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Type: Journal article
Title: Relic density and Pamela events in a heavy wino dark matter model with Sommerfeld effect
Author: Mohanty, S.
Rao, S.
Roy, D.
Citation: International Journal of Modern Physics A: particles and fields; gravitation; cosmology; nuclear physics, 2012; 27(6):1250025-1-1250025-20
Publisher: World Scientific Publishing Company
Issue Date: 2012
ISSN: 0217-751X
Statement of
Subhendra Mohanty, Soumya Rao, D. P. Roy
Abstract: In a wino LSP scenario the annihilation cross-section of winos gravitationally bound in galaxies can be boosted by a Sommerfeld enhancement factor which arises due to the ladder of exchanged W bosons between the initial states. The boost factor obtained can be in the range S ≃10⁴ if the mass is close to the resonance value of M ≃4 TeV. In this paper we show that if one takes into account the Sommerfeld enhancement in the relic abundance calculation then the correct relic density is obtained for 4 TeV wino mass due to the enhanced annihilation after their kinetic decoupling. At the same time the Sommerfeld enhancement in the χχ→W⁺ W⁻ annihilation channel is sufficient to explain the positron flux seen in PAMELA data without significantly exceeding the observed antiproton signal. We also show that (e⁻+e⁺) and γ-ray signals are broadly compatible with the Fermi-LAT observations. In conclusion we show that a 4 TeV wino DM can explain the positron and antiproton fluxes observed by PAMELA and at the same time give a thermal relic abundance of CDM consistent with WMAP observations.
Keywords: Dark matter; relic density; cosmic ray; Sommerfeld enhancement
Rights: © World Scientific Publishing Company
DOI: 10.1142/S0217751X1250025X
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