Four-Body Bound-States Systems in Relativistic Scalar Quantum Field Theory: Variational Basis-State Approach

The variational method within the Hamiltonian formalism of quantum field theory has been used in order to investigate the effect of virtual pairs for four-body scalar systems consisting of two particles and two antiparticles of the same mass. The scalar particles and antiparticles interact via a massive or massless mediating scalar field. The ground state energy solutions of Fock-space variational trial states (\(|N{\bar {N}}N{\bar {N}}{ \rangle }+|N{\bar {N}}N{\bar {N}}N{\bar {N}\rangle }\)) of the relativistic wave equations have been studied. We have compared these results with the previous work of four-body system (variational trial states of the form \(|N{ \bar {N}}N{\bar {N}}{\rangle }\)) and we have shown that the inclusion of virtual pairs has a noticeable effect at low coupling and at high coupling the energy of the system is changed by an important amount. In other words, the calculations show that the inclusion of virtual pairs augments the binding energy of the four-body system by a substantial amount at strong coupling. This study can pave the way for some new ideas in order to investigate the effect of virtual pairs, for example, for a bound-states quark-antiquark or tetraquark systems in future.     

Infrared emission spectroscopy of liquid samples with multivariate calibration as a model for process analytical applications

Infrared emission spectroscopy and multivariate calibration are used to provide a method for the quantitative analysis of liquid samples. Differing forms of the data including second derivative and interferogram representation are used for prediction of sample composition, thickness and temperature. Comparisons are made with transmission measurements of the same samples. In some situations emission measurements may be the preferred method of analysis.     

Spin hamiltonian parameters for Cu(II)-prion peptide complexes from L-band electron paramagnetic resonance spectroscopy

Cu(II) is an essential element for life but is also associated with numerous and serious medical conditions, particularly neurodegeneration. Structural modeling of crystallization-resistant biological Cu(II) species relies on detailed spectroscopic analysis. Electron paramagnetic resonance (EPR) can, in principle, provide spin hamiltonian parameters that contain information on the geometry and ligand atom complement of Cu(II). Unfortunately, EPR spectra of Cu(II) recorded at the traditional X-band frequency are complicated by (i) strains in the region of the spectrum corresponding to the g(∥) orientation and (ii) potentially very many overlapping transitions in the g(⊥) region. The rapid progress of density functional theory computation as a means to correlate EPR and structure, and the increasing need to study Cu(II) associated with biomolecules in more biologically and biomedically relevant environments such as cells and tissue, have spurred the development of a technique for the extraction of a more complete set of spin hamiltonian parameters that is relatively straightforward and widely applicable. EPR at L-band (1-2 GHz) provides much enhanced spectral resolution and straightforward analysis via computer simulation methods. Herein, the anisotropic spin hamiltonian parameters and the nitrogen coordination numbers for two hitherto incompletely characterized Cu(II)-bound species of a prion peptide complex are determined by analysis of their L-band EPR spectra.     

Rotational—vibrational dipole transitions in HD

The transition moments are computed for several lines in the X¹Σ⁺_g state of HD. The results are obtained by taking into account interactions with Σ_u and Π_u states. It is shown that the latter influence appreciably the transition probabilities in the 00 band. The permanent dipole moment is also computed for several vibrational and rotational states.     

Omega- and Omega+ production in central Pb + Pb collisions at 40 and 158A GeV

Results are presented on Omega production in central Pb+Pb collisions at 40 and 158A GeV beam energy. For the first time in heavy ion reactions, rapidity distributions and total yields were measured for the sum Omega(-) + Omega(+) at 40A GeV and for Omega(-) and Omega(+) separately at 158A GeV. The yields are strongly underpredicted by the string-hadronic UrQMD model but agree better with predictions from hadron gas models.     

Comment on real-time finite-temperature gauge field propagators

The gauge-fixing terms of the free, real-time thermal gauge field propagators corresponding to quantization in a covariant gauge obtained by Kobes, Semenoff, and Weiss are shown to be incorrect, apart from well-known signature ambiguities in the off-diagonal elements, and to differ from those obtained by Landsman using the method of the Klein-Gordon divisor. We obtain the correct forms which are then shown to coincide with Landsman's results by means of a distributional identity.     

A multi-coincident study of the quasimolecular 1s σ radiation and its angular distribution in 40 MeV Ni-Ni collisions

The production mechanism of quasimolecular (MO) x-rays in 40 MeV Ni-Ni collisions was investigated in a multi-parameter experiment. Impact parameter dependent MO x-ray production probabilities were determined. The study of the angular distribution of the emitted radiation allowed the determination of impact parameter dependent alignment parameters for this process. Triple coincident MO x-ray — NiK x-ray — scattered projectile data provided for the determination of state selective MO x-ray production probabilities. The results are compared to dynamical calculations describing the time dependent evolution of the relevant quasimolecular states and the radiative couplings among them.