2,584 research outputs found

    Relationship Between Mechanical And Physiological Energy Costs And Efficiency Of Treadmill Walking In Active And Inactive Females

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    Energy costs of walking are traditionally examined from two perspectives biomechanical and physiological. Biomechanists use mechanical energy costs to calculate mechanical work (MW) performed by the body. Physiologists use energy expenditure to calculate metabolic cost (MC) of the activity. These two values are then used to calculate efficiency values for walking. However, few researchers have examined the rela tionship between these two forms of energy cost (MW and MC) and the calculated efficiency value (EFF). The purpose of this study was to examine the relationship between MW and MC, MW and EFF, and MC and EFF during treadmill walking in active (ACT) and inactive (INCT) females. It was hypothesized that a high correlation would exist between MW and MC because the amount of work done by the segments would be dependent on the amount of energy expended by the muscles for muscle contraction to move the segments. Two groups (ACT and INCT) of 12 females participated in a 10-min submax walking test. Submax V02 and 3D film records (100 fps) were obtained during the final minute of the test. MW, MC, and EFF were calculated using the method recommended by Cavanagh and Williams (1983). Correlations for each group were calculated between MW and MC (ACT: r= .340; INCT: r= .429), MC and EFF (ACT: r= -.271; INCT: r = -.149), and MW and EFF (ACT: r= .854; INCT: r= .817). Significant correlations were found between MW and EFF for both groups (p f. .01). No relationship was found between MW and MC for either group. Biomechanists have attempted to adjust MW by developing methods for approximating the amount of mechanical energy conserved by energy transfer within and between segments, by the storage of elastic energy, and by the performance of negative work as opposed to positive work. This leads to a more accurate representation of mechanical energy cost related

    R-parity-violating SUSY and CP violation in B --> phi K_s

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    Recent measurements of CP asymmetry in B --> phi K_S appear to be inconsistent with Standard Model expectations. We explore the effect of R-parity-violating SUSY to understand the data.Comment: Equations corrected. Conclusions unchanged. Latex, 6 pages, one fi

    Evidence for CP Violation in B0 -> D+D- Decays

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    We report measurements of the branching fraction and CP violation parameters in B0 -> D+D- decays. The results are based on a data sample that contains 535 x 10^6 BBbar pairs collected at the Upsilon(4S) resonance, with the Belle detector at the KEKB asymmetric-energy e+e- collider. We obtain [1.97 +- 0.20 (stat) +- 0.20 (syst)] x 10^(-4) for the branching fraction of B0 -> D+D-. The measured values of the CP violation parameters are: S = -1.13 +- 0.37 +- 0.09, A = 0.91 +- 0.23 +- 0.06, where the first error is statistical and the second is systematic. We find evidence of CP violation in B0 -> D+D- at the 4.1 sigma confidence level. While the value of S is consistent with expectations from other measurements, the value of the parameter A favors large direct CP violation at the 3.2 sigma confidence level, in contradiction to Standard Model expectations.Comment: 12 pages, 3 figures, submitted to PR

    Search for the h_c meson in B^+- ->h_c K^+-

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    We report a search for the hch_c meson via the decay chain B±hcK±B^{\pm}\to h_c K^{\pm}, \etac \gamma with ηcKS0K±π\eta_c \to K_S^0 K^{\pm} \pi^{\mp} and ppˉp\bar{p}. No significant signals are observed. We obtain upper limits on the branching fractions for B±ηcγK±B^{\pm} \to \eta_c\gamma K^{\pm} in bins of the ηcγ\eta_c\gamma invariant mass. The results are based on an analysis of 253 fb1^{-1} of data collected by the Belle detector at the KEKB e+ee^+e^- collider.Comment: 12 pages, 6 figures, submitted to Phys. Rev.

    Measuring V_ub and probing SUSY with double ratios of purely leptonic decays of B and D mesons

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    The experimental prospects for precise measurements of the leptonic decays B_u -> tau nu / mu nu, B_s -> mu+ mu-, D -> mu nu and D_s -> mu nu / tau nu are very promising. Double ratios involving four of these decays can be defined in which the dependence on the values of the decay constants is essentially eliminated, thus enabling complementary measurements of the CKM matrix element V_ub with a small theoretical error. We quantify the experimental error in a possible future measurement of |V_ub| using this approach, and show that it is competitive with the anticipated precision from the conventional approaches. Moreover, it is shown that such double ratios can be more effective than the individual leptonic decays as a probe of the parameter space of supersymmetric models. We emphasize that the double ratios have the advantage of using |V_ub| as an input parameter (for which there is experimental information), while the individual decays have an uncertainty from the decay constants (e.g. f_B_s), and hence a reliance on theoretical techniques such as lattice QCD.Comment: 21 pages, 4 figure

    A Phenomenological Analysis of Non-resonant Charm Meson Decays

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    We analyse the consequences of the usual assumption of a constant function to fit non-resonant decays from experimental Dalitz plot describing charmed meson decays. We first show, using the D+Kˉ0π+π0D^+\to \bar{K}^0\pi^+\pi^0 decay channel as an example, how an inadequate extraction of the non-resonant contribution could yield incorrect measurements for the resonant channels. We analyse how the correct study of this decay will provide a test for the validity of factorization in D meson decays. Finally, we show how form factors could be extracted from non-resonant decays. We particularly discuss about the form factor that can be measured from the Ds+ππ+π+D^+_s\to \pi^-\pi^+\pi^+ decay. We emphasize on its relevance for the study of the decay τντ3π\tau \to \nu_{\tau} 3\pi and the extraction of the a1a_1 meson width.Comment: 14 pages, Latex including 6 eps 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

    Meson-Meson Scattering in the Quark Model: Spin Dependence and Exotic Channels

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    We apply a quark interchange model to spin-dependent and exotic meson-meson scattering. The model includes the complete set of standard quark model forces, including OGE spin-orbit and tensor and scalar confinement spin-orbit. Scattering amplitudes derived assuming SHO and Coulomb plus linear plus hyperfine meson wavefunctions are compared. In I=2 pi pi we find approximate agreement with the S-wave phase shift from threshold to 1.5 GeV, where we predict an extremum that is supported by the data. Near threshold we find rapid energy dependence that may reconcile theoretical estimates of small scattering lengths with experimental indications of larger ones based on extrapolation of measurements at moderate kpi^2. In PsV scattering we find that the quark-quark L*S and T forces map into L*S and T meson-meson interactions, and the P-wave L*S force is large. Finally we consider scattering in J^PC-exotic channels, and note that some of the Deck effect mechanisms suggested as possible nonresonant origins of the pi_1(1400) signal are not viable in this model.Comment: 51 pages, 10 figures, uses epsf.sty epsfig.st

    Heavy Baryon Production and Decay

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    The branching ratio B(Lambda_c -> p K- pi+) normalizes the production and decay of charmed and bottom baryons. At present, this crucial branching ratio is extracted dominantly from B.bar -> baryons analyses. This note questions several of the underlying assumptions and predicts sizable B.bar -> D(*) N N'.bar X transitions, which were traditionally neglected. It predicts B(Lambda_c -> p K- pi+) to be significantly larger (0.07 +/- 0.02) than the world average. Some consequences are briefly mentioned. Several techniques to measure B(Lambda_c -> p K- pi+) are outlined with existing or soon available data samples. By equating two recent CLEO results, an appendix obtains B(D0 -> K- pi+)= 0.035 +/- 0.002, which is somewhat smaller than the current world average.Comment: 27 pages, 4 eps figures, revte
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