PAMELA excess from neutralino annihilation in the NMSSM

Journal Article · Tue Sep 01 04:00:00 EDT 2009 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.80.055004· OSTI ID:21322618

Yang, Bai; Lykken, Joseph ^[1]; Carena, Marcela ^[1]

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1. Theoretical Physics Department, Fermilab, Batavia, Illinois 60510 (United States)

We examine whether the cosmic ray positron excess observed by PAMELA can be explained by neutralino annihilation in the next-to-minimal supersymmetric standard model (NMSSM). The main dark matter annihilation products are the lightest CP-even scalar h{sub 1} plus the lightest CP-odd scalar a{sub 1}, with the a{sub 1} decaying into two muons. The energetic positrons needed to explain PAMELA are thus obtained in the NMSSM simply from kinematics. The required large annihilation cross section is obtained from an s-channel resonance with the heavier CP-odd scalar a{sub 2}. Various experiments constrain the PAMELA-favored NMSSM parameter space, including collider searches for a light a{sub 1}. These constraints point to a unique corner of the NMSSM parameter space, having a lightest neutralino mass around 160 GeV and a very light pseudoscalar mass less than a GeV. A simple parametrized formula for the charge-dependent solar modulation effects reconciles the discrepancy between the PAMELA data and the estimated background at lower energies. We also discuss the electron and gamma-ray spectra from the Fermi LAT observations, and point out the discrepancy between the NMSSM predictions and Fermi LAT preliminary results and possible resolution. An NMSSM explanation of PAMELA makes three striking and uniquely correlated predictions: the rise in the PAMELA positron spectrum will turn over at around 70 GeV, the dark matter particle mass is less than the top quark mass, and a light sub-GeV pseudoscalar will be discovered at colliders.

• OSTI ID: 21322618
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 5 Vol. 80; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANNIHILATION
COSMIC RADIATION
CROSS SECTIONS
ELECTRONS
FORECASTING
GAMMA SPECTRA
GEV RANGE 10-100
MASS
MODULATION
MUONS
NONLUMINOUS MATTER
PARTICLES
POSITRONS
RESOLUTION
RESONANCE
S CHANNEL
STANDARD MODEL
SUPERSYMMETRY
T QUARKS