Muon anomalous magnetic moment from effective supersymmetry

We present a detailed analysis on the possible maximal value of the muon (g-2)μ ≡2 aμ within the context of effective SUSY models with R parity conservation. First of all, mixing among the second and the third family sleptons can contribute at one loop level to aμSUSY and τ→μγ simultaneously. One finds that aμSUSY can be as large as (10 - 20) x 10-10 for any tan β, imposing an upper limit on the τ→μγ branching ratio. Furthermore, the two loop Barr-Zee type contributions to aμSUSY may be significant for large tan β, if a stop is light and μ and At are large enough (∝O(1) TeV). In this case, it is possible to have aμSUSY up to O(10) x 10-10 without conflicting with τ→lγ. We conclude that the possible maximal value for aμSUSY is about ∝20 x 10-10 for any tanβ. Therefore the BNL experiment on the muon aμ can exclude the effective SUSY models only if the measured deviation is larger than ∝30 x 10-10. (orig.)