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Lepton Universality In Question, a Standard Model Assumption

Soulskill posted about 2 months ago | from the we'ere-slightly-more-wrong-than-we-thought dept.

Science 62

Charliemopps writes: "Over the past few years, more and more experiments have started to question one of the core assumptions of the standard model: Lepton Universality. Simply put, the weak nuclear force is assumed to work equally on all Leptons (electron, muon and tau). Two years ago The Babar experimental collaboration reported that measurements indicated this may not have been the case. But the measurements were not accurate enough to be definitive.

Now, a report from The LHC shows that they have analyzed their entire dataset of proton-proton collisions and found a rather large discrepancy. These measurements are still not all that accurate. These decays happen so rarely that even with this huge data set there is still about a 1% change they are incorrect. One explanation for such measurements is an as-yet-undiscovered, charged Higgs particle. It would have to be extremely heavy: greater than 109GeV possibly even as high as 150GeV. This is predicted by some models outside of the Standard Model, like Supersymmetry."

cancel ×

62 comments

No Problem: (4, Funny)

Tablizer (95088) | about 2 months ago | (#47167657)

To "fix" it, just add one or more of the following to the model:

* More turtles
* More nested epicycles
* More dimensions
* Invent dark [something] to plug it
* Say God did it

Profit!

Re:No Problem: (1)

lazy genes (741633) | about 2 months ago | (#47167671)

More fields, maybe proton decay is responsible for the higgs field.

Re:No Problem: (1, Funny)

Anonymous Coward | about 2 months ago | (#47167713)

We can invent a dark, energy-less, massless particle that travels backwards in time and only interacts with other particles on Tuesday afternoons. Got to keep propping up the standard "model".

Re:No Problem: (0)

Anonymous Coward | about 1 month ago | (#47169229)

What else can we do, until a viable replacement theory is found? Science gotta go on, man.

Re:No Problem: (-1)

Anonymous Coward | about 2 months ago | (#47167735)

Are you ok with taking a cock up the ass in the name of dumbfuckery?

Re:No Problem: (1)

Tablizer (95088) | about 1 month ago | (#47169257)

What happens if I answer "no"?

Re:No Problem: (0)

Anonymous Coward | about 2 months ago | (#47167773)

Can you lend me some dimensions for the weekend? I get a visit from relatives and want to impress them.

Re:No Problem: (0)

Anonymous Coward | about 2 months ago | (#47168067)

I'm a Lepton and "They're always after my lucky charm quarks.".

Re:No Problem: (0)

Anonymous Coward | about 2 months ago | (#47168221)

The 13-D Dark Turtle God did it, and has the rings to prove it.

Re:No Problem: (5, Insightful)

Anonymous Coward | about 2 months ago | (#47168685)

Just remember if you propose a new thoery that can explain the data and make quantitative, it still needs to past the most important test: the gut instinct of forum posters on the internet. They seem to act like science shouldn't propose new theories when new data conflicts with old theories... or insist new theories are ok, except for the ones they don't like.

Re:No Problem: (-1)

Anonymous Coward | about 1 month ago | (#47169563)

Go to hell, you stupid little nigger faggot.

Re:No Problem: (0)

Anonymous Coward | about 1 month ago | (#47169579)

"

To "fix" it, just add one or more of the following to the model:

* More turtles
* More nested epicycles
* More dimensions
* Invent dark [something] to plug it
* Say God did it

Profit!
"

I'm sure you meant to say "Prophet"...

How convenient! (-1, Troll)

93 Escort Wagon (326346) | about 2 months ago | (#47167759)

A new theory that will require an even more massive supercollider to prove or disprove!

Re:How convenient! (2)

MightyMartian (840721) | about 2 months ago | (#47167837)

Gosh science is so expensive. Let's shut it down so we can remain ignorant fucktards forever!

Big Science is expensive (1)

Ottibus (753944) | about 1 month ago | (#47171267)

Gosh science is so expensive. Let's shut it down so we can remain ignorant [] forever!

Science in cheap, Big Science is expensive. So, yes, let's shut down some of the expensive Big Science experiments and fund hundreds of other smaller experiments in a range of different fields. No so flashy, but much better value.

Re: Big Science is expensive (0)

Anonymous Coward | about 1 month ago | (#47171823)

Just open LHC's BIOS and overclock that bitch. Some bitchin' cables, LEDs, and a see through case might help.

It sounds like these scientists are complete tools. Do they even know what a CPU multiplier is?

Re:How convenient! (1)

CRCulver (715279) | about 2 months ago | (#47167869)

A new theory that will require an even more massive supercollider to prove or disprove!

If I'm not mistaken, the 109-150GeV range that would have to be searched is within the LHC's present capabilities.

.

Re:How convenient! (1)

amorsen (7485) | about 2 months ago | (#47167959)

I could not find the 109-150GeV range in the original article, but the Higgs that has been found already has a mass around 126GeV. It seems like an additional Higgs in that range should already have been found by the LHC.

Re:How convenient! (3, Informative)

cjameshuff (624879) | about 2 months ago | (#47168143)

Consider how long it took to gather enough of the right events to be reasonably certain about the Higgs, the various false alarms that vanished as more data was collected, etc. Another version just a bit rarer could easily be lost in the noise. Or the two could be similar enough that their signals aren't distinguishable from each other yet.

Re:How convenient! (3, Insightful)

Ost99 (101831) | about 2 months ago | (#47168453)

Wan't the confirmation just slightly different from what they expected.
The deviation might actually be traces of this unknown 2nd Higgs particle.

Re:How convenient! (1)

jfengel (409917) | about 1 month ago | (#47173963)

That's correct: there were discrepancies that might-could-possibly have been caused by a Higgs+.

Or by any of a zillion other things, but it was a hypothesis that merited further experimentation.

Re:How convenient! (1)

Anonymous Coward | about 1 month ago | (#47168845)

It is not just about the energy reachable, but the luminosity, which expresses how many particles it has interacting at relevant energy. Fermilab could have reached those energies, but the LHC has twenty times the luminosity, and at higher energy levels you can increase the chances of some reactions too even though they are at lower energy than the beam energy. This is why the next upgrade at CERN in ~2020 might not involve increasing the particle energy, but instead an increase of 5-10 times in luminosity which could be as important in answering some current questions.

Re:How convenient! (1)

Anonymous Coward | about 2 months ago | (#47167913)

A new theory that will require an even more massive supercollider to prove or disprove!

Fine by me. Beats the hell out of another fruitless military adventure in the middle of nowhere or more pork barrel appropriations.

But... (5, Informative)

Stormy Dragon (800799) | about 2 months ago | (#47167833)

This is predicted by some models outside of the Standard Model, like Supersymmetry.

Except that that LHC's ongoing failure to find any SUSY particles is making it increasingly unlikely Supersymmetry is right either:

http://scienceblogs.com/starts... [scienceblogs.com]

Re:But... (4, Informative)

jfengel (409917) | about 2 months ago | (#47167935)

The data go a long way to ruling out the Minimal Supersymetric Standard Model (MSSM), but other SUSY theories are still in the running. The MSSM has the advantage of being, well, minimal, but there's no special reason to expect the universe to have made it that easy on us.

It's hard to say which theory this points us to, if any, but the Two Higgs Doublet Model (2HDM) is a part of several. Those theories will help refine what kind of data to look for and what kinds of experiments to configure.

Re:But... (1)

Stormy Dragon (800799) | about 2 months ago | (#47167973)

Yes, but as I understand it, the whole point of supersymmetry was to solve the Hierarchy problems. Even if one of those other variants of supersymmetry holds, they would do so at an energy too high to still resolve the hierarchy problem. So the question becomes what the point of them is, other than having supersymmetry purely for the sake of having supersymmetry.

Re:But... (1)

Pausanias (681077) | about 1 month ago | (#47175491)

Let's face it---supersymmetry's entire cachet is based on the minimal supersymmetric standard model. If the minimal model goes away, it will lose so many supporters that it will become yet another one of "those" theories that few (other than its proponents) care about.

Null experiment for the 21st century (4, Interesting)

Anonymous Coward | about 2 months ago | (#47168007)

With regards to Supersymmetry I have the feeling the LHC is going to end up being this century's version of Michelson-Morley.

However, given what happened after Michelson-Morley, we may be in for some very exciting new physics in the years to come if we can disprove Supersymmetry.

(At least I hope we are... :-))

Re:Null experiment for the 21st century (-1)

Anonymous Coward | about 1 month ago | (#47169581)

WARNING!!! It appears we have a space nutter faggot here. Everyone step back and wait for the little critter to 3D print himself on another planet.

Preferably Jupiter.

captcha: panties

Re:Null experiment for the 21st century (1)

jandersen (462034) | about 1 month ago | (#47170039)

I think this is what we all hope - that the existing theories may finally be proven wrong. To a scientist, it is always the unsolved problems that are interesting; the journey and the fun is over when you reach your goal.

I'm not sure about Supersymmetry, though - it's only intuition, but my feeling is that it should have been a minimal form of Supersymmetry, if any. Occam's Razor and all that - I believe Einstein once used the expression 'As simple as possible, but no simpler than that'. I think the next big step forward will always be something that seems like a beautiful and simple explanation to what looked like a big mess. Both GM and QM were that in the beginning, and I'm sure whatever replaces (ie. refines) them, will be something that makes us all go 'Ah, of course'. Give or take a few, crinkly equations ;-)

Re:Null experiment for the 21st century (1)

Philomathie (937829) | about 1 month ago | (#47170767)

What on Earth would make you say that? I see no similarities between this experiment and the Michelson-Morley experiment.

Re:Null experiment for the 21st century (2)

ricky-road-flats (770129) | about 1 month ago | (#47171681)

It's true, physically it's a very different experiment. However, I think what the poster was referring to was what Michelson-Morley led to, which was huge. From Wikipedia:

It attempted to detect the relative motion of matter through the stationary luminiferous aether ("aether wind"). The negative results are generally considered to be the first strong evidence against the then prevalent aether theory, and initiated a line of research that eventually led to special relativity, in which the stationary aether concept has no role. The experiment has been referred to as "the moving-off point for the theoretical aspects of the Second Scientific Revolution".

In other words, although the aims of Michelson-Morley were proved wrong, what they did find eventually led to big new science - and the same might apply here once hindsight is brought to bear.

"still about a 1% change" (2, Funny)

Anonymous Coward | about 2 months ago | (#47167835)

Change you can believe in!

"chance", you idiots!!!

Re:"still about a 1% change" (0)

Anonymous Coward | about 1 month ago | (#47169593)

Actually he meant 1% change. It will have the effect of changing about 1% of scientific minds.

Change-Chance. Can you even spell E.D.I.T.O.R. ? (-1)

Anonymous Coward | about 2 months ago | (#47167921)

Editor by name, moron by nature.

The nature of the Standard Model (0)

Anonymous Coward | about 2 months ago | (#47167983)

The Standard Model is an excellent computational tool - and little else.

Re:The nature of the Standard Model (1)

gargleblast (683147) | about 2 months ago | (#47168369)

The Standard Model is a coherent, thorough description of a very large number of physical phenomena: atomic theory, radioactivity, antimatter, electromagnetism, the nuclear forces, neutral currents, neutrinos, the bewildering range of particles produced by colliders - and much more.

Re:The nature of the Standard Model (2)

rubycodez (864176) | about 1 month ago | (#47169177)

the Standard Model is completely useless for describing the forces that shape and evolve the cosmos: gravitation, dark energy, dark matter. It does not explain neutrino oscillation (neutrino mass). Doesn't give reason for the observed dominance of matter over antimatter. It has a huge number of arbitrary constants not related to each other and no way to predict or give reason for there values.

In short, it's obviously half-assed, a "cooking the books" production

Re:The nature of the Standard Model (2)

jfengel (409917) | about 1 month ago | (#47174015)

That's not a very good way to describe it. It's like blaming Boyle's Law for not predicting nuclear fusion. The Standard Model is anything but half-assed. It made a lot of predictions, including previously unseen quarks, mesons, and the Higgs Boson.

Nobody was trying to say that it was the final theory. They know it doesn't incorporate gravity; that's why there's string theory and alternatives (and the challenge of putting together an experiment with sufficient energy to show the discrepancies between general relativity and the Standard Model). They know it doesn't explain all of its own parameters; that's why they're looking for supersymmetry (or alternatives) and the presence of unpredicted particles to narrow it down.

It's all just physics. That's how science works. It's a process. It seems weak to run down the process for not being finished, when it's clear that the process does make progress (and when it comes to these questions, it's the only thing that makes progress).

Re:The nature of the Standard Model (3, Informative)

ceoyoyo (59147) | about 1 month ago | (#47168787)

The standard model is an extremely comprehensive collection of theories that makes incredibly accurate predictions. It's a crappy computational tool. It's so computationally intractable that it requires supercomputers to simulate even simple multi-particle systems.

Particles are more unique than thought (-1, Troll)

MatthiasF (1853064) | about 2 months ago | (#47168287)

I know most people think of molecules, atoms, nucleus, neutrons, quarks, leptons, etc., are all precisely the same across all similar items. But they are not.

Two hydrogen atoms are completely unique to one another but it is harder to measure the differences than larger items because of the difference in scale and since they both generally behave the same way no on cares to explore their uniqueness until the difference is noticeable and worth exploration.

We know this to be true because nothing can be perfectly split and if nothing can be perfectly split then there cannot be two particles that are exactly the same. If a single particle cannot be split into two equal particles, then no two combination of particles can produce the same unique item again. Therefore, all particles must be truly and absolutely unique in some fashion.

So, the idea that contrary leptons can be symmetric is absurd.

Re:Particles are more unique than thought (2)

Typical Slashdotter (2848579) | about 2 months ago | (#47168505)

Um, what? Insane pseudoscience at its finest.

Re:Particles are more unique than thought (0)

Anonymous Coward | about 2 months ago | (#47168585)

depends on what you consider properties of particles. after all, the position of the particle indicates its potential energy, thus two particles in different places are "different" in at least that respect. then there's also particle's speed, mass, etc., all of which could vary with energy, etc., on the other hand, ignoring those properties, all "electrons are the same" is likely a mostly valid statement.

Re:Particles are more unique than thought (1)

Anonymous Coward | about 2 months ago | (#47168731)

We know this to be true because nothing can be perfectly split

Says what theory? This seems arbitrary and runs contrary to a large amount of particle physics, including some rather basic predictions of things of quantum mechanics and quantum field theory that would be covered in intro level courses on the topic. If the particles leaving an interaction were distinguishable and not "perfectly split," the results of the calculations would be off by a factor of two from measurements because of the way states work out, but they are not.

If a single particle cannot be split into two equal particles, then no two combination of particles can produce the same unique item again.

Even if the previous statement was true, this doesn't follow.

Therefore, all particles must be truly and absolutely unique in some fashion.

This seems to amount to circular reasoning in the end, and regardless disagrees with large number of experiments. This includes precision experiments that aren't about the basic assumptions of current theories, but checking that things like energy levels and things like charge of electron are constant and don't change because it is important to some work on redefining SI units.

Re:Particles are more unique than thought (4, Insightful)

ceoyoyo (59147) | about 1 month ago | (#47168799)

And that's the problem with applying pop logic to a fuzzy understanding of a vastly simplified description.

Modern quantum theory suggests not only that two examples of the same type of particle are not only completely identical except for certain features like position, but that even talking about particles as if they had individual existence doesn't really make sense.

Re:Particles are more unique than thought (3, Funny)

Anonymous Coward | about 1 month ago | (#47169605)

Sounds like the simulation we are living in uses some de-duplication in the file system.to save space.

Re:Particles are more unique than thought (0)

Anonymous Coward | about 1 month ago | (#47169669)

And a multiverse dos make sense?

Re:Particles are more unique than thought (0)

Anonymous Coward | about 1 month ago | (#47171671)

Modern quantum theory suggests not only that two examples of the same type of particle are not only completely identical except for certain features like position,

Position is a property. If the information of 2 things are identical they are the same thing not 2 things.

but that even talking about particles as if they had individual existence doesn't really make sense.

However you divide the universe (or entagled existance at least) up this could be said to be true. It would take something as complex as the universe to model it fully though so to be able to make useful predictions we have to split it somehow.

Re:Particles are more unique than thought (1)

qeveren (318805) | about 1 month ago | (#47169359)

Actually, you're entirely wrong. Subatomic particles of the same type are fundamentally indistinguishable from each other.

Re:Particles are more unique than thought (0)

Anonymous Coward | about 1 month ago | (#47171721)

If they have the same information they are the same particle. If they don't they are distinguishable.

Re:Particles are more unique than thought (2)

jandersen (462034) | about 1 month ago | (#47170089)

So, the idea that contrary leptons can be symmetric is absurd.

Not at all. Because, while your considerations are valid in a sense, you fail to take into account the fact that a 'particle' is an abstract entity - a theoretical construct that attempts to sum up a set of measurable characteristics in the data. Whenever we construct a theory, we are looking for things that are looking symmetrical and harmonic in some sense, so the elements in our theory will almost unavoidably be objects with this sort of universal properties.

Of course, being a only model means that any theory must fail at some point, when our observations become sophisticated enough, and that is probably what all true scientists are hoping for. The frustrating problem we have had for a long time is that we have observations that are not covered by our theory, but none of the predictions we have been able to produce with the help of our models turn out to be false. IOW, we know that our understanding of the universe is fundamentally flawed, but we can't see how or where. Things like the apparent problem with lepton universality may show us a way forward, so it is in fact very good news.

Re:Particles are more unique than thought (2)

radtea (464814) | about 1 month ago | (#47171957)

Two hydrogen atoms are completely unique to one another...

That statement is false. Quantum mechanics deals explicitly with "identical particles", which are particles that are literally indistinguishable from each other, but are not the same particle. This is an empirically demonstrable violation of the principle of "identity of indiscernibles", which states that if two things are indiscernible any means whatsoever, even in principle, they are the same thing. Even though we have known this principle to be false for almost a century, philosophers still take it seriously for some reason.

There is a relatively simple proof that atoms of the same kind are indiscernible. The heat capacity of solids is a measure of how much the temperature goes up as you add energy to a block of material. The temperature is just the average energy per vibrational mode of the crystal lattice. The number of vibrational modes is intimately linked to the number of distinguisable particles in the crystal. N distinguishable particles have a different number of modes than N indistinguishable particles, so crystals will have a different heat capacity depending on which situation actually obtains.

This can be seen by considering a pair of distinguishable coiins vs a pair of indistinguishable coins. If we have two coins that are distinguished by the labels A and B, we have four ways of arranging them by which face is showing (H for heads, T for tails): AH/BH, AT/BH, AH/BH, AT/BT. If they are not distinguishable we only have three states: H/H, H/T, T/T because there is no way to distinguish AT/BH from AH/BT when we remove the labels.

So by a simple macroscopic measurements like the heat capacity of crystalline solids we can prove positively and directly by experiment that atoms of the same kind are in fact indistinguishable, and that the principle of the identity of indiscernibles is false. It is not false "for quantum particles" but false, absolutely--it just happens that quantum particles are the only case we know of where different particles are genuinely indiscernible from each other. But there is no limited domain of application to this result, and philosopher's attempts to treat it as somehow restrictive to the quantum domain are simply misguided (it turns out that the identity of indiscernibles being false makes nonsense of a bunch of other things philosophers want badly to believe, not least of which is how utterly useless the human imagination is in deciding what is and is not true of the world.)

Re:Particles are more unique than thought (0)

Anonymous Coward | about 1 month ago | (#47172375)

If they are "literally indistinguishable" the universe wouldn't be able to distinguish between them and so would be the same particle. If you can tell there are 2 particles they are distinguishable.

Wrong universality? (3, Funny)

Trogre (513942) | about 1 month ago | (#47168875)

When I grow up I'm going to Lepton University!

No wait...

Re:Wrong universality? (0)

Anonymous Coward | about 1 month ago | (#47175695)

You're not fooling anyone, we know you're 40+ :)

where are the systematic uncertainties? (1)

naminori (947101) | about 1 month ago | (#47169869)

As I could not find it on the arXiv (http://xxx.lanl.gov/), nor inspire (http://inspirehep.net) nor any official statement from CERN I assume this is just a preliminary result so far. Even as such I would expect some kind of estimate on the systematic uncertainties which go with this measurement. Without that it is not particularly relevant yet as those uncertainties could be substantial. So at the moment it is premature to talk about a discrepancy with the standard model (nor the previous measurements).

1% change they are incorrect (1)

Paradigma11 (645246) | about 1 month ago | (#47170073)

Is there really a 1% probability that they are incorrect or is there a 1% to get such data if they were wrong?

Re:1% change they are incorrect (0)

Anonymous Coward | about 1 month ago | (#47175687)

With our current knowledge wouldn't they be the same?

My Lepton University acceptance letter (0)

Anonymous Coward | about 1 month ago | (#47170741)

I applied to Lepton University and I just received a letter in the mail so I put it inside a box.

It is both a thick acceptance letter and a thin rejection letter. I'm not really sure where I'm going this fall semester.

Oh well, there's always Quark Community College, I guess.

Last gasps of supersymmetry (1)

Lawrence_Bird (67278) | about 1 month ago | (#47171055)

Honestly.. a 2.6 sigma result? History is littered with 3 sigma results that vanish as more data is taken and detectors and other experimental hardware/software become better understood and modeled.

Re:Last gasps of supersymmetry (1)

Charliemopps (1157495) | about 1 month ago | (#47171107)

Yes, but this isn't the only result. There have been many over the past 10yrs. None are definitive, but they all seem to agree. That's hard to swallow as a random statistical anomaly. Don't get me wrong, it still could be... But it's worth our interest.

august institution (1)

Ginger Unicorn (952287) | about 1 month ago | (#47173063)

I read the headline as "Lepton University"
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