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We present a supersymmetric model with two dark matter (DM) componentsexplaining the galactic positron excess observed by PAMELA/HEAT andATIC/PPB-BETS: One is the conventional (bino-like) lightest supersymmetricparticle (LSP) \chi, and the other is a TeV scale meta-stable neutral singletN_D, which is a Dirac fermion (N,N^c). In this model, N_D decays dominantlyinto \chi e^+e^- through an R parity preserving dimension 6 operator with thelife time \tau_N\sim 10^{26} sec. We introduce a pair of vector-like superheavySU(2) lepton doublets (L,L^c) and lepton singlets (E,E^c). The dimension 6operator leading to the N_D decay is generated from the leptophilic Yukawainteractions by W\supset Ne^cE+Lh_dE^c+m_{3/2}l_1L^c with the dimensionlesscouplings of order unity, and the gauge interaction by {\cal L}\supset \sqrt{2}g'\tilde{e}^{c*}e^c\chi + h.c. The superheavy masses of the vector-like leptons(M_L, M_E\sim 10^{16} GeV) are responsible for the longevity of N_D. The lowenergy field spectrum in this model is just the MSSM fields and N_D. Even forthe case that the portion of N_D is much smaller than that of \chi in the totalDM density [{\cal O}(10^{-10}) \lesssim n_{N_D}/n_\chi], the observed positronexcess can be explained by adopting relatively lighter masses of thevector-like leptons (10^{13} GeV \lesssim M_{L,E} \lesssim 10^{16} GeV). Thesmallness of the electron mass is also explained. This model is easily embeddedin the flipped SU(5) grand unification, which is a leptophilic unified theory.

PAMELA/ATIC anomaly from the meta-stable extra dark matter component and the leptophilic Yukawa interaction