Clockwork graviton contributions to muon \$g-2\$
(Jun 28, 2017)Abstract
The clockwork mechanism for gravity introduces a tower of massive graviton
modes, "clockwork gravitons," with a very compressed mass spectrum, whose
interaction strengths are much stronger than that of massless gravitons. In
this work, we compute the lowest order contributions of the clockwork gravitons
to the anomalous magnetic moment, \$g-2\$, of muon in the context of extra
dimensional model with a five dimensional Planck mass (or cutoff), \$M\_5\$. It is
found that the total contributions are rather insensitive to the detailed model
parameters, and mostly determined by the value of \$M\_5\$. In order to account
for the current muon \$g-2\$ anomaly, \$M\_5\$ should be around \$0.2\~TeV\$, and
the size of the extra dimension has to be quite large, \$l\_5 \gtrsim
10^-7\,\$m. For \$M\_5\gtrsim1\~TeV\$, the clockwork graviton contributions
are too small to explain the current muon \$g-2\$ anomaly. We also compare the
clockwork graviton contributions with other extra dimension models such as
Randall-Sundrum models or large extra dimension models, and find that all the
leading contributions to the muon \$g-2\$ in the small curvature limit are
independent of 5D geometries and graviton mass spectra, giving universally
\$\Delta a\_\mu(5/16\pi^3) (m/M\_5)^2\$.