Implication of the PAMELA antiproton data for dark matter indirect detection at LHC

TL;DR

This paper investigates how PAMELA antiproton data impacts dark matter models, showing that large couplings to heavy quarks are possible without conflicting with observations, but LHC production prospects are limited due to parton distribution effects.

Contribution

It demonstrates that PAMELA antiproton measurements do not exclude dark matter models with strong quark couplings, and analyzes the implications for LHC production channels.

Findings

Large quark couplings are compatible with PAMELA data.

LHC production prospects are limited by parton distribution functions.

Dark matter models with heavy quark couplings remain viable.

Abstract

Since the PAMELA results on the "anomalously" high positron fraction and the lack of antiproton excess in our Galaxy, there has been a tremendous number of studies advocating new types of dark matter, with larger couplings to electrons than to quarks. This raises the question of the production of dark matter particles (and heavy associated coloured states) at LHC. Here, we explore a very simple benchmark dark matter model and show that, in spite of the agreement between the PAMELA antiproton measurements and the expected astrophysical secondary background, there is room for large couplings of a WIMP candidate to heavy quarks. Contrary to what could have been naively anticipated, the PAMELA pbar/p measurements do not challenge dark matter model building, as far as the quark sector is concerned. A quarkophillic species is therefore not forbidden.Owing to these large couplings, one would expect that a new production channel opens up at the LHC, through quark--quark and quark--gluon interactions. Alas, when the PDF of the quark is taken into account, prospects for a copious production fade away.