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shakeel
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what is R Parity and why?
R-parity is a symmetry often imposed in supersymmetric models.shakeel said:what is R Parity and why?
shakeel said:why there is a need for a new type of parity? is cpt voilated in supersymmetry
mormonator_rm said:R-parity is useful in the supersymmetric model of fundamental particles. You see, the standard fundamental particles, such as leptons, quarks, and the vector bosons all have positive R-parity, while the supersymmetric partners, such as sleptons, squarks, neutralinos and charginos have negative R-parity. This means that, in order to conserve the R-parity, only the following two-body decay transitions are allowed;
N --> NN
N --> SS
S --> NS
along with the following two-body scattering transitions;
NN --> NN
NN --> SS
SS --> SS
NS --> NS
where I have labeled "normal" (N) or standard fundamental particles and "supersymmetric" (S) fundamental particles. This means, for example, that a top quark could not decay into a charm quark and a neutralino, but a top quark could decay into a charm "squark" and a neutralino. Similarly, a "squark" cannot decay into another "squark" and a neutralino, but can decay into a quark and a neutralino. In all this, the standard decays which are well known in experimental physics remain allowed, such as quark transitions involving weak bosons. But it should be pointed out that a supersymmetric particle cannot decay into two new supersymmetric particles. All of these rules are a direct result of R-parity.
In order to prove the existence of R-parity, we now need to find some supersymmetric particles that exhibit these kinds of transitions. Experimentalists may be getting closer to this possibility, I hope.
nrqed said:Thank you for a very informative post! I have tried to understand the exact consequences of R parity by reading articles on SUSY but it has never been clear like that.
nrqed said:So a consequence of this is that the lightest SUSY particle is absolutely stable, even if it is much more massive than non-susy particles, right?
What is the lightest susy particle in MSSM?