7,437 research outputs found

    Evaluation of ADAM/1 model for advanced coal extraction concepts

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    Several existing computer programs for estimating life cycle cost of mining systems were evaluated. A commercially available program, ADAM/1 was found to be satisfactory in relation to the needs of the advanced coal extraction project. Two test cases were run to confirm the ability of the program to handle nonconventional mining equipment and procedures. The results were satisfactory. The model, therefore, is recommended to the project team for evaluation of their conceptual designs

    Characteristic impedance of microstrip lines

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    The dyadic Green's function for a current embedded in a grounded dielectric slab is used to analyze microstrip lines at millimeter wave frequencies. The dyadic Green's function accounts accurately for fringing fields and dielectric cover over the microstrip line. Using Rumsey's reaction concept, an expression for the characteristic impedance is obtained. The numerical results are compared with other reported results

    Electroweak Model Independent Tests for SU(3) Symmetry in Hadronic B Decays

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    We study effects of new physics beyond the Standard Model on SU(3) symmetry in charmless hadronic two body B decays. It is found that several equalities for some of the decay amplitudes, such as A(Bd(Bu)π+π,π+K(πKˉ0))=A(BsK+π,KK+(K0Kˉ0))A(B_d (B_u) \to \pi^+\pi^-,\pi^+ K^- (\pi^- \bar K^0)) =A(B_s \to K^+ \pi^-, K^- K^+ (K^0 \bar K^0)), A(Bdπ+ρ,πρ+,Kρ+,π+K)=A(BsK+ρ,πK+,KK+,K+K)A(B_d \to \pi^+\rho^-, \pi^- \rho^+, K^-\rho^+, \pi^+ K^{*-}) = A(B_s \to K^+ \rho^-, \pi^- K^{*+}, K^- K^{*+}, K^+ K^{*-}), A(Bd(Bu)ρ+ρ,ρ+K(ρKˉ0))=A(BsK+ρ,KK+(K0Kˉ0))A(B_d (B_u) \to \rho^+\rho^-, \rho^+ K^{*-}(\rho^- \bar K^{*0})) =A(B_s \to K^{*+} \rho^-, K^{*-} K^{*+} (K^{*0} \bar K^{*0})), predicted by SU(3) symmetry in the SM are not affected by new physics. These relations provide important electroweak model independent tests for SU(3) symmetry in B decays.Comment: 4 pages, revte

    A method for determining CP violating phase γ\gamma

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    A new way of determining the phases of weak amplitudes in charged BB decays based on SU(3) symmetry is proposed. The CP violating phase γ\gamma can now be determined without the previous difficulty associated with electroweak penguins.Comment: 9 pages plus one figure, Revte

    Spin Effects in the Local Density of States of GaAs

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    We present spin-resolved measurements of the local density of states in Si doped GaAs. Both spin components exhibit strong mesoscopic fluctuations. In the magnetic quantum limit, the main features of the spin-up and spin-down components of the local density of states are found to be identical apart from Zeeman splitting. Based on this observation, we introduce a mesoscopic method to measure the gg-factor in a material where macroscopic methods are severely restricted by disorder. Differences between the spin-up and spin-down components are discussed in terms of spin relaxation due to spin-orbit coupling.Comment: 4 pages and 5 figure

    Bˉ0π+X\bar B^0 \to \pi^+ X in the Standard Model

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    In this paper we investigate the possibility of studying BπB\to \pi form factor using the semi-inclusive decays Bˉ0π++Xq\bar B^0 \to \pi^+ + X_q. In general BPXB\to PX semi-inclusive decays involve several hadronic parameters. But for Bˉ0π+Xq\bar B^0 \to \pi^+ X_q decays we find that in the factorization approximation, the only unknown hadronic parameters are the form factors F0,1BπF^{B\to \pi}_{0,1}. Therefore these form factors can be studied in Bˉ0π+Xq\bar B^0 \to \pi^+ X_q decays. Using theoretical model calculations for the form factors the branching ratios for Bˉ0π+Xd(ΔS=0)\bar B^0 \to \pi^+ X_d(\Delta S = 0) and Bˉ0π+Xs(ΔS=1)\bar B^0 \to \pi^+ X_s (\Delta S = -1), with the cut Eπ>2.1E_{\pi} > 2.1 GeV, are estimated to be in the ranges of (3.14.9)×105(F1Bπ(0)/0.33)2(3.1\sim 4.9) \times 10^{-5}(F^{B\to \pi}_1(0)/0.33)^2 and (2.54.2)×105(F1Bπ(0)/0.33)2(2.5\sim 4.2)\times 10^{-5}(F_1^{B\to \pi}(0)/0.33)^2, respectively, depending on the value of γ\gamma. The combined branching ratio for Bˉ0π+(Xd+Xs)\bar B^0 \to \pi^+ (X_d+ X_s) is about 7.4×105(F1Bπ(0)/0.33)27.4\times 10^{-5} (F^{B\to \pi}_1(0)/0.33)^2 and is insensitive to γ\gamma. We also discuss CP asymmetries in these decay modes.Comment: RevTex 8 pages and two figure

    Constraints on the phase γ\gamma and new physics from BKπB\to K\pi Decays

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    Recent results from CLEO on BKπB\to K\pi indicate that the phase γ\gamma may be substantially different from that obtained from other fit to the KM matrix elements in the Standard Model. We show that γ\gamma extracted using BKπ,ππB\to K\pi, \pi\pi is sensitive to new physics occurring at loop level. It provides a powerful method to probe new physics in electroweak penguin interactions. Using effects due to anomalous gauge couplings as an example, we show that within the allowed ranges for these couplings information about γ\gamma obtained from BKπ,ππB\to K \pi, \pi\pi can be very different from the Standard Model prediction.Comment: Revised version with analysis done using new data from CLEO. RevTex, 11 Pages with two figure

    The CP violating phase γ\gamma from global fit of rare charmless hadronic B decays

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    We study constraints on the CP violating phase γ\gamma in the Kobayashi-Maskawa model using available experimental data. We first follow the conventional method to up date the constraint on γ\gamma by performing a χ2\chi^2 analysis using data from ϵK|\epsilon_K|, ΔmBd,s\Delta m_{B_{d,s}} and Vub/Vcb|V_{ub}/V_{cb}|. We also include the recent information on sin2β\sin2\beta in the analysis. We obtain the best fit for γ\gamma to be 6666^\circ and the 95% C.L. allowed range to be 428742^\circ \sim 87^\circ. We then develop a method to carry out a χ2\chi^2 analysis based on SU(3) symmetry using data from BππB\to \pi \pi and BKπB\to K \pi. We also discuss SU(3) breaking effects from model estimate. We find that present data on Bππ,KπB\to \pi\pi, K \pi can also give some constraint on γ\gamma although weaker than the earlier method limited by the present experimental errors. Future improved data will provide more stringent constraint. Finally we perform a combined fit using data from ϵK|\epsilon_K|, ΔmBd,s\Delta m_{B_{d,s}}, Vub/Vcb|V_{ub}/V_{cb}|, sin2β\sin2\beta and rare charmless hadronic B decays. The combined analysis gives γ=67\gamma=67^\circ for the best fit value and 438743^\circ \sim 87^\circ as the 95% C.L. allowed range. Several comments on other methods to determine γ\gamma based on SU(3) symmetry are also provided.Comment: Revised verion with the new experimental data from Belle and Babar included in the analysis to obtain the global fit for the CP violating phase gamma. RevTex, 32 pages and 8 figure

    Effects of R-parity violation on direct CP violation in B decays and extraction of γ\gamma

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    In the standard model, direct CP-violating asymmetries for B±π±KB^\pm \to \pi^\pm K are roughly 2% based on perturbative calculation. Rescattering effects might enhance it to at most (20-25)%. We show that lepton-number-violating couplings in supersymmetric models without R-parity are capable of inducing as large as 100% CP asymmetry in this channel. Such effects drastically modify the allowed range of the CKM parameter γ\gamma arising from the combinations of the observed charged and neutral B decays in the πK\pi K modes. With a multichannel analysis in B decays, one can either discover this exciting new physics, or significantly improve the existing constraints on it.Comment: Latex, 5 pages; minor changes, to appear in Phys Rev Let

    Implications of LEP Results for SO(10) Grandunification with Two Intermediate Stages

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    We consider the breaking of the grand unification group SO(10)SO(10) to the standard model gauge group through several chains containing two intermediate stages. Using the values of the gauge coupling constants at scale MZM_Z derived from recent LEP data, we determine the range of their intermediate and unification scales. In particular, we identify those chains that permit new gauge structure at relatively low energy (1TeV)(\sim 1\, {\rm TeV}).Comment: (LATEX, 9 pages + 3 pages of figures not included) OITS-48
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