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SLAC Publication: SLACPUB15306
SLAC Release Date: November 6, 2013
Dichromatic Dark Matter
Bai, Yang.
Both the robust INTEGRAL 511 keV gammaray line and the recent tentative hint of the 135 GeV gammaray line from FermiLAT have similar signal morphologies, and may be produced from the same dark matter annihilation. Motivated by this observation, we construct a dark matter model to explain both signals and to accommodate the two required annihilation cross sections that are different by more than six orders of magnitude. In our model, to generate the lowenergy positrons for INTEGRAL, dark matt... Show Full Abstract
Both the robust INTEGRAL 511 keV gammaray line and the recent tentative hint of the 135 GeV gammaray line from FermiLAT have similar signal morphologies, and may be produced from the same dark matter annihilation. Motivated by this observation, we construct a dark matter model to explain both signals and to accommodate the two required annihilation cross sections that are different by more than six orders of magnitude. In our model, to generate the lowenergy positrons for INTEGRAL, dark matter particles annihilate into a complex scalar that couples to photon via a chargeradius operator. The complex scalar contains an excited state decaying into the ground state plus an offshell photon to generate a pair of positron and electron. Two charged particles with nondegenerate masses are necessary for generating this chargeradius operator. One charged particle is predicted to be longlived and have a mass around 3.8 TeV to explain the dark matter thermal relic abundance from its late decay. The other charged particle is predicted to have a mass below 1 TeV given the ratio of the two signal cross sections. The 14 TeV LHC will concretely test the main parameter space of this lighter charged particle.
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