Search

The new precise LEP measurements of alphas and the electroweak mixing angle as well as the new LEP II mass limits for supersymmetric particles and new calculations for the radiative (penguin) decay of the b-quark into sgamma allow a further restriction in the parameter space of the Constrained Minimal Supersymmetric Standard Model (CMSSM)., Comment: latex + 5 eps figs, 7 pages, Higgs masses updated in corrected version, to be published in the Proc. of ICHEP97, Jerusalem, 1997

Within the Constrained Minimal Supersymmetric Standard Model it is possible to predict the low energy gauge couplings and masses of the 3. generation particles from a few parameters at the GUT scale. In addition the MSSM predicts elektroweak symmetry breaking due to large radiative corrections from Yukawa couplings, thus relating the Z^0 boson mass to the top quark mass. From a \chi^2 analysis, in which these constraints can be considered simultaneously, one can calculate the probability for each point in the MSGUT parameter space. Our fits include full second order corrections for the gauge and Yukawa couplings, low energy treshold effects, contributions of all (s)particles to the Higgs potential and corrections to m_b from qluinos and higgsinos, which exclude (in our notation) positive values of the mixing parameter in the Higgs potential \mu for the large tan \beta region. Further constraints can be derived from the branching ratio for the radiative (penguin) decay of the b-quark into s \gamma and the lower limit on the lifetime of the universe, which requires the dark matter density due to the Lightest Supersymmetric Particle (LSP) not to overclose the universe. For particles, which are most likely to have masses in the LEP II energy range, the cross sections are given for the various energy scenarios at LEP II. For low tan \beta the production of the lightest Higgs boson, which is expected to have a mass below 103 GeV, is the most promising channel, while for large tan \beta the production of charginos and/or neutralinos covers the preferred parameter space., Comment: LaTeX + 28 eps figs, 43 pages

Within the framework of the Minimal Supersymmetric Standard Model (MSSM) the Higgs masses and LEP II production cross sections are calculated for a wide range of the parameter space. In addition, the parameter space restricted by unification, electroweak symmetry breaking and other low energy constraints is considered in detail, in which case the masses of all SUSY partners can be estimated, so that their contributions to the radiative corrections can be calculated. Explicit analytical formulae for these contribution are derived. The radiative corrections from the Yukawa couplings of the third generation are found to dominate over the contributions from charginos and neutralinos. Large Higgs mass uncertainties are due to the top mass uncertainty and the unknown sign of the Higgs mixing parameter. For the low tanb scenario the mass of the lightest Higgs is found to be below 103 GeV for a top mass below 190 GeV. The cross section at a LEP energy of 192 GeV is sufficient to find or exclude this low tanb scenario for a top mass below 180 GeV. For the high tanb scenario only a small fraction of the parameter space can be covered, since the Higgs mass is predicted between 105 and 125 GeV in most cases. At the theoretically possible LEP II energy of 205 GeV part of the parameter space for the large tanb scenario would be accessible., Comment: latex + 6 eps figs, 22 pages, final version

In this report we review the prospects for Higgs physics at LEP2. The theoretical aspects and the phenomenology of Higgs particles are discussed within the Standard Model (SM) and the Minimal Supersymmetric Standard Model (MSSM). The experimental search techniques are described and the discovery limits for Higgs bosons in the LEP2 energy range are summarized. In addition, opportunities of detecting Higgs particles in non-minimal extensions of the SM and the MSSM are investigated., Comment: 112 pages, latex file + figures (some bitmapped), to appear in Vol. 1, Report of the Workshop on Physics at LEP2, G. Altarelli, T. Sjostrand and F.Zwirner (eds), CERN 96-01. (Full postscript and uuencoded files, including full resolution figures are available at the www address http://surya11.cern.ch/surya_info/users/mcarena in finrep.ps, finrep.uu)

Within the Constrained Minimal Supersymmetric Standard Model (CMSSM) it is possible to predict the low energy gauge couplings and masses of the 3.generation particles from a few parameters at the GUT scale, and electroweak symmetry breaking. Further constraints can be derived from the branching ratio for the radiative (penguin) decay of the b-quark into s gamma and the lower limit on the lifetime of the universe, which requires the dark matter density due to the Lightest Supersymmetric Particle (LSP) not to overclose the universe. From a chi^2 analysis, in which these constraints can be considered simultaneously, one can calculate the probability for each point in the MSGUT parameter space. The recently measured top quark mass prefers two solutions for the mixing angle in the Higgs sector: tan beta in the range between 1 and 3 or alternatively tan beta approx 25-50. For both cases we find a unique chi^2 minimum in the parameter space. For the low tan beta solution these additional constraints can be fulfilled simultaneously for quite a large region of the parameter space. In contrast, for the high tan beta solution the correct value for the b --> s gamma rate is obtained only for small values of the gaugino scale. For particles, which are most likely to have masses in the LEP II energy range, the cross sections are given for the various energy scenarios at LEP II. The highest LEP II energies (205 GeV) are just high enough to cover a large region of the preferred parameter space, both for the low and high tan beta solutions. For low tan beta the production of the lightest Higgs boson, which is expected to have a mass below 115 GeV, is the most promising channel, while for large tan beta the production of charginos and/or neutralinos covers the preferred parameter space., Comment: 39 pages, latex + 28 eps figs, replaced for additional refs. and typo corrections, ftp://ekpux3.physik.uni-karlsruhe.de/IEKP-KA9507.ps.Z

It is shown that a top mass of 174+/-17 GeV, as quoted recently by the CDF Collaboration, constrains the mixing angle between the Higgs doublets in the Minimal Supersymmmetric extension of the Standard Model (MSSM) to: 1.2

The MSSM distinguishes itself from other GUT's by a successful prediction of many unrelated phenomena with a minimum number of parameters. Among them: a) Unification of the couplings constants; b)Unification of the masses; c) Proton decay; d) Electroweak symmetry breaking. A combined fit of the free parameters in the MSSM to these low energy constraints shows that the MSSM model can satisfy these constraints simultaneously. From the fitted parameters the masses of the as yet unobserved superpartners of the SM particles are predicted. The 2nd order QCD coupling constant is required to be between 0.108 and 0.132. It is shown that a top mass of $174\pm16$ GeV, as suggested recently by the CDF Collaboration, constrains the mixing angle between the Higgs doublets in the MSSM to: $1.2<\tb<5.5$ at the 90% C.L.. The most probable value corresponds to $\tb = 1.56$, which leads to a stop mass below the top mass. In this case the stop production in $p\bar{p}$ collisions would contribute to the top signature. This could be an explanation for the large effective $t\bar{t}$ cross section observed by CDF., Comment: latex + eps fig IEKP-KA/94-05

Within the Minimal Supersymmetric Grand Unified Theory (MSGUT) masses of the predicted supersymmetric particles are constrained by the world averaged values of the electroweak and strong coupling constants, the lower limits on the proton lifetime,the lower limit on the lifetime of the universe, which implies an upper limit on the dark matter density, the electroweak symmetry breaking originating from radiative corrections due to the heavy top quark, and the ratio of the masses of the b-quark and tau-lepton. A combined fit shows that indeed the MSGUT model can satisfy all these constraints simultaneously and the corresponding values for all SUSY masses are given within the minimal model, taking into account the complete second order renormalisation group equations for the couplings and the one-loop corrections to the Higgs potential for the calculation of the Z-mass and the Higgs masses. These one-loop corrections to MZ have been derived explicitly as function of the stop- and top masses and found to be small for the best solution, but unnaturally large for the 90% C.L. upper limits on the SUSY masses., Comment: IEKP-KA/93-13 preprint, hep-ph/yymmnnn latex + eps fig (epsf macros)

Improved sewing technique for high-temperature insulating blankets prevents stitch failure in hot, turbulent environments. Standard lockstitch modified to isolate single-stitch failures. Bobbin thread kept at blanket surface. Silicone adhesive applied to all bobbin/needle intersections, so failure at one point will not propagate along thread. Suitable for use in aerodynamic and other applications where there is turbulence.

A design allowables test program was conducted on Celion 6000/LARC-160 graphite polyimide composite to establish material performance over a 116 K (-250 F) to 589 K (600 F) temperature range. Tension, compression, in-plane shear and short beam shear properties were determined for uniaxial, quasi-isotropic and + or - 45 deg laminates. Effects of thermal aging and moisture saturation on mechanical properties were also evaluated. Celion 6000/LARC-160 graphite/polyimide can be considered an acceptable material system for structural applications to 589 K (600 F).

The concepts explored in a state of the art review of those engineering fracture mechanics considered most applicable to the space shuttle vehicle include fracture toughness, precritical flaw growth, failure mechanisms, inspection methods (including proof test logic), and crack growth predictive analysis techniques.

Method uses assembly consisting of single pictorial display showing cutaway view of assembly, subassemblies identified by name and materials, and processes identified by both specification and commercial design. Display is used in engineering, manufacturing, and personnel training.