Indirect detection of the partial p wave via the s wave in the annihilation cross section of dark matter

Abstract

For many dark matter models, the annihilation cross section to two-body final states is difficult to probe with current experiments because the dominant annihilation channel is velocity or helicity suppressed. The inclusion of gauge boson radiation for three-body final states can lift the helicity suppression, allowing a velocity-independent cross section to dominate the annihilation process, and providing an avenue to constrain these models. Here we examine experimental constraints on dark matter that annihilates to two leptons plus a bremsstrahlung boson,l þ l þ γ=W=Z. We consider experimental constraints on photon final states from Fermi-LAT using both diffuse photon data and data from dwarf spheroidal galaxies, and compare to the implied constraints from 21 cm measurements. Diffuse photon line searches are generally the strongest over the entire mass regime. We in particular highlight the model in which dark matter annihilates to two neutrinos and a photon, and show that these models are more strongly constrained through photon measurements than through existing neutrino bounds.

Status, Challenges and Directions in Indirect Dark Matter Searches

“…Another way to avoid the suppression of s-wave annihilations is through the Sommerfeld enhancement in models with self-interactions in the dark matter sector [75][76][77][78][79][80]. In such case the new potential enhances the s-wave cross section through the well known Sommerfeld effect [81] by factors as high as three orders of magnitude, making such models testable with the messengers and sources mentioned in the sections below.…”

Neutrino Portal to FIMP Dark Matter with an Early Matter Era

“…Future searches for gamma-ray and cosmic-ray signals with existing (H.E.S.S.-II [92]) and planned (CTA [93], GAMMA-400 [94]) experiments might become able to probe DM annihilations cross-sections into SM particles as low as order 10 −28 cm 3 /s in the light dark matter mass regime [44][45][46][95][96][97][98][99]. Indeed, potential gamma-ray lines from DM annihilation might be finally confirmed or ruled-out [97].…”

Constraining New Physics with Possible Dark Matter Signatures from a Global CKM Fit

“…The phenomenology of such pseudoscalar mediators have been extensively studied in [5,[11][12][13][14]. While the pseudoscalar operators help weaken the direct detection scattering cross-section with a momentum suppression, they also amplify the chances of probing the WIMP at indirect detection experiments through initial/final state radiation or bremsstrahlung processes [15][16][17][18][19][20]. On the other hand, the only way to obtain a spin-independent direct detection cross-section is to have a non-zero scalar-scalar effective interaction i.e C s , C s = 0.…”