Dipole-interacting fermionic dark matter in positron, antiproton, and gamma-ray channels

Abstract

Cosmic ray signals from dipole-interacting dark matter annihilation are considered in the positron, antiproton, and photon channels. The predicted signals in the positron channel could nicely account for the excess of positron fraction from Fermi LAT, PAMELA, HEAT, and AMS-01 experiments for the dark matter mass larger than 100 GeV with a boost (enhancement) factor of 30-80. No excess of antiproton over proton ratio at the experiments also gives a severe restriction for this scenario. With the boost factors, the predicted signals from Galactic halo and signals as monoenergetic gamma-ray lines (monochromatic photons) for the region close to the Galactic center are investigated. The gamma-ray excess of recent tentative analyses based on Fermi LAT data and the potential probe of the monochromatic lines at a planned experiment, AMS-02, are also considered.

Anapole dark matter

“…Eq. (14) shows the (Z/A) 2 dependence typical of comparisons between electromagnetically-interacting dark matter and dark matter coupling identically to all nucleons. While Z/A is larger for lighter target nuclei, the current XENON100 225 live day results [34] are so much more restrictive than any other published limits over much of the mass range of interest that we will use them here as our standard of comparison.…”

“…The exact nature of the dark matter remains a mystery. Recently, a variety of authors have explored the possibility that the dark matter might interact electromagnetically with ordinary matter, via an electric or magnetic dipole moment [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Direct detection experiments strongly constrain such dipole moments for particle masses > ∼ 10 GeV.…”

Anapole dark matter at the LHC

“…Dark matter with an integer electric charge number ∼ O(1) has long been ruled out, and even millicharged dark matter is strongly disfavored [2]. Hence, the most attention has been paid to models in which the dark matter particle has an electric or magnetic dipole moment, which we will call generically dipole dark matter (DDM) [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. If one assumes a thermal production history for the dark matter, fixing the dipole moment coupling to provide the correct relic abundance, then the corresponding rate in direct detection experiments rules out a wide range of DDM mass [4,6,13].…”

Constraints on light magnetic dipole dark matter from the ILC and SN 1987A

“…Facing the wide-open possibilities for the properties of DM, we study the interaction of MeV-scale DM particles that possess a magnetic dipole moment and therefore interact with the photon. The DM magnetic dipole moment can be easily generated in many extensions of the SM such as asymmetric DM models and there have been many studies of the dipole DM, in particular for the light DM whose interactions with the SM particles can enjoy infrared enhancement due to the small momentum transfer in the photon exchange [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17].…”