164 research outputs found

    Higgs Physics with a gamma gamma Collider Based on CLIC 1

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    We present the machine parameters and physics capabilities of the CLIC Higgs Experiment (CLICHE), a low-energy γγ\gamma\gamma collider based on CLIC 1, the demonstration project for the higher-energy two-beam accelerator CLIC. CLICHE is conceived as a factory capable of producing around 20,000 light Higgs bosons per year. We discuss the requirements for the CLIC 1 beams and a laser backscattering system capable of producing a γγ\gamma\gamma total (peak) luminosity of 2.0(0.36)×10342.0 (0.36) \times 10^{34} cm2^{-2}s1^{-1} with ECM(γγ)115E_{CM}(\gamma \gamma) \sim 115 GeV. We show how CLICHE could be used to measure accurately the mass, bˉb\bar b b, WWWW and γγ\gamma \gamma decays of a light Higgs boson. We illustrate how these measurements may distinguish between the Standard Model Higgs boson and those in supersymmetric and more general two-Higgs-doublet models, complementing the measurements to be made with other accelerators. We also comment on other prospects in γγ\gamma\gamma and eγe^- \gamma physics with CLICHE.Comment: 34 pages, 20 figures, Latex. submitted to Eur. Phys. Jou

    CLIC Beam Delivery System

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    We review the present design for the CLIC beam delivery system as configured for 3 TeV and for 500 GeV, describe some recent developments (including the combined effect of solenoid, crab cavity, and crossing angle), highlight open questions, and outline future studies

    Long-Term Warming Alters Carbohydrate Degradation Potential in Temperate Forest Soils

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    As Earth\u27s climate warms, soil carbon pools and the microbial communities that process them may change, altering the way in which carbon is recycled in soil. In this study, we used a combination of metagenomics and bacterial cultivation to evaluate the hypothesis that experimentally raising soil temperatures by 5°C for 5, 8, or 20 years increased the potential for temperate forest soil microbial communities to degrade carbohydrates. Warming decreased the proportion of carbohydrate-degrading genes in the organic horizon derived from eukaryotes and increased the fraction of genes in the mineral soil associated with Actinobacteria in all studies. Genes associated with carbohydrate degradation increased in the organic horizon after 5 years of warming but had decreased in the organic horizon after warming the soil continuously for 20 years. However, a greater proportion of the 295 bacteria from 6 phyla (10 classes, 14 orders, and 34 families) isolated from heated plots in the 20-year experiment were able to depolymerize cellulose and xylan than bacterial isolates from control soils. Together, these findings indicate that the enrichment of bacteria capable of degrading carbohydrates could be important for accelerated carbon cycling in a warmer world

    Design Status of the CLIC 3-TeV Beam Delivery System and Damping Rings

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    We describe the present design status of beam delivery and damping rings for CLIC at 3 TeV cm energy, and outline our future plans. The beam delivery system comprises collimation, final focus and post-IP exit line. Critical design aspects include halo collimation, machine protection, beam removal, and thermal stability analysis. In order to attain the design spot size at the collision point, the damping rings must provide beams of extremely small emittances. In this paper, we focus on collimation and spent beam

    Exact Three Dimensional Casimir Force Amplitude, CC-function and Binder's Cumulant Ratio: Spherical Model Results

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    The three dimensional mean spherical model on a hypercubic lattice with a film geometry L×2L\times \infty ^2 under periodic boundary conditions is considered in the presence of an external magnetic field HH. The universal Casimir amplitude Δ\Delta and the Binder's cumulant ratio BB are calculated exactly and found to be Δ=2ζ(3)/(5π)0.153051\Delta =-2\zeta (3)/(5\pi)\approx -0.153051 and B=2π/(5ln3[(1+5)/2]).B=2\pi /(\sqrt{5}\ln ^3[(1+\sqrt{5})/2]). A discussion on the relations between the finite temperature CC-function, usually defined for quantum systems, and the excess free energy (due to the finite-size contributions to the free energy of the system) scaling function is presented. It is demonstrated that the CC-function of the model equals 4/5 at the bulk critical temperature TcT_c. It is analytically shown that the excess free energy is a monotonically increasing function of the temperature TT and of the magnetic field H|H| in the vicinity of Tc.T_c. This property is supposed to hold for any classical dd-dimensional O(n),n>2,O(n),n>2, model with a film geometry under periodic boundary conditions when d3d\leq 3. An analytical evidence is also presented to confirm that the Casimir force in the system is negative both below and in the vicinity of the bulk critical temperature Tc.T_c.Comment: 12 pages revtex, one eps figure, submitted to Phys. Rev E A set of references added with the text needed to incorporate them. Small changes in the title and in the abstrac

    Mesons on a transverse lattice

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    The meson eigenstates of the light-cone Hamiltonian in a coarse transverse lattice gauge theory are investigated. Building upon previous work in pure gauge theory, the Hamiltonian and its Fock space are expanded in powers of dynamical fields. In the leading approximation, the couplings appearing in the Hamiltonian are renormalised by demanding restoration of space-time symmetries broken by the cut-off. Additional requirements from chiral symmetry are discussed and difficulties in imposing them from first principles in the leading approximation are noted. A phenomenological calculation is then performed, in which chiral symmetry in spontaneously broken form is modelled by imposing the physical pion-rho mass splitting as a constraint. The light-cone wavefunctions of the resulting Hamiltonian are used to compute decay constants, form factors and quark momentum and spin distributions for the pion and rho mesons. Extensions beyond leading order, and the implications for first principles calculations, are briefly discussed.Comment: 31 pages, 7 figure

    Photon-Photon and Electron-Photon Colliders with Energies Below a TeV

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    We investigate the potential for detecting and studying Higgs bosons in γγ\gamma\gamma and eγe\gamma collisions at future linear colliders with energies below a TeV. Our study incorporates realistic γγ\gamma\gamma spectra based on available laser technology, and NLC and CLIC acceleration techniques. Results include detector simulations. We study the cases of: a) a SM-like Higgs boson based on a devoted low energy machine with see200\sqrt{s_{ee}}\le 200 GeV; b) the heavy MSSM Higgs bosons; and c) charged Higgs bosons in eγe\gamma collisions.We investigate the potential for detecting and studying Higgs bosons in γγ\gamma\gamma and eγe\gamma collisions at future linear colliders with energies below a TeV. Our study incorporates realistic γγ\gamma\gamma spectra based on available laser technology, and NLC and CLIC acceleration techniques. Results include detector simulations. We study the cases of: a) a SM-like Higgs boson based on a devoted low energy machine with see200\sqrt{s_{ee}}\le 200 GeV; b) the heavy MSSM Higgs bosons; and c) charged Higgs bosons in eγe\gamma collisions

    Prospective Environmental Life Cycle Assessment of Nanosilver T-Shirts

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    A cradle-to-grave life cycle assessment (LCA) is performed to compare nanosilver T-shirts with conventional T-shirts with and without biocidal treatment. For nanosilver production and textile incorporation, we investigate two processes: flame spray pyrolysis (FSP) and plasma polymerization with silver co-sputtering (PlaSpu). Prospective environmental impacts due to increased nanosilver T-shirt commercialization are estimated with six scenarios. Results show significant differences in environmental burdens between nanoparticle production technologies: The "cradle-to-gate" climate footprint of the production of a nanosilver T-shirt is 2.70 kg of CO2-equiv (FSP) and 7.67-166 kg of CO2-equiv (PlaSpu, varying maturity stages). Production of conventional T-shirts with and without the biocide triclosan has emissions of 2.55 kg of CO2-equiv (contribution from triclosan insignificant). Consumer behavior considerably affects the environmental impacts during the use phase. Lower washing frequencies can compensate for the increased climate footprint of FSP nanosilver T-shirt production. The toxic releases from washing and disposal in the life cycle of T-shirts appear to be of minor relevance. By contrast, the production phase may be rather significant due to toxic silver emissions at the mining site if high silver quantities are require
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