W/Z bremsstrahlung as the dominant annihilation channel for dark matter

Nicole F. Bell, James B. Dent, Thomas D. Jacques, and Thomas J. Weiler
Phys. Rev. D 83, 013001 – Published 6 January 2011

Abstract

Dark matter annihilation to leptons, χχ¯, is necessarily accompanied by electroweak radiative corrections, in which a W or Z boson is radiated from a final-state particle. Given that the W and Z gauge bosons decay dominantly via hadronic channels, it is thus impossible to produce final-state leptons without accompanying protons, antiprotons, and gamma rays. Significantly, while many dark matter models feature a helicity-suppressed annihilation rate to fermions, radiating a massive gauge boson from a final-state fermion removes this helicity suppression, such that the branching ratios Br(νW), Br(+Z), and Br(νν¯Z) dominate over Br(¯). W/Z bremsstrahlung thus allows indirect detection of many weakly interacting massive particle models that would otherwise be helicity suppressed, or v2 suppressed. Antiprotons and even antideuterons become consequential final-state particles. This is an important result for future dark matter searches. We discuss the implications of W/Z bremsstrahlung for “leptonic” dark matter models which aim to fit recent cosmic ray positron and antiproton data.

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  • Received 25 September 2010

DOI:https://doi.org/10.1103/PhysRevD.83.013001

© 2011 American Physical Society

Authors & Affiliations

Nicole F. Bell1, James B. Dent2, Thomas D. Jacques1, and Thomas J. Weiler3

  • 1School of Physics, The University of Melbourne, Victoria 3010, Australia
  • 2Department of Physics and School of Earth and Space Exploration, Arizona State University, Tempe, Arizona 85287-1404, USA
  • 3Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA

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Issue

Vol. 83, Iss. 1 — 1 January 2011

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