Dark matter and collider phenomenology of split-UED

TL;DR

Split-UED, an extension of the UED model, can explain cosmic-ray anomalies and predicts distinctive collider signatures with suppressed hadronic signals, making it testable at the LHC.

Contribution

This paper demonstrates that split-UED can account for cosmic-ray anomalies and provides detailed collider phenomenology predictions with large KK quark mass splittings.

Findings

KK dark matter predominantly annihilates into leptons

Antiproton flux matches observations with no excess

Collider signals include high p_T jets and missing energy

Abstract

We explicitly show that split-universal extra dimension (split-UED), a recently suggested extension of universal extra dimension (UED) model, can nicely explain recent anomalies in cosmic-ray positrons and electrons observed by PAMELA and ATIC/PPB-BETS. Kaluza-Klein (KK) dark matters mainly annihilate into leptons because the hadronic branching fraction is highly suppressed by large KK quark masses and the antiproton flux agrees very well with the observation where no excess is found . The flux of cosmic gamma-rays from pion decay is also highly suppressed and hardly detected in low energy region (E<20 GeV). Collider signatures of colored KK particles at the LHC, especially q_1 q_1 production, are studied in detail. Due to the large split in masses of KK quarks and other particles, hard p_T jets and missing E_T are generated, which make it possible to suppress the standard model background and discover the signals.