Neutron

[Little Bang]

The caterpillar has a genetic code sensitive to certain environmental conditions that tell it to build a cocoon and then tells the cells to rearrange into a butterfly.

An imaginary picture of the hydrogen atom, the proton is composed of two red up quarks and one blue down quark with the electron being a yellow point. What do you suppose the code is that mixes the electron with one of the red quarks to make a blue quark and thus a neutron?

[Farsight]

There is no "code", LittleBang. Read up on Beta decay. Beta-minus decay is where a neutron decays into a proton,an electron, and an antineutrino. Beta-plus "decay" is more of a constructive event rather than a destructive event, where input energy is used to turn a proton into a neutron, a positron, and a neutrino. You can do the same sort of thing with the antiparticles.

[CraigD]

An imaginary picture of the hydrogen atom, the proton is composed of two red up quarks and one blue down quark ...

This is not the correct quantum chromodynamic description of a proton.

 

The correct description is “a proton is composed of 2 up quarks and 1 down quark. There must be one quark of each of the colors red, blue, and green.”

 

In the pseudoclassical sense that it meaningful to talk about knowing the state of a quark at a given instant with certainty, a given up or down quark is equally likely at any instant to be any one of the 3 colors. They change color often, and in nonclassical terms, may be considered to be in superpositions of all 3 colors. Pseudoclassically, all 3 quarks may even be the same color at the same instant, provided that the R,G,B total color charge of their nucleon is conserved by the color charge of its gluons: for example, 2 red up quarks, 1 red down quark, a blue-antired gluon, and a green-antired gluon are permitted.

 

…with the electron being a yellow point.

This is not correct, because according to QCD, electrons have no color charge. Only quarks and gluons do, and there are only 3 colors, yellow not one of them.

 

It’s important to understand that the term “color” in QCD refers to a very different thing than it does in optics and visual perception. In optics, colors are simply words describing ranges of photon wavelengths (or alternately, frequencies), so there are many such words. In human visual perception, colors are perceived by the triggering of different combinations of 3 kinds of retinal cells sensitive to photons of 3 wavelength ranges. That there are 3 colors in QCD, and 3 important in human color perception, and that we usually give them the same names – red, blue, and green – is due not to any physical similarity, but because naming the property “color charge” and its 3 values after the 3 primary colors made discussing and studying them easier than less intuitive terms like “SU(3)”.

 

The caterpillar has a genetic code sensitive to certain environmental conditions that tell it to build a cocoon and then tells the cells to rearrange into a butterfly.

...

What do you suppose the code is that mixes the electron with one of the red quarks to make a blue quark and thus a neutron?

Keeping in mind that a proton and a neutron forming a neutron (eg: inverse beta decay) doesn’t involve any color charge interaction with the electron, because electrons have no color charge, I suppose that it isn’t, at present, very useful to draw an analogy between the how genes control the physical development of animal cells and how fundamental particles interact. Although today’s fundamental particles – by definition, ones that can’t be decomposed into subparticles – may someday be revealed to be decomposable into subparticles, until that can be done, there’s no physical thing small enough to encode and express rules governing the interaction of fundamental particles.

[Little Bang]

Did you see anywhere in my post the word chromodynamics? A free neutron decays in ~ fifteen minutes into a proton an electron and an electron antineutrino. I realize this is obviously a silly question but how, since a neutron doesn't require an electron when it is made, does the electron get produced when the neutron decays?

[Qfwfq]

I realize this is obviously a silly question but how, since a neutron doesn't require an electron when it is made, does the electron get produced when the neutron decays?

Ok then, here's an obviously silly answer: Lagrange waves his magic wand and some things disappear (and are no longer there) while others appear (that weren't there previously). Therefore it isn't necessary for the electron to have been there when the neutron was made.

 

Salagadoola means

mechicka booleree.

But the thingmabob

that does the job

is quantumfield-theeheeoh-ry.

[CraigD]

Did you see anywhere in my post the word chromodynamics?

No, I did not see anywhere in your post the word chromodynamics. I saw the phrase

... two red up quarks and one blue down quark ...

The theory that assigns the colors red, blue, and green to quarks is quantum chromodynamics, so I concluded that you were discussing this theory.

[Farsight]

...A free neutron decays in ~ fifteen minutes into a proton an electron and an electron antineutrino. I realize this is obviously a silly question but how, since a neutron doesn't require an electron when it is made, does the electron get produced when the neutron decays?

You've got pair production going on under the covers. Imagine you've got a 1022keV photon and a proton in your gedanken fist, and you're squeezing hard trying to emulate beta-plus "decay". Squeeze hard enough and and the 1022keV photon interacts with the proton and undergoes pair production, turning into a 511keV electron and a 511keV positron. Open your hand at the right time and the positron escapes leaving you with an electron and a proton sitting on the palm of your hand. But this isn't a neutron, this is a hydrogen atom. To make a neutron, you have to repeat the gedankenexperiment with a more energetic photon, enough to create an electron and a positron, and a neutrino and an antineutrino. Then the proton and the electron and the antineutrino combine to make a neutron sitting on the palm of your hand whilst the positron and the neutrino escape. But then when you wait for fifteen minutes, all your hard work is undone. The neutron decays into a proton, an electron, and an antineutrino.

[Qfwfq]

All this is more complicated and raises the similar question about the electron, positron, neutrino and antineutrino not having been there when the proton and photon were made. The answer of course remains the same; quantum field theory can do that too, except that it must be a tiny tiny contribution to the amplitude, especially due to the factor for vertex where the proton, electron and antineutrino combine to make a neutron.

[Farsight]

I'd say the best place to look for conceptual grasp of the underlying reality is Topological quantum field theory, which was developed by people like Ed Witten and Michael Atiyah about twenty years ago. It seems to be somewhat overlooked these days, I'm not sure why, but I hope WItten and others are looking at it afresh. In a nutshell it's related to knot theory, so you can think of different particles as different stress-energy configurations in momentum space. Hence the "trefoil" proton, which fits really well with the bag model of quark confinement. But anyway, Little Bang, I hope you're now happy with the antineutron.

[Little Bang]

John, I owe you an apology. Please email me so I can tell you why.

[Farsight]

I don't think you do, LB, but willco. Sorry I've not been around for a few days.

[Little Bang]

How does the standard model address this. http://physicsworld.com/cws/article/news/7064

[HydrogenBond]

One thing that has always bothered me is that accelerator experiments are conducted at relatively low gravity. Since gravity is not a big variable in the experiments, how do we know that if extreme gravity was included, most of these particles would or would not exist? In words, this data does not accurately reflect something like the BB, since it doesn't include gravity. I was wondering what conditions in the universe are similar to the accelerators experiments; gravity can be ignored. Could this be synthetic matter due to the unique conditions in which we create?

 

Don't get me wrong, synthetic can have practical value, if we don't over extrapolate into nature. For example, polyethylene is a synthetic material with many uses, made from the free radial polymerization of ethylene. Say we decided to extrapolate this synthetic into natural and assume the oil deposits of the earth formed from the free radical polymerization of early earth ethylene. Without O2 and Ozone, we get more UV for free radicals. Pre-life then made use of this to form their early membranes without the need for such synthesis. Life then spread over billions of years, into the primal hydrocarbon mixtures, which were also being subject to heat, oxidation, pressure, continental upheaval to create the impression of a living source.

 

Extrapolating synthetic into natural can create what appears to be legitimate extrapolations which may or may not be real. We can probably demonstrate this theory in the lab but what does that prove other that we can make this stuff synthetically. The accelerator data may help with particle beam weapons, propulsion or communication but that doesn't mean natural.

[Little Bang]

That's really not the issue Hydro. The point is that according to the standard model the tetraneutron is impossible . If it is confirmed then we have to throw away our current understanding of the nucleus and nuclear forces.

[CraigD]

How does the standard model address this. http://physicsworld.com/cws/article/news/7064

... The point is that according to the standard model the tetraneutron is impossible . If it is confirmed then we have to throw away our current understanding of the nucleus and nuclear forces.

Though I hadn’t heard of Marques's 2002 GANIL experiment before your post, LB, from what I gather from sources such as wikipedia article “tetraneutron” and its references, especially Steven Pieper’s 2004 paper Can Modern Nuclear Hamiltonians Tolerate a Bound Tetraneutron?, you’re correct that confirmation of the existence of a nucleus consisting of 4 neutrons – the tetraneutron – would require a dramatic change to current nuclear physics and the Standard Model.

 

However, since Marques’s 2002 experiment, attempts to reproduce his results have failed, leading to the conclusion that the experiment and its analysis were flawed. In short, Marques’s team’s hopes that future experiments would confirm their initial results have not been fulfilled.

[Little Bang]

Thanks Craig I had not seen that.

[Rade]

See this 2008 paper on theoretical possibility of "resonance" for tetraneutron:

 

http://arxiv.org/PS_cache/nucl-th/pdf/0612/0612020v1.pdf

 

The Standard Model does allow for cluster structure in isotopes, and this paper argues that tetraneutron may exist as a type of resonance composed of the two cluster combination of {n + 3n} + {2n + 2n}--well, this is how I understand the situation. I do not know if the Standard Model would allow for such cluster coexistence.

 

The paper also provides a somewhat recent review (2008) of the literature plus experiments that have been conducted on tetraneutron since 2002.