The Most Precise-Ever Measurement of W Boson Mass Suggests the Standard Model Needs Improvement (phys.org) 35
After 10 years of careful analysis and scrutiny, scientists of the CDF collaboration at the U.S. Department of Energy's Fermi National Accelerator Laboratory announced today that they have achieved the most precise measurement to date of the mass of the W boson, one of nature's force-carrying particles. Phys.Org reports: Using data collected by the Collider Detector at Fermilab, or CDF, scientists have now determined the particle's mass with a precision of 0.01% -- twice as precise as the previous best measurement. It corresponds to measuring the weight of an 800-pound gorilla to 1.5 ounces. The new precision measurement, published in the journal Science, allows scientists to test the standard model of particle physics, the theoretical framework that describes nature at its most fundamental level. The result: The new mass value shows tension with the value scientists obtain using experimental and theoretical inputs in the context of the standard model. If confirmed, this measurement suggests the potential need for improvements to the standard model calculation or extensions to the model.
survey says -- (Score:2)
Since it's not in the summary, the measured mass "is about 80 times the mass of a proton, or approximately 80,000 MeV/c2."
I wish I understood how this works... It seems like this is saying that the mass of this one particle is greater than the first quarter of the elements in the periodic table, and greater than many molecules. Does mass mean something different in the world of force carriers?
Re:survey says -- (Score:5, Informative)
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It comes down to fermions and bosons, short version: fermions being solid matter and bosons being force carriers. They have different spin with bosons having integer and fermions having fractional spins, fermions can’t occupy the same place in the same state (like electrons) while you can stack bosons for days and they don’t mind (like photons). The W moderates the weak force along with the Z. W essentially moderates neutrino emissions while Z moderates momentum spin and energy and both are extremely short lived due to the high mass, not allowing for much distance to be travelled and thus limit the range of the weak interaction.
Every time I come across descriptions like this I am in awe of human ingenuity in the ability to frame experiments and interpret results to come out with this kind of model.
Fermions don't give matter its solidity (Score:3)
Its electron bonding and repulsion and that gives matter its solid feel. Protons and neutrons have nothing to do with it (neutron stars excepted but no one knows how they would "feel" if you could touch it), they just give it mass. Yes, electrons are fermions too but they never actually touch in normal matter - Paulis exclusion principle. So what we feel as solid is actually repelling forces.
Physics says... (Score:2)
W essentially moderates neutrino emissions while Z moderates momentum spin and energy
That's utterly wrong. Both W and Z couple to neutrinos equally: the vertex factors in feynman diagrams are identical for both and neutrino emission in high energy interactions can come from both. Both W and Z bosons have momentum, spin and energy as do all vector bosons i.e. the photon and the gluons too and so all "moderate" these quantities..
The two key differences between W and Z bosons are that W bosons can change quark flavours while Z bosons cannot. The Z boson also has slightly different coupling
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I wish I understood how this works... It seems like this is saying that the mass of this one particle is greater than the first quarter of the elements in the periodic table, and greater than many molecules. Does mass mean something different in the world of force carriers?
Things like the W boson are very different from ordinary, everyday particles and matter. Everything you interact with is made up of 2 composite particles and 1 fundamental particle: the neutron, the proton, and the electron (respectively), the neutron and proton being made up of up and down quarks. Photons are also quite common in everyday experience.
None of the other bosons (such as the W boson in question) ever fully exist outside of particle detectors or high-energy physical events (cosmic ray showers,
That's Exactly what it says (Score:2)
It seems like this is saying that the mass of this one particle is greater than the first quarter of the elements in the periodic table, and greater than many molecules.
Yes, that's exactly what it is saying. The Z boson is more massive at 90 GeV/c2 and the Higgs boson even more so at 125 GeV/c2.
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Basically, no. The rest mass is typically expressed in terms of the energy equivalence, related via the "E=Mc^2" equivalence. Obviously a moving particle has energy from that rest mass, plus it's kinetic energy.
I need to go back to school. (Score:4, Insightful)
And it seems there are also the fundamental particles before getting to the simple to understand protons, electrons, and neutrons.
Re: I need to go back to school. (Score:2)
Bottom line up front is that it's all mathematical constructs that appear to have predictive power when extrapolated up to the macro level.
Whether they represent anything "real" kind of becomes a silly question by the time you scale down below the regime where questions like "can I see/hear/smell/touch/taste it" stop making sense.
You can taste electrons (as toddler me learned many decades ago after licking the tracks while playing with my toy train). I'm told that trying to feel a proton beam is possible bu
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That symetry is old as einstein (Emily Noether was a peer of Einstein for whom Einstein was *very* enthusiastic about her work.)
However, the idea *everything* has an anti isn't quite right. Plenty of things are their own anti.
The idea of C-, P- and T- symmetry isn't really in question however, we've had a century of experimental science finding those predictions are spot on the money.
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Electrons *are* fundamental particles.
Neutrons consist of 2x Down Quark + 1 Up Quark and Protons consist of 1x Down Quark + 1 Up Quark. (With gluons gluing them together).
Plus a bunch of Bosons gluing all that shit together.
Re: I need to go back to school. (Score:1)
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So much appears to have changed in 30 years beyond protons, electrons, and neutrons.
I think it has been longer than 30 years since you were in school! The Standard Model has been around since 1974 and I learnt about it in school 35 years ago.
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I think it has been longer than 30 years since you were in school! The Standard Model has been around since 1974 and I learnt about it in school 35 years ago.
Yeah, I remember learning about quarks in grade school, in the early 90s. While the number of elementary particles has expanded since then, at least some people were taught about them 30 years ago.
It may have helped that I grew up near a particle physics lab...
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... and Peter Higgs (and a few others, including his Nobel co-laureate, FranÃois Englert) developed the theory later named the "Higgs Field" in the early 1960s, publishing it in 1964. So it's almost twice as old as the 30-year look-back the OP is having.
That said, I can't particularly remember hearing about the Higgs (particle, or field) when reading "science news" as a student in the mid-80s. Then the thing people (including me) were trying to get their he
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The 1974 birth of the Standard Model was very different - it as known at the November Revolution for a reason since the discovery of the J/Psi could only be explained by the quark model and it was very much ex
I have an idea (Score:1)
Measure it three times and take the average. You just increased the precision by a lot.
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I can't tell if you are making a joke or not. From the article:
So, yeah, they took the average.
Standard model (Score:5, Insightful)
Literally everyone knows the standard model cannnot possibly be right, the only problem is that it has withstood every challenge to it. So far, nobody has shown to be wrong. All attempts to replace it turn out to be more whacky than the standard model itself.
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Literally everyone knows the standard model cannnot possibly be right, the only problem is that it has withstood every challenge to it. So far, nobody has shown to be wrong. All attempts to replace it turn out to be more whacky than the standard model itself.
Form Douglas Adams:
There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another theory which states that this has already happened.
Neutrino Oscillations (Score:2)
So far, nobody has shown to be wrong.
Sorry, but we have had established beyond the Standard Model physics for about 20 years now: neutrino oscillations. These show that neutrinos have mass and that lepton flavour is not conserved neither of which the Standard Model allows for. It's not hard to extend the SM to account for these but you do have to change it to stop it from being wrong.
Pounds, ounces? (Score:2)
Unless there's 800000 ounces in an 800 pound gorilla then the "simplification" is more complex than just simply giving the percentage.
Just googled it, 16 oz in a pound. Of course it is, otherwise it would be too easy to understand. So let's see 1.5 / 800 * 16 = fuck it 0.01% is good enough for me. That's like measuring a 1000kg car to an accuracy of 100g.
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That's like measuring a 1000kg car to an accuracy of 100g.
Dude, that's like measure the mass of a 1979 Volkswagen Beetle to within four AA batteries. Or for Slashdot, like measuring the mass of the Library of Congress to within 52.33 Big Macs.
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I remember an American telling me that a "pint is a pound, the world around", but here a pint is a pound and a quarter, from which I infer that American pounds are different to pounds "the world around".
Have some of the different States enacted their right to independent State measures? Yet?
Double slit experiment (Score:2)
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The DS experiment proves that particles are also waves going through the slits. This included up to 100 atom Bucky Balls: https://arstechnica.com/scienc... [arstechnica.com]
The SMoPP has always been flawed as it doesn't yet explain: Gravity, Dark Energy/Matter, Neutrino masses, and Matter/Anti-matter asymmetry: https://en.wikipedia.org/wiki/... [wikipedia.org]