Dark Atoms and the Positron-Annihilation-Line Excess in the Galactic Bulge

It was recently proposed that stable particles of charge −2, O--, can exist and constitute dark matter after they bind with primordial helium in O-helium (OHe) atoms. We study here in detail the possibility that this model provides an explanation for the excess of gamma radiation in th...

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Main Authors: J.-R. Cudell, M. Yu. Khlopov, Q. Wallemacq
Format: Article
Language:English
Published: Wiley 2014-01-01
Series:Advances in High Energy Physics
Online Access:http://dx.doi.org/10.1155/2014/869425
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author J.-R. Cudell
M. Yu. Khlopov
Q. Wallemacq
author_facet J.-R. Cudell
M. Yu. Khlopov
Q. Wallemacq
author_sort J.-R. Cudell
collection DOAJ
description It was recently proposed that stable particles of charge −2, O--, can exist and constitute dark matter after they bind with primordial helium in O-helium (OHe) atoms. We study here in detail the possibility that this model provides an explanation for the excess of gamma radiation in the positron-annihilation line from the galactic bulge observed by INTEGRAL. This explanation assumes that OHe, excited to a 2s state through collisions in the central part of the Galaxy, deexcites to its ground state via an E0 transition, emitting an electron-positron pair. The cross-section for OHe collisions with excitation to 2s level is calculated and it is shown that the rate of such excitations in the galactic bulge strongly depends not only on the mass of O-helium, which is determined by the mass of O--, but also on the density and velocity distribution of dark matter. Given the astrophysical uncertainties on these distributions, this mechanism constrains the O-- mass to lie in two possible regions. One of these is reachable in the experimental searches for stable multicharged particles at the LHC.
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spelling doaj-art-6dfa2b0daf294443bb54e9878be3bdd72025-02-03T00:59:30ZengWileyAdvances in High Energy Physics1687-73571687-73652014-01-01201410.1155/2014/869425869425Dark Atoms and the Positron-Annihilation-Line Excess in the Galactic BulgeJ.-R. Cudell0M. Yu. Khlopov1Q. Wallemacq2IFPA, “Département d'AGO”, Université de Liège, Sart Tilman, 4000 Liège, BelgiumNational Research Nuclear University “Moscow Engineering Physics Institute,” Moscow 115409, RussiaIFPA, “Département d'AGO”, Université de Liège, Sart Tilman, 4000 Liège, BelgiumIt was recently proposed that stable particles of charge −2, O--, can exist and constitute dark matter after they bind with primordial helium in O-helium (OHe) atoms. We study here in detail the possibility that this model provides an explanation for the excess of gamma radiation in the positron-annihilation line from the galactic bulge observed by INTEGRAL. This explanation assumes that OHe, excited to a 2s state through collisions in the central part of the Galaxy, deexcites to its ground state via an E0 transition, emitting an electron-positron pair. The cross-section for OHe collisions with excitation to 2s level is calculated and it is shown that the rate of such excitations in the galactic bulge strongly depends not only on the mass of O-helium, which is determined by the mass of O--, but also on the density and velocity distribution of dark matter. Given the astrophysical uncertainties on these distributions, this mechanism constrains the O-- mass to lie in two possible regions. One of these is reachable in the experimental searches for stable multicharged particles at the LHC.http://dx.doi.org/10.1155/2014/869425
spellingShingle J.-R. Cudell
M. Yu. Khlopov
Q. Wallemacq
Dark Atoms and the Positron-Annihilation-Line Excess in the Galactic Bulge
Advances in High Energy Physics
title Dark Atoms and the Positron-Annihilation-Line Excess in the Galactic Bulge
title_full Dark Atoms and the Positron-Annihilation-Line Excess in the Galactic Bulge
title_fullStr Dark Atoms and the Positron-Annihilation-Line Excess in the Galactic Bulge
title_full_unstemmed Dark Atoms and the Positron-Annihilation-Line Excess in the Galactic Bulge
title_short Dark Atoms and the Positron-Annihilation-Line Excess in the Galactic Bulge
title_sort dark atoms and the positron annihilation line excess in the galactic bulge
url http://dx.doi.org/10.1155/2014/869425
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