3,162 research outputs found

    Four problems with global carbon markets: a critical review

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    This article offers a critique of global carbon markets and trading, with a special focus on the Clean Development Mechanism of the Kyoto Protocol. It explores problems with the use of tradable permits to address climate change revolving around four areas: homogeneity, justice, gaming, and information. Homogeneity problems arise from the non-linear nature of climate change and sensitivity of emissions, which complicate attempts to calculate carbon offsets. Justice problems involve issues of dependency and the concentration of wealth among the rich, meaning carbon trading often counteracts attempts to reduce poverty. Gaming problems include pressures to promote high-volume, least-cost projects and the consequences of emissions leakage. Information problems encompass transaction costs related to carbon trading and market participation and the comparatively weak institutional capacity of project evaluators

    Scattering of relativistic particles with Aharonov-Bohm-Coulomb interaction in two dimensions

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    The Aharonov-Bohm-Coulomb potentials in two dimensions may describe the interaction between two particles carrying electric charge and magnetic flux, say, Chern--Simons solitons, or so called anyons. The scattering problem for such two-body systems is extended to the relativistic case, and the scattering amplitude is obtained as a partial wave series. The electric charge and magnetic flux is (q-q, ϕ/Z-\phi/Z) for one particle and (ZqZq, ϕ\phi) for the other. When (Zq2/c)21(Zq^2/\hbar c)^2\ll 1, and qϕ/2πcq\phi/2\pi\hbar c takes on integer or half integer values, the partial wave series is summed up approximately to give a closed form. The results exhibit some nonperturbative features and cannot be obtained from perturbative quantum electrodynamics at the tree level.Comment: revtex, 11 pages, no figur

    Stopping power of hot QCD plasma

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    The partonic energy loss has been calculated taking both the hard and soft contributions for all the 222 \to 2 processes, revealing the importance of the individual channels. Cancellation of the intermediate separation scale has been exhibited. Subtleties related to the identical final state partons have properly been taken into account. The estimated collisional loss is compared with its radiative counter part. We show that there exists a critical energy (EcE_c) below which the collisional loss is more than its radiative counterpart. In addition, we present closed form formulas for both the collision probabilities and the stopping power (dE/dxdE/dx)Comment: revised version, section added, 9pages with 5 figure

    Supersymmetric Method for Constructing Quasi-Exactly and Conditionally-Exactly Solvable Potentials

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    Using supersymmetric quantum mechanics we develop a new method for constructing quasi-exactly solvable (QES) potentials with two known eigenstates. This method is extended for constructing conditionally-exactly solvable potentials (CES). The considered QES potentials at certain values of parameters become exactly solvable and can be treated as CES ones.Comment: 17 pages, latex, no figure

    A quantum exactly solvable non-linear oscillator related with the isotonic oscillator

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    A nonpolynomial one-dimensional quantum potential representing an oscillator, that can be considered as placed in the middle between the harmonic oscillator and the isotonic oscillator (harmonic oscillator with a centripetal barrier), is studied. First the general case, that depends of a parameter aa, is considered and then a particular case is studied with great detail. It is proven that it is Schr\"odinger solvable and then the wave functions Ψn\Psi_n and the energies EnE_n of the bound states are explicitly obtained. Finally it is proven that the solutions determine a family of orthogonal polynomials Pn(x){\cal P}_n(x) related with the Hermite polynomials and such that: (i) Every Pn{\cal P}_n is a linear combination of three Hermite polynomials, and (ii) They are orthogonal with respect to a new measure obtained by modifying the classic Hermite measure.Comment: 11 pages, 11 figure

    Supersymmetric quantum mechanics with nonlocal potentials

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    We consider supersymmetric quantum mechanical models with both local and nonlocal potentials. We present a nonlocal deformation of exactly solvable local models. Its energy eigenfunctions and eigenvalues are determined exactly. We observe that both our model Hamiltonian and its supersymmetric partner may have normalizable zero-energy ground states, in contrast to local models with nonperiodic or periodic potentials.Comment: 4 pages, REVTeX, Minor revisions for clarificatio

    Thermal Radiation from Au + Au Collisions at \sqrt{s} = 200 GEV/A Energy

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    The transverse momentum distribution of the direct photons measured by the PHENIX collaboration in Au+AuAu + Au collisions at s=200\sqrt{s}=200 GeV/A has been analyzed. It has been shown that the data can be reproduced reasonably well assuming a deconfined state of thermalized quarks and gluons with initial temperature more than the transition temperature for deconfinement inferred from lattice QCD. The value of the initial temperature depends on the equation of state of the evolving matter. The sensitivities of the results on various input parameters have been studied. The effects of the modifications of hadronic properties at non-zero temperature have been discussed.Comment: minor modifications in the text, accepted for publicatio

    PT-symetrically regularized Eckart,Poeschl-Teller and Hulthen potentials

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    Version 1: The well known Eckart's singular s-wave potential is PT-symmetrically regularized and continued to the whole real line. The new model remains exactly solvable and its bound states remain proportional to Jacobi polynomials. Its real and discrete spectrum exhibits several unusual features. Version 2: Parity times time-reversal symmetry of complex Hamiltonians with real spectra is usually interpreted as a weaker mathematical substitute for Hermiticity. Perhaps an equally important role is played by the related strengthened analyticity assumptions. In a constructive illustration we complexify a few potentials solvable only in s-wave. Then we continue their domain from semi-axis to the whole axis and get the new exactly solvable models. Their energies come out real as expected. The new one-dimensional spectra themselves differ quite significantly from their s-wave predecessors.Comment: Original 10-page letter ``PT-symmetrized exact solution of the singular Eckart oscillator" is extended to a full pape

    Tensor Coupling and Vector Mesons in Dense Nuclear Matter

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    The effects of magnetic interaction between vector mesons and nucleons on the propagation (mass and width) of the ρ\rho-meson in particular moving through very dense nuclear matter is studied and the modifications, qualitative and quantitative, due to the relevant collective modes (zero-sound and plasma frequencies) of the medium discussed. It is shown that the ρ\rho-mesons produced in high-energy nuclear collisions will be longitudinally polarized in the region of sufficiently dense nuclear matter, in the presence of such an interaction.Comment: Plain Latex file. Three figures, not appended, may be obtained on request to [email protected]

    Quasi-classical path integral approach to supersymmetric quantum mechanics

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    {}From Feynman's path integral, we derive quasi-classical quantization rules in supersymmetric quantum mechanics (SUSY-QM). First, we derive a SUSY counterpart of Gutzwiller's formula, from which we obtain the quantization rule of Comtet, Bandrauk and Campbell when SUSY is good. When SUSY is broken, we arrive at a new quantization formula, which is found as good as and even sometime better than the WKB formula in evaluating energy spectra for certain one-dimensional bound state problems. The wave functions in the stationary phase approximation are also derived for SUSY and broken SUSY cases. Insofar as a broken SUSY case is concerned, there are strong indications that the new quasi-classical approximation formula always overestimates the energy eigenvalues while WKB always underestimates.Comment: 13 pages + 5 figures, complete paper submitted as postscript file, to appear in Phys. Rev.
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