How exactly will LHC detect superpartners?

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In summary, the Large Hadron Collider (LHC) will detect superpartners by looking for a quantity called R-parity in models like the Minimal Supersymmetric Standard Model (MSSM). The lightest partner, also known as the Lightest Supersymmetric Partner (LSP), will leave the detector without being seen, leaving a signature of missing momentum. This will serve as evidence for the existence of superpartners and, in combination with other measurements such as spin and couplings, can help identify them as different from other particles. The LHC will also be able to detect the Higgs boson through various signals, such as its decay to two photons, and can use measurements of spin and couplings to confirm its identity.
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bananan
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How exactly will LHC detect superpartners? Presumably they will have higher mass, are there other ways to detect them?
 
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It really depends on the model. In models like the (Minimal Supersymmetric Standard Model) MSSM, there is a quantity called R-parity. Each Standard Model particle has R-parity +1 and each partner has R-parity -1. R-parity is conserved in interactions which means that the lightest partner (R-parity -1 state) will be stable (since it can only has R-parity +1 states that are lighter).

This Lightest Supersymmetric Partner (LSP) then leaves the detector without being seen. This is a real smoking gun because then the momentum in the plane transverse to the beam will not be conserved by the visible particles (the momentum parallel to the beam isn't either, but this is useless because one doesn't know the initail particle momenta, only their direction).
 
  • #3
Severian said:
It really depends on the model. In models like the (Minimal Supersymmetric Standard Model) MSSM, there is a quantity called R-parity. Each Standard Model particle has R-parity +1 and each partner has R-parity -1. R-parity is conserved in interactions which means that the lightest partner (R-parity -1 state) will be stable (since it can only has R-parity +1 states that are lighter).

This Lightest Supersymmetric Partner (LSP) then leaves the detector without being seen. This is a real smoking gun because then the momentum in the plane transverse to the beam will not be conserved by the visible particles (the momentum parallel to the beam isn't either, but this is useless because one doesn't know the initail particle momenta, only their direction).

Thanks for the reply.

I guess while we are on subject, how will LHC see the higgs boson, and how could it see higher dimensions if they exist?
 
  • #4
Severian said:
It really depends on the model. In models like the (Minimal Supersymmetric Standard Model) MSSM, there is a quantity called R-parity. Each Standard Model particle has R-parity +1 and each partner has R-parity -1. R-parity is conserved in interactions which means that the lightest partner (R-parity -1 state) will be stable (since it can only has R-parity +1 states that are lighter).

This Lightest Supersymmetric Partner (LSP) then leaves the detector without being seen. This is a real smoking gun because then the momentum in the plane transverse to the beam will not be conserved by the visible particles (the momentum parallel to the beam isn't either, but this is useless because one doesn't know the initail particle momenta, only their direction).

I wonder whether such a signature would prove SUSY, as opposed to a non-SUSY previously unknown particle with similar mass.
 
  • #5
Yes, to prove it is SUSY you really need to do two things:

1. Prove the particles differ by spin 1/2.
2. Prove that the partners have the same couplings as the SM ones.

I have seen it claimed that 1 is only possible at a linear collider, but there have been some papers more recently on this, e.g. http://arxiv.org/abs/hep-ph/0605067 and http://arxiv.org/abs/hep-ph/0605286, which discuss measurements at the LHC.

As for the Higgs boson, there are various signals. For example, Higgs decays to two photons are nice because the diphoton invariant mass will give a peak at exactly the Higgs boson mass. This is a rather clean channel, and as soon as it is seen I am sure there will be a discovery announcement.

However, again, one has to be careful to make sure it is a Higgs and not something else. To do this, you really need to measure its spin (to see it is a scalar) and its couplings (to show they are proportional to the mass of the particle it couples to). Eventually if you can measure itself couplings you can actually reconstruct the shape of the mexican hat potential of the Higgs boson. Unfortunately this last thing won't be possible at the LHC.
 
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1. How will the LHC detect superpartners?

The LHC (Large Hadron Collider) will use high-energy particle collisions to search for evidence of superpartners. These collisions will create new particles, which will then decay into other particles, including the superpartners. By analyzing the properties and behavior of these decay products, scientists can infer the presence of superpartners.

2. What is the role of the detectors in detecting superpartners?

The LHC has four main detectors - ATLAS, CMS, ALICE, and LHCb - which are responsible for detecting and measuring the properties of particles produced in collisions. These detectors use advanced technologies such as electromagnetic calorimeters, muon detectors, and tracking systems to accurately record the particles and their properties, including the superpartners.

3. How will the LHC distinguish superpartners from other particles?

Superpartners are predicted to have similar properties to their corresponding Standard Model particles, but with different masses. The LHC will use the laws of conservation of energy and momentum to identify these differences and distinguish superpartners from other particles.

4. Can the LHC directly observe superpartners?

No, the LHC cannot directly observe superpartners. Instead, it can only infer their presence through the detection of their decay products. Superpartners are expected to be unstable and decay into other particles almost immediately after their creation, making it difficult to observe them directly.

5. What happens if the LHC does not find any evidence of superpartners?

If the LHC does not find any evidence of superpartners, it does not necessarily mean that they do not exist. It may simply mean that they have a higher mass or different properties than what is currently expected. The search for superpartners will continue with future experiments and advancements in technology.

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