Loopy constraints on leptophilic dark matter and internal bremsstrahlung

Abstract

A sharp and spatially extended peak in an astrophysical gamma ray spectrum would provide very strong evidence for the existence of dark matter (DM), given that there are no known astrophysical processes that could mimic such a signal. From the particle physics perspective, perhaps the simplest explanation for a gamma ray peak is internal bremsstrahlung in DM annihilation through a charged t-channel mediator η close in mass to the DM particle χ. Since DM annihilation to quarks is already tightly constrained in this scenario, we focus here on the leptophilic case. We compute the electromagnetic anapole and dipole moments that DM acquires at 1-loop, and we find an interesting enhancement of these moments if the DM particle and the mediator are close in mass. We constrain the DM anapole and dipole moments using direct detection data, and then translate these limits into bounds on the DM annihilation cross section. Our bounds are highly competitive with those from astrophysical gamma ray searches. In the second part of the paper, we derive complementary constraints on internal bremsstrahlung in DM annihilation using LEP mono-photon data, measurements of the anomalous magnetic moments of the electron and the muon, and searches for lepton flavor violation. We also comment on the impact of the internal bremsstrahlung scenario on the hyperfine splitting of true muonium.

You can hide but you have to run: direct detection with vector mediators

“…This RG Evolution (RGE) typically introduces mixing between different DM-SM interactions, affecting the size of couplings, or even inducing new couplings which do not appear in a naïve comparison [11][12][13][14][15][16][17][18][19][20][21][22][23]. These effects do not depend on the properties of the Dark Sector and are not optional; they arise solely from RGE of the couplings via SM loops.…”

Dark matter complementarity and theZ′portal

“…Such gauge bosons have been extensively studied in many different contexts [7,8,11], but our focus here is on the dark matter phenomenology.…”

New Constraints on Dark Matter Effective Theories from Standard Model Loops

“…However, different search strategies probe different energy scales, and such a separation of scales may have striking consequences when a connection between different experiments or ultraviolet (UV) complete models with experiments is attempted. Indeed, in some cases loop corrections are known to dramatically alter direct detection (DD) rates [21][22][23][24][25][26][27][28][29].In this Letter we consider the case of a SM gauge singlet Dirac DM (χ), with m χ < Λ, and we calculate the complete set of one-loop effects induced by SM fields for operators up to dimension 6 that contribute to spin-independent (SI) DM-nucleon scattering. The separation between Λ and the DD scale is systematically taken into account via a proper renormalization group (RG) analysis.…”

“…However, different search strategies probe different energy scales, and such a separation of scales may have striking consequences when a connection between different experiments or ultraviolet (UV) complete models with experiments is attempted. Indeed, in some cases loop corrections are known to dramatically alter direct detection (DD) rates [21][22][23][24][25][26][27][28][29].…”