Dark matter bound-state formation at higher order: a non-equilibrium quantum field theory approach

Journal of High Energy Physics

Kyohei Mukaida¹  Tobias Binder²  Burkhard Blobel³  Julia Harz⁴ 

[1]Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, D-22607, Hamburg, Germany

[2]Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa, 277-8583, Chiba, Japan

[3]Mathematisches Institut, Bunsenstr. 3–5, 37073, Göttingen, Germany

[4]Physik Department T70, Technische Universität München, James-Franck-Straße, 85748, Garching, Germany

关键词: Beyond Standard Model;    Cosmology of Theories beyond the SM;    Thermal;    Field Theory;   

DOI  :  10.1007/JHEP09(2020)086

来源: Springer

【 摘 要 】

The formation of meta-stable dark matter bound states in coannihilating scenarios could efficiently occur through the scattering with a variety of Standard Model bath particles, where light bosons during the electroweak cross over or even massless photons and gluons are exchanged in the t-channel. The amplitudes for those higher-order processes, however, are divergent in the collinear direction of the in- and out-going bath particles if the mediator is massless. To address the issue of collinear divergences, we derive the bound-state formation collision term in the framework of non-equilibrium quantum field theory. The main result is an expression for a more general cross section, which allows to compute higher-order bound-state formation processes inside the primordial plasma background in a comprehensive manner. Based on this result, we show that next-to-leading order contributions, including the bath-particle scattering, are i) collinear finite and ii) generically dominate over the on-shell emission for temperatures larger than the absolute value of the binding energy. Based on a simplified model, we demonstrate that the impact of these new effects on the thermal relic abundance is significant enough to make it worthwhile to study more realistic coannihilation scenarios.

【 授权许可】

CC BY