Resummed photon spectrum from dark matter annihilation for intermediate and narrow energy resolution

Abstract

The annihilation cross section of weakly interacting TeV scale dark matter particles χ 0 into photons is affected by large quantum corrections due to electroweak Sudakov logarithms and the Sommerfeld effect. We extend our previous work on the resummation of the semi-inclusive photon energy spectrum in χ 0 χ 0 → γ + X in the vicinity of the maximal photon energy E γ = m χ with NLL' accuracy from the case of narrow photon energy resolution E γ res of order m 2 W /m χ to intermediate resolution of order E γ res ∼ m W . We also provide details on the previous narrow resolution calculation. The two calculations, performed in different effective field theory set-ups for the wino dark matter model, are then shown to match well, providing an accurate representation up to energy resolutions of about 300 GeV.

Precise yield of high-energy photons from Higgsino dark matter annihilation

“…First, one has to take into account the so-called Sommerfeld effect, which is generated by the electroweak Yukawa force acting on the DM particles prior to their annihilation [13][14][15][16]. Secondly, for heavy DM annihilation into energetic particles, electroweak Sudakov (double) logarithms O((α 2 ln 2 (m χ /m W ))) are large and need to be resummed to all orders in the coupling constant [17][18][19][20][21][22][23]. The treatment of the Sommerfeld effect for Higgsino DM is well known.…”

“…In recent papers we [22,23] and others [17][18][19][20][21] discussed these effects for the pure electroweak Majorana triplet model (wino-like neutralino) [24]. In those papers we established factorization formulas and obtained precise predictions for the photon yield for two different telescope energy-resolution regimes by using SCET methods [25][26][27][28].…”

“…In order to prove such factorization formulas, some assumptions on the resolution E γ res of the photon energy measurement are necessary. In [23] we distinguished three parametrically different resolution regimes:…”

“…Given the projected energy resolution of the upcoming CTA experiment [12] and the thermal Higgsino DM mass m χ ≈ 1 TeV, it is clear that the narrow and intermediate resolution regimes defined above are the most appropriate when computing the resummed cross section (see Figure 1 in [23]). The article is organized as follows.…”

“…We refer to [31] for a comprehensive discussion of the rich Higgsino mass splitting phenomenology. The derivation of the factorization of the photon spectrum in the γ+X final state from DM annihilation near maximal photon energy 1 E γ = m χ has been thoroughly discussed in Section 2.1 of [23], and holds for generic weakly interacting DM. For the sake of brevity, we will therefore provide here the model-specific expressions for the Higgsino and recommend the reader to consult [23] for theoretical background information.…”