Feynman diagrams - neutrino interactions

• billbray
In summary, the conversation discusses the interaction of a neutrino at a vertex with a w boson, emitting an electron. The rate of interaction is small but not zero, which explains why a neutrino can travel through 18 light years of lead without interacting. The concept of beta decay is mentioned, where a neutrino can be the initial probe. The interaction of neutrinos mainly occurs through inverse beta decay.
billbray
I have some well ordered feyman diagrams which have an incoming neutrino interacting at a vertex with a w boson and emitting an electron. since a neutrino can pass through some 18 light years of led without interacting, I'm wandering how a single neutrino interacts at this vertex?

The interaction rate is small, but not zero. That's why it's 18 light years and not 180 or 1800.

The first thing you should think of is beta-decay where a neutrino is emitted, if a particle can be the final product, it can also be the initial probe (time symmetry).

here is the beta decay:
http://teachers.web.cern.ch/teachers/archiv/HST2002/feynman/exampl2.gif
(the wavy line is the W boson)

and this is the process if p was heavier than n:
http://hyperphysics.phy-astr.gsu.edu/Hbase/astro/imgast/ppfustep.gif

W couples to lepton and its neutrino, e.g. electron + (anti) electron neutrino (lepton # must be conserved)

Z couples to lepton and antilepton, e.g. eletron + positron / electron neutrino + anti electron neutrino

Neutrinos mainly interact with matter (as incoming particles) via inverse beta decay

1. What are Feynman diagrams and how are they used in neutrino interactions?

Feynman diagrams are graphical representations that depict the particle interactions in a physical process. They are used to visualize and calculate the probabilities of different particle interactions in quantum field theory. In neutrino interactions, Feynman diagrams are used to understand and predict the behavior of neutrinos as they interact with other particles.

2. What is the role of neutrinos in Feynman diagrams?

Neutrinos are depicted as lines in Feynman diagrams, representing their paths in the interaction. They are important particles in these diagrams because they play a crucial role in many physical processes, such as nuclear reactions and particle decays.

3. How do Feynman diagrams help in understanding neutrino oscillations?

Feynman diagrams are useful in understanding neutrino oscillations, which refers to the phenomenon where neutrinos change from one type (flavor) to another as they travel. These diagrams help visualize the different interactions that can lead to neutrino oscillations and calculate their probabilities.

4. Can Feynman diagrams be used to study neutrino interactions in different mediums?

Yes, Feynman diagrams can be used to study neutrino interactions in different mediums, such as in a vacuum, in water, or in matter. The interactions of neutrinos with other particles may vary depending on the medium, and Feynman diagrams can help visualize and calculate these differences.

5. Are there any limitations to using Feynman diagrams in studying neutrino interactions?

While Feynman diagrams are a powerful tool in understanding and predicting particle interactions, they do have limitations. These diagrams only consider a few particles and interactions at a time and may not accurately represent more complex interactions involving multiple particles. Additionally, Feynman diagrams are based on classical physics and do not take into account the effects of quantum mechanics, which may be important in certain interactions involving neutrinos.

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