812 research outputs found

    Discovery potential for Higgs bosons beyond the SM

    Get PDF
    The discovery potential of the CMS detector for the MSSM neutral and charged Higgs bosons at the LHC is presented based on studies with full detector simulation and event reconstruction of the principal discovery channels.Comment: Prepared for International Europhysics Conference on High Energy Physics (EPS-HEP2007), Manchester, England, 19-25 Jul 200

    Dense Antihydrogen: Its Production and Storage to Envision Antimatter Propulsion

    Full text link
    We discuss the possibility that dense antihydrogen could provide a path towards a mechanism for a deep space propulsion system. We concentrate at first, as an example, on Bose-Einstein Condensate (BEC) antihydrogen. In a Bose-Einstein Condensate, matter (or antimatter) is in a coherent state analogous to photons in a laser beam, and individual atoms lose their independent identity. This allows many atoms to be stored in a small volume. In the context of recent advances in producing and controlling BECs, as well as in making antihydrogen, this could potentially provide a revolutionary path towards the efficient storage of large quantities of antimatter, perhaps eventually as a cluster or solid.Comment: 12 pages, 3 figure

    Evidence for the positive-strangeness pentaquark Θ+\Theta^+ in photoproduction with the SAPHIR detector at ELSA

    Get PDF
    The positive--strangeness baryon resonance Θ+\Theta^+ is observed in photoproduction of the nK+Ks0\rm nK^+K^0_s final state with the SAPHIR detector at the Bonn ELectron Stretcher Accelerator ELSA. It is seen as a peak in the nK+\rm nK^+ invariant mass distribution with a 4.8σ4.8\sigma confidence level. We find a mass MΘ+=1540±4±2\rm M_{\Theta^+} = 1540\pm 4\pm 2 MeV and an upper limit of the width ΓΘ+<25\rm \Gamma_{\Theta^+} < 25 MeV at 90% c.l. From the absence of a signal in the pK+\rm pK^+ invariant mass distribution in γppK+K\rm\gamma p\to pK^+K^- at the expected strength we conclude that the Θ+\Theta^+ must be isoscalar.Comment: 9 pages, 4 figure

    Florida Atlantic Coast Telemetry (FACT) Array: A Working Partnership

    Get PDF
    The Florida Atlantic Coast Telemetry (FACT) Array is a collaborative partnership of researchers from 24 different organizations using passive acoustic telemetry to document site fidelity, habitat preferences, seasonal migration patterns, and reproductive strategies of valuable sportfish, sharks, and marine turtles. FACT partners have found that by bundling resources, they can leverage a smaller investment to track highly mobile animals beyond a study area typically restrained in scale by funds and manpower. FACT is guided by several simple rules: use of the same type of equipment, locate receivers in areas that are beneficial to all researchers when feasible, maintain strong scientific ethics by recognizing that detection data on any receiver belongs to the tag owner, do not use other members detection data without permission and acknowledge FACT in publications. Partners have access to a network of 480 receivers deployed along a continuum of habitats from freshwater rivers to offshore reefs and covers 1100 km of coastline from the Dry Tortugas, Florida to South Carolina and extends to the Bahamas. Presently, 49 species, (25 covered by Fisheries Management Plans and five covered by the Endangered Species Act) have been tagged with 2736 tags in which 1767 tags are still active

    K0-Sigma+ Photoproduction with SAPHIR

    Full text link
    Preliminary results of the analysis of the reaction p(gamma,K0)Sigma+ are presented. We show the first measurement of the differential cross section and much improved data for the total cross section than previous data. The data are compared with model predictions from different isobar and quark models that give a good description of p(gamma,K+)Lambda and p(gamma,K+)Sigma0 data in the same energy range. Results of ChPT describe the data adequately at threshold while isobar models that include hadronic form factors reproduce the data at intermediate energies.Comment: 4 pages, Latex2e, 4 postscript figures. Talk given at the International Conference on Hypernuclear and Strange Particle Physics (HYP97), Brookhaven National Laboratory, USA, October 13-18, 1997. To be published in Nucl. Phys. A. Revised version due to changes in experimental dat

    A Dynamical Principle For 3D-4D Interlinkage In Salpeter-like Equations

    Get PDF
    The half-century old Markov-Yukawa Transversality Principle (MYTPMYTP) which provides a theoretical rationale for the covariant instantaneous approximation (CIACIA) that underlies all Salpeter-like equations, is generalized to a covariant null-plane ansatz (CNPACNPA). A common characteristic of both formulations is an exact 3D-4D interlinkage of BS amplitudes which facilitates a two-tier description: the 3D form for spectroscopy, and the 4D form for transition amplitudes as 4D loop integrals. Some basic applications of MYTPMYTP on the covariant null plane (quark mass function, vacuum condensates, and decay constants) are given on the lines of earlier applications to these processes under CIACIA. PACS: 03.65.-w ; 03.65.Co ; 11.10.Qr ; 11.10.St Keywords: Markov-Yukawa Transversality Principle (MYTPMYTP); Salpeter-like eqs; Cov Instantaneity Ansatz (CIACIA); Cov Null-Plane Ansatz (CNPACNPA); 3D-4D interlinkage; Vertex function; 4D loopsComment: LaTeX file, 25 pages, to be published in Nuclear Phys.

    Semileptonic six fermion processes at future e+ee^+ e^- colliders: signal and irreducible background for top and WWZ physics

    Get PDF
    We compute several total and differential cross sections relevant to top and WWZ physics at future e+ee^+e^- colliders taking into account the full set of Feynman diagrams for six fermion final states. We also include in our calculations initial state radiation and beamstrahlung effects, and the most important QCD corrections in an approximate (naive) form. We compare such a complete approach with "production x decay" approximation and we suggest that in many physical studies the former is needed.Comment: 28 pages including 8 figures (7 ps). Latex. Uses Axodraw. Minor changes and some typos correcte

    A new Perspective on the Scalar meson Puzzle, from Spontaneous Chiral Symmetry Breaking Beyond BCS

    Full text link
    We introduce coupled channels of Bethe-Salpeter mesons both in the boundstate equation for mesons and in the mass gap equation for chiral symmetry. Consistency is insured by the Ward Identities for axial currents, which preserve the Goldstone boson nature of the pion and prevents a systematic shift of the hadron spectrum. We study the decay of a scalar meson coupled to a pair of pseudoscalars. We also show that coupled channels reduce the breaking of chiral symmetry, with the same Feynman diagrams that appear in the coupling of a scalar meson to a pair of pseudoscalar mesons. Exact calculations are performed in a particular confining quark model, where we find that the groundstate I=0,3P0qqˉI=0, ^3P_0 q \bar q meson is the f_0(980) with a partial decay width of 40MeV. We also find a 30% reduction of the chiral condensate due to coupled channels.Comment: 17 pages, Revtex, 8 eps figures, and several eps diagrams in equation

    Measurement of polarisation observables in Ks0Σ+K^0_s\Sigma^+ photoproduction off the proton

    Get PDF
    The reaction γpKS0Σ+\gamma \, p \rightarrow K^0_S\,\Sigma^+ is studied in the photon energy range from threshold. Linearly polarised photon beams from coherent bremsstrahlung enabled the first measurement of photon beam asymmetries in this reaction up to Eγ=2250E_\gamma = 2250 MeV. In addition, the recoil hyperon polarisation was determined through the asymmetry in the weak decay Σ+pπ0\Sigma^+ \rightarrow p \pi^0 up to Eγ=1650E_\gamma = 1650 MeV. The data are compared to partial wave analyses, and the possible impact on the interpretation of a recently observed cusp-like structure near the KK^* thresholds is discussed.Comment: 6 pages, 5 figures. References [8,9,10,11] which were not on the original submission are now include

    Photoproduction of Neutral Pions off Protons

    Get PDF
    Photoproduction of neutral pions has been studied with the CBELSA/TAPS detector in the reaction γppπ0\gamma p\to p\pi^0 for photon energies between 0.85 and 2.50 GeV. The π0\pi^0 mesons are observed in their dominant neutral decay mode: π0γγ\pi^0\to\gamma\gamma. For the first time, the differential cross sections cover the very forward region, θc.m.<60\theta_{\rm c.m.}<60^\circ. A partial-wave analysis of these data within the Bonn-Gatchina framework observes the high-mass resonances G17G_{17}(2190), D13D_{13}(2080), and D15D_{15}(2070).Comment: 12 pages, 9 figures, minor modifications to PWA sectio
    corecore