Light stringy states and the g − 2 of the muon

Abstract

In this work, we evaluate the contributions to the anomalous magnetic moment of the muon ((g − 2)μ) coming from light stringy states in a D-brane semi-realistic configuration. A scalar which couples only to the muon can have a mass sufficiently light to provide a significant contribution to the (g − 2)μ. This scenario can arise in intersecting D-brane models, where such light scalars correspond to the first stringy excitations of an open string stretched between two D-branes intersecting with a very small angle. In this article, we show that there is a region in the space of the geometric parameters of the internal manifold where such scalar light stringy states can explain (part) of the observed discrepancy in the (g − 2)μ. In a low string scale framework with Ms ≳ 10 TeV, we show that an excited Higgs with mass mathcal{O} (250 MeV), living in an intersection with an angle of order mathcal{O} (10−10), can provide a significant contribution of one-tenth of the (g − 2)μ discrepancy. This leads to a lower bound for the compact dimension where the branes intersect of order mathcal{O} (10−8 GeV−1). We also study patterns in D-brane configurations that realize our proposal, both in three and four stacks models.