989112
Equation of State of Asymmetric Nuclear Matter and Collisions of Neutron-Rich Nuclei
The ratio of pre-equilibrium neutrons to protons from collisions of neutron-rich nuclei is studied as a function of their kinetic energies. This ratio is found to be sensitive to the density dependence of the nuclear symmetry energy, but is independent of the compressibility of symmetric nuclear matter and the in-medium nucleon-nucleon cross sections. The experimental measurement of this ratio thus provides a novel means for determining the nuclear equation of state of asymmetric nuclear matter. {copyright} {ital 1997} {ital The American Physical Society}
126298012
New Geiger-Nuttall law for alpha decay of heavy 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.
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.
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.
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.
117483857
Search for quark contact interactions in dijet angular distributions in pp collisions at s=7 TeV measured with the ATLAS detector
Dijet angular distributions from the first LHC pp collisions at center-of-mass energy sqrt(s) = 7 TeV have been measured with the ATLAS detector. The dataset used for this analysis represents an integrated luminosity of 3.1 pb-1. Dijet $\chi$ distributions and centrality ratios have been measured up to dijet masses of 2.8 TeV, and found to be in good agreement with Standard Model predictions. Analysis of the $\chi$ distributions excludes quark contact interactions with a compositeness scale $\Lambda$ below 3.4 TeV, at 95% confidence level, significantly exceeding previous limits.
21554167
Measurement of the muon reconstruction performance of the ATLAS detector using 2011 and 2012 LHC proton–proton collision data
This paper presents the performance of the ATLAS muon reconstruction during the LHC run with $$pp$$pp collisions at $$\sqrt{s}=7$$s=7–8 TeV in 2011–2012, focusing mainly on data collected in 2012. Measurements of the reconstruction efficiency and of the momentum scale and resolution, based on large reference samples of $${J/\psi \rightarrow \mu \mu }$$J/ψ→μμ, $$Z \rightarrow \mu \mu $$Z→μμ and $${\Upsilon \rightarrow \mu \mu }$$Υ→μμ decays, are presented and compared to Monte Carlo simulations. Corrections to the simulation, to be used in physics analysis, are provided. Over most of the covered phase space (muon $$|\eta |<2.7$$|η|<2.7 and $$5 \lesssim p_{\mathrm{T}}\lesssim 100$$5≲pT≲100 GeV) the efficiency is above $$99\,\%$$99% and is measured with per-mille precision. The momentum resolution ranges from $$1.7\,\%$$1.7% at central rapidity and for transverse momentum $$p_{\mathrm{T}}\simeq 10$$pT≃10 GeV, to $$4\,\%$$4% at large rapidity and $$p_{\mathrm{T}}\simeq 100$$pT≃100 GeV. The momentum scale is known with an uncertainty of $$0.05\,\%$$0.05% to $$0.2\,\%$$0.2% depending on rapidity. A method for the recovery of final state radiation from the muons is also presented.
115470739
Flavor tagged time-dependent angular analysis of the $B_s \rightarrow J/\psi \phi$ decay and extraction of $\Delta\Gamma$s and the weak phase $\phi_s$ in ATLAS
A measurement of the B0s→J/ψϕ decay parameters, updated to include flavor tagging is reported using 4.9  fb−1 of integrated luminosity collected by the ATLAS detector from s√=7  TeV pp collisions recorded in 2011 at the LHC. The values measured for the physical parameters are 
ϕs0.12±0.25(stat)±0.05(syst)  radΔΓs0.053±0.021(stat)±0.010(syst)  ps−1Γs0.677±0.007(stat)±0.004(syst)  ps 1|A∥(0)|20.220±0.008(stat)±0.009(syst)|A0(0)|20.529±0.006(stat)±0.012(syst)δ⊥=3.89±0.47(stat)±0.11(syst)  rad 
where the parameter ΔΓs is constrained to be positive. The S-wave contribution was measured and found to be compatible with zero. Results for ϕs and ΔΓs are also presented as 68% and 95% likelihood contours, which show agreement with the Standard Model expectations.
73533447
Measurement of J/ψ photoproduction at large momentum transfer at HERA
The proton-dissociative diffractive photoproduction of J/ψ mesons has been studied in ep collisions with the ZEUS detector at HERA using an integrated luminosity of 112 pb−1. The cross section is presented as a function of the photon-proton centre-of-mass energy and of the squared four-momentum transfer at the proton vertex. The results are compared to perturbative QCD calculations.
56102023
Production of Z(0) bosons in elastic and quasi-elastic ep collisions at HERA
The production of Z 0 bosons in the reaction ep→eZ 0 p (*) , where p (*) stands for a proton or a low-mass nucleon resonance, has been studied in ep collisions at HERA using the ZEUS detector. The analysis is based on a data sample collected between 1996 and 2007, amounting to 496pb -1 of integrated luminosity. The Z 0 was measured in the hadronic decay mode. The elasticity of the events was ensured by a cut on η max max is the maximum pseudorapidity of energy deposits in the calorimeter defined with respect to the proton beam direction. A signal was observed at the Z 0 mass. The cross section of the reaction ep→eZ 0 p (*) was measured to be σ(ep→eZ 0 p (*) )=0.13±0.06(stat.)±0.01(syst.) pb, in agreement with the Standard Model prediction of 0.16 pb. This is the first measurement of Z 0 production in ep collisions. © 2012 Elsevier B.V.