Higgs Dark Matter in UEDs: A Good WIMP with Bad Detection Prospects

TL;DR

This paper investigates the first Kaluza-Klein excitation of the Higgs boson in universal extra dimensions as a dark matter candidate, analyzing its relic abundance and detection prospects, and finds it consistent with observed dark matter density but difficult to detect.

Contribution

It introduces the first-level Higgs boson as a dark matter candidate in UED models and calculates its relic abundance and detection challenges.

Findings

Relic abundance matches observed dark matter density for masses above 2 TeV.

Detection prospects are very challenging despite the particle being a WIMP.

Mass range for the Higgs KK mode can vary from 1 to 4 TeV with coannihilations.

Abstract

We study the first Kaluza-Klein excitation of the Higgs boson in universal extra dimensions as a dark matter candidate. The first-level Higgs boson could be the lightest Kaluza-Klein particle, which is stable due to the conservation of Kaluza-Klein parity, in non-minimal models where boundary localized terms modify the mass spectrum. We calculate the relic abundance and find that it agrees with the observed dark matter density if the mass of the first-level Higgs boson is slightly above 2 TeV, not considering coannihilations and assuming no relative mass splitting among the first-level Kaluza-Klein modes. In the case of coannihilations and a non-zero mass splitting, the mass of the first-level Higgs boson can range from 1 TeV to 4 TeV. We study also the prospects for detection of this dark matter candidate in direct as well as indirect detection experiments. Although the first-level Higgs boson is a typical weakly interacting massive particle, an observation in any of the conventional experiments is very challenging.