Fermions Bosons vertices in SM - but no SUSY

In summary, in the Standard Model, fermions interact through exchanges of massless spin-1 particles, but this interaction does not turn fermions into bosons. This is different from the SUSY transformation, which suggests that there is a bosonic partner particle for each fermion. However, the gauge fields in the Standard Model are not the generators of symmetry, and in supergravity, the gravitino can transform particles into their superpartners.
  • #1
Lapidus
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In the Standard Model fermions interact via exchanges of massless (virtual) spin-1 particles. Fermions are turned into a boson. How is that different from the SUSY transformation that turns fermions into bosons?
 
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  • #2
Lapidus said:
In the Standard Model fermions interact via exchanges of massless (virtual) spin-1 particles. Fermions are turned into a boson
Fermions are not turned into bosons in the exchange in the SM (unless in s-channel where two fermions combine into a generally off-shell boson).
 
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  • #3
In addition the Orodruin's answer: An interaction (something physical happening) is not a symmetry transformation (a mathematical operation).
 
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  • #4
Also note that the weak interaction is mediated by massive vector bosons, the ##W## (charged) and ##Z## (neutral) bosons.
 
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  • #5
SUSY is not telling you that a fermion becomes a boson, it tells you that for each fermion there is a bosonic partner particle (super-partner). The two are related via supersymmetric transformations.
So the fact that the electron+positron annihilate let's say to 2 photons, doesn't tell you that the photon is the superpartner of the electrons/positrons (which are the selectrons)...
 
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  • #6
Parhaps the question can be reformulated to how different
mfb said:
In addition the Orodruin's answer: An interaction (something physical happening) is not a symmetry transformation (a mathematical operation).

But the W and Z and gamma are symmetry transformations, generator of SU(2)xU(1), and they are particles too. It could be argued that they just happen to be particles in the defining representation of the symmetry, but then the question translates to "when do symmetries have associated particles"?

Particularly, er, specifically, what happens with the generator of supersymmetry? It seems that in this case it is not compulsed to appear as an associated particle interacting with all the others, is it? If it were, we should have diagrams where a fermion interacts with another one and becomes a boson.
 
  • #7
Not the gauge fields are the generators of the symmetry but the corresponding Noether-charge operators. Of course you are right in saying that the gauge fields are Lie-algebra valued vector fields, i.e., something like ##\mathcal{A}_{\mu} =A_{\mu}^a \hat{t}^a##, where ##\hat{t}^a## are the Lie-algebra basis matrices in the representation of the field you apply the corresponding gauge-covariant derivative to, ##\mathrm{D}_{\mu} = \partial_{\mu} + \mathrm{i} g \mathcal{A}##.
 
  • #8
arivero said:
what happens with the generator of supersymmetry?
See 7.5 of Stephen Martin. When global susy is spontaneously broken, the resulting goldstino can transform particles to their superpartners. In local susy, i.e. supergravity, the gravitino has this property.
 

1. What are fermions and bosons in the Standard Model?

Fermions and bosons are two types of particles in the Standard Model of particle physics. Fermions are particles with half-integer spin, such as quarks and leptons. Bosons are particles with integer spin, such as photons and W and Z bosons.

2. What is the significance of vertices in the Standard Model?

Vertices are points where particles interact with one another in the Standard Model. These interactions are described by Feynman diagrams and are crucial for understanding the behavior of particles and their interactions.

3. Why is supersymmetry (SUSY) important in particle physics?

Supersymmetry is a theoretical framework that proposes a new symmetry between fermions and bosons. It is important because it provides a solution to several problems in the Standard Model, such as the hierarchy problem and the lack of a dark matter candidate.

4. Why have fermions, bosons, and vertices been extensively studied in the Standard Model?

Fermions, bosons, and vertices are fundamental building blocks of the Standard Model and play a crucial role in understanding the behavior of particles and their interactions. Studying these concepts allows scientists to make predictions and test the validity of the Standard Model.

5. What is the current state of research on fermions, bosons, and vertices in the Standard Model without SUSY?

Currently, scientists are still exploring the behavior of fermions, bosons, and vertices in the Standard Model without SUSY. Many experiments, such as those at the Large Hadron Collider, are searching for evidence of new particles or interactions that may provide a better understanding of these concepts. However, the Standard Model without SUSY remains a well-tested and successful theory in explaining the behavior of particles.

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