Neutralino annihilation beyond leading order

Abstract

High-precision measurements of the relic dark matter density and the calculation of dark matter annihilation branching fractions in the sun or the galactic halo today motivate the computation of the neutralino annihilation cross section beyond leading order. We consider neutralino annihilation via squark exchange and parameterize the effective annihilation vertex as a dimension-six operator suppressed by two powers of the squark mass and related to the divergence of the axial vector current of the final-state quarks. Since the axial vector current is conserved at tree level in the limit of massless quarks, this dimension-six operator contains a suppression by the quark mass. The quark mass suppression can be lifted in two ways: (1) by corrections to the dimension-six operator involving the anomalous triangle diagram, and (2) by going to dimension-eight. We address the first of these possibilities by evaluating the anomalous triangle diagram, which contributes to neutralino annihilation to gluon pairs. We relate the triangle diagram via the anomaly equation to the decay of a pseudoscalar into two gluons and use the Adler-Bardeen theorem to extract the next-to-leading order (NLO) QCD corrections to chi chi --> gg from the known corrections to pseudoscalar decay. The strong dependence of the dominant chi chi --> q qbar cross section on the relative velocity of the neutralinos makes these NLO corrections unimportant at chi decoupling but significant today.

arXiv comment17 pages, 7 figures. v2: added refs and discussion of present-day neutralino annihilation. v3: PLB version

References in corpus (11)

• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters
• Big Bang Nucleosynthesis (in "The Review of Particle Properties" 2004)
• Particle Dark Matter: Evidence, Candidates and Constraints
• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Preliminary Maps and Basic Results
• Cosmological parameters from SDSS and WMAP
• HIGGS BOSON PRODUCTION AT THE LHC
• DarkSUSY: Computing Supersymmetric Dark Matter Properties Numerically
• Effective QCD Interactions of CP-odd Higgs Bosons at Three Loops
• Exact Cross Sections for the Neutralino WIMP Pair-Annihilation
• Neutralino Annihilation to Gluons
• Loop induced Higgs and Z boson couplings to Neutralinos and implications for collider and Dark Matter searches

Cited by in corpus (6)

• Full one-loop corrections to the relic density in the MSSM: A few examples
• High energy neutrinos from neutralino annihilations in the Sun
• Relic density at one-loop with gauge boson pair production
• Radiative corrections to co-annihilation processes
• Neutralino annihilation to q qbar g
• QCD Correction to Neutralino Annihilation Process and Dark Matter Density in Supersymmetric Models