Bodenstein, S., Bordes, J., Dominguez, C. A., Peñarrocha, J., & Schilcher, K. (2011). QCD sum rule determination of the charm-quark mass. Phys. Rev. D, 83(7), 074014–4pp.
Abstract: QCD sum rules involving mixed inverse moment integration kernels are used in order to determine the running charm-quark mass in the (MS) over bar scheme. Both the high and the low energy expansion of the vector current correlator are involved in this determination. The optimal integration kernel turns out to be of the form p(s) = 1 -(s(0)/s)(2), where s(0) is the onset of perturbative QCD. This kernel enhances the contribution of the well known narrow resonances, and reduces the impact of the data in the range s similar or equal to 20-25 GeV2. This feature leads to a substantial reduction in the sensitivity of the results to changes in s(0), as well as to a much reduced impact of the experimental uncertainties in the higher resonance region. The value obtained for the charm-quark mass in the (MS) over bar scheme at a scale of 3 GeV is (m) over bar (c)(3 GeV) = 987 +/- 9 MeV, where the error includes all sources of uncertainties added in quadrature.
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Pato, M., Baudis, L., Bertone, G., Ruiz de Austri, R., Strigari, L. E., & Trotta, R. (2011). Complementarity of dark matter direct detection targets. Phys. Rev. D, 83(8), 083505–11pp.
Abstract: We investigate the reconstruction capabilities of the dark matter mass and spin-independent cross section from future ton-scale direct detection experiments using germanium, xenon, or argon as targets. Adopting realistic values for the exposure, energy threshold, and resolution of dark matter experiments which will come online within 5 to 10 years, the degree of complementarity between different targets is quantified. We investigate how the uncertainty in the astrophysical parameters controlling the local dark matter density and velocity distribution affects the reconstruction. For a 50 GeV WIMP, astrophysical uncertainties degrade the accuracy in the mass reconstruction by up to a factor of similar to 4 for xenon and germanium, compared to the case when astrophysical quantities are fixed. However, the combination of argon, germanium, and xenon data increases the constraining power by a factor of similar to 2 compared to germanium or xenon alone. We show that future direct detection experiments can achieve self-calibration of some astrophysical parameters, and they will be able to constrain the WIMP mass with only very weak external astrophysical constraints.
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BABAR Collaboration(del Amo Sanchez, P. et al), Azzolini, V., Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2011). Study of B -> pi lv and B -> rho lv decays and determination of |Vub|. Phys. Rev. D, 83(3), 032007–45pp.
Abstract: We present an analysis of exclusive charmless semileptonic B-meson decays based on 377 x 10(6) B (B) over bar pairs recorded with the BABAR detector at the Y(4S) resonance. We select four event samples corresponding to the decay modes B-0 -> pi(-)l(+)v, B+ -> pi(0)l(+)v, B-0 -> rho(-)l(+)v, and B+ -> rho(0)l(+)v and find the measured branching fractions to be consistent with isospin symmetry. Assuming isospin symmetry, we combine the two B -> pi lv samples, and similarly the two B -> rho lv samples, and measure the branching fractions B(B-0 -> pi(-)l(+)v) = (1.41 +/- 0.05 +/- 0.07) x 10(-4) and B(B-0 -> rho(-)l(+)v) = (1.75 +/- 0.15 +/- 0.27) x 10(-4), where the errors are statistical and systematic. We compare the measured distribution in q(2), the momentum transfer squared, with predictions for the form factors from QCD calculations and determine the Cabibbo-Kobayashi-Maskawa matrix element vertical bar V-ub vertical bar. Based on the measured partial branching fraction for B -> pi lv in the range q(2) < 12 GeV2 and the most recent QCD light-cone sum-rule calculations, we obtain vertical bar V-ub vertical bar = (3.78 +/- 0.13(-0.40)(+0.55)10(-3), where the errors refer to the experimental and theoretical uncertainties. From a simultaneous fit to the data over the full q(2) range and the FNAL/MILC lattice QCD results, we obtain vertical bar V-ub vertical bar = (2.95 +/- 0.31) x 10(-3) from B -> pi lv, where the error is the combined experimental and theoretical uncertainty.
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Roca, L., & Oset, E. (2010). Asymmetry observables in e(+)e(-) -> pi(+) pi(-) gamma in the phi region within a chiral unitary approach. Phys. Rev. D, 81(1), 014010–8pp.
Abstract: We make a theoretical study of the charge and forward-backward pion asymmetries in the e(+)e(-) -> pi(+) pi(-) gamma process on and off the phi resonance energy. These observables are rather sensitive to the inner details of the theoretical models to describe the reaction. In addition to the standard implementation of the initial state radiation and the bremsstrahlung contribution to the final state radiation, we use the techniques of the chiral unitary approach to evaluate the contribution from the mechanisms of phi decay into pi(+) pi(-) gamma. This contribution involves the implementation of final state interaction from direct chiral loops, the exchange of vector and axial-vector resonances and the final state interaction through the consideration of the meson-meson unitarized amplitudes, which were found important in a previous work describing the phi -> pi pi gamma. We find a good reproduction of the experimental data from KLOE for the forward-backward asymmetry, both at the phi peak and away from it. We also make predictions for the angular distributions of the charge asymmetry and show that this observable is very sensitive to the chiral loops involved in phi radiative decay.
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Warnecke, S., Sevryuk, M. B., Ceperley, D. M., Toennies, J. P., Guardiola, R., & Navarro, J. (2010). The structure of para-hydrogen clusters. Eur. Phys. J. D, 56(3), 353–358.
Abstract: The path integral Monte Carlo calculated radial distributions of para-hydrogen clusters (p-H-2) N consisting of N = 4-40 molecules interacting via a Lennard-Jones potential at T = 1.5 K show evidence for additional peaks compared to radial distributions calculated by diffusion Monte Carlo (T = 0 K) and path integral Monte Carlo at T <= 0.5 K. The difference in structures is attributed to quantum delocalization at the lowest temperature. The new structures at finite temperatures appear to be consistent with classical structures calculated for an effective Morse potential, which in order to account for the large zero point energy, is substantially softer than the Lennard-Jones potential.
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