Angular momentum of the physical electron

The angular momentum of the physical electron, modelled as a Dirac fermion coupled to the electromagnetic field, is found to be hbar/2, the same as that of a bare Dirac fermion and independent of the size of the electric charge.Comment: revision, 3 pages pd

Pushing NRQCD to the limit

Lattice NRQCD has proven successful in describing the physics of the upsilon system and B-mesons, though some concerns arise when it is used in simulations of charm quarks. It is certainly possible that the NRQCD expansion is not converging fast enough at this scale. We present some preliminary results on the low-mass breakdown of NRQCD, in particular the behaviour of heavy quarkonium and heavy-light meson spectra as the bare heavy quark mass is decreased well below 1, with the aim of understanding more about the manifestation of this breakdown.Comment: Lattice 99 submission, 3 Pages, 3 eps figure

Ground State Baryons in U(12) Scheme

The properties of ground-state baryons of light-quarks are investigated in U(12)-classification scheme of hadrons, recently proposed by us. In U(12), in addition to the ordinary 56 of SU(6)SF, the existence of the extra 56 with positive-parity and 70 with negative-parity appear as ground-states in lower mass region. The N(1440), Lambda(1600) and Sigma(1660) have the plausible properties of masses and strong decay widths as the flavor-octet of extra 56, while the ordinary radially-excited octet states are expected not to be observed as resonances because of their large predicted widths of the decays to extra 70 baryons. The extra 70 baryons are not observed directly as resonances for the same reason, except for only the Lambda(1406), of which properties are consistently explained through the singlet-octet mixing. The baryon properties in lower mass regions are consistently explained in U(12) scheme.Comment: 11 pages, uses elsart.cl

Classical Simulation of Quantum Fields II

We consider the classical time evolution of a real scalar field in 2 dimensional Minkowski space with a $\lambda \phi^4$ interaction. We compute the spatial and temporal two-point correlation functions and extract the renormalized mass of the interacting theory. We find our results are consistent with the one- and two-loop quantum computation. We also perform Monte Carlo simulations of the quantum theory and conclude that the classical scheme is able to produce more accurate results with a fraction of the CPU time.Comment: 16 pages, 8 figures, now matches published versio

Quasi-Two-Body Decays of Nonstrange Baryons

We examine the decays of nonstrange baryons to the final states $\Delta\pi$, $N\rho$, $N\eta$, $N\eta^\prime$, $N\omega$, $N1/2^+(1440)\pi$, and $\Delta3/2^+(1600)\pi$, in a relativized pair-creation($^3P_0$) model which has been developed in a previous study of the $N\pi$ decays of the same baryon states. As it is our goal to provide a guide for the possible discovery of new baryon states at CEBAF and elsewhere, we examine the decays of resonances which have already been seen in the partial-wave analyses, along with those of states which are predicted by the quark model but which remain undiscovered. The level of agreement between our calculation and the available widths from the partial-wave analyses is encouraging.Comment: 41 pages, CEBAF-TH-93-1

Using tanks for indirect fire – an attempt to reactivate training

Indirect fire is a domain of artillery. Tanks due to their combat capabilities (mobility, hit resistance and accuracy of fire) were hardly used for such type of tasks, although being prepared from constructional point of view. Nevertheless, evaluation of a concept of tanks utilization in a battlefield frequently oscillated around a support of infantry or just operation support. Closing down and ceasing development of artillery units as a result of the Polish Armed Forces’ transformation led to a situation under which the lack of an adequately intensive artillery fire significantly affecting support of first echelon units can be faced during real operations. For this reason, the General Command of Branches of Armed Forces bearing in mind tanks’ capability of fulfilling the aforementioned task decided to reactivate the competence of indirect fire by tanks’ crews, especially because the execution of this task was terminated at the beginning of the 1990s. The article presents the analysis of documents in force related to conducting indirect fire by a tank subunit and characteristics of individual undertakings required for preparation of a subunit to fulfil above-mentioned tasks based on the experience gained by a tank battalion of the 15th Mechanized Brigade in Gizycko, as well as realization of numerous organizational projects necessary for shooting preparation and fire control execution during fulfillment of this type of fire tasks. Results of practical indirect fire execution by tanks lead to constructive observations referred to achieving high results of an accurate indirect fire by tanks and implementing changes in documents which normalize training and shooting processes, adjusting an organizational portion of the project to the current organizational structures of tank and artillery subunits and to correlations resulting from this fact. The article also inclines to discussion regarding the direction of changes indispensable for conducting the indirect fire by tanks and the rationale of the execution of these tasks in a contemporary battlefield

Ultrarelativistic bound states in spinor and scalar QED

Nonperturbative integral equations are developed variationally for two-particle bound states in spinor and scalar quantum electrodynamics. The equations are solved numerically in the massive case and analytically in the massless case. The coupling constant is varied in order to study the bound states in the ultrarelativistic region