121404916
Microscopic calculation of α-decay half-lives within the cluster model
Abstract The α-decay half-lives of heavy and superheavy nuclei are systematically calculated using a radial wave function within the cluster model. The decaying state is considered as an isolated quasi-bound state, and the α-decay process is interpreted as the quantum transition from the quasi-bound state to the scattering state. Then the quasi-bound state wave function and the scattering state wave function, in combination with the difference of potentials, are used to give a clear expression of the α-decay width. The present study is mainly restricted to even–even nuclei with N > 126 , including the superheavy mass region. The obtained α-decay half-lives are found to be in good agreement with the experimental data. Moreover, the study has been extended to the newly observed heaviest nuclei. It is worth noting that the aim of this work is not only to reproduce the experimental data better, but also to extend our understanding of α decay.
122795101
Relativistic eikonal approaches to parity violating electron-nucleus scattering
The Coulomb electron scattering on even-even nuclei and the magnetic electron scattering on odd-$A$ nuclei have been investigated in the relativistic eikonal approximation and in the plane wave Born approximation, respectively. In this article, we generalize the relativistic eikonal approximation to the parity violating electron scattering on even-even nuclei. The parity violating asymmetries at electron energy of 850 MeV are calculated for three typical cases: Ca isotopes, $N=50$ isotones, and $N=Z$ doubly magic nuclei. In calculations the proton and neutron densities are obtained from the relativistic mean-field theory. The parity violating asymmetries are analyzed by comparing both the form factors and the densities of neutrons and protons. It is found that the parity violating asymmetries are sensitive to the differences between neutron and proton densities. Our results provide useful references for the parity violating electron-nucleus scattering experiments in the future.
126298012
New Geiger-Nuttall law for alpha decay of heavy nuclei
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.
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.
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.
116979994
The search for strange pentaquarks at ZEUS
A study of states and enhancements reconstructed using the invariant‐mass spectra associated with strange baryons has been performed in ep collisions with the ZEUS detector at HERA using an integrated luminosity of 121 pb−1. The invariant‐mass spectra were reconstructed in several kinematic regions with the main emphasis on the spectra which are sensitive to the production of pentaquarks. The candidate Θ+ signal was found to be produced predominantly in the forward hemisphere in the laboratory frame. This is unlike the case for the Λ(1520) or the Λc, and indicates that the Θ+ may have an unusual production mechanism related to proton‐remnant fragmentation.
122743677
Multijet production in neutral current deep inelastic scattering at HERA and determination of alpha(s)
Multijet production rates in neutral current deep inelastic scattering have been measured in the range of exchanged boson virtualities 10 5 GeV and -1 < η LAB jet < 2.5. Next-to-leading-order QCD calculations describe the data well. The value of the strong coupling constant α s (M Z ), determined from the ratio of the trijet to dijet cross sections, is α s (M Z ) = 0.1179 ± 0.0013 (stat.) -0.0046 -0.0028 (exp.) -0.0046 +0.0064 (th.). © Springer-Verlag / Societa Italiana di Fisica 2005.
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.
125401428
Measurement of the cross section of high transverse momentum $\it{Z\rightarrow b\bar{b}}$ production in proton--proton collisions at $\sqrt{s}=8 TeV$ with the ATLAS Detector
3955280
Combination and QCD analysis of charm production cross section measurements in deep-inelastic ep scattering at HERA
Measurements of open charm production cross sections in deep-inelastic ep scattering at HERA from the H1 and ZEUS Collaborations are combined. Reduced cross sections $\sigma_{\rm red}^{c\bar{c}}$ for charm production are obtained in the kinematic range of photon virtuality 2.5≤Q2≤2000 GeV2 and Bjorken scaling variable 3⋅10−5≤x≤5⋅10−2. The combination method accounts for the correlations of the systematic uncertainties among the different data sets. The combined charm data together with the combined inclusive deep-inelastic scattering cross sections from HERA are used as input for a detailed NLO QCD analysis to study the influence of different heavy flavour schemes on the parton distribution functions. The optimal values of the charm mass as a parameter in these different schemes are obtained. The implications on the NLO predictions for W± and Z production cross sections at the LHC are investigated. Using the fixed flavour number scheme, the running mass of the charm quark is determined.