Searches for Dark Matter.

[摘要] We examine indirect detection for neutralino dark matter. After a brief review ofcosmic ray propagation, we discuss signals for positrons, antiprotons, synchrotronradiation and gamma rays from wino annihilation in the galactic halo. The PAMELAdata may admit an interpretation as a signal from a wino-like LSP of mass about 200GeV, normalized to the local relic density, and annihilating mainly into W-bosons.This possibility requires the current conventional estimate for the energy loss rateof positrons be too large by roughly a factor of five. Data from anti-protons andgamma rays also provide tension with this interpretation, but there are significantastrophysical uncertainties associated with each. Forthcoming PAMELA and Fermidata should provide important clues as to whether this scenario is correct. We thengo on to propose a scenario that favors production of positrons over antiprotons.Dark matter annihilates through channels involving a new heavy vectorlike leptonwhich then decays by mixing with Standard Model leptons. If charged, this heavylepton might be produced at the LHC, and could lead to multi-lepton final states orto long-lived charged tracks. Large neutrino detectors such as ANTARES or IceCubemight be sensitive to a monochromatic neutrino line.We study the correlation between spin-independent and spin-dependent scatteringin the context of MSSM neutralino dark matter for both thermal and non-thermalhistories. We explore the generality of this relationship with reference to other models.We discuss why either fine-tuning or numerical coincidences are necessary forthe correlation to break down. We derive upper bounds on spin-dependent scatteringmediated by a Z boson.Finally, for convincing dark matter indirect detection, astrophysical backgroundswould need to be disentangled to determine the dark matter contribution to cosmicray signals. We show that synchrotron emission from electron-positron pairs injectedinto the interstellar medium by the galactic population of pulsars with energies inthe 1 to 100 GeV range can explain the WMAP haze. The same spectrum of highenergy electron-positron pairs from pulsars, which gives rise to the haze, may alsogenerate the observed excesses in PAMELA.

[发布机构] University of Michigan

[效力级别] Physics

[关键词] Dark Matter;Physics;Science;Physics