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We propose a scenario where the saxion dominates the energy density of the Universe and reheats the standard model sector via the dilatonic coupling, while its axionic partner contributes to dark matter decaying into photons via the same…

High Energy Physics - Phenomenology · Physics 2014-04-29 Tetsutaro Higaki , Kwang Sik Jeong , Fuminobu Takahashi

The excesses of the cosmic positron fraction recently measured by PAMELA and the electron spectra by ATIC, PPB-BETS, Fermi and H.E.S.S. indicate the existence of primary electron and positron sources. The possible explanations include dark…

Astrophysics · Physics 2009-09-02 Juan Zhang , Xiao-jun Bi , Jia Liu , Si-Ming Liu , Peng-fei Yin , Qiang Yuan , Shou-hua Zhu

We study the prospects in the search of dark matter offered by the newly selected NASA MeV mission COSI (Compton Spectrometer and Imager). This instrument is designed and optimized to detect spectral lines, and we show it offers an…

High Energy Physics - Phenomenology · Physics 2023-07-07 Andrea Caputo , Michela Negro , Marco Regis , Marco Taoso

Axions are a promising dark matter candidate that were motivated to solve the strong CP problem and that may also address the cosmological matter-antimatter asymmetry. Axion-photon conversion is possible in the presence of the strong…

Cosmology and Nongalactic Astrophysics · Physics 2020-08-26 Jeremy Darling

The observed values of the cosmological constant {\it and} the abundance of Dark Matter (DM) can be successfully understood, using certain measures, by imposing the anthropic requirement that density perturbations go non-linear and…

High Energy Physics - Phenomenology · Physics 2015-03-13 Francesco D'Eramo , Lawrence J. Hall , Duccio Pappadopulo

We apply the axion-photon conversion mechanism to the 130 GeV $\gamma$-ray line observed by the Fermi satellite. Near the Galactic center, some astrophysical sources and/or particle dark matter can produce energetic axions (or axionlike…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-09 Masato Yamanaka , Kazunori Kohri , Kunihito Ioka , Mihoko M. Nojiri

A combined interpretation of the CALET $e^+\, +\, e^-$ spectrum up to 3 TeV and the AMS-02 positron spectrum up to 500 GeV was performed and the results are discussed. To parametrize the background electron flux, we assume a smoothly broken…

High Energy Astrophysical Phenomena · Physics 2018-10-23 S. Bhattacharyya , H. Motz , Y. Asaoka , S. Torii

We study the origin of the positron excess observed in the local cosmic-ray spectrum at high energies, and relate it to the cosmic rays and gamma-ray emission across the entire Galaxy. In particular, we explore the hypothesis of a single,…

High Energy Astrophysical Phenomena · Physics 2024-03-07 Manuel Rocamora , Yago Ascasibar , Miguel A. Sánchez-Conde , Maneenate Wechakama , Pedro de la Torre Luque

Precision astrometry offers a way to probe new physics. By measuring the angular position of light sources at unprecedented precision, astrometry could probe minuscule fluctuations of underlying spacetime. This work explores the possibility…

High Energy Physics - Phenomenology · Physics 2024-06-07 Hyungjin Kim

Axions are a well-motivated dark matter candidate, with a host of experiments around the world searching for direct evidence of their existence. The ORGAN Experiment is a type of axion detector known as an axion haloscope, which takes the…

High Energy Physics - Phenomenology · Physics 2023-06-08 Ben T. McAllister , Aaron Quiskamp , Ciaran O'Hare , Paul Altin , Eugene Ivanov , Maxim Goryachev , Michael Tobar

We investigate the influence of axion dark matter as a background on the spin-independent axion forces between nucleons. Notably, we find that the potential for axion forces scales from $1/r^3$ in a vacuum-only context to $1/r$ when the…

High Energy Physics - Phenomenology · Physics 2025-05-06 Yu Cheng , Shuailiang Ge

Dark matter may consist of axion-like particles (ALPs). When polarized electromagnetic radiation passes through the dark-matter media, interaction with background ALPs affects the polarization of photons. The condensate of axionic dark…

High Energy Physics - Phenomenology · Physics 2025-05-02 D. Davydov , Alexander Libanov

The anomalies observed in recent cosmic ray experiments seem to strongly constrain the nature of the dark matter. In this letter, we investigate a possibility of the fermionic dark matter with a minimal extension of the standard model. We…

High Energy Physics - Phenomenology · Physics 2010-04-30 Koichi Hamaguchi , Satoshi Shirai , T. T. Yanagida

The strongest experimental evidence for dark matter is the Galactic Center gamma-ray excess observed by the Fermi telescope and even predicted prior to discovery as a potential dark matter signature via WIMP dark matter self-annihilations.…

High Energy Astrophysical Phenomena · Physics 2025-08-11 Moorits Mihkel Muru , Joseph Silk , Noam I. Libeskind , Stefan Gottloeber , Yehuda Hoffman

Recent observations of lepton cosmic rays, coming from the PAMELA and FERMI experiments, have pushed our understanding of the interstellar medium and cosmic rays sources to unprecedented levels. The imprint of dark matter on lepton cosmic…

High Energy Astrophysical Phenomena · Physics 2011-01-27 Roberto A. Lineros

The center of the Milky Way is predicted to be the brightest region of gamma-rays generated by self-annihilating dark matter particles. Excess emission about the Galactic center above predictions made for standard astrophysical processes…

High Energy Physics - Phenomenology · Physics 2017-05-10 Christopher Karwin , Simona Murgia , Tim M. P. Tait , Troy A. Porter , Philip Tanedo

The existence of dark matter (DM) and the origin of the baryon asymmetry are persistent indications that the SM is incomplete. More recently, the ATLAS and CMS experiments have observed an excess of diphoton events with invariant mass of…

High Energy Physics - Phenomenology · Physics 2016-06-08 Mads T. Frandsen , Ian M. Shoemaker

The search for a particle dark matter signal in terms of radiation produced by dark matter annihilation or decay has to cope with the extreme faintness of the predicted signal and the presence of masking astrophysical backgrounds. It has…

Cosmology and Nongalactic Astrophysics · Physics 2022-11-11 S. Arcari , E. Pinetti , N. Fornengo

The nature of dark matter is one of the most pressing questions in modern cosmology. Much work has been focussed in the past upon probing potential particle dark matter via gamma-rays resulting from its annihilation or decay. These processs…

High Energy Astrophysical Phenomena · Physics 2019-12-09 Geoff Beck

A huge amount of good quality data converges towards the picture of a spatially flat universe undergoing the today observed phase of accelerated expansion. This new observational trend is commonly addressed as Precision Cosmology. Despite…

General Relativity and Quantum Cosmology · Physics 2008-12-02 S. Capozziello