Closing in on t-channel simplified dark matter models

Chiara Arina,Benjamin Fuks,Luca Mantani,Hanna Mies,Luca Panizzi,Jakub Salko

doi:10.1016/j.physletb.2020.136038

Abstract

A comprehensive analysis of cosmological and collider constraints is presented for three simplified models characterised by a dark matter candidate (real scalar, Majorana fermion and real vector) and a coloured mediator (fermion, scalar and fermion respectively) interacting with the right-handed up quark of the Standard Model. Constraints from dark matter direct and indirect detection and relic density are combined with bounds originating from the re-interpretation of a full LHC run 2 ATLAS search targeting final states with multiple jets and missing transverse energy. Projections for the high-luminosity phase of the LHC are also provided to assess future exclusion and discovery reaches, which show that analogous future search strategies will not allow for a significant improvement compared with the present status. From the cosmological point of view, we demonstrate that thermal dark matter is largely probed (and disfavoured) by constraints from current direct and indirect detection experiments. These bounds and their future projections have moreover the potential of probing the whole parameter space when combined with the expectation of the high-luminosity phase of the LHC.

Highlights

The nature of dark matter and the way it is connected to the Standard Model (SM) is one of the most puzzling issues in particle physics today
We show projected 2σ exclusion and 5σ discovery reaches for the HL-LHC, which corresponds to a luminosity of 3 ab−1
We present the expected sensitivity of future SI (LZ [41]) and SD (LZ, PICO-500 [42] and COSINUS [43]) direct detection experiments, the latter being extracted from ref. [44] for the O4 operator

Summary

Introduction

The nature of dark matter and the way it is connected to the Standard Model (SM) is one of the most puzzling issues in particle physics today. Experimental searches at colliders, in underground nuclear recoil experiments and with gamma-ray telescopes put stronger and stronger constraints on the viability of any dark matter model. Those bounds are very often explored, in a model-independent approach, as limits on a set of simplified models for dark matter phenomenology. The dark matter candidate is a real particle, singlet under the SM gauge group, so that its stability can be ensured through a Z2 symmetry This contrasts with other t-channel models including a complex dark matter field and exhibiting instead a continuous unbroken global U (1) symmetry.

The t-channel simplified models

Collider bounds

Cosmological bounds

Combining dark matter searches

Findings

Conclusions