Search results for "Ground state"
showing 10 items of 928 documents
Spins, moments and charge radii in the isotopic series181Hg-191Hg
1976
The hyperfine structure splitting and the isotope shift in the (6 s2 1S0 - 6s 6p3P1,λ=2,537 A) line of very neutron deficient Hg isotopes were determined by the β radiation detected optical pumping method (β-RADOP). In addition, nuclear magnetic resonance was observed in the atomic ground state. The results are Mean-square nuclear charge radii are calculated. Interpreting the sudden change of nuclear radius between187Hg and185Hg δ〈r2〉187,185=0.42(5)fm2 as oblate-prolate shape transition, one obtains δ〈β2〉 =0.054(5).
Soft modes and mode splitting in paramagnetic TbP§
1980
In contrast to spin-only systems the paramagnetic phases of systems with crystal field split ground multiplets exhibit magnetic excitations of finite energy. In the presence of a magnetic exchange coupling the excitons will propagate through the lattice. A measurement of the dispersion allows in principle an insight into the exchange interaction, which is of fundamental importance for the understanding of the magnetic phenomena. Unfortunately the evolution of the dispersion at low temperatures is in most cases interrupted by the onset of magnetic order due to an alignment of the magnetic moments of the crystal field ground state. A noticeable dispersion of well-defined excitons is only expe…
Analyzing lepton flavor universality in the decays Λb→Λc(*)(12±,32−)+ℓν¯ℓ
2018
Lepton flavor universality can be tested in the semileptonic decays Λb→Λc(*), where Λc(*) denotes either the ground state Λc(2286) (with JP=1/2+) or its orbital excitations Λc(2595) (with JP=1/2−) and Λc(2625) (with JP=3/2−). We calculate the differential decay rates as well as the branching fractions of these decays for both tauonic and muonic modes with form factors obtained from a covariant confined quark model previously developed by us. We present results for the rate ratios of the tauonic and muonic modes which provide important tests of lepton flavor universality in forthcoming experiments.
Masses and magnetic moments of ground-state baryons in covariant baryon chiral perturbation theory
2012
We report on some recent developments in our understanding of the light-quark mass dependence and the SU(3) flavor symmetry breaking corrections to the magnetic moments of the ground-state baryons in a covariant formulation of baryon chiral perturbation theory, the so-called EOMS formulation. We show that this covariant ChPT exhibits some promising features compared to its heavy-baryon and infrared counterparts.
Electron Anomalous Magnetic Moment in Basis Light-Front Quantization Approach
2011
We apply the Basis Light-Front Quantization (BLFQ) approach to the Hamiltonian field theory of Quantum Electrodynamics (QED) in free space. We solve for the mass eigenstates corresponding to an electron interacting with a single photon in light-front gauge. Based on the resulting non-perturbative ground state light-front amplitude we evaluate the electron anomalous magnetic moment. The numerical results from extrapolating to the infinite basis limit reproduce the perturbative Schwinger result with relative deviation less than 0.6%. We report significant improvements over previous works including the development of analytic methods for evaluating the vertex matrix elements of QED.
Semi-leptonic charm baryon decays in the relativistic spectator quark model
1991
We calculate the exclusive semi-leptonic charm baryon decays of the lowest lying charm baryon states into the ground state strangeness baryons using the covariant spectator quark model approach. We present results on rates,q 2- andE l -spectra as well as on the angular decay distribution in the cascade decay $$\Omega _c \to \Omega ( \to \Xi \pi ,\Lambda {\rm K})$$ .
Photonic Nambu-Goldstone bosons
2017
We study numerically the spatial dynamics of light in periodic square lattices in the presence of a Kerr term, emphasizing the peculiarities stemming from the nonlinearity. We find that, under rather general circumstances, the phase pattern of the stable ground state depends on the character of the nonlinearity: the phase is spatially uniform if it is defocusing whereas in the focusing case, it presents a chess board pattern, with a difference of $\pi$ between neighboring sites. We show that the lowest lying perturbative excitations can be described as perturbations of the phase and that finite-sized structures can act as tunable metawaveguides for them. The tuning is made by varying the in…
Positron Production In Heavy-Ion Collisions
1985
Atomic systems with a nuclear charge Z much greater than 100 exhibit a number of unique features not otherwise found in nature. Two characteristic properties are illustrated in Figs. 1 and 2. In Fig. 1 we have plotted the binding energy of a K-shell electron around hypothetical nuclei up to Z ≈ 200. For Z > 150 the binding energy exceeds the rest energy m e c 2 of the electron; i.e., adding the electron to the nucleus actually diminishes the total mass of the system. At the critical charge Z c ≈ 170–175 the binding energy reaches twice the electron rest mass, the threshold for spontaneous creation of an electron-positron pair. As has been discussed extensively in the literature (Pieper and …
The Topological Phase Transitions Related to Fermion Condensate
2014
In this chapter, we consider so-called topological phase transitions, taking place in normal Fermi liquid. In other words, here we are dealing with different instabilities of normal Fermi liquids relative to several kinds of perturbations of initial quasiparticle spectrum \(\varepsilon (p)\) and occupation numbers \(n(p)\) associated with the emergence of a multi-connected Fermi surface. Depending on the parameters and analytical properties of the Landau interaction, such instabilities lead to several possible types of restructuring of initial Landau Fermi liquid ground state. This restructuring generates topologically distinct phases. One of them is the FC discussed above, another one belo…
Magnetic field and temperature dependent correlations in the singlet ground state system CsFeBr3
1992
Abstract In the singlet ground state system CsFeBr 3 the temperature and magnetic field dependence of the magnetic dispersion curves have been measured by inelastic neutron scattering. At a field of 4.1 T magnetic Bragg peaks appear at (⅓ ⅓ 1) and (⅔ ⅔ 1). The correlation lengths were derived from the experimental data by integrating the constant Q -scans over the energy transfer. The Q -dependence was fitted to Lorentzians and correlations lengths were extracted for different directions in the lattice. These correlation lengths decrease with increasing temperature and increase with increasing field. Above the phase transition the correlation lengths decrease again.