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.
125583963
Properties of deformed even-even nuclei near Z = 20 in an improved quark mass density-dependent model
An improved quark mass density-dependent model is applied to study the ground-state properties of axially deformed even-even nuclei using the deformed quark-meson coupling calculation. The present study is mainly focused on the nuclei with the available experimental data ranging from Z = 14 to Z = 26. The ground-state binding energies, two-neutron separation energies, two-proton separation energies, quadrupole deformations, and root-mean-square (rms) charge radii are studied. The shell effect of the neutron magic number N = 20 can be demonstrated by our model. It has been shown that the improved quark mass density-dependent model can give a reasonable description of the axially deformed nuclei. DOI: 10.1103/PhysRevC.87.014335
117858276
Probe the $2s_{1/2}$ and $1d_{3/2}$ state level inversion with electron-nucleus scattering
The neutron-rich even-even nuclei 26–40Mg, 28–46Si, 30–48S, and 32–56Ar are calculated with the RMF model and the phase-shift electron scattering method. Results show that level inversion of the 2s1/2 and 1d3/2 proton states may occur for the magnesium, silicon, sulphur, and argon isotopes with more neutrons away from the stability line. Calculations show that the variation of the central charge densities for 30–48S, and 32–56Ar are very sensitive to the 2s1/2 and 1d3/2 proton state level inversion, and the level inversion can lead to a large measurable central charge depletion to the charge density distributions for the neutron-rich isotopes. Calculations also show that the charge density differences between the isotopes with and without central charge depletion can reveal not only the level inversion of the 2s1/2 and 1d3/2 proton states but also the behavior of the proton wave functions of both states. The results can provide references for the possible study of the nuclear level inversion and nuclear bubble phenomenon with electron scattering off short-lived nuclei at RIKEN or/and GSI in the future. In addition, direct nuclear reaction 44S(n, d)43P or 44S(3H, α)43P might also be a possible way to study the 2s1/2 and 1d3/2 proton state level inversion.
123803933
Nuclear charge radii of heavy and superheavy nuclei from the experimental alpha-decay energies and half-lives
The radius of a nucleus is one of the important quantities in nuclear physics. Although there are many researches on ground-state properties of superheavy nuclei, researches on charge radii of superheavy nuclei are rare. In this article, nuclear root-mean-square (rms) charge radii of heavy and superheavy nuclei are extracted from the experimental alpha-decay data. alpha-decay calculations are performed within the generalized density-dependent cluster model, where alpha-decay half-lives are evaluated using quasibound state wave functions. The charge distribution of daughter nuclei is determined in the double-folding model to reproduce the experimental alpha-decay half-lives. The rms charge radius is then calculated using the resulting charge distribution. In addition, a simple formula is also proposed to calculate nuclear charge radii with the experimental alpha-decay energies and half-lives. The formula is directly derived from the Wentzel-Kramers-Brillouin barrier penetration probability with some approximations. The two different methods show good agreement with the experimental data for even-even nuclei, and the deduced results are consistent with other theoretical models. Moreover, nuclear radii of heavy and superheavy nuclei with Z = 98-116 are extracted from the alpha-decay data, for which alpha decay is a unique tool to probe nuclear sizes at present. This is the first result on nuclear charge radii of superheavy nuclei based on the experimental alpha-decay data. DOI: 10.1103/PhysRevC.87.024310
123612851
Calculations of the beta-decay half-lives of neutron-rich nuclei
The beta-decay half-lives of neutron-rich nuclei have been systematically investigated using the proton-neutron quasiparticle random-phase approximation (pnQRPA) with a delta-form Gamow-Teller residual interaction. The particle-hole and particle-particle components of the Gamow-Teller residual interaction are consistently taken into account in dealing with the pnQRPA matrix equation, and the dependence of the results on them is discussed. Even-even nuclei with atomic numbers Z = 6-58 are considered in the calculations, where some newly measured neutron-rich nuclei are included. The calculated beta(-)-decay half-lives are found to be in good agreement with the available experimental data. The comparison with other theoretical results is also given. Moreover, predictions on beta-decay half-lives are made for some extremely neutron-rich nuclei, which could be useful for future experiments.
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.
202105722
Search for strong gravity signatures in same-sign dimuon final states using the ATLAS detector at the LHC
A search for microscopic black holes has been performed in a same-sign dimuon final state using 1.3 fb(-1) of proton-proton collision data collected with the ATLAS detector at a centre of mass energy of 7 TeV at the CERN Large Hadron Collider. The data are found to be consistent with the expectation from the Standard Model and the results are used to derive exclusion contours in the context of a low scale gravity model.
119256577
Measurement of high-Q2 neutral current deep inelastic e−p scattering cross sections with a longitudinally polarised electron beam at HERA
AbstractMeasurements of the neutral current cross sections for deep inelastic scattering in e−p collisions at HERA with a longitudinally polarised electron beam are presented. The single-differential cross-sections dσ/dQ2, dσ/dx and dσ/dy and the double-differential cross sections in Q2 and x are measured in the kinematic region y<0.9 and Q2>185 GeV2 for both positively and negatively polarised electron beams and for each polarisation state separately. The measurements are based on an integrated luminosity of 169.9 pb−1 taken with the ZEUS detector in 2005 and 2006 at a centre-of-mass energy of 318 GeV. The structure functions 
$x\tilde{F_{3}}$ 
and xF3γZ are determined by combining the e−p results presented in this paper with previously measured e+p neutral current data. The asymmetry parameter A− is used to demonstrate the parity violating effects of electroweak interactions at large spacelike photon virtuality. The measurements agree well with the predictions of the Standard Model.
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.
119209819
Events with an isolated lepton and missing transverse momentum and measurement of W production at HERA
A search for events containing an isolated electron or muon and missing transverse momentum produced in e±p collisions is performed with the H1 and ZEUS detectors at HERA. The data were taken in the period 1994–2007 and correspond to an integrated luminosity of 0.98 fb−1. The observed event yields are in good overall agreement with the Standard Model prediction, which is dominated by single W production. In the e+p data, at large hadronic transverse momentum PTX > 25GeV, a total of 23 events are observed compared to a prediction of 14.0 ± 1.9. The total single W boson production cross section is measured as 1.06 ± 0.16 (stat.) ± 0.07 (sys.) pb, in agreement with an Standard Model (SM) expectation of 1.26 ± 0.19 pb.
209835401
Search for events with large missing transverse momentum, jets, and at least two tau leptons in 7 TeV proton–proton collision data with the ATLAS detector
A search for events with large missing transverse momentum, jets, and at least two tau leptons has been performed using 2 fb(-1) of proton-proton collision data at root s = 7 TeV recorded with the ...