Decaying hidden gauge boson and the PAMELA and ATIC/PPB-BETS anomalies

We show that the PAMELA anomaly in the positron fraction as well as the ATIC/PPB-BETS excesses in the e^- +e⁺ flux are simultaneously explained in our scenario that a hidden U(1)_h gauge boson constitutes dark matter of the Universe and decays into the standardmodel particles through a kinetic mixing with an U(1)_b-l gauge boson. Interestingly, the B - L charge assignment suppresses an antiproton flux in consistent with the PAMELA and BESS experiments, while the hierarchy between the B - L symmetry breaking scale and the weak scale naturally leads to the right lifetime of O(10²⁶) seconds.