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Particles and Fields

Eur. Phys. J. C 24, 613-618 (2002)
DOI: 10.1007/s10052-002-0971-5

Muon anomalous magnetic moment from effective supersymmetry

S. Baek1, P. Ko2 and Jae-hyeon Park2

1  School of Physics, KIAS, Seoul 130-012, Korea
2  Department of Physics, KAIST, Daejeon 305-701, Korea

(Received: 29 March 2002 / Published online: 14 June 2002 )

We present a detailed analysis on the possible maximal value of the muon $(g-2)_\mu \equiv 2 a_\mu$ 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 $a_\mu^{\mathrm {SUSY}}$ and $\tau \rightarrow \mu \gamma$ simultaneously. One finds that $a_\mu^{\mathrm {SUSY}}$ can be as large as (10- $ 20)\times 10^{-10}$ for any $\tan\beta$, imposing an upper limit on the $\tau \rightarrow \mu \gamma$ branching ratio. Furthermore, the two loop Barr-Zee type contributions to $a_\mu^{\mathrm {SUSY}}$ may be significant for large $\tan\beta$, if a stop is light and $\mu$ and At are large enough ( $\sim O(1)$ TeV). In this case, it is possible to have $a_\mu^{\mathrm {SUSY}}$ up to $O(10) \times 10^{-10}$ without conflicting with $\tau \rightarrow l \gamma$. We conclude that the possible maximal value for $a_\mu^{\mathrm {SUSY}}$ is about $\sim 20 \times 10^{-10}$ for any $\tan\beta$. Therefore the BNL experiment on the muon $a_\mu$ can exclude the effective SUSY models only if the measured deviation is larger than $\sim 30 \times 10^{-10}$.

© Società Italiana di Fisica, Springer-Verlag 2002