Speaker
Alejandro Lopez
Description
It is shown that a Weakly Interacting Massive dark matter Particle (WIMP)
interpretation for the positron excess observed in a variety of experiments,
HEAT, PAMELA, and AMS-02, is highly constrained by the Fermi/LAT observations
of dwarf galaxies. In particular, this paper has focused on the annihilation
channels that best fit the current AMS-02 data (Boudaud et al., 2014). The
Fermi satellite has surveyed the $\gamma$-ray sky, and its observations of
dwarf satellites are used to place strong bounds on the annihilation of WIMPs
into a variety of channels. For the single channel case, we find that dark
matter annihilation into {$b\bar{b}$, $e^+e^-$, $\mu^+\mu^-$, $\tau^+\tau^-$,
4-$e$, or 4-$\tau$} is ruled out as an explanation of the AMS positron excess
(here $b$ quarks are a proxy for all quarks, gauge and Higgs bosons). In
addition, we find that the Fermi/LAT 2$\sigma$ upper limits, assuming the
best-fit AMS-02 branching ratios, exclude multichannel combinations into
$b\bar{b}$ and leptons. The tension between the results might relax if the
branching ratios are allowed to deviate from their best-fit values, though a
substantial change would be required. Of all the channels we considered, the
only viable channel that survives the Fermi/LAT constraint and produces a good
fit to the AMS-02 data is annihilation (via a mediator) to 4-$\mu$, or mainly
to 4-$\mu$ in the case of multichannel combinations.
| Oral or Poster Presentation | Oral |
|---|
Primary author
Alejandro Lopez
Co-authors
Christopher Savage
(NORDITA)
Doug Adams
(Stockholm University)
Doug Spolyar
(Stockholm University)
