Decaying Hidden Gauge Boson and the PAMELA and ATIC/PPB-BETS Anomalies

Abstract

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 standard-model 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(10^26) seconds.

Figures (4)

• Figure 1: (a) The predicted positron fraction from $A_H$ decay via the kinetic mixing with $U(1)_{B-L}$ (blue line) and $U(1)_5$ (magenta line), compared with the experimental data Barwick:1997igAguilar:2007yf, including the recent PAMELA results Adriani:2008zr; (b) For $U(1)_{B-L}$ case only, using different sets of parameters in solving diffusion equation.
• Figure 2: (a) The predicted $(e^-+e^+)$ spectrum from $A_H$ decay via the kinetic mixing with $U(1)_{B-L}$ (blue line) and $U(1)_5$ (magenta line), compared with the various observational data DuVernois:2001bbTorii:2001aw including the latest ATIC ATIC-new and PPB-BETS Torii:2008xu results. (b) For $U(1)_{B-L}$ case only, using different sets of parameters in solving diffusion equation.
• Figure 3: The predicted flux of the diffuse gamma-ray background from $A_H$ decay via the kinetic mixing with $U(1)_{B-L}$ (blue line) and $U(1)_5$ (magenta line), compared with the EGRET data Sreekumar:1997unStrong:2004ry
• Figure 4: The predicted $\bar{p}/p$ ratio and the BESS and PAMELA data. The red solid (dahsed) lines corresponds to $\tau = 5 \times 10^{25}$ sec ($10^{26}$ sec) for the $B-L$ case, while the purple line represents the fiveness.