Abstract:The relic density of TeV-scale wino-like neutralino dark matter in the MSSM is subject to potentially large corrections as a result of the Sommerfeld effect. A recently developed framework enables us to calculate the Sommerfeld-enhanced relic density in general MSSM scenarios, properly treating mixed states and multiple co-annihilating channels as well as including off-diagonal contributions. Using this framework, including on-shell oneloop mass splittings and running couplings and taking into account the latest experimental constraints, we perform a thorough study of the regions of parameter space surrounding the well known pure-wino scenario: namely the effect of sfermion masses being non-decoupled and of allowing non-negligible Higgsino or bino components in the lightest neutralino. We further perform an investigation into the effect of thermal corrections and show that these can safely be neglected. The results reveal a number of phenomenologically interesting but so far unexplored regions where the Sommerfeld effect is sizeable. We find, in particular, that the relic density can agree with experiment for dominantly wino neutralino dark matter with masses ranging from 1.7 to beyond 4 TeV. In light of these results the bounds from Indirect Detection on wino-like dark matter should be revisited.

There is an increasing interest in accurate dark matter relic density predictions, which requires next-to-leading order (NLO) calculations. The method applied up to now uses zero-temperature NLO calculations of annihilation cross sections in the standard Boltzmann equation for freeze-out, and is conceptually problematic, since it ignores the finite-temperature infrared (IR) divergences from soft and collinear radiation and virtual effects. We address this problem systematically by starting from non-equilibrium quantum field theory, and demonstrate on a realistic model that soft and collinear temperaturedependent divergences cancel in the collision term. Our analysis provides justification for the use of the freeze-out equation in its conventional form and determines the leading finite-temperature correction to the annihilation cross section. This turns out to have a remarkably simple structure.

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Erratum to: JHEP10(2014)045ArXiv ePrint: 1409.3049In ref.[1] a systematic approach starting from non-equilibrium quantum field theory to relic density computations at next-to-leading order (NLO) was presented. The primary purpose of this work was to demonstrate the cancellation of the temperature-dependent infrared divergences. In addition, the leading finite temperature-dependent correction in a model, where dark matter annihilation into Standard Model (SM) fermions is mediated by an electrically charged scalar, was computed and found to be of O(T 2 ) . It was also noted that this correction exhibited a surprisingly simple structure. This result is incorrect, and the O(T 2 ) correction actually vanishes altogether. Below we list the corrections to the original manuscript and provide the leading finite-temperature contribution, which is of order O(T 4 ) . An explanation of the temperature-dependence of the correction and the absence of the O(T 2 ) term can be given in terms of an operator product expansion [2].1. The diagram from the photon-tadpole contribution to the scalar self-energy was missed in ref.[1]. This diagram is infrared-finite and vanishes at T = 0, but contributes at finite temperature at order τ 2 = T 2 /m 2 χ . Tables 4 and 5

Abstract:We apply the operator product expansion (OPE) technique to the decay and annihilation of heavy particles in a thermal medium with temperature below the heavy particle mass, m χ . This allows us to explain two interesting observations made before: a) that the leading thermal correction to the decay width of a charged particle is the same multiplicative factor of the zero-temperature width for a two-body decay and muon decay, and b) that the leading thermal correction to fermionic dark matter annihilation arises only at order T 4 /m 4 χ . The OPE further considerably simplifies the computation and factorizes it into model-independent matrix elements in the thermal background, and short-distance coefficients to be computed in zero-temperature field theory.