When LEP and Tevatron combined with WMAP and XENON100 shed light on the nature of Dark Matter

TL;DR

The paper investigates whether light thermal dark matter (DM) that couples to Standard Model particles can satisfy the relic-density bound while evading LEP, Tevatron, and XENON100 constraints. Using an EFT framework with separate leptonic and hadronic couplings, it derives annihilation rates and relic-density implications for both fermionic and scalar DM, incorporating LEP mono-photon bounds and WMAP limits, and then tests these against Tevatron mono-jet and XENON100 direct-detection data. The analysis shows that for DM mass near a few to 10 GeV, a predominantly hadronic annihilation final state is typically required to avoid overclosure, which is in tension with collider bounds; consequently, light electrophilic DM is largely excluded, while scalar DM faces strong constraints, and no-electronic-coupling scenarios remain only at the cost of tight indirect constraints. Overall, combining LEP, Tevatron, WMAP, and XENON100 data substantially narrows the viable parameter space for light DM with electron couplings, signaling that viable models must either evade electronic couplings or inhabit highly constrained regions of hadronic couplings, pending further data from future colliders or direct-detection experiments.

Abstract

Recently, several astrophysical data or would-be signals has been observed in different dark-matter oriented experiments. In each case, one could fit the data at the price of specific nature of the coupling between the Standard Model (SM) particles and a light Dark Matter candidate: hadrophobic (INTEGRAL, PAMELA) or leptophobic (WMAP Haze, dijet anomalies of CDF, FERMI Galactic Center observation). In this work, we show that when one takes into account the more recent LEP and Tevatron analysis, a light thermal fermionic Dark Matte (\lesssim 10 GeV) that couples to electrons is mainly ruled out if one combines the analysis with WMAP constraints. We also study the special case of scalar dark matter, using a mono-photon events simulation to constrain the coupling of dark matter to electron.

Figures (6)

• Figure 1: DELPHI lower limit on $\Lambda_e \equiv \Lambda/\sqrt{g_e}$ as a function of the dark matter mass for the different types of couplings : vector (red dashed), scalar (blue dashed-dotted), axial (green full--line) and t-channel scalar (magenta dotted).
• Figure 2: Minimum hadronic branching ratio needed to respect WMAP upper bound in the case of electronic couplings (model A, top), charged-leptonic couplings (model B, middle) and universal-leptonic couplings (model C, bottom) with 4 different types of interactions: vector (red dashed), scalar (blue dashed-dotted), axial (green full--line) and t-channel scalar (magenta dotted). Bounds coming from LEP constraints on leptonic couplings.
• Figure 3: (top). Lower limits on $\Lambda_S/g_e$ (solid-red) coming from DELPHI experiment DELPHI:2005, at a 90$\%$ C.L. For reference, the resulting limits on $\Lambda/\sqrt{g_e}$ (fermionic dark matter) coming from a vector-like effective operator, using the same cuts as before, are shown (dashed-green), to be compared with the correspondent result shown in Fig.\ref{['Fig:LEP']}, here in (dotted-blue). (bottom) Distribution of photon energies in single-photon events at DELPHI. The histogram shows the signal$+$background coming from a hypothetical scalar dark matter, as in (\ref{['scalarDM']}), with mass $m_\chi = 10$ GeV, and a suppression scale $\Lambda_S/g_e = 300$ GeV. See body text.
• Figure 4: CDF lower limit on $\Lambda_h \equiv \Lambda/\sqrt{g_h}$ as a function of the dark matter mass for the different types of couplings : vector (red dashed), scalar (blue dashed-dotted) and axial (green full--line).
• Figure 5: Hadronic ratio coupling for the annihilation of dark matter as function of the dark matter mass in the case of universal-leptonic couplings for a vector--like interaction after a scan on $\Lambda_e$ and $\Lambda_h$. After applying the constraint of WMAP (top) mono--jet events from LEP, Tevatron and XENON100 constraint (bottom). See the text for details.