3,483 research outputs found

    New Signatures of Squarks

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    When the gluino is light and long lived, missing energy is a poor signature for both squarks and gluinos. Instead, SqSq∗S_q S_q^* production in e+e−e^+ e^- and ppˉp \bar{p} collisions characteristically results in events with ≥4\ge 4 jets. Methods are proposed for deciding whether an observed excess of 4-jet events is due to SqSq∗S_q S_q^* production. The recent report by ALEPH of observation of 14 4-jet events when 7 were expected is discussed.Comment: 12/22/95 version (put on net 1/1/96) elaborates remarks on squarks as possible source of ALEPH 4-jet excess and adds a ref. latex, 10 pages (including 1 figure), uufile

    Detecting Gluino-Containing Hadrons

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    When SUSY breaking produces only dimension-2 operators, gluino and photino masses are of order 1 GeV or less. The gluon-gluino bound state has mass 1.3-2.2 GeV and lifetime > 10^{-5} - 10^{-10} s. This range of mass and lifetime is largely unconstrained because missing energy and beam dump techniques are ineffective. With only small modifications, upcoming K^0 decay experiments can study most of the interesting range. The lightest gluino-containing baryon (uds-gluino) is long-lived or stable; experiments to find it and the uud-gluino are also discussed.Comment: 13 pp, 1 figure (uuencoded). Descendant of hep-ph/9504295, hep-ph/9508291, and hep-ph/9508292, focused on experimental search techniques. To be published in Phys Rev Let

    Neutron Stars with a Stable, Light Supersymmetric Baryon

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    If a light gluino exists, the lightest gluino-containing baryon, the \OSO, is a possible candidate for self-interacting dark matter. In this scenario, the simplest explanation for the observed ratio Ωdm/Ωb≈6−10\Omega_{dm}/\Omega_b \approx 6-10 is that mS0∼900m_{S^0} \sim 900\MeVcs; this is not at present excluded by particle physics. Such an \OSO could be present in neutron stars, with hyperon formation serving as an intermediate stage. We calculate equilibrium compositions and equation of state for high density matter with the \OSO, and find that for a wide range of parameters the properties of neutron stars with the \OSO are consistent with observations. In particular, the maximum mass of a nonrotating star is 1.7−1.8M⊙1.7-1.8 M_\odot, and the presence of the \OSO is helpful in reconciling observed cooling rates with hyperon formation.Comment: ApJL submitted, 4 pages, using emulateapj (very very minor changes to match published versio

    Dark Matter and the Baryon Asymmetry

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    We present a mechanism to generate the baryon asymmetry of the Universe which preserves the net baryon number created in the Big Bang. If dark matter particles carry baryon number BXB_X, and σXˉannih<σXannih\sigma^{\rm annih}_{\bar{X}} < \sigma^{\rm annih}_{X} , the Xˉ\bar{X}'s freeze out at a higher temperature and have a larger relic density than XX's. If m_X \lsi 4.5 B_X GeV and the annihilation cross sections differ by O\mathcal{O}(10%) or more, this type of scenario naturally explains the observed ΩDM≈5Ωb\Omega_{DM} \approx 5 \Omega_b. Two concrete examples are given, one of which can be excluded on observational grounds

    Scattering from a Domain Wall in a Spontaneously Broken Gauge Theory

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    We study the interaction of particles with a domain wall at a symmetry-breaking phase transition by perturbing about the domain wall solution. We find the particulate excitations appropriate near the domain wall and relate them to the particles present far from the wall in the uniform broken and unbroken phases. For a quartic Higgs potential we find analytic solutions to the equations of motion and derive reflection and transmission coefficients. We discover several bound states for particles near the wall. Finally, we apply our results to the electroweak phase transition in the standard model.Comment: 48 pages, 10 figures, LaTeX / epsf, revised to include references to earlier related wor

    Mock Catalogs for UHECR Studies

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    We provide realistic mock-catalogs of cosmic rays above 40 EeV, for a pure proton composition, assuming their sources are a random subset of ordinary galaxies in a simulated, volume-limited survey, for various choices of source density: 10^-3.5 Mpc^-3, 10^-4.0 Mpc^-3 and 10^-4.5 Mpc^-3. The spectrum at the source is taken to be E^-2.3 and the effects of cosmological redshifting as well as photo-pion and e^+ e^- energy losses are included.Comment: 7 pages, 4 figure

    Radiative Decay of Vector Quarkonium: Constraints on Glueballs and Light Gluinos

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    Given a resonance of known mass, width, and J^{PC}, we can determine its gluonic branching fraction, b(R->gg), from data on its production in radiative vector quarkonium decay, V -> gamma+R. For most resonances b(R->gg) is found to be O(10%), consistent with being q-qbar states, but we find that both pseudoscalars observed in the 1440 MeV region have b(R->gg) ~ 1/2 - 1, and b(f_0^{++}->gg) ~ 1/2. As data improves, b(R->gg) should be a useful discriminator between q-qbar and gluonic states and may permit quantitative determination of the extent to which a particular resonance is a mixture of glueball and q-qbar. We also examine the regime of validity of pQCD for predicting the rate of V -> gamma+eta_gluino, the ``extra'' pseudoscalar bound state which would exist if there were light gluinos. From the CUSB limit on peaks in Upsilon -> gamma X, the mass range 3 GeV < m(eta_gluino) < 7 GeV can be excluded. An experiment must be significantly more sensitive to exclude an eta_gluino lighter than this.Comment: 36pp (inc figs),RU-94-04. (Replaces original which didn't latex correctly and didn't have figures.

    Flammability screening tests of resins

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    Selected flammability characteristics of glass cloth laminates of thermosetting resins are evaluated. A protocol for the evaluation of the flammability hazards presented by glass cloth laminates of thermosetting resins and the usefulness of that protocol with two laminates are presented. The glass laminates of an epoxy resin, M-751 are evaluated for: (1) determination of smoke generation from the laminates; (2) analysis of products of oxidative degradation of the laminates; (3) determination of minimum oxygen necessary to maintain flaming oxidation; (4) evaluation of toxicological hazards
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