgrounds though.
(Good) scientific "instinct" comes into play too. Many non-scientists & Media don't get this?
I tend to follow press releases from Physics Labs rather than (legion of) re-tweeters. 😉

P.S. I did once have a FIVE SD peak in one of my MANY plots... but sadly it "went away"? 🤣

We now hand you back to The Science (qv):

The "Perils of Capitalisation": The... Standard Model?! Fun (Pro-experimentalist?) meme! 😎
https://www.symmetrymagazine.org/article/six-fabulous-facts-about-the-standard-model

Edited by Macavity
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8 hours ago, saac said:

Tx corncrake, Level 5 seems to ring a bell - I remember reading an explanation in a book somewhere what it actually translated to in terms of getting the same result in successive coin tosses. Some googling required I think.  :) 

Does this help?

https://en.m.wikipedia.org/wiki/68–95–99.7_rule

Seems to imply 99.99994% confidence for 5 Sigma. I had read 3 sigma being 1 in a thousand chance of it being correct and 5 as one in a million but I suspect that was just simplifying stuff for the likes of...., well me! 🤣🤪

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I always struggle with the Null hypothesis but I think 5 sigma amounts to a 1 in 3.5 million of the result being due to chance alone.

Something has to be wrong with the standard model as we are here (excess in matter over antimatter)  and it is symmetric in this regard.

Maybe this will point the way.

Now back to Stoppards play Rosencrantz and Gildenstern are dead. Heads, heads, heads....

 

Regards Andrew 

 

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Posted (edited)

Despite what I said above, sometimes re-Tweets of stuff can be useful.
I still persist with my idea of *rigourously* citing sources and potential
for (often inadvertently!) "stealing" credit for exciting discoveries?!? 🥳

In the interests of *UK science* maybe you/we/I should ALL watch:
*PPD_STFC!*  "We design, build and operate detectors worldwide,
analyse data and support the UK particle physics community" ! 😅

Assuming Twitter "works for you" - click on the POST below!?!? 😉

Edited by Macavity
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19 hours ago, andrew s said:

This is worth a look. Seems a new calculation puts it back into the standard model

Errr ! I very much respect your view on these things, you have a much better grasp than I but,, the dreaded but !,,,

I looked, of course, but,,,  TLDR !

Well I did for starters, but heck the first bit put me off

"   Either Fermilab has confirmed that it is extremely likely that there are new physics out there, based on the pre-today gold standard calculation of the Standard Model prediction, or this new result, combined with two new calculations of the parts of the Standard Model prediction that account for most of the theoretical error in that prediction, which were released today, combined to show that the Standard Model is complete and there are no new physics out there. "

Turtle who ?!

does he understand that sigma5 is/has been  chosen to obviate this sort of "he says this" "but  he says other"

They plainly state sig4.1 nothing more nothing less. sig3 has previously vanished (cos of error) this may do so also, but with a decreasing , , oh well, let's wait an see :) any estimates on how long ;;;; ducks.

A presis of Turtle's (s all the way down) thinking for lesser mortals would be helpful !

 

 

Edited by Corncrake
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@Corncrake. In summary a new calculation of the magnetic moment of the muon using the standard model puts it in line with the measured value.

The calculations are not easy and the previous method used empirically determined values. The new one avoided this but it needs to be confirmed.

Regards Andrew 

Edited by andrew s
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1 hour ago, andrew s said:

@Corncrake. In summary a new calculation of the magnetic moment of the muon using the standard model puts it in line with the measured value.

The calculations are not easy and the previous method used empirically determined values. The new one avoided this but it needs to be confirmed.

Regards Andrew 

Interesting (although I am so far past the limits of my knowledge it’s not true!)

My only valid question is whether this new calculation was a coincidence or whether it was driven by a need to try to explain this new finding?

From reading the articles, it seems the expected result depends on some extremely complex calculations, which themselves may be open to question, which is what this new calculation does. Is that correct?

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1 hour ago, Stu said:

Interesting (although I am so far past the limits of my knowledge it’s not true!)

My only valid question is whether this new calculation was a coincidence or whether it was driven by a need to try to explain this new finding?

From reading the articles, it seems the expected result depends on some extremely complex calculations, which themselves may be open to question, which is what this new calculation does. Is that correct?

Good point. The abstract to the calculation points out the error estimate in the calculated and measured values were about the same. However, the error in the measured values were about to be reduced by (from memory) 4 times and hence the need for the new calculation.  

As far as I am aware there was no collusion between groups. Indeed the calculation paper must have been being refereed during the measurement given how long these things take. Also I am sure claiming new physics is every experimenters dream.

All the code used to do the calculations is available to other researchers and the group which did it have a good track record.

Regards Andrew 

Edited by andrew s
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I follow Woit's blog Not Even Wrong, referred to in the link above. I don't understand enough to appreciate the detail, but I find it a useful balance to the string/supersymmetry/multiverse crowd, and to the popular journalists who seem keen to declare "physics is broken" at every opportunity.

So, not really surprising that Woit is cautious about the recent g-2 announcements (and Brookhaven was some years ago). But I think he is right to emphasize that this isn't just about validating the recent experimental values to sufficient accuracy - no-one is going to dispute that part of it. But it's only a significant discrepancy if we are sure that the theoretical value taken as a comparison is really the best that the current standard model can predict, and there seems to be some doubt about that, with this other paper. It's a bit different from some previous "chasing the 5 sigma" episodes, where the question was often "have we found a new particle with mass X or not?". This seems to have been missed by most of the reports I've read. From an epistomological perspective, it would be preferable if the alternative calculation was done prior to knowledge of the Fermilab results.

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27 minutes ago, Zermelo said:

. From an epistomological perspective, it would be preferable if the alternative calculation was done prior to knowledge of the Fermilab results.

There has been a discrepancy for some time the current measurement reduces the error bars and so highlighted the difference.

I am sure the calculation is in good faith. They have made their code accessible  to other research groups and it is common in this area to get other groups of theorists to cross check using the same or different methods. Given the nature of the calculation it would be difficult to fix on a specific number. 

However, you are right intellectual phase-locking has been known so we need to await confirmation by other groups as the theory group freely admits.

Regards Andrew 

PS Here is a link to the Nature paper. The summary is very readable but you will have to pay for the full article 

Edited by andrew s
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Kind of  funny, I did a  project  on iodine 138 decay many years ago as part of my university third year astrophysics project. One of the products is a positron and a neutrino.

It's quite easy to measure neutrino mass squared, it always comes out negative but there is an error bar which could could just make  it positive.

Convention is always to take extreme positive value as it can't possibly be negative 🤣 many unwanted things seem to get explained away in physics

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