Viability of complex self-interacting scalar field as dark matter

Fabio Briscese

doi:10.1016/j.physletb.2010.12.064

paper

Viability of complex self-interacting scalar field as dark matter

arXiv:1101.0028 · doi:10.1016/j.physletb.2010.12.064

Abstract

We study the viability of a complex scalar field $χ$ with self-interacting potential $V = m_{0}^{χ} /2 ∣ χ ∣^{2} + h ∣ χ ∣^{4}$ as dark matter. The scalar field is produced at reheating through the decay of the inflaton field and then, due to the self-interaction, a Bose-Einstein condensate of $χ$ particles forms. The condensate represents dark matter in that model. We analyze the cosmological evolution of the model, stressing how, due to the presence of the self-interaction, the model naturally admits dark matter domination at late times, thus avoiding any fine tuning on the energy density of the scalar field at early times. Finally we give a lower bound for the size of dark matter halos at present time and we show that our model is compatible with dark matter halos greater than $0.1 K p c$ and with BBN and CMB bounds on the effective number of extra neutrinos $Δ_{ν}^{e f f}$ . Therefore, the model is viable and for $h ≃ 1 0^{- 4} - 1 0^{- 12}$ one obtains a mass $m^{χ} ≃ m_{0}^{χ} ≃ 1 - 1 0^{- 2} e V$ for dark matter particles from radiation-matter equality epoch to present time, but at temperatures $T_{γ} ≫ 10 e V$ , where $T_{γ}$ is the photons temperature, thermal corrections to $m_{0}^{χ}$ due to the self-coupling $h$ are dominant.

7 pages, some reference added

Viability of complex self-interacting scalar field as dark matter

Abstract

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