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.
|
Orrigo, S. E. A. et al, Rubio, B., Gelletly, W., Agramunt, J., Algora, A., & Molina, F. (2016). beta decay of the exotic T-z =-2 nuclei Fe-48, Ni-52, and Zn-56. Phys. Rev. C, 93(4), 044336–18pp.
Abstract: The results of a study of the beta decays of three proton-rich nuclei with T-z = -2, namely Fe-48, Ni-52, and Zn-56, produced in an experiment carried out at GANIL, are reported. In all three cases we have extracted the half-lives and the total beta-delayed proton emission branching ratios. We have measured the individual beta-delayed protons and beta-delayed. rays and the branching ratios of the corresponding levels. Decay schemes have been determined for the three nuclei, and new energy levels are identified in the daughter nuclei. Competition between beta-delayed protons and. rays is observed in the de-excitation of the T = 2 isobaric analog states in all three cases. Absolute Fermi and Gamow-Teller transition strengths have been determined. The mass excesses of the nuclei under study have been deduced. In addition, we discuss in detail the data analysis taking as a test case Zn-56, where the exotic beta-delayed gamma-proton decay has been observed.
|
Orrigo, S. E. A. et al, Rubio, B., Gelletly, W., Agramunt, J., Algora, A., & Molina, F. (2016). Observation of the 2(+) isomer in Co-52. Phys. Rev. C, 94(4), 044315–8pp.
Abstract: We report the first observation of the 2(+) isomer in Co-52, produced in the beta decay of the 0(+), Ni-52 ground state. We have observed three. rays at 849, 1910, and 5185 keV characterizing the beta de-excitation of the isomer. We have measured a half-life of 102(6) ms for the isomeric state. The Fermi and Gamow-Teller transition strengths for the beta decay of Co-52m to Fe-52 have been determined. We also add new information on the beta decay of the 6(+), Co-52 ground state, for which we have measured a half-life of 112(3) ms.
|
Ortega, P. G., Segovia, J., Entem, D. R., & Fernandez, F. (2016). Molecular components in P-wave charmed-strange mesons. Phys. Rev. D, 94(7), 074037–11pp.
Abstract: Results obtained by various experiments show that the D-s0(*)(2317) and D-s1(2460) mesons are very narrow states located below the DK and D*K thresholds, respectively. This is markedly in contrast with the expectations of naive quark models and heavy quark symmetry. Motivated by a recent lattice study which addresses the mass shifts of the c _ s ground states with quantum numbers J(P) = 1+ [D-s1 (2317)] and JP = 1(+) [D-s1(2460)] due to their coupling with S-wave D-(*) K thresholds, we perform a similar analysis within a nonrelativistic constituent quark model in which quark-antiquark and meson-meson degrees of freedom are incorporated. The quark model has been applied to a wide range of hadronic observables, and thus the model parameters are completely constrained. The coupling between quark- antiquark and mesonmeson Fock components is done using a P-3(0) model in which its only free parameter gamma has been elucidated, performing a global fit to the decay widths of mesons that belong to different quark sectors, from light to heavy. We observe that the coupling of the 0(+)(1(+)) meson sector to the DK (D*K) threshold is the key feature to simultaneously lower the masses of the corresponding D-s0(*)(2317) and D-s1(2460) states predicted by the naive quark model and describe the D-s1(2536) meson as the 1(+)state of the j(q)(p) =3/2(+) doublet predicted by heavy quark symmetry, reproducing its strong decay properties. Our calculation allows us to introduce the coupling with the D- wave D*K channel and the computation of the probabilities associated with the different Fock components of the physical state.
|
Ortega, P. G., Segovia, J., Entem, D. R., & Fernandez, F. (2016). Canonical description of the new LHCb resonances. Phys. Rev. D, 94(11), 114018–7pp.
Abstract: The LHCb Collaboration has recently observed four J/psi phi structures called X(4140), X(4274), X(4500), and X(4700) in the B+ -> J/psi phi K+ decays. We study them herein using a nonrelativistic constituent quark model in which the degrees of freedom are quark-antiquark and meson-meson components. The X(4140) resonance appears as a cusp in the J/psi phi channel due to the near coincidence of the D-s(+/-) D-s(*+/-) and J/psi phi mass thresholds. The remaining three [X(4274), X(4500), and X(4700)] appear as conventional charmonium states with quantum numbers 3(3)P(1), 4(3)P(0), and 5(3)P(0), respectively, and their masses and widths are slightly modified due to their coupling with the corresponding closest meson-meson thresholds. A particular feature of our quark model is a lattice-based screened linear confining interaction that has been constrained in the light-quark sector and usually produces higher excited heavy-quark states with lower masses than standard quark model predictions.
|
Oset, E. et al, Albaladejo, M., Nieves, J., Fernandez-Soler, P., & Sun, Z. F. (2016). Weak decays of heavy hadrons into dynamically generated resonances. Int. J. Mod. Phys. E, 25(1), 1630001–105pp.
Abstract: In this paper, we present a review of recent works on weak decay of heavy mesons and baryons with two mesons, or a meson and a baryon, interacting strongly in the final state. The aim is to learn about the interaction of hadrons and how some particular resonances are produced in the reactions. It is shown that these reactions have peculiar features and act as filters for some quantum numbers which allow to identify easily some resonances and learn about their nature. The combination of basic elements of the weak interaction with the framework of the chiral unitary approach allow for an interpretation of results of many reactions and add a novel information to different aspects of the hadron interaction and the properties of dynamically generated resonances.
|
Oset, E., Bayar, M., Dote, A., Hyodo, T., Khemchandani, K. P., Liang, W. H., et al. (2016). Two-, Three-, Many-body Systems Involving Mesons. Multimeson Condensates. Acta Phys. Pol. B, 47(2), 357–365.
Abstract: In this paper, we review results from studies with unconventional many-hadron systems containing mesons: systems with two mesons and one baryon, three mesons, some novel systems with two baryons and one meson, and finally, systems with many vector mesons, up to six, with their spins aligned forming states of increasing spin. We show that in many cases, one has experimental counterparts for the states found, while in some other cases, they remain as predictions, which we suggest to be searched in BESIII, Belle, LHCb, FAIR and other facilities.
|
Oset, E., Chen, H. X., Feijoo, A., Geng, L. S., Liang, W. H., Li, D. M., et al. (2016). Study of reactions disclosing hidden charm pentaquarks with or without strangeness. Nucl. Phys. A, 954, 371–392.
Abstract: We present results for five reactions, Lambda(b) -> J/psi K(-)p, Lambda(b) -> J/psi eta Lambda, Lambda(b) -> J/psi pi(-)p, Lambda(b) -> J/psi K-0 Lambda and Xi(-)(b) -> J/psi K-Lambda, where combining information from the meson baryon interaction, using the chiral unitary approach, and predictions made for molecular states of hidden charm, with or without strangeness, we can evaluate invariant mass distributions for the light meson baryon states, and for those of J/psi p or J/psi Lambda. We show that with the present available information, in all of these reactions one finds peaks where the pentaquark states show up. In the Lambda(b) -> J/psi K(-)p, and Lambda(b) -> J/psi pi(-)p reactions we show that the results obtained from our study are compatible with present experimental observations.
|
Pagura, V. P., Gomez Dumm, D., Noguera, S., & Scoccola, N. N. (2016). Magnetic susceptibility of the QCD vacuum in a nonlocal SU(3) Polyakov-Nambu-Jona-Lasinio model. Phys. Rev. D, 94(5), 054038–13pp.
Abstract: The magnetic susceptibility of the QCD vacuum is analyzed in the framework of a nonlocal SU(3) Polyakov-Nambu-Jona-Lasinio model. Considering two different model parametrizations, we estimate the values of the u-and s-quark tensor coefficients and magnetic susceptibilities and then we extend the analysis to finite temperature systems. Our numerical results are compared to those obtained in other theoretical approaches and in lattice QCD calculations.
|
PANDA Collaboration(Singh, B. et al), & Diaz, J. (2016). Study of doubly strange systems using stored antiprotons. Nucl. Phys. A, 954, 323–340.
Abstract: Bound nuclear systems with two units of strangeness are still poorly known despite their importance for many strong interaction phenomena. Stored antiprotons beams in the GeV range represent an unparalleled factory for various hyperon-antihyperon pairs. Their outstanding large production probability in antiproton collisions will open the floodgates for a series of new studies of systems which contain two or even more units of strangeness at the PANDA experiment at FAIR. For the first time, high resolution gamma-spectroscopy of doubly strange Lambda Lambda-hypernuclei will be performed, thus complementing measurements of ground state decays of Lambda Lambda-hypernuclei at J-PARC or possible decays of particle unstable hypernuclei in heavy ion reactions. High resolution spectroscopy of multistrange Xi(-) -atoms will be feasible and even the production of Omega(-) -atoms will be within reach. The latter might open the door to the vertical bar S vertical bar = 3 world in strangeness nuclear physics, by the study of the hadronic Omega(-) -nucleus interaction. For the first time it will be possible to study the behavior of Xi(+) in nuclear systems under well controlled conditions.
|
