R-parity

This lightest particle (if it exists) may therefore account for the observed missing mass of the universe that is generally called dark matter.

Typically the dark matter candidate of the MSSM is a mixture of the electroweak gauginos and Higgsinos and is called a neutralino.

In extensions to the MSSM it is possible to have a sneutrino be the dark matter candidate.

The strongest constraint involving this coupling alone is the violation universality of Fermi constant

The strongest constraint involving this coupling alone is the violation universality of Fermi constant in leptonic charged current decays.

The strongest constraint involving this coupling alone is that it leads to a large neutrino mass.

Since the proton lifetime is observed to be greater than 1033 to 1034 years (depending on the exact decay channel), this would highly disfavour the model.

R-parity sets all of the renormalizable baryon and lepton number violating couplings to zero and the proton is stable at the renormalizable level and the lifetime of the proton is increased to 1032 years and is nearly consistent with current observational data.

A very attractive way to motivate R-parity is with a B − L continuous gauge symmetry which is spontaneously broken at a scale inaccessible to current experiments.

is only broken by scalar vacuum expectation values (or other order parameters) that carry even integer values of 3(B − L), then there exist an exactly conserved discrete remnant subgroup which has the desired properties.

[7][8][9][10][11] The crucial issue is to determine whether the sneutrino (the supersymmetric partner of neutrino), which is odd under R-parity, develops a vacuum expectation value.