Not a discovery, but a provocation
April 9, 2022 2:04 PM   Subscribe

A new analysis of W bosons suggests these particles are significantly heavier than predicted by the Standard Model of particle physics. Original article in Science.
posted by Rumple (42 comments total) 10 users marked this as a favorite
 
Can you really trust researchers when they openly admit, "I like big bosons and I cannot lie"?
posted by clawsoon at 2:13 PM on April 9, 2022 [16 favorites]


Obviously the unhealthy diet of late capitalism has really gotten deep into the system.
posted by hippybear at 2:24 PM on April 9, 2022 [2 favorites]


Are they fat bosons or phat brosons?

I’ll show my self out. No, really … NOT THE STICK! NOT THE STICK!
posted by JustSayNoDawg at 2:43 PM on April 9, 2022 [4 favorites]


Matthias Schott who worked on earlier measurements of W-Boson mass says that before re-evauating the Standard Model they need to figure out why this measurement is so different from previous ones:

So I do not think, we have to discuss which new physics could explain the discrepancy between CDF and the Standard Model - we first have to understand, why the CDF measurement is in strong tension with all others.

posted by straight at 3:03 PM on April 9, 2022 [4 favorites]


If I read correctly, this is an analysis of 9 years of data whose collection ended 11 years ago! In those 11 years the Tevatron itself has been shut down, but it appears they did additional work using naturally occurring cosmic ray muons to more finely calibrate the detector and thereby wring more precision out of the banked data. Is that about right?

It’s also interesting how investigators are only given the exact data they need for their parts of the analysis and shielded from the rest until it’s all rolled up in the final analysis, which seems to be SOP these days in physics. Then they get everyone together for a big “reveal” event at the end.
posted by sjswitzer at 3:19 PM on April 9, 2022 [4 favorites]


Imagine the dinner-table conversations during that decade. “How’d it go at the lab today, hun?” “Nobody knows. Literally nobody.”
posted by sjswitzer at 3:21 PM on April 9, 2022 [3 favorites]


Mostly I haven't a clue about physics, but I'm strangly attracted to reading this type of light article. Physics jargon is delightful, and this author had to be writing tongue in cheek.
physicists predict[ed] the mass of a particle called the top quark
Of course there has to be a top quark! And he should have his own Saturday morning cartoon show.
...one or both groups has overlooked some subtle quirk of their experiments...
Subtle quirk could be the arch-villian!
...detect any wonky wires
Of course the wires are wonky, it's a cartoon show.
With the Tevatron gathering dust...
Now I'm just confused. Wasn't gathering *space*dust its job? Is it working when it's on or off or both when nobody is around?
Physics is hard!
posted by BlueHorse at 3:25 PM on April 9, 2022 [3 favorites]


Of course there has to be a top quark!

There's also a bottom quark. And a quark playroom with slings and crisco. But now I've said too much.
posted by hippybear at 3:31 PM on April 9, 2022 [24 favorites]


One more time hippybear and yr banned from quark playroom.
posted by sjswitzer at 3:39 PM on April 9, 2022 [2 favorites]


Come find me at the bar with the strange and charm quarks.
posted by sjswitzer at 3:41 PM on April 9, 2022 [5 favorites]


The problem is, if you observe me, you change me. Such are the rules of the quark playroom.
posted by hippybear at 3:41 PM on April 9, 2022 [13 favorites]


Nah, I’ve got your (quantum) number.
posted by sjswitzer at 3:51 PM on April 9, 2022 [1 favorite]



Come find me at the bar with the strange and charm quarks.


I couldn't find you. Perhaps the error bar was too large?
posted by lalochezia at 4:03 PM on April 9, 2022 [3 favorites]


Nah, I’ve got your (quantum) number.

Oh, sj.... sj don't lose my number... 'cause I'm not anywhere... if you can't find me......
posted by hippybear at 4:10 PM on April 9, 2022 [2 favorites]


Come find me at the bar with the strange and charm quarks.

It's really hard to write a sentence using terms from quantum mechanics that doesn't sound like a line from a Beck song.
posted by kersplunk at 4:39 PM on April 9, 2022 [7 favorites]


Damnit I should have said h-bar
posted by sjswitzer at 4:41 PM on April 9, 2022 [7 favorites]


Also "quark" is a strange sort of dairy food I encountered in Germany. It's not really yogurt, it's not really sour cream, I'm not really sure what it is because it has no equivalent in the US. But it was delicious. Delicious delicious quarks.
posted by hippybear at 4:47 PM on April 9, 2022 [1 favorite]


You need to try Skyr, hippybear. Kind of a more yogurty Quark, so a little more acid. Similar consistency and deliciousness.
posted by pipeski at 5:02 PM on April 9, 2022 [1 favorite]


The term quark was introduced by Murray Gell-Man who took it from a line in Joyce's Finnegans Wake, which may well have been referring to the strange sort of dairy food in Germany (usually described as a kind of cheese): "Three quarks for Muster Mark", although it was not beyond Joyce to totally make up a word.

There was a time when top and bottom were called Truth and Beauty, in a sort of whimsical parallel to Strange and Charm.

So far I'm seeing a mixture of skepticism of the result, hope that finally we'll have something beyond the Standard Model to sink our teeth into, and also some speculation of what it could be: multiple Higgs particles, which could possibly be an explanation for dark matter.
posted by Schmucko at 5:46 PM on April 9, 2022 [5 favorites]


The possibility of systemic error can’t be discounted, though they have been very very very (did I say very?) careful to account for that. The only way to be sure if this is really a thing is to corroborate it on different kit. I assume the LHC will be on that shortly but the article wasn’t quite clear about that. This is a way bigger and more careful study than the superluminal neutron thing, but that’s still a cautionary tale.
posted by sjswitzer at 6:12 PM on April 9, 2022 [1 favorite]


The ATLAS detector at CERN put out their measurement in 2017 and found it was consistent with the standard model. In slide 14 they show previous W mass measurements. It's a nice demonstration of the effort that goes into getting a good result. I hope they and CDF are able to pin down their discrepancy.
posted by Emmy Noether at 6:50 PM on April 9, 2022 [1 favorite]


There's also a bottom quark. And a quark playroom with slings and crisco. But now I've said too much.

Wait until you hear about Upsilon mesons, sometimes referred to as bare bottom quarks.
posted by dephlogisticated at 7:41 PM on April 9, 2022 [2 favorites]


What was peculiar about W was that he entirely had zero mass, but his effect was infinite. Truly some of the worst years of our history.

Wait, what were we talking about?
posted by hippybear at 7:43 PM on April 9, 2022 [3 favorites]


Upsilon mesons, sometimes referred to as bare bottom quarks.

Now if it turned out that they had more mass than predicted, it would be important evidence of their role in making this rockin' world go round.
posted by straight at 8:35 PM on April 9, 2022 [14 favorites]


I haven't had a chance to dig into this but I saw physicist Sabine Hossenfelder on Twitter today say: "This result was teased out from old data and doesn't so so much disagree with the standard model as with other data. ... Could this mean the standard model is wrong? Yes. But more likely it's a problem with their data analysis." She recommends this article.
posted by neuron at 8:44 PM on April 9, 2022 [2 favorites]


The linked video on the Standard Model is really superb. One or two more like that — or maybe just one or two more watches — and I might actually understand something.
posted by jamjam at 9:14 PM on April 9, 2022 [1 favorite]


Isn’t it just, well, nice to see smart people working hard on finicky details?

Like, ahhhhhh, maybe the next twelve thousand years won’t entirely suck? Yessssss, I can now relax. Slightly.
posted by aramaic at 9:56 PM on April 9, 2022 [1 favorite]


Sometimes a discrepancy between two different measurements of the same physical value isn’t an issue of measurement error or data analysis issues; the method of measurement could be different.

That’s what is likely going on in the Hubble constant tension (5sigma significance, and much talked about— this W mass issue is at 7sigma so even bigger). In the Hubble case there’s multiple ways to measure the value (this article has a decent explanation). But there it’s not one measurement against the rest, it’s one class of measurements (cosmic microwave background ) not matching another class (supernovae and gravitational waves). Each class is consistent with itself, but the classes don’t match.

This new W issue, it’s one analysis (of a lot of data!) against all the others. I am not qualified to comment (I’m neither a particle person nor an experimentalist, even if I am writing this jetlagged at April Meeting), but if there’s a physics explanation, then there should be a reason this kind of measurement/analysis falls into a different class than the rest. Of course the best way to find out what separates it would be to have another experiment/analysis also come up with this value. Then we can ask what they have in common that no other measurement shares.
posted by nat at 11:45 PM on April 9, 2022 [5 favorites]


You need to try Skyr,
Maybe also try ayran.

posted by pompomtom at 12:01 AM on April 10, 2022


"The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka' but 'That's funny...'" -- Isaac Asimov
posted by BiggerJ at 12:44 AM on April 10, 2022 [5 favorites]


Yes, lots of great lines from that article. I like "the W boson has to be the same on both sides of the Atlantic.” Seriously, I love me some physics mysteries, now if only they could whip up some substance in their particle labs that could help me understand them.
posted by blue shadows at 1:04 AM on April 10, 2022


Two layman's questions about the Standard Model video. First: the video seems to suggest that only matter particles (fermions) have mass: mass comes from the Higgs boson, whose "role is to endow all fermions with a mass" (12:29). That would make the new measurement even more striking... What am I misunderstanding here? Second: why does the weak force require two bosons, instead of just one? I would be grateful for explanations at more or less the level of this video, if possible.
posted by bleston hamilton station at 3:10 AM on April 10, 2022


I miss physicsmatt.
posted by biogeo at 7:05 AM on April 10, 2022 [5 favorites]


Mostly I haven't a clue about physics, but I'm strangly attracted to reading this type of light article.
posted by BlueHorse


Actually, strange attractors are mathematics, not physics.

Of course I jest with you. :)
posted by Splunge at 8:04 AM on April 10, 2022 [1 favorite]


bleston hamilton station:

I think I can answer your questions for you! It is NOT only true that fermions have mass. In the Standard Model, the W+ and W- as well as the neutral Z, which are all given mass by interactions with the Higgs. What's surprising is the particular mass found for the W.

Why 3 bosons for the weak force? Well, there are actually in a sense 8 bosons, different versions of the gluon, for the strong nuclear force.

It comes down, in group theory lingo, to the "symmetry group" of the standard model being SU(3) x SU(2) x U(1), with SU(3) being the strong nuclear force and (this is a simplification I'll correct soon!) SU(2) being the weak force and U(1) being the electromagnetic force. And so the number of bosons is the square of the dimension of the symmetry group (minus 1 if the group has S in front of it), so SU(3) has 3^2-1=8 bosons, SU(2) has 2^2-1=3 bosons, and the electromagnetic force has 1^2=1 boson (the photon).

It's actually more complicated: there's a mixing between the original SU(2) and U(1) that happens with symmetry breaking, and SU(2) only applies to "left-handed particles" so not every version of a particle feels the weak nuclear force.

SU(3) means Special Unitary group expressed by multiplication tables using 3x3 matrices of complex numbers that are unitary (flipping around diagonal and exchanging i with -i creates the inverse) and special (have determinant exactly equal to 1.) That quality of having to be Special cuts down the number of bosons (the independent basis matrices) by 1.

I really like this graphic in Wikipedia showing how the Standard Model works. It gets into some details other graphics don't. Above the line: before "symmetry breaking", under: after. Symmetry breaking.
posted by Schmucko at 12:08 PM on April 10, 2022 [7 favorites]


Schmucko: Thanks for the Wiki link.
posted by aleph at 12:31 PM on April 10, 2022 [1 favorite]


aleph: I keep that pinned in my Google Keep and look at it every day, exclaiming: WTF, Nature?
posted by Schmucko at 12:33 PM on April 10, 2022


I might add in SU(2) I was calling the 2 a dimension but that's the wrong term!
posted by Schmucko at 3:29 PM on April 10, 2022


A lot of us gained some weight during Covid lockdowns.
posted by gimonca at 6:29 PM on April 10, 2022 [2 favorites]


Ayran, doogh, dhallë, daw or tan is a cold savory yogurt-based beverage of Turkic origin, popular across Western Asia, Central Asia, South Asia, Southeastern Europe and Eastern Europe.

Ayran, so far away...
posted by snuffleupagus at 5:30 AM on April 11, 2022


the W boson has to be the same on both sides of the Atlantic.

Are we absolutely sure? It is said that everything is bigger in America, maybe that also goes for the tiniest things.
posted by ymgve at 8:59 PM on April 11, 2022


Actually, strange attractors are mathematics, not physics

Nah, actually they're music.
posted by pompomtom at 6:33 AM on April 12, 2022


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