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AGATA Collaboration(Ralet, D. et al), Gadea, A., & Perez-Vidal, R. M. (2017). Toward lifetime and g factor measurements of short-lived states in the vicinity of Pb-208. Phys. Scr., 92(5), 054004–4pp.
Abstract: The multi-nucleon transfer reaction mechanism was used to produce and study nuclei in the vicinity of 208Pb. This mass region is a test case for the nuclear shell model. The mass identification of the fragments was performed with the large acceptance magnetic spectrometer VAMOS++ coupled to the AGATA gamma-tracking array. This experiment aimed to determine both lifetimes and gyromagnetic ratios of excited states with the Cologne plunger device. The analysis indicates promising results with the possibility to determine several new lifetimes in this region.
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IDS Collaboration(Lica, R. et al), & Morales, A. I. (2017). beta decay studies of n-rich Cs isotopes with the ISOLDE Decay Station. J. Phys. G, 44(5), 054002–14pp.
Abstract: Neutron-rich Ba isotopes are expected to exhibit octupolar correlations, reaching their maximum in isotopes around mass A = 146. The odd-A neutron-rich members of this isotopic chain show typical patterns related to non-axially symmetric shapes, which are however less marked compared to even-A ones, pointing to a major contribution from vibrations. In the present paper we present results from a recent study focused on Cs148-150 beta-decay performed at the ISOLDE Decay Station equipped with fast-timing detectors. A detailed analysis of the measured decay half-lives and decay scheme of Ba-149 is presented, giving a first insight in the structure of this neutron-rich nucleus.
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Hernandez, E., & Nieves, J. (2017). Neutrino-induced one-pion production revisited: The nu(mu)n -> mu(-)n pi(+) channel. Phys. Rev. D, 95(5), 053007–18pp.
Abstract: Understanding single pion production reactions on free nucleons is the first step towards a correct description of these processes in nuclei, which are important for signal and background contributions in current and near future accelerator neutrino oscillation experiments. In this work, we reanalyze our previous studies of neutrino-induced one-pion production on nucleons for outgoing pi N invariant masses below 1.4 GeV. Our motivation is to get a better description of the nu(mu)n -> mu(-)n pi(+) cross section, for which current theoretical models give values significantly below data. This channel is very sensitive to the crossed Delta(1232) contribution and thus, to spin 1/2 components in the Rarita-Schwinger Delta propagator. We show how these spin 1/2 components are nonpropagating and give rise to contact interactions. In this context, we point out that the discrepancy with experiment might be corrected by the addition of appropriate extra contact terms and argue that this procedure will provide a natural solution to the nu(mu)n -> mu(-)n pi(+) puzzle. To keep our model simple, in this work, we propose to change the strength of the spin 1/2 components in the. propagator and use the nu(mu)n -> mu(-)n pi(+) data to constraint its value. With this modification, we now find a good reproduction of the nu(mu)n -> mu(-)n pi(+) cross section without affecting the good results previously obtained for the other channels. We also explore how this change in the. propagator affects our predictions for pion photoproduction and find also a better agreement with experiment than with the previous model.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2017). Measurement of the B-+/- production asymmetry and the CP asymmetry in B-+/-> J/psi K-+/- decays. Phys. Rev. D, 95(5), 052005–13pp.
Abstract: The B-+/- meson production asymmetry in pp collisions is measured using B-+/- -> (D) over bar (0)pi(+) decays. The data were recorded by the LHCb experiment during Run 1 of the LHC at center- of- mass energies of ffiffiffi root s = 7 and 8 TeV. The production asymmetries, integrated over transverse momenta in the range 2 < p(T) < 30 GeV/c, and rapidities in the range 2.1 < y < 4.5 are measured to be A(prod)(B+, root s = 7 TeV) = (-0.41 +/- 0.49 +/- 0.10) x 10(- 2), A(prod)(B+, root s = 8 TeV = (- 0.53 +/- 0.31 +/- 0.10) x 10(-2), where the first uncertainties are statistical and the second are systematic. These production asymmetries are used to correct the raw asymmetries of (B+ -> J/psi K+) decays, thus allowing a measurement of the CP asymmetry, A(CP)(B+-> J/psi K+) = (0.09 +/- 0.27 +/- 0.07) x 10(-2)
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2017). Measurements of charm mixing and CP violation using D-0 -> K-+/-pi(-/+) decays. Phys. Rev. D, 95(5), 052004–14pp.
Abstract: Measurements of charm mixing and CP violation parameters from the decay-time-dependent ratio of D-0 -> K+pi(-) to D-0 -> K-pi(+) decay rates and the charge-conjugate ratio are reported. The analysis uses (B) over bar -> D*(+) μX-, and charge-conjugate decays, where D *(+) -> D-0 pi(+), and D-0 -> K-+/-pi(-/+). The pp collision data are recorded by the LHCb experiment at center-of-mass energies root s = 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb(-1). The data are analyzed under three hypotheses: (i) mixing assuming CP symmetry, (ii) mixing assuming no direct CP violation in the Cabibbo-favored or doubly Cabibbo-suppressed decay amplitudes, and (iii) mixing allowing either direct CP violation and/or CP violation in the superpositions of flavor eigenstates defining the mass eigenstates. The data are also combined with those from a previous LHCb study of D-0 -> K pi decays from a disjoint set of D*(+) candidates produced directly in pp collisions. In all cases, the data are consistent with the hypothesis of CP symmetry.
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