Bernabeu, J., Mavromatos, N. E., & Villanueva-Perez, P. (2013). Consistent probabilistic description of the neutral Kaon system. Phys. Lett. B, 724(4-5), 269–273.
Abstract: The neutral Kaon system has both CF violation in the mass matrix and a non-vanishing lifetime difference in the width matrix. This leads to an effective Hamiltonian which is not a normal operator, with incompatible (non-commuting) masses and widths. In the Weisskopf-Wigner Approach (WWA), by diagonalizing the entire Hamiltonian, the unphysical non-orthogonal “stationary” states K-L,K-S are obtained. These states have complex eigenvalues whose real (imaginary) part does not coincide with the eigenvalues of the mass (width). matrix. In this work we describe the system as an open Lindblad-type quantum mechanical system due to Kaon decays. This approach, in terms of density matrices for initial and final states, provides a consistent probabilistic description, avoiding the standard problems because the width matrix becomes a composite operator not included in the Hamiltonian. We consider the dominant decay channel to two pions, so that one of the Kaon states with definite lifetime becomes stable. This new approach provides results for the time dependent decay rates in agreement with those of the WWA.
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LHCb Collaboration(Aaij, R. et al), Oyanguren, A., & Ruiz Valls, P. (2013). Search for D-(s)(+) -> pi(+)mu(+)mu(-) and D-(s)(+) -> pi(-)mu(+)mu(+) decays. Phys. Lett. B, 724(4-5), 203–212.
Abstract: A search for non-resonant D-(s)(+) -> pi(+)mu(+)mu(-) and D-(s)(+) -> pi(-)mu(+)mu(+) decays is performed using protonproton collision data, corresponding to an integrated luminosity of 1.0 fb(-1), at root s = 7 TeV recorded by the LHCb experiment in 2011. No signals are observed and the 90% (95%) confidence level (CL) limits on the branching fractions are found to be B(D+ -> pi(+)mu(+)mu(-)) < 7.3 (8.3) x 10(-8), B(D-s(+) -> pi(+)mu(+)mu(-)) < 4.1 (4.8) x 10(-7), B(D-s(+) -> pi(+)mu(+)mu(-)) < 2.2 (2.5) x 10(-8), B(D-s(+) -> pi(+)mu(+)mu(-)) < 1.2 (1.4) x 10(-7). These limits are the most stringent to date.
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Salvatelli, V., Marchini, A., Lopez-Honorez, L., & Mena, O. (2013). New constraints on coupled dark energy from the Planck satellite experiment. Phys. Rev. D, 88(2), 023531–9pp.
Abstract: We present new constraints on coupled dark energy from the recent measurements of the cosmic microwave background anisotropies from the Planck satellite mission. We found that a coupled dark energy model is fully compatible with the Planck measurements, deriving a weak bound on the dark matter-dark energy coupling parameter xi = -0.49(-0.31)(+0.19) at 68% C.L. Moreover if Planck data are fitted to a coupled dark energy scenario, the constraint on the Hubble constant is relaxed to H-0 = 72.1(-2.3)(+3.2) km/s/Mpc, solving the tension with the Hubble Space Telescope (HST) value. We show that a combined PLANCK + HST analysis provides significant evidence for coupled dark energy finding a nonzero value for the coupling parameter xi, with -0.90 < xi < -0.22 at 95% C.L. We also consider the combined constraints from the Planck data plus the baryon acoustic oscillation measurements of the 6dF Galaxy Survey, the Sloan Digital Sky Survey and the Baron Oscillation Spectroscopic Survey.
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Helo, J. C., Kovalenko, S. G., Hirsch, M., & Pas, H. (2013). Neutrinoless double beta decay and lepton number violation at the LHC. Phys. Rev. D, 88(1), 011901–5pp.
Abstract: We compare the discovery potential of the LHC for lepton number violating (LNV) signals with the sensitivity of current and future double beta decay experiments, assuming 0 nu beta beta decay is dominated by heavy particle exchange. We consider charged scalar, leptoquark and diquark mechanisms of 0 nu beta beta decay, covering the 0 nu beta beta decay operators with both, the smallest and largest, possible rates. We demonstrate, if 0 nu beta beta decay were found with a half-life below 10(26)-10(27) years a positive signal should show up at the LHC, except for some particular cases of the leptoquark mechanism, and vice versa, if the LHC does not find any hints for LNV, a “short-range” explanation for a finite 0 nu beta beta decay half-life will be ruled out in most cases. We argue, if a positive LNV signal were found at the LHC, it is possible to identify the dominant contribution to 0 nu beta beta. Two different kinds of observables which could provide such “model discriminating” power are discussed: different invariant mass peaks and the charge asymmetry.
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Perez-Cerdan, A. B., Rubio, B., Gelletly, W., Algora, A., Agramunt, J., Nacher, E., et al. (2013). Deformation of Sr and Rb isotopes close to the N = Z line via beta-decay studies using the total absorption technique. Phys. Rev. C, 88(1), 014324–15pp.
Abstract: A study of the Gamow-Teller strength distributions B(GT) in the beta decay of Sr-78 and Rb-76,Rb-78 has been made using a total absorption spectrometer (TAS). Following the success in deducing the sign of the deformation for Sr-76, a similar approach is adopted for Sr-78 based on a comparison of the measured B(GT) with quasiparticle random-phase approximation calculations. This work confirms its previously expected prolate deformation in the ground state. Conclusions about the structure of the odd-odd Rb-76,Rb-78 isotopes have been drawn based on their measured B(GT) distributions.
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