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Mijatovia, T., Szilner, S., Corradi, L., Montanari, D., Pollarolo, G., Fioretto, E., et al. (2016). Study of the cross section determination with the PRISMA spectrometer: The Ar-40+Pb-208 case. Eur. Phys. J. A, 52(4), 113–6pp.
Abstract: The PRISMA spectrometer's response function was successfully applied to match three angular and magnetic settings over a wide angular range for measurements of quasi-elastic reactions in Ar-40 + Pb-208 . The absolute scale of cross sections has been obtained by using the Rutherford cross section at the forward angles and the information from the energy distributions measured with the spectrometer without and with coincidences with the CLARA -array. The semi-classical model GRAZING has been used to test the unfolding procedure and for comparison with the corrected cross sections.
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Bayar, M., Fernandez-Soler, P., Sun, Z. F., & Oset, E. (2016). States of rho B*(B)over-bar* with J=3 within the fixed center approximation to Faddeev equations. Eur. Phys. J. A, 52(4), 106–8pp.
Abstract: In this work we stu dy the rho B*(B) over bar* three-body system solving the Faddeev equations in the fixed center approximation. We assume the B*B* system forming a cluster, and in terms of the two-body rho B* unitarized scattering amplitudes in the local hidden gauge approach we find a new I(J(PC)) = 1(3(--)) state. The mass of the new state corresponds to a two-particle invariant mass of the rho B* system close to the resonant energy of the B-2(*) (5747), indicating that the role of this J = 2 resonance is important in the dynamical generation of the new state.
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Uchino, T., Liang, W. H., & Oset, E. (2016). Baryon states with hidden charm in the extended local hidden gauge approach. Eur. Phys. J. A, 52(3), 43–16pp.
Abstract: The s-wave interaction of (D) over bar Lambda(c), (D) over bar Sigma(c),(D) over bar*Lambda(c), (D) over bar*Sigma(c) and (D) over bar Sigma(c)*, (D) over bar*Sigma(c)*, is studied within a unitary coupled channels scheme with the extended local hidden gauge approach. In addition to the Weinberg-Tomozawa term, several additional diagrams via the pion exchange are also taken into account as box potentials. Furthermore, in order to implement the full coupled channels calculation, some of the box potentials which mix the vector-baryon and pseudoscalar-baryon sectors are extended to construct the effective transition potentials. As a result, we have observed six possible states in several angular momenta. Four of them correspond to two pairs of admixture states, two of (D) over bar Sigma(c) – (D) over bar*Sigma(c) with J – 1/2, and two of (D) over bar Sigma(c)* – (D) over bar*Sigma(c)* with J = 3/2. Moreover, we find a (D) over bar*Sigma(c) resonance which couples to the (D) over bar Lambda(c) channel and one spin degenerated bound state of (D) over bar*Sigma(c)* with J = 1/2, 5/2.
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n_TOF Collaboration(Zugec, P. et al), Domingo-Pardo, C., Giubrone, G., & Tain, J. L. (2016). Integral measurement of the C-12(n, p)B-12 reaction up to 10 GeV. Eur. Phys. J. A, 52(4), 101–13pp.
Abstract: The integral measurement of the C-12(n, p)B-12 reaction was performed at the neutron time-of-flight facility nTOF at CERN. The total number of B-12 nuclei produced per neutron pulse of the nTOF beam was determined using the activation technique in combination with a time-of-flight technique. The cross section is integrated over the n_TOF neutron energy spectrum from reaction threshold at 13.6 MeV to 10 GeV. Having been measured up to 1 GeV on basis of the U-235(n, f) reaction, the neutron energy spectrum above 200 MeV has been re-evaluated due to the recent extension of the cross section reference for this particular reaction, which is otherwise considered a standard up to 200 MeV. The results from the dedicated GEANT4 simulations have been used to evaluate the neutron flux from 1 GeV up to 10 GeV. The experimental results related to the C-12(n, p)B-12 reaction are compared with the evaluated cross sections from major libraries and with the predictions of different GEANT4 models, which mostly underestimate the B-12 production. On the contrary, a good reproduction of the integral cross section derived from measurements is obtained with TALYS-1.6 calculations, with optimized parameters.
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Mach, H., Lindroth, A., Ruchowska, E., Kvasil, J., Fogelberg, B., Gulda, K., et al. (2016). On the enhanced E1 transitions in the K=3/2 parity doublet band in Ra-223. Eur. Phys. J. A, 52(6), 172–10pp.
Abstract: We have applied the fast timing beta gamma gamma(t) technique to remeasure lifetimes of selected states in Ra-223 populated in the beta(-) decay of Fr-223. T-1/2 = 587(12) ps and 210(13) ps have been obtained for the 3/2(-) and 5/2(-) states at 50.1 and 79.7 keV, that are more accurate than the previous values of 630(70) ps and 166(55) ps, respectively. Our vertical bar D0 vertical bar value of 0.155(10) e.fm obtained for the K = 3/2 configuration together with the available values of vertical bar D0 vertical bar for the K = 1/2 and K = 5/2 parity doublet bands establish the configuration dependence of vertical bar D0 vertical bar at low spins in this nucleus. Results of theoretical calculations performed for Ra-223, using the quasiparticle-phonon model (QPM) with inclusion of the Coriolis coupling, reasonably well reproduce octupole correlations in this nucleus.
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Orce, J. N. et al, & Rubio, B. (2016). Search for two-phonon octupole excitations in Gd-146. Eur. Phys. J. A, 52(6), 166–7pp.
Abstract: The low-spin structure of the nearly spherical nucleus Gd-146 was studied using the Sm-144(He-4, 2n) fusion-evaporation reaction. High-statistics gamma-gamma coincidence measurements were performed at iThemba LABS with 7x10(9) gamma-gamma coincidence events recorded. Gated gamma-ray energy spectra show evidence for the 6(2)(+) -> 3(1)(-) -> 0(1)(+) cascade of E3 transitions in agreement with recent findings by Caballero and co-workers, but with a smaller branching ratio of I-gamma = 4.7(10) for the 6(2)(+) -> 3(1)(-) 1905.1 keV gamma ray. Although these findings may support octupole vibrations in spherical nuclei, sophisticated beyond mean-field calculations including angular-momentum projection are required to interpret in an appropriate way the available data due to the failure of the rotational model assumptions in this nucleus.
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Taprogge, J. et al, Gadea, A., & Montaner-Piza, A. (2016). Proton-hole and core-excited states in the semi-magic nucleus In-131(82). Eur. Phys. J. A, 52(11), 347–10pp.
Abstract: The decay of the N = 83 nucleus Cd-131 has been studied at the RIBF facility at the RIKEN Nishina Center. The main purpose of the study was to identify the position of the and proton-hole states and the energies of core-excited configurations in the semi-magic nucleus In-131. From the radiation emitted following the decay, a level scheme of In-131 was established and the feeding to each excited state determined. Similarities between the single-particle transitions observed in the decays of the N = 83 isotones In-132 and Cd-131 are discussed. Finally the excitation energies of several core-excited configurations in In-131 are compared to QRPA and shell-model calculations.
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Guo, F. K., Meissner, U. G., Nieves, J., & Yang, Z. (2016). Remarks on the P-c structures and triangle singularities. Eur. Phys. J. A, 52(10), 318–6pp.
Abstract: It was proposed that the narrow P-c(4450) structure observed by the LHCb Collaboration in the reaction Lambda(b) -> J/psi pK might be due to a triangle singularity around the chi(c1)-proton threshold at 4.45 GeV. We discuss the occurrence of a similar triangle singularity in the J/psi p invariant mass distribution for the decay Lambda(b) -> J/psi p pi, which could explain the bump around 4.45 GeV in the data. More precise measurements of this process would provide valuable information towards an understanding of the P-c structures.
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PANDA Collaboration(Singh, B. et al), & Diaz, J. (2016). Feasibility studies of time-like proton electromagnetic form factors at PANDA at FAIR. Eur. Phys. J. A, 52(10), 325–23pp.
Abstract: Simulation results for future measurements of electromagnetic proton form factors at PANDA (FAIR) within the PandaRoot software framework are reported. The statistical precision with which the proton form factors can be determined is estimated. The signal channel (p) over barp -> e(+)e(-) is studied on the basis of two different but consistent procedures. The suppression of the main background channel, i.e. (p) over barp -> pi(+)pi(-), is studied. Furthermore, the background versus signal efficiency, statistical and systematical uncertainties on the extracted proton form factors are evaluated using two different procedures. The results are consistent with those of a previous simulation study using an older, simplified framework. However, a slightly better precision is achieved in the PandaRoot study in a large range of momentum transfer, assuming the nominal beam conditions and detector performance.
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ATLAS Collaboration(Aad, G. et al), Alvarez Piqueras, D., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Fernandez Martinez, P., et al. (2016). Search for flavour-changing neutral current top-quark decays to q Z in pp collision data collected with the ATLAS detector at root s=8 TeV. Eur. Phys. J. C, 76(1), 12–24pp.
Abstract: A search for the flavour-changing neutral-current decay is presented. Data collected by the ATLAS detector during 2012 from proton-proton collisions at the Large Hadron Collider at a centre-of-mass energy of root s = 8 TeV, corresponding to an integrated luminosity of 20.3 fb(-1), are analysed. Top-quark pair-production events with one top quark decaying through the t -> qZ (q = u,c) channel and the other through the dominant Standard Model mode t -> bW are considered as signal. Only the decays of the Z boson to charged leptons and leptonic W boson decays are used. No evidence for a signal is found and an observed (expected) upper limit on the t -> qZ branching ratio of 7 x 10(-4) (8 x 10(-4)) is set at the 95 % confidence level.
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