120076526
Relativistic mean-field description of a proton halo in the first excited ( 1 / 2 ) + state of 17 F
The newly discovered proton halo in the first excited ${(1/2)}^{+}$ state of ${}^{17}$F [R. Morlock et al., Phys. Rev. Lett. 79, 3837 (1997)] is investigated in the nonlinear relativistic mean-field model. It is shown that this model, without introducing any specifically adjusted parameters, can reproduce well not only the ground state properties of ${}^{17}$F but also the proton halo in the excited ${(1/2)}^{+}$ state. The possibility of the existence of a proton halo in the neighboring nucleus ${}^{18}$Ne is also discussed.
119699060
β-decay half-lives including first-forbidden contributions for neutron-rich Zn isotopes in the extended QRPA with neutron-proton pairing
The β decays of neutron-rich Zn isotopes are investigated within the extended quasiparticle random-phase approximation, where neutron-neutron, proton-proton, and neutron-proton pairing correlations are considered in the similar manner. The Bruckner G-matrix obtained with the charge-dependent Bonn nucleon-nucleon force is used for the residual particle-particle and particle-hole interactions in addition to the pairing interactions. Contributions from both allowed Gamow-Teller and first-forbidden transitions are considered, and β-decay half-lives together with β-delayed neutron emission probabilities are calculated. The calculated results are found to agree well with the available experimental data.
120877746
Temporal variation of the fine structure constant and the strong interaction parameter in the 229Th transition
Abstract The very low energy ( 7.6 ± 0.5 eV ) of the long-lived isomer state in 229Th has inspired the idea that the transition between this isomer and the ground state might be used to measure the temporal variation of some fundamental physical constants with great enhanced sensitivity in laboratory. Physicists have used several models to test whether this significantly enhanced sensitivity does exist. However, incongruous conclusions were reached. Based on the formulae derived from Feynman–Hellmann theorem, we reexamine the physics involved in those argument by the relativistic mean field theory. The results show that the correlation between the nuclear strong interaction and Coulomb force is important and cannot be neglected. The sensitivity to variations of fine structure constant, nucleon mass and meson masses could be enhanced by several orders of magnitude in the 229Th transition.
120766429
Systematic calculations of the ground state properties of superheavy nuclei
We investigate the ground state properties of the nuclei with proton number $Z=94\char21{}110$ within the framework of deformed relativistic mean-field (RMF) theory. A systematic comparison between calculated binding energies and experimental data is made. The calculated binding energies are in good agreement with experimental ones. The reliability of the RMF model for superheavy nuclei has been tested by this comparison. The experimental data of alpha-decay energies and half-lives are reasonably reproduced by calculations. Calculated results further show that a prolate deformation is important for the ground state of these nuclei. The properties of some unknown nuclei are predicted and these are useful for future experimental researches of superheavy nuclei.
121943751
Theoretical study of nuclear charge densities with elastic electron scattering
The calculated cross sections for elastic Coulomb electron scattering from the phase-shift analysis method and the eikonal approximation are compared. It is shown that the phase-shift analysis method can reproduce the experimental data very well for both light and heavy nuclei. Then the phase-shift analysis is used to investigate elastic electron scattering along the O and S isotopic chains, where the charge densities are obtained from relativistic mean-field theory. Results show that the minima of the differential cross section shift inward and upward with the increase of the neutron number.
121588345
Coupled-channels study of fine structure in the {alpha} decay of well deformed nuclei
We formulate a theoretical model for the {alpha} decay of well-deformed even-even nuclei based on the coupled-channel Schroedinger equation. The {alpha}-decay half-lives and fine structures observed in {alpha} decay are well described by the five-channel microscopic calculations. Since the branching ratios to high-spin states are hard to understand in the traditional {alpha}-decay theories, this success could be important to interpret future observations of heavier nuclei. It is also found that the {alpha} transition to high-spin states is a powerful tool to probe the energy spectrum and deformation of daughter nuclei.
115206076
Search for strange pentaquark resonances with ZEUS at HERA
14504346
Production of excited charm and charm-strange mesons at HERA
The production of excited charm, D1(2420)0 and D2*(2460)0, and charm-strange, Ds1(2536)±, mesons in ep collisions was measured with the ZEUS detector at HERA using an integrated luminosity of 126 pb−1. Masses, widths and helicity parameters were determined. The measured yields were converted to the rates of c quarks hadronising as a given excited charm meson and to the ratios of the dominant D2*(2460)0 and Ds1(2536)± branching fractions. A search for the radially excited charm meson, D*′(2640)±, was also performed. The results are compared with those measured previously and with theoretical expectations.
119312790
Study of taupair production at HERA
A study of events containing two tau leptons with high transverse momentum has been performed with the ZEUS detector at HERA, using a data sample corresponding to an integrated luminosity of 0.33 fb−1. The tau candidates were identified from their decays into electrons, muons or hadronic jets. The number of tau-pair candidates has been compared with the prediction from the Standard Model, where the largest contribution is expected from Bethe-Heitler processes. The total visible cross section was extracted. Standard Model expectations agree well with the measured distributions, also at high invariant mass of the tau pair.
209834301
Search for supersymmetry in events with photons, bottom quarks, and missing transverse momentum in proton–proton collisions at a centre-of-mass energy of 7 TeV with the ATLAS detector
A search has been performed for the experimental signature of an isolated photon with high transverse momentum, at least one jet identified as originating from a bottom quark, and high missing transverse momentum. Such a final state may originate from supersymmetric models with gauge-mediated supersymmetry breaking in events in which one of a pair of higgsino-like neutralinos decays into a photon and a gravitino while the other decays into a Higgs boson and a gravitino. The search is performed using the full dataset of 7 TeV proton–proton collisions recorded with the ATLAS detector at the LHC in 2011, corresponding to an integrated luminosity of 4.7 fb−1. A total of 7 candidate events are observed while 7.5±2.2 events are expected from the Standard Model background. The results of the search are interpreted in the context of general gauge mediation to exclude certain regions of a benchmark plane for higgsino-like neutralino production.
53324568
Measurement of heavy-quark jet photoproduction at HERA
Photoproduction of beauty and charm quarks in events with at least two jets has been measured with the ZEUS detector at HERA using an integrated luminosity of 133 pb−1. The fractions of jets containing b and c quarks were extracted using the invariant mass of charged tracks associated with secondary vertices and the decay-length significance of these vertices. Differential cross sections as a function of jet transverse momentum, $p_{\mathrm {T}}^{\mathrm{jet}}$, and pseudorapidity, ηjet, were measured. The data are compared with previous measurements and are well described by next-to-leading-order QCD predictions.