Non-perturbative Effect on Thermal Relic Abundance of Dark Matter

Abstract

We point out that thermal relic abundance of the dark matter is strongly altered by a non-perturbative effect called the Sommerfeld enhancement, when constituent particles of the dark matter are non-singlet under the SU(2) L gauge interaction and much heavier than the weak gauge bosons. Typical candidates for such dark matter particles are the heavy wino-and higgsino-like neutralinos. We investigate the non-perturbative effect on the relic abundance of dark matter for the wino-like neutralino as an example. We show that its thermal abundance is reduced by 50% compared to the perturbative result. The wino-like neutralino mass consistent with the observed dark matter abundance turns out to be 2.7 TeV m 3.0 TeV.

Semi-inclusive wino and higgsino annihilation to LL′

“…Thus, the only operator in the expansion that can contribute to the vev is proportional to the identity and is therefore IR safe. 3 This can also be seen by considering the the recoil jet content, which has soft(p s ) as well asn collinear(pn) radiation. The invariant mass of this recoil would then have momentum scaling p s + pn ∼ M χ (λ, 1, λ) which has an invariant mass of M 2 χ λ.…”

“…For the case of higgsino LSP, we can additionally expand in µ/M 1,2 , as we will always consider scenarios with at least a factor of a few hierarchy to avoid large mixing effects. In this case, the neutralino mass eigenststes are very nearly a bino-likeÑ 1 ≈B; a wino-likeÑ 2 ≈W 0 ; and higgsino-likeÑ 3 …”

“…relic, this fixes their masses to be M wino ≡ (M χ ) = 2.7-2.9 TeV or M higgsino ≡ (M χ ) = 1 TeV [2][3][4]. Thus, the simple SUSY dark matter story has an electroweak LSP at or above 1 TeV, and thus has no observable collider signature for the foreseeable future.…”

The ATLAS diboson resonance in non-supersymmetric SO(10)

“…As far as we know, the thermal relic abundance of a triplet Dirac fermion has not been computed yet with the Sommerfeld enhancement effect included. However, we expect that the favored mass for a Dirac triplet is smaller than that for a Majorana triplet (which was found to be ∼ 2.7 TeV [84]), since the thermallyaveraged annihilation cross section of Dirac dark matter is a factor of two smaller than that of Majorana dark matter.…”

A cosmological upper bound on superpartner masses

“…The resulting bound onm as a function of m 3/2 is shown in figure 1 for α eff = 0.03, relevant for a (perturbative) wino LOSP. We do not include the non-perturbative Sommerfeld effect [27], which results in an O(1) shift in α eff . When gravitinos are not thermalized, the key point is the differing dependences of the three terms in eq.…”