arXiv subjects
Publications and source records attributed to L. Bergstrom.
We analyze the direct detection rate of minimal supersymmetric neutralino dark matter in germanium, sapphire and sodium iodide detectors, imposing cosmological and accelerator bounds including those from \bsg\ decay. In contrast with several other recent analyses we find models with light charged higgsinos and large stop mixing in which the counting rate in solid state detectors exceeds 10 events/kg/day.
We analyze the rate of detection of minimal supersymmetric neutralino dark matter in germanium, sapphire and sodium iodide detectors, imposing cosmological and recent accelerator bounds including those from \bsg\ decay. We find, in contrast with several other recent analyses, that although the \bsg\ constraint reduces the number of viable models, models still remain where the counting rate in solid state detectors exceeds 10 kg$^{-1}$ day$^{-1}$.
We calculate, using unitarity, a lower bound on the branching ratio $χχ\to γγ$ and $χχ\to γZ$, where $χ$ is any halo dark matter particle that has $W^+W^-$ as one of the major annihilation modes. Examples of such particles are supersymmetric particles with a dominant Higgsino component, or heavy triplet neutrinos. A substantial branching ratio is found for the $γγ$ and $γZ$ modes. We estimate the strength of the monoenergetic $γ$ ray lines that result from such annihilations in the Galactic or LMC halos. (Latex file; 2 compressed uuencoded postscript figures available by anonymous ftp from vanosf.physto.se in file pub/figures/lines.uu)
We calculate next to leading order QCD corrections to the direct decays b -> J/Psi + X and b -> eta_c + X. The strong renormalization scale dependence is seen to persist also in this order and in fact the rate is driven to an unphysical negative value at the M_b scale. We show that this is a consequence of the strong suppression and scale dependence in the leading order term. Large cancellations take place between terms from three different orders in alpha_s. Lacking a third order calculation we are forced to throw away the leading order term and all but one of the next to leading order terms. The remaining ccbar gluon emission term could very well be the dominant one. Even if this is not the case, the picture of a rate at least as suppressed as in the leading logarithmic approximation survives.