Muon anomalous magnetic moment in supersymmetric scenarios with an intermediate scale and nonuniversality

Abstract

We analyze the anomalous magnetic moment of the muon ${a}_{\ensuremath{\mu}}$ in supersymmetric scenarios. First we concentrate on scenarios with universal soft terms. We find that a moderate increase of ${a}_{\ensuremath{\mu}}$ can be obtained by lowering the unification scale ${M}_{\mathrm{GUT}}$ to intermediate values of ${10}^{10}$ to ${10}^{12} \mathrm{GeV}.$ However, large values of $\mathrm{tan}\ensuremath{\beta}$ are still favored. Then we study the case of nonuniversal soft terms. For the usual value ${M}_{\mathrm{GUT}}\ensuremath{\approx}{10}^{16} \mathrm{GeV},$ we obtain ${a}_{\ensuremath{\mu}}$ in the favored experimental range even for moderate $\mathrm{tan}\ensuremath{\beta}$ regions $(\mathrm{tan}\ensuremath{\beta}\ensuremath{\gtrsim}5).$ Finally, we give an explicit example of these scenarios. In particular, we show that in a D-brane model, where the string scale is naturally of the order of ${10}^{10}$ to ${10}^{12} \mathrm{GeV}$ and the soft terms are nonuniversal, ${a}_{\ensuremath{\mu}}$ is enhanced with low $\mathrm{tan}\ensuremath{\beta}.$