96 research outputs found

    e±e^\pm Excesses in the Cosmic Ray Spectrum and Possible Interpretations

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    The data collected by ATIC, PPB-BETS, FERMI-LAT and HESS all indicate that there is an electron/positron excess in the cosmic ray energy spectrum above \sim 100 GeV, although different instrumental teams do not agree on the detailed spectral shape. PAMELA also reported a clear excess feature of the positron fraction above several GeV, but no excess in anti-protons. Here we review the observational status and theoretical models of this interesting observational feature. We pay special attention to various physical interpretations proposed in the literature, including modified supernova remnant models for the e±e^\pm background, new astrophysical sources, and new physics (the dark matter models). We suggest that although most models can make a case to interpret the data, with the current observational constraints the dark matter interpretations, especially those invoking annihilation, require much more exotic assumptions than some astrophysical interpretations. Future observations may present some ``smoking-gun'' observational tests to differentiate among different models and to identify the correct interpretation to the phenomenon.Comment: 48 pages, including 10 figures and 1 tabel. Invited review to be published in IJMP

    On the role of the final state interactions in rare B-decays

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    The effects of final state interactions (FSI) in hadronic B-decays are investigated. The model for FSI, based on Regge phenomenology of high-energy hadronic interactions is proposed. It is shown that this model explains the pattern of phases in matrix elements of BππB\to\pi\pi and BρρB\to\rho\rho decays. These phases play an important role for CP-violation in B-decays. The most precise determination of the unitarity triangle angle α\alpha from BdρπB_d\to \rho\pi decays is performed. The relation between CP-asymmetries in BKπB\to K\pi decays is discussed. It is emphasized that the large distance FSI can explain the structure of polarizations of the vector mesons in B-decays and other puzzles like a very large branching ratio of the B-decay to ΞˉcΛc\bar\Xi_c\Lambda_c.Comment: 19 page

    Cosmological constraints on R-parity violation from neutrino decay

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    If the neutrino mass is non-zero, as hinted by several experiments, then R-parity-violating supersymmetric Yukawa couplings can drive a heavy neutrino decay into lighter states. The heavy neutrino may either decay radiatively into a lighter neutrino, or it may decay into three light neutrinos through a Z-mediated penguin. For a given mass of the decaying neutrino, we calculate its lifetime for the various modes, each mode requiring certain pairs of R-parity-violating couplings be non-zero. We then check whether the calculated lifetimes fall in zones allowed or excluded by cosmological requirements. For the latter case, we derive stringent new constraints on the corresponding products of R-parity-violating couplings for given values of the decaying neutrino mass.Comment: 13 pages, Latex, uses axodraw.sty; version to appear in Physical Review

    The Next-to-Minimal Supersymmetric extension of the Standard Model reviewed

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    The next-to-minimal supersymmetric extension of the Standard Model (NMSSM) is one of the most favored supersymmetric models. After an introduction to the model, the Higgs sector and the neutralino sector are discussed in detail. Theoretical, experimental, and cosmological constraints are studied. Eventually, the Higgs potential is investigated in the approach of bilinear functions. Emphasis is placed on aspects which are different from the minimal supersymmetric extension.Comment: 75 pages, 20 figures, revised version adapted to the journal publicatio

    Non-Baryonic Dark Matter - Observational Evidence and Detection Methods

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    The evidence for the existence of dark matter in the universe is reviewed. A general picture emerges, where both baryonic and non-baryonic dark matter is needed to explain current observations. In particular, a wealth of observational information points to the existence of a non-baryonic component, contributing between around 20 and 40 percent of the critical mass density needed to make the universe geometrically flat on large scales. In addition, an even larger contribution from vacuum energy (or cosmological constant) is indicated by recent observations. To the theoretically favoured particle candidates for non-baryonic dark matter belong axions, supersymmetric particles, and of less importance, massive neutrinos. The theoretical foundation and experimental situation for each of these is reviewed. Direct and indirect methods for detection of supersymmetric dark matter are described in some detail. Present experiments are just reaching the required sensitivity to discover or rule out some of these candidates, and major improvements are planned over the coming years.Comment: Submitted to Reports on Progress in Physics, 59 pages, LaTeX, iopart macro, 14 embedded postscript figure

    Astrophysical Axion Bounds

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    Axion emission by hot and dense plasmas is a new energy-loss channel for stars. Observational consequences include a modification of the solar sound-speed profile, an increase of the solar neutrino flux, a reduction of the helium-burning lifetime of globular-cluster stars, accelerated white-dwarf cooling, and a reduction of the supernova SN 1987A neutrino burst duration. We review and update these arguments and summarize the resulting axion constraints.Comment: Contribution to Axion volume of Lecture Notes in Physics, 20 pages, 3 figure

    Mass Bounds on a Very Light Neutralino

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    Within the Minimal Supersymmetric Standard Model (MSSM) we systematically investigate the bounds on the mass of the lightest neutralino. We allow for non-universal gaugino masses and thus even consider massless neutralinos, while assuming in general that R-parity is conserved. Our main focus are laboratory constraints. We consider collider data, precision observables, and also rare meson decays to very light neutralinos. We then discuss the astrophysical and cosmological implications. We find that a massless neutralino is allowed by all existing experimental data and astrophysical and cosmological observations.Comment: 36 pages, 13 figures, minor modification in astro-physical bounds. EPJC versio

    Decoupling property of the supersymmetric Higgs sector with four doublets

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    In supersymmetric standard models with multi Higgs doublet fields, selfcoupling constants in the Higgs potential come only from the D-terms at the tree level. We investigate the decoupling property of additional two heavier Higgs doublet fields in the supersymmetric standard model with four Higgs doublets. In particular, we study how they can modify the predictions on the quantities well predicted in the minimal supersymmetric standard model (MSSM), when the extra doublet fields are rather heavy to be measured at collider experiments. The B-term mixing between these extra heavy Higgs bosons and the relatively light MSSM-like Higgs bosons can significantly change the predictions in the MSSM such as on the masses of MSSM-like Higgs bosons as well as the mixing angle for the two light CP-even scalar states. We first give formulae for deviations in the observables of the MSSM in the decoupling region for the extra two doublet fields. We then examine possible deviations in the Higgs sector numerically, and discuss their phenomenological implications.Comment: 26 pages, 24 figures, text sligtly modified,version to appear in Journal of High Energy Physic

    Conference of Soviet and American Jurists on the Law of the Sea and the Protection of the Marine Environment

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    Included in the papers for the Conference of Soviet and American Jurists on the Law of the Sea and the Protection of the Marine Environment: Introduction by Milton Katz and Richard R. Baxter, p. 1 Freedom of Scientific Research in the World Ocean by A.F. Vysotsky, p. 7 The International Law of Scientific Research in the Oceans by Richard R. Baxter, p. 27 Responsibility and Liability for Harm to the Marine Environment by Robert E. Stein, p. 41 Liability for Marine Environment Pollution Damage in Contemporary International Sea Law by A. L. Makovsky, p. 59 Protection of the Marine Environment from Pollution by Richard A. Frank, p. 73 The Freedom of Navigation and the Problem of Pollution of the Marine Environment by V. A. Kiselev, p. 93 The Freedom of Navigation Under International Law by William E. Butler, p. 107 International Fisheries Management Without Global Agreement: United States Policies and Their Impact on the Soviet Union by H. Gary Knight, p. 119 Some Biological Background for International Legal Acts on Rational Utilization of the Living Resources of the World Ocean by P. A. Moiseev, p. 143 An International Regime for the Seabed Beyond National Jurisdiction by Thomas M. Franck, p. 151 Settlement of Disputes Under the Law of Ocean Use, with Particular Reference to Environmental Protection by John Lawrence Hargrove, p. 18
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