# Tag Info

5

Feynman diagrams are most definitely not a representation of what's going on between the particles. Feynman diagrams are simply a tool to help you remember formulas: if you want to calculate the probability that two electrons will scatter off each other in so-and-so angle, you draw all possible diagrams with two incoming electrons and two outgoing electrons ...

5

Sometimes, they are the same particles and are not "arranged in some different way", for example photons are their own antiparticles, as are the hypothetical Majorana fermions. However the most common way that this happens is that every matter-particle, for example the electron, has an antiparticle (in this case, the positron). If you wanted to talk about ...

3

To start with this is the table of elementary particles: A corresponding table exists for antiparticles for the blue and the green colored ones, which are fermions. From the rest which are bosons the neutral ones are the antiparticles of themselves, and the antiparticle of W+ is W- and vice verso. By definition the antiparticle has the opposite in ...

2

The angle of the particle lines is irrelevant and it's just a convention. You could as well draw them as straight vertical lines. It doesn't affect the calculation of its contribution to the probability amplitude of scattering. For the same reason, Feynman diagrams do not intent to show attraction nor repulsion. They are just a bookkeeping graphical tool for ...

1

For the lifetime of the neutron to be different, the weak interaction coupling constant would be different. As far as nuclei are concerned the unstable ones with beta decays would have different lifetimes. In general all weak interaction mediated decays would have different lifetimes.

1

Ryan is correct. In addition I would point to beta decay, in one form of which a neutron is transformed into a proton, inside the nucleus. This is called $\beta^-$ decay and is accompanied by the emission of an electron $e^-$ by the affected nucleus.

1

The halflife of the neutron is set by three things (more or less): the mass difference between the neutron and the proton, the number (two) of light particles that accompany the decay and the strength of the weak interaction. Changing number (3) effects the lifetime of all weak mediated processes, but all of them in the same sense. Changing (1) ...

1

I will try to address the first point raised by the OP, i.e. the occurrence of spontaneous symmetry breaking in Bose-Einstein condensation. The free boson gas is described by the hamiltonian: $$H_V=\int_V\frac{d^sx}{2m}\big|\nabla\phi(x)\big|^2.$$ The ground state satisfies $H_V\Psi_0 = 0,\ \forall V$ and hence $\nabla \phi(x)\Psi_0=0,\ \forall x.$ ...

1

If you will allow me to make your question slightly more precise, I think you are asking the following: In spontaneous symmetry breaking (SSB), generally speaking, we say that the system has a range (either continuous or discrete) of possible degenerate values, and as a result it picks at random one of these configurations, resulting in a state without the ...

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