Recent content by goronx

Thanks, it's seems to be useful for my purpose.

Ok, thank you both. So, neutrino and anti-neutrino have parallel spins, which means that I'm in a triplet state. The Z has spin=1 so I can use the conservation of angular momentum, there's no problem with it, right? This implies that also initial particles must have parallel spins and, because...

The only certain thing is that I'm confused. :-p Let's fix this first doubt. I have this: \left|\uparrow,\downarrow\right\rangle=\left|0;0\right\rangle+\left|1;0\right\rangle Does it mean that if I have two particles with opposite spins I can be or in a singulet state or in a triplet one...

Maybe I'm wrong (and it is my mistake), but I thought that having a boson with unitary spin (such as Z) is a problem for the conservation of angular momentum. Considering the two neutrinos with opposed helicity (particle and antiparticle), they must have spin directed into the same direction...

Ok, I did not think about it, thanks.

Why are you talking about two photons? Sorry, but may I ask you to be more explicit on this argument? Really, I'm trying to solve this "simple" problem since 1 week, if I had any idea regarding how to proceed I would have done by miself. Thank you. 1- I can't find nothing about conservation of...

No one?

The problem is that I don't think that exists something like the conservation of helicity.

In this case they are considered as massless particles, so their helicity is fixed. As next step, I thought that the starting point is to think them in the center of mass system, then I can represent neutrino and antineutrino with spins into the same direction because of what we said about...

Ok, let's say that both neutrino and anti-neutrino have fixed helicity (respectively -1 and +1), what's the next step? I thought that, because the have fixed and opposite helicity, they have also the same spin, but I don't know what to do now. Is it important if the propagator is a photon...

I can try to be more explicit: my problem is that I don't understand how Weyl field can be used to describe particles and antiparticles and obtain information about their helicity. Theoretically is it clear what a Weyl field is but I can't see how they are used in practice.

This is an extract from my book: If we neglect the small masses indicated by the oscillations experiments, the neutrinos in the Standard Model are described by massless left-handed Weyl fields. The neutrino has h =−1/2 and the antineutrino has h =+1/2. Anyway, if you know an other way to...

Hi, I have a problem involving helicity. Homework Statement In a scattering e^{+}+e^{-} \rightarrow \nu_{\mu}+\overline{\nu}_{\mu} I have to determine for which values of the helicity of initial particles the cross section is not 0. Homework Equations The Attempt at a Solution On a...

Hi, I'm new on this forum. I have a doubt regarding helicity and Weyl spinors: I can't understand when I have to use left or right-handed Weyl spinors in order to describe particles or antiparticles. What i have understood is that a charged current is described by left-handed Weyl fields...