Running Constants: Unifying Gaugino Masses in SUSY

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Discussion Overview

The discussion revolves around the concept of running constants in the context of supersymmetry (SUSY) and their implications for gaugino masses at different energy scales. Participants explore the relationship between gaugino masses and the energy scale of SUSY breaking, as well as comparisons to fermion masses in the Standard Model.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants express confusion about how gaugino masses can be discussed if SUSY breaking occurs below the GUT scale, suggesting that gauginos would be massless in unbroken SUSY.
  • Others draw parallels between gaugino masses and fermion masses in the Standard Model, indicating that running constants may depend on Yukawa couplings rather than direct mass values.
  • There is a question about whether W and Z bosons become massless above the electroweak symmetry breaking (EWSB) scale, with some participants speculating on the implications for high-energy collisions.
  • One participant mentions the possibility of a supersymmetric theory without gauge interactions, suggesting that mass equality in supersymmetric multiplets can exist without gauge invariance.
  • Another participant questions the understanding of the implications of SUSY breaking on particle masses, indicating a need for clarification on the topic.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the implications of SUSY breaking for gaugino masses, with multiple competing views presented regarding the relationship between mass and energy scales in both SUSY and the Standard Model.

Contextual Notes

Participants highlight the complexity of discussing particle masses in the context of SUSY and the Standard Model, noting that assumptions about gauge invariance and the nature of symmetry breaking may affect interpretations.

ChrisVer
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Well I am having some difficulty in understanding the running constants... I am not sure if this applies to the Standard Model as well, but I saw that in SUSY recently...
If we take the value of the gaugino masses m_{\bar{g}},m_{\bar{W}},m_{\bar{B}} (by bar I mean Gluino,W-ino and B-ino) to be equal at some energy scale (~MGUT) then we can go to lower energy scales (let's say at TeV) to find their ratio:
m_{\bar{g}}:m_{\bar{W}}:m_{\bar{B}}≈6:2:1
I guess this ratio depends on the model.

My problem is that I don't understand how we can do that, in the case the SuSy breakdown occurs at lower energies than M_GUT... While SuSy is unbroken, the gauginos will have to be massless, right? If the breakdown occurs at around 2TeV let's say, then it's meaningless to speak about their masses...
 
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The same thing happens with fermion masses in the Standard Model. Typically it is just a matter of sloppy wording and what really is running are the Yukawa couplings (at least above EWSB). I am no SUSY expert, but I suspect there is something similar at work here.
 
ChrisVer said:
My problem is that I don't understand how we can do that, in the case the SuSy breakdown occurs at lower energies than M_GUT... While SuSy is unbroken, the gauginos will have to be massless, right? If the breakdown occurs at around 2TeV let's say, then it's meaningless to speak about their masses...

In SUSY models where you have some unification of masses etc. at the GUT scale, then it is at the GUT scale where the SUSY breaking is hypothesised to be happening. So no, that sort of unification doesn't make any sense if the SUSY breaking scale is way below the GUT scale.
 
Orodruin said:
The same thing happens with fermion masses in the Standard Model. Typically it is just a matter of sloppy wording and what really is running are the Yukawa couplings (at least above EWSB). I am no SUSY expert, but I suspect there is something similar at work here.

yes, the same question I could ask for the Standard Model as well for above the EWSB...
For example do the W and Z bosons we know become massless? I think they do (at least effectively) because you will have energies above the vev energy...
 
ChrisVer said:
yes, the same question I could ask for the Standard Model as well for above the EWSB...
For example do the W and Z bosons we know become massless? I think they do (at least effectively) because you will have energies above the vev energy...

Yeah actually I'd like to know the details of this too. Does anyone have a good reference? The whole point of the Higgs mechanism is that the fermions have no mass before symmetry breaking, but how literally can this be "undone" in high energy collisions? What is happening? If we calculate say the running top mass in some renormalisation scheme or other, does it go to zero above the symmetry breaking scale? What will happen experimentally to reflect this?
 
Be careful here, it is possible to have a supersymmetric theory of scalars and fermions which does not have gauge interactions. In this case, a supersymmetric multiplet necessarily have the same mass because supercharges commute with the momentum operator, so a supercharge acting on a state does not alter the eigenvalue of pμpμ.

The equality of masses is a result of presence of auxiliary field which has no kinetic term and eliminating it by EOM yields the constraints on fermion boson masses and coupling constant.
 
I can't say that I understand what your point is.
 
andrien said:
Be careful here, it is possible to have a supersymmetric theory of scalars and fermions which does not have gauge interactions. In this case, a supersymmetric multiplet necessarily have the same mass because supercharges commute with the momentum operator, so a supercharge acting on a state does not alter the eigenvalue of pμpμ.
It is meaningful to talk about masses of particles in a supersymmetric theory even when the SUSY breaking has not taken place if you don't have requirement of gauge invariance.
 
andrien said:
It is meaningful to talk about masses of particles in a supersymmetric theory even when the SUSY breaking has not taken place if you don't have requirement of gauge invariance.

Ahh I see. Interesting.
 

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