  We study the trapping of a ground-state cesium atom in a small region around
the midpoint between two coupled identical parallel optical nanofibers. We
suggest to use a blue-detuned guided light field in the odd
$\mathcal{E}_z$-sine array mode to produce an optical potential with a local
minimum of exact zero at the midpoint between the nanofibers. We find that the
effects of the van der Waals potential on the total trapping potential around
the minimum point are not significant when the fiber separation distance and
the power of the guided light field are large. For appropriate realistic
parameters, a net trapping potential with a significant depth of about 1 mK, a
large coherence time of several seconds, and a large recoil-heating-limited
trap lifetime of several hours can be obtained. We investigate the dependencies
of the trapping potential on the power of the guided light field, the fiber
radius, the wavelength of light, and the fiber separation distance.
