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back to article LHC spots mesons flipping between matter and antimatter

The LHC might be inactive at the moment, but the science goes on: a group of researchers trawling the instrument's vats of data has spotted a matter-antimatter oscillation that completes their “zoo” of meson “flips”. In a paper published at Arxiv and accepted by Physical Review Letters, the researchers say they've spotted D …

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Holmes

Very nice

How does that look in a Feynman diagram though? Does the arrow along the "one of the infinitely possible particle paths" alternatively point to the future and to the past?

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Facepalm

Re: And the "Standard Model" is?

This is unbeliveable, I have just given Eadon an up vote!

Today, he is clearly Beyond His Standard Model.

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Boffin

Re: And the "Standard Model" is?

"A former CERN particle collider - the LEP stuck the knife SUSY. The LHC then killed her completely"

Absolutely wrong on both accounts. LEP came nowhere close to ruling out even the minimal Supersymmetric model (MSSM). The LHC has ruled out large areas of the MSSM to the point where things are getting strained but this is the _minimal_ SUSY model. Go to the next-to-minimal model (nMSSM) and there is no problem. Even the LHCb results - which the experiment keep on touting to the press as ruling out SUSY - only constrain it to appear more Standard Model-like than absolutely required.

However if none of that convinced you then ask yourself this: why are so many of us working on the LHC experiments still actively searching for it if we already know it is not there?

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Anonymous Coward

Re: And the "Standard Model" is?

I often think that particle physics since the 1960s is the replacement for advanced theology. The kit is even bigger (and actually works), and important insights about the nature of reality come out from time to time, but the actual impact on people's lives is almost nonexistent (unlike cheap, unglamorous solid state and condensed matter physics which are transforming the world we live in, particle physics has nothing to show like the silicon integrated circuit). Particle physics was briefly of great importance when it nearly resulted in our destroying ourselves with nuclear bombs, but since then its contributions to society have been peripheral.

I can therefore imagine that yes, scientists with careers to forge and budgets to spend might keep searching for something they know deep down inside is unlikely to exist, just as many theologians are far too well educated to believe in "God". Because that's human nature.

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Coat

Re: And the "Standard Model" is?

love those names

is the one after the next-to-minimal-model on-the-bus-with-minimal-model ?

mines with one with the Hawkwind album in the pocket

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Alien

Re: And the "Standard Model" is?

Cracking album that... although you can't go past WOTEOT for all-round trippiness!

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Re: And the "Standard Model" is?

I still don't really understand how this means that windows is crap.......

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Coat

Re: And the "Standard Model" is?

Personally, I'm looking forward to the No' As Big As Medium Model But Bigger Than Wee Model Model

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Roo
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Alien

Re: And the "Standard Model" is?

Warrior on the Edge of Time has some pretty neat bits in it, but I think you can go quite a bit further as far as "all-round trippiness" within the Hawkind catalogue - like their first album ("Hawkwind") for example.

My favourite Hawkiwind album remains Doremi... On some happy occasions I still get to read some old 2000AD comics while listening to early 70s Hawkwind - which oddly enough is what got me interested in Physics and then computing in the first place.

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Anonymous Coward

Re: And the "Standard Model" is?

What people forget is that SUSY makes the SM worse anyway

You know, that's an excellent phrase to take entirely out of context..

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Boffin

Re: And the "Standard Model" is?

@Eadon, "What people forget is that SUSY makes the SM worse anyway, by introducing a 100 extra parameters that can have arbitrary values. The SM has about 18, I think"

Something like 18 yes, but 18 parameters that have to be incredibly finely tuned if the model is valid at high energy. Radiative corrections to the Higgs mass scale quadratically as you go up in energy, and only by finely tuning the SM parameters can you cancel these corrections and recover a sensible Higgs mass value. That's a horrible type of feature in any physical model.

SUSY neatly solves this 'Hierarchy Problem' since each particle type's radiative corrections to the Higgs mass are cancelled by the superpartner.

Sure, it's theoretical and there's no proof. But it simplifies the SM rather than complicating it. Add to that the fact that in SUSY models the EM, weak & strong coupling constants converge to a single value at high energies (something like 10^16 GeV for the MSSM), hinting at possible grand unification.

Then there's also the lightest neutralino, a weakly interacting massive particle and a perfect candidate for dark matter.

Certainly, there's no evidence yet, but the LHC hasn't ruled out SUSY and as Mallorn said LEP didn't come close. Theories are being constrained, just like the Higgs mass was being constrained right up until it was (probably) discovered in the last unconstrained region. People were proclaiming the death of the Higgs too, even back in LEP's day. It's far too early to rule out such a promising theory as SUSY.

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Boffin

Re: And the "Standard Model" is?

"When LEP found no SUSY physicists were already casting doubt on the existence of SUSY."

Not true. Thermal models of Big Bang WIMP production predict a Dark Matter mass around 1 TeV/c2. LEP could not reach anywhere even close to that. While I did not work on LEP I was at CERN at the time and knew a lot who did and I can honestly say that I knew nobody who though the LEP results cast any doubts on SUSY - simply that the mass scale was higher than LEP could reach.

"SUSY is dead in the view of most serious physicists."

Again not true - talk to my colleagues on ATLAS. We have a huge SUSY group actively looking for it (and I'm not even a member of it!). It is true to say that the MSSM is looking somewhat constrained but you massively overstate the case by saying we think it is dead...well unless you think that none of us working on the LHC are "serious physicists". ;-) If you look at the mass limits for the ATLAS and CMS searches most of these are around 1 TeV/c2. At this scale the hierarchy problem is still very readily solvable by SUSY. However if we do not see it after the long shutdown, then I would agree that at this stage the mass limits (expected to be several TeV and rising) will start to raise issues.

"What people forget is that SUSY makes the SM worse anyway, by introducing a 100 extra parameters that can have arbitrary values. The SM has about 18, I think."

Again you misstate the case. SUSY is effectively like a second Standard Model and has all the free parameters that the Standard Model had UNTIL we measured a lot of them and found them to be zero or forbidden. For example the SM has a free parameter 'theta' which gives the strength of CP violation in strong interactions. However this is not usually listed as a free parameter because, experimentally, theta is exactly zero. So while the MSSM has 120+ free parameters many of these may well turn out to be zero if SUSY is out there and it may well be that you end up with something close to the 25 free parameters of the SM.

So by all means say that if SUSY is out there it is not as obvious as we would have naively expected it to be but, at the moment, I would completely disagree that most physicists think it is dead as an explanation of the hierarchy problem and dark matter. It's under threat - which is the best place for a theory to be because it means we have a chance to either find it or rule it out - but we are not quite there yet.

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IT Angle

@Eadon Re: And the "Standard Model" is?

I'm sorry, but where is the anti-MS angle?

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Beauty returns to quantum physics

Genuine physics aside, I am delighted to see that the bottom quark has oscillated back into its beauty state.

I was very disappointed when the original Truth and Beauty names for the T & B quarks were replaced by the mundane and unimaginative Top and Bottom. Although I suppose there is a place for Tops and Bottoms in an SM theory ...

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Re: Beauty returns to quantum physics

@Eadon - Most men?

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nothing to show

oh come on what's this www thingy we're using here .... direct from particle physics.

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Anonymous Coward

You lost me after "The"

I was away the day we did quarks at school.

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Headmaster

Re: You lost me after "The"

In France, one would not be allowed to do quarks!

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Go

Mesons play for both sides in polarity switch shocker!

So where's the sexy footage of mesons oscillating?

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Thumb Up

Re: Mesons play for both sides in polarity switch shocker!

The people demand that it be illustrated through the medium of Playmobil.

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Naive understanding of antimatter...

[Mesons] don't annihilate because that only occurs when a particle is confronted with its own antiparticle; in the case of mesons, the mis-match between quark types prevents this from happening.

Tell that to the J/ψ meson (charm/anticharm).

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Bronze badge

So, to someone who didn't do any more physics than 1st year undergrad, how much closer does this get us to huge antimatter factories in tight solar orbit pumping out grammes of the stuff?

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About the lifetime of a typical meson

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Boffin

I'm confused

If a meson is composed of both a quark and an anti-quark, how can it have an anti-partner? Surely that, too would be composed of an anti-quark and quark; what then distinguishes this from it's normal matter counterpart?

Is it just by convention that we call a meson composed of a anti-charmed quark and a down quark as matter, but one composed of an anti-down quark and charmed quark as antimatter? How does flipping between the two cause CP violation, or is it to do with the quarks having different charge/spin/colour values?

I'm sure the answers are out there for me to google if I so wish, but I feel the article should at least explain what the actual transition that has been observed is, and why it demonstrates charge/parity violation. After all, if this does go towards explaining why the universe contains matter at all, it is an important result.

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Boffin

Re: I'm confused

"If a meson is composed of both a quark and an anti-quark, how can it have an anti-partner?"

D0 meson = charm quark + up anti-quark

anti-D0 meson = charm anti-quark + up quark

Since a charm quark is distinct from a charm anti-quark these are two different particles. However you can get mesons consisting of the quark and anti-quark of the same flavour (e.g. phi meson = strange+anti-strange). These are their own anti-particles just like a photon!

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Happy

Bambleweeny 57 Sub-Meson Brain ...

and a nice hot cup of tea.

Simples!

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Anonymous Coward

labor prices in different countries

just for the record, in order to warn any non-westerners:

"The cost [...] has been evaluated, taking into account realistic labor prices in different countries. The total cost is X (with a western equivalent value of Y) [where Y>X]

source: LHCb calorimeters : Technical Design Report

ISBN: 9290831693 http://cdsweb.cern.ch/record/494264

http://cdsweb.cern.ch/record/1127343?ln=en

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Joke

LHC Collider?

Why do we need to collide Lettuce, Ham & Cheese with Layers of Extra Pickle and Squeezy Mustard ?

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Trollface

So THAT'S where the anit-matter is hiding.

Fascinating...

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Perhaps matter itself is a fractal; the deeper you go, the more you find.

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Coat

Errrrrrrr

Could you please redo this article as a series of photos, using playmobil characters?

Trying to make sense of this drove me quarkers

/gets coat

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How lovely in scope and color and charming to behold

the Standard Model is beautiful. One should also appreciate the purpose of naming unique mathematical characterizations charm, and color. How sad that we have up and down, top and bottom, for these words impart to the mind a familiar behavior with no connection to their use in the SM.

What is amusing is that we are told that only "serious physicists" etc. No one in their right mind will accept the results of the LHC as proven until the Higgs has shown by further yet to be defined experimentation that it has the right "stuff".

ANd how can anyone be satisfied with this years accelerator energies when Dark Matter and Dark Energy rule the Universe and are untamed by "serious physicists".

I predict the way forward will be through the DARKness and into the light of Beyond the Standard Model.

Please don't take me seriously.

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Alien

Vacuum Energy

So with all these virtual anti-particles, how much longer before vacuum energy will become a reality? It seems if these virtual particles really exist in the vacuum, they could theoretically be manipulated virtually, then supplied with enough energy (E=MC^2) to bring them out of the hidden dimension they are in, to annihilate with their reality counterpart. (which should produce two times E=MC^2) This sounds like Sci-Fi, but there has to be a way to create an energy efficient way to produce a strong stream of anti-particles that could be used as an energy source that would be much more efficient than even fusion. Perhaps this is off topic, but they were talking about anti-matter here. Even a way to produce a steady stream of positrons could do the trick, you would think, and one source could be the virtual positrons that surround each real electron. Imagine how much energy you could produce by colliding a stream of naked electrons with their positron counterparts.

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Anonymous Coward

Prists versus scholars

Higgs V Non Higgs, God V Big Bang, LHC V LEP....

just more people talking out their arses about their team being better, in the end it has no impact on the real world, just as it has not for years.

What productivity that has helped humanity has come from knowing that there are particles smaller than we can use in life have there been?

spend the money on the starving world or create better ways of feeding them

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Stop

Re: Prists versus scholars

"What productivity that has helped humanity has come from knowing that there are particles smaller than we can use in life have there been?"

Says the person posting a message on a website using a computer. The fact that you have a computer is because 100 years ago Rutherford was bouncing alpha particles of a gold foil and Schrodinger, Heisenberg et al were developing quantum mechanics. Oh and the web itself was invented by CERN to help large, international groups of particle physicists to communicate with each other. So how about we start with those two.

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