Proton-neutron mass difference explained

In summary, the mass difference between protons and neutrons can be explained by the presence of gluons, which are responsible for the strong nuclear force that holds these particles together. Protons have a slightly higher mass due to the presence of two up quarks and one down quark, while neutrons have two down quarks and one up quark. The difference in mass between protons and neutrons is essential for the stability of atomic nuclei and plays a crucial role in nuclear reactions and energy production. Understanding the proton-neutron mass difference is essential in the fields of physics, chemistry, and nuclear engineering.
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Orodruin
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According to the newly published paper

http://www.sciencemag.org/content/347/6229/1452
Ab initio calculation of the neutron-proton mass difference
Science 27 March 2015:
Vol. 347 no. 6229 pp. 1452-1455
DOI: 10.1126/science.1257050

we owe our existence to an interplay between electromagnetic and mass isospin breaking effects. The preprint can be found at http://arxiv.org/abs/1406.4088

This is one of the problems one of my favourite lecturers as an undergrad said he wanted an answer to before he dies (he is still alive).
 
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Orodruin said:
This is one of the problems one of my favourite lecturers as an undergrad said he wanted an answer to before he dies (he is still alive).
Did you contact him about it? :)
 
  • #3
He is still around on Tuesdays when he gives a course on the history and epistemology of physics to our grad students. I think he will not be satisfied with this though, he will also want to know why the quark masses have their values and it seems to me they used them as input.
 
  • #4
They are free parameters in the SM. I don't know where they got the masses from, as using the proton/neutron mass difference looks like a sensible place to evaluate them.
 
  • #5
mfb said:
They are free parameters in the SM

Indeed. I think he will not be satisfied until a superseeding theory predicts the values of the quark masses.
 
  • #6
Using Lattice gauge theory is nice and of course correct, but it would be nice to have some understanding of this from more analytic methods.
 

FAQ: Proton-neutron mass difference explained

1. What is the proton-neutron mass difference?

The proton-neutron mass difference refers to the difference in mass between a proton and a neutron, which are both subatomic particles found in the nucleus of an atom. Protons have a positive charge and neutrons have no charge, but both have approximately the same mass. However, there is a small difference in their masses, which is known as the proton-neutron mass difference.

2. Why is the proton-neutron mass difference important?

The proton-neutron mass difference plays a crucial role in understanding the structure and stability of atomic nuclei. It is also a key factor in nuclear reactions and energy production, as well as in the study of fundamental particles and their interactions.

3. What causes the proton-neutron mass difference?

The proton-neutron mass difference is primarily due to the different masses of their constituent particles. Protons are made up of two up quarks and one down quark, while neutrons are made up of one up quark and two down quarks. The mass of the up quark is slightly lower than the mass of the down quark, which results in a small difference in the overall mass of protons and neutrons.

4. How is the proton-neutron mass difference measured?

The proton-neutron mass difference can be measured using high-precision techniques such as mass spectrometry. By comparing the masses of protons and neutrons, scientists can determine the exact difference between them. This measurement is important for understanding nuclear properties and for verifying the predictions of theoretical models.

5. Does the proton-neutron mass difference have any practical applications?

Yes, the proton-neutron mass difference has several practical applications in fields such as nuclear energy, radiology, and astrophysics. Understanding this difference is crucial for designing nuclear reactors, developing new medical imaging techniques, and studying the evolution of stars and galaxies.

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