bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU (3) Symmetry Scheme, A Review
Authors: London Georges W. 
Published: July 2007

AbstractThis review is intended for non‐experts (experimentalists, students, etc.) as an introduction to the applications of group theory to strong interactions. It contains no new results nor is it a complete survey of the field. The analogy, both formal and philosophical, with isospin invariance and charge independence is emphasized. The paper briefly reviews the elements of group theory and then, as an example, discusses the isospin group. Rank two groups in general, SU (3) in particular, are then discussed. The connection to physics is made through the identification of the basis vectors of the different group representations with physical states. i.e. particles. The concept of U‐spin is introduced to derive some dynamic predictions of the model. The violation of SU (3) invariance is then discussed. The mass formulae, relating the medium‐strong and electromagnetic splittings within a multiplet, are derived to first order. The extension of SU (3) symmetry to weak interactions is briefly discussed.
Dirac Formalism for Arbitrary Spin in S‐Matrix Theory
Authors: Enflo B. O. , Laurent B. E. 
Published: July 2007

AbstractThe S‐matrix formalism is built up from the beginning, for particles with and without mass, through systematic use of the representation Ds,0 D0,s of the homogeneous Lorentz group. Only concepts referring to space and time are considered. Within the framework of the formalism, the close interdependence between CPT, spin and statistics, crossing symmetry and unitarity is explicitly emphasized. The concepts of intrinsic parity, spin‐flip and particle conjugation are re‐examined. A comparison is made with conventional field‐theoretic formalism.
An Unitarized Model of Quasi‐Two‐Body Contributions to Single Pion Production by Mesons
Authors: Baracca A. , Bergia S. 
Published: July 2007

AbstractA general formulation is presented of resonant final state interactions (isobars) in single pion production by mesons with particular reference to the N* case.An essential use is made of the separation of the process into the quasi‐two‐body production and the decay steps. This allows the insertion of the isobar hypothesis into a scheme capable of dealing correctly with the spin‐angular momentum aspects.A general scheme is developed for the exploitment of the two‐channel unitarity conditions in a partial wave analysis of the isobar production amplitudes.The method for computing normalized distributions is finally outlined.
Algebraic Geometry and Feynman Amplitudes
Authors: Cunningham John 
Published: July 2007

AbstractThe representation method of obtaining first and second type Landau curves from the Landau criteria is described. The Plucker characteristic analysis of singular curves is outlined and its relationship with the theory of automorphic functions indicated. A differential approach to singularity classification is discussed and a possible extension of the method to obtain asymptotic behaviour is conjectured.A preliminary form of some of the material here presented was the basis of a lecture given by the author at the University of Wales Colloquium in Applied Mathematics, Gregynog, 1969.
Spectra and Distributions in a Unitarized Model of Quasi‐Two‐Body Contributions to Single Pion Production by Mesons
Authors: Baracca A. , Bergia S. , Bramon A. , de Santis Y. , Gomis J. , Montoto A. , Monzoni V. 
Published: July 2007

AbstractWe study the general properties of single pion production processes in boson‐nucleon collisions in the hypothesis that any couple of the final particles may undergo a resonant final state interaction.The aim is to supply the experimentalists with a tool apt to interpret Dalitz‐plots and distributions as they stand, as an alternative to the normal method of selecting samples of events to study one particular quasi‐two‐body process.General expressions of spectra and distributions are obtained.
Theoretische Untersuchungen zur Asymmetrie der Pionphotoproduktion mit einem polarisierten Target
Authors: Kramer G. 
Published: July 2007

AbstractThe theoretical importance of experiments with polarised targets for pion photoproduction at high energies is discussed.In an introductory chapter the basic formulas and simple Regge pole models are introduced in connection with elastic pion‐proton scattering. The relevance of Regge‐cut models is considered in connection with pion‐charge‐exchange scattering. In the main part we write down formulas for the polarisation parameters in terms of the helicity amplitudes for pion photoproduction. Then we concentrate on the target asymmetry A for photoproduction of neutral and charged pions. Several models with Regge poles and Regge cuts generated by absorption are presented and discussed concerning the results forA. In the last part we report a fit to π± photoproduction data and give predictions of A for γp → π+n and γn → π−p.
Methods of Quantum Field Theory with Rapidly Increasing Spectral Functions
Authors: Volkov M. K. 
Published: July 2007

AbstractA review of the methods of constructing the scattering amplitudes and Green functions in the non‐renormalizable quantum field theories with rapidly increasing spectral functions is given. Such theories as the theories with the chiral Lagrangians, those which describe the interactions with gravitational fields and the theories of weak interactions can be taken as examples. Three big groups of these methods are presented here. In particular, these are as follows: construction of the scattering amplitude in x‐space (the function F(x)), construction of the scattering amplitude in momentum space (the function F˜ (p)) and definition of the scattering amplitudes by solving the appropriate equations (in x‐ or p‐Space).This works was reported at the Second International Symposium on Non‐local Quantum Field Theory in 1970 at Azau, USSR.
Comparison of Various K̄N Partial Wave Analyses in the Region 0–1400 MeV/c
Authors: Gupta Madan L. , Arndt R. A. , Roper L. David 
Published: July 2007

AbstractA comprehensive comparative study of the available K̄N partial wave analyses is made with a view to bring out their similarities and disagreements and to point towards those momentum regions that require particular attention in all future analyses. The multichannel nature of the K̄N scattering is discussed along with the presently available scattering cross‐section data for various channels. The parametrization of the various partial wave analyses is discussed and their amplitudes calculated and compared under the set of conventions proposed by Levi Setti.
Single Particle Distributions from Veneziano Amplitudes II
Authors: Bebel D. , Biebl K. J. , Ebert D. , Otto H. J. 
Published: July 2007

AbstractThe x‐ and p⟂2‐dependence of the distribution function for the inclusive reaction A + B → C + anything has been investigated for some typical cases using the dual six point function in the tree approximation as a model for T33. It is found that the form the x‐distribution depends critically on the trajectory intercepts in the AC̄ and BC̄ channels, respectively. The p⟂2‐dependence is nearly exponential for large x. For small x‐values a steeper behaviour in the small p⟂2 region is obtained which is especially pronounced for small masses of the observed particles. Diagrams with twists contributing to the distribution function for inclusive reactions with neutral pions lead to oscillations and dips near the nonsense wrong signature points of the AC̄ and BC̄ channel trajectories.
Some Approximations in the Theorie of Moments and Transitions for Even‐Odd Nuclei
Authors: Weigel M. 
Published: July 2007

AbstractIn the framework of Green's functions, the theory of moments and transitions for even‐odd‐nuclei is developed. It is shown, how these quantities are connected with the effective particle‐hole force and the generalized linear response function for the neighbour even‐even nuclei. The response function describes the change of the single‐particle propagator due to an external perturbation. For superfluid systems the Nambu [1] – Engelsberg [2] – Belyaev [3] technique has been used. The connection between earlier treatments is established, especially with the semiphenomenological approach of Migdal [4] and co‐workers. Some approximations for the relevant effective particle‐hole force emerging from the many‐body theory are discussed in detail. Furthermore the generalization of the RPA‐approximation for the auto‐correlation function of density fluctuations in the case of superfluidity is given.
Invariant Spinors and their Use for Expansions of Scattering Amplitudes
Authors: Enflo B. O. , Laurent B. E. 
Published: July 2007

AbstractA general covariant scheme is proposed for the kinematical analysis of arbitrary reactions. By this scheme the problem of finding invariant amplitudes and corresponding kinematical covariants can be solved systematically. The amplitudes are labelled by two invariant indices for each particle related to spin and parity. The method provides a tool for exploiting the symmetries of the M‐function, including crossing symmetry and the Pauli principle. Amplitudes free from kinematical singularities can easily be constructed.
A Re‐Examination of the Arguments for Baryon Parity Doublets
Authors: Enflo B. O. 
Published: July 2007

AbstractThe arguments for baryon parity doubling are re‐examined by use of a spin formalism developed by the author together with B. E. LAURENT. It is shown that the transformation between good parity amplitudes and helicity flip and non‐flip amplitudes in πN scattering is ambiguous. It is further shown that the unitary condition for boson‐fermion scattering gives no information of the parity of intermediate states contributing to a good parity amplitude. These ambiguities follow from the fact that for boson‐fermion scattering the CPT transformation of an amplitude does not commute with the projection on a definite parity. It is finally shown how a Regge pole model with linear trajectories without parity doubling can be constructed without any specific dynamical assumptions or artifices. The constraints on the residues needed in this case do not violate any general principles.
Algebraic Methods in Ordinary Quantum Mechanics Revisited
Authors: Ghirardi Gian Carlo 
Published: July 2007

AbstractWe reconsider the problem of giving an algebraic treatment to quantum problems within the framework of ordinary quantum mechanics. After a concise review of the irreducible representations of the relevant Lie algebra, we formulate the general scheme within which all previous approaches can be easily fitted. We then show which are the explicit connexions between this general scheme and the specific approaches found in the literature. The whole paper constitutes a concise and synthetic summary of algebraic techniques in ordinary quantum mechanics.
Bhabha Equations for Unique Mass and Spin
Authors: Santhanam T. S. , Tekumalla A. R. 
Published: July 2007

AbstractLinear relativistic wave equations of Bhabha's type are discussed. Conditions for unique mass and unique spin are analysed in detail. It is shown that if one relaxes the diagonalisability of βo by a weaker block form one gets a class of equations describing a spin‐half particle. Several algebras which emerge and their representations are studied. The existence or otherwise of the hermitianising matrix in such cases is explicitly discussed. The properties of the new equations in the presence of minimally coupled electro‐magnetic field are discussed.
Effective Range Expansion for Electron‐Neutrino and Electron‐Antineutrino Scattering
Authors: Kramer G. 
Published: July 2007

AbstractWeak interactions from a pure S‐matrix point of view are considered in order to get an idea about the high‐energy behaviour. To have the weak interaction as undisturbed as possible by electromagnetic and strong interactions we study only the leptonic processes eν → νe, eν → νe and eē → νν. We calculate the corresponding partial wave amplitudes for s and p waves and constrain them by low energy behaviour coming from the lowest order approximation, analyticity and unitarity. Several examples of partial wave cross sections for the three reactions with resonant behaviour in the eν or eν channel are calculated numerically.
Zerfallende Zustände als physikalisch nichtisolierbare Teilsysteme
Authors: Szász Gy. I. 
Published: July 2007

AbstractPresently the investigations of decaying quantum mechanical systems lack a well‐founded concept, which is reflected by several formal difficulties of the corresponding mathematical treatment. In order to clarify in some respect the situation, we investigate, within the framework of nonrelativistic quantum mechanics, the resonant scattering of an initially well localized partial wave packet ϕl(r, t). If the potential decreases sufficiently fast for r → ∞, ϕl(r, t) can be expressed at sufficiently long time after the scattering has taken place, as ϕl(r, t) = I(r, t) + ∑ Niϕl(Ki, r) exp {–iKi2 t/2M} × Θ(ki – γi – Mr/t), ϕl(Ki, r) being the resonant solution with complex “momentum” Ki = ki – iγi. From this heuristic relation one can deduce not only the probability for the creation of unstable particles but also obtain some hints to a connection between decaying states and physically nonisolable partial systems. On the other hand, this connection can perhaps display the inadequacy of attempts which suggest to solve the problem of decaying states within the usual Hilbert space methods.
Regge Models and Dispersion Relations for Partial Waves
Authors: Kaschluhnxs F. , Müller‐Preussker M. 
Published: July 2007

AbstractThe asymptotic behaviour of partial wave amplitudes is calculated supposing various Regge models for the total scattering amplitude A(s, t, u). The high energy partial wave behaviour obtained is combined with the validity of partial wave dispersion relations. It is shown that consistency of these assumptions can only be achieved by demanding.1) a definite asymptotic behaviour of the discontinuity of the left hand cut of partial wave amplitudes.2) the validity of partial wave sum rules of similar kind as the well‐known finite energy sum rules for the total amplitude.All steps of the derivation shall first be demonstrated for elastic scattering of identical scalar particles. Then within the helicity formalism the results are generalized for particles with arbitrary spin and different masses. Finally the question is studied whether the sum rules can be employed to determine unknown CDD‐pole parameters in an N/D approach for the I = J = 1/2 state in πN scattering. It is shown that the sum rules of highest order are able to do that.
Pseudoscalar Mesons as Goldstone Bosons in Chiral SU(4) ⊗ SU(4) Symmetry
Authors: Bose S. K. 
Published: July 2007

AbstractWe study the pseudoscalar mesons in the framework of broken chiral SU(4) SU(4) symmetry when the symmetry‐breaking Hamiltonian, HSB, is taken as –(u0 + cu8 + du15) and the symmetry of the Hamiltonian is realized in Goldstone‐Nambu way. An interesting property of two chimeral SU(4) subgroups and the Goldstone nature of some of the pseudoscalar mesons in certain symmetry limits are exploited to obtain some mass relations and the ratio c/d.
Quantum Theory of Path‐Dependent Field Operator Based on Characteristics of Displacement Operators
Authors: Okabayashi Takao 
Published: July 2007

AbstractThe path‐dependent operator formalism of quantum electrodynamics proposed by Mandelstam is reformulated through quantum field theory based on characteristics of displacement operators in Minkowski space. It is shown that total energy‐ and total angular‐momentum operators can generate inhomogeneous Lorentz transformations on any local operator including path‐independent bilinear forms constructed of path‐dependent electron operator Ψ(x, P), but that generators for Ψ(x, P) itself are only their Ψ(x, P)‐dependent parts. Such an unfamiliar feature is characteristic of the path‐dependent operator formalism. The present approach possesses unique merits in making the logic of the formalism transparent as described in the following: i) Quantum electrodynamics can be formulated but for the help of potential operator even as a tool for calculation up to a final step. ii) Some restriction, which can be used to discuss propriety of gauge conditions, can be figured out. iii) By introducing a path‐rearrangement operator, we can keep infinite variety of space‐like pathes with the same end point throughout our formulation as they stand. iv) Several points which must be modified in the presence of magnetic monopole are closed up.
Duality Properties of Virtual Compton Amplitudes
Authors: Jersák J. 
Published: July 2007

AbstractThe duality hypothesis based on the light cone behaviour of the current commutator is applied to the nonforward Compton amplitudes and the restrictions which the duality imposes on these amplitudes in various high energy limits are reviewed. It is shown how the duality of the Compton amplitudes can be tested experimentally in deep inelastic annihilation and exclusive electroproduction of mesons. A dual pole model of the Compton amplitude is constructed.
Parametrische Instabilitäten in Plasmen
Authors: Spatschek K. H. 
Published: July 2007

AbstractLinear and nonlinear theoretical aspects of parametric instabilities in plasmas are reviewed. Applications in laser‐fusion and heating of toroidally confined plasmas are considered. We start with the electrostatic decay and modulational instabilities in homogeneous, unmagnetized plasmas. The basic equations are derived in a physically simple manner. Electromagnetic modes are included using a wave description for the scattering instabilities (Raman and Brillouin scattering). Kinetic limits where quasi‐modes are involved (Compton scattering) and the corresponding instabilities in magnetic plasmas are discussed. Using a WKB‐analysis the effects of density, temperature, and expansion velocity gradients as well as turbulence, finite laser bandwidth, boundaries, and oblique incidence are estimated. The calculations are extended to include such phenomena as sidescattering and decay near the quartercritical and critical density where the WKB approximation breaks down. Nonlinear saturation mechanisms are discussed for Raman, Brillouin, decay, and modulational instabilities. Special attention is given to pump depletion and particle trapping. The existence of solitary waves and the stability of the latter are investigated. The conclusions are compared with results of experiments as well as computer simulations.
Consequences of Crossed Channel Structure for High Energy Elastic Scattering
Authors: Haan Oswald 
Published: July 2007

AbstractThis review describes a field in the S‐matrix theory of elastic stattering. Analyticity and elastic unitarity in the crossed t‐channel are shown in a rigorous manner to yield constraints on s‐channel quantities. Strong restrictions on s‐channel partial wave with angular momenta l ⩾√s/2(b0 + λ In s) follow from realistic assumptions on the amplitude in the unphysical domain (Mandelstam analyticity and Regge behaviour). The possibility of phenomenological application of these results is discussed.
The Algebraic Structure of the Thirring Model
Authors: Heck Lydia 
Published: July 2007

AbstractWe summarize the representation theory of the group SU(1,1) as needed for the massless Thirring model. Representations of the current operator algebra are given taking account of conformal covariance. The conformal covariance transformation behaviour of the Thirring field is investigated. The Haag‐Araki‐Kastler observable algebra of the Thirring field is reconstructed from the Wightman theory of this model.
Einstein‐Maxwell Equations: Gauge Formulation and Solutions for Radiating Bodies
Authors: Carmeli Moshe , Kaye Michael 
Published: July 2007

AbstractThe subject of the SL(2, c) gauge theory of gravitation is reviewed. A detailed discussion is given on the differential geometry and the fibre bundle structure of such a theory. The coupling of Maxwell's field equations to those of gravitation is also given. The field equations obtained, which are shown to be equivalent to the coupled Einstein‐Maxwell equations, are subsequently solved. The solutions sought after are radiating type ones of the kind of the Kerr metric, but with the mass of the body being variable and is a function of the retarded time. A generalization of the Kerr metric is presented and its energy‐momentum tensor is analyzed in detail. The classification of the field obtained according to the Petrov scheme is also given.
Nonlocal Quark Model and Meson Decays
Authors: Dubničková A. Z. , Efimov G. V. , Ivanov M. A. 
Published: July 2007

AbstractIn the framework of nonlocal quantum field theory we have constructed a quantized field called the virton field satisfying the conditions:

the field of free virton quanta is equal identically to zero
the causal function of this virton field differs from zero.

We consider this virton field can be a good candidate for the description of quark confinement.It is suggested that the physical particles are described by the ordinary quantized fields but they interact with each other through the quark‐virton field only. Using the simplest form of the interaction Lagrangian invariant under transformations of the SU(3) × SUc(3) × U1 group, the mass corrections, some strong, weak and electromagnetic decays of the vector and pseudoscalar mesons are considered. A good agreement with experiment is obtained.
Polarization Phenomena in Elastic Electron‐Proton Scattering
Authors: Kobayashi Masaaki 
Published: July 2007

AbstractA unified treatment is given by using the scattering matrix in the Pauli spin spaces and polarization density matrices. Various quantities such as polarization P, asymmetry A, spin correlation parameters Cαβ, double polarization asymmetry Aαβ, polarization transfer parameters Dt, At, Rt and depolarization and spin rotation parameters D, A, R are expressed in terms of six coefficients which appear in the scattering matrix. Some explicit expressions as well as numerical results for these quantities are also given in the one photon exchange approximation.
Space‐Time Approach to the Description of Cumulative‐Type Processes
Authors: Kalinkin B. N. , Cherbu A. V. , Shmonin V. L. 
Published: July 2007

AbstractAn approach to the description of cumulative‐like processes is developed. It explicitly uses space‐time factors determining the development of these processes and some general features of hadronic inclusive spectra. The results are compared with all the available experimental data. The predictions testable in current and planned experiments are given.
Problems of Deep Inelastic Lepton‐Nucleus Interaction
Authors: Darbaidze Ya. Z. , Esakia S. M. , Garsevanishvili V. R. , Menteshashvili Z. R. 
Published: July 2007

AbstractThe deep inelastic scattering of electrons (muons) and neutrinos on the nuclei and the process of lepton pair production in hadron‐nucleus collisions are considered. The expressions for the corresponding differential cross‐sections are derived provided the final lepton and the spectator fragment of the initial nucleus are detected in coincidence. The structure functions of the processes under consideration are analysed by the principle of automodelity. Some scale‐invariant regularities are established for them. In the framework of “light front” formalism for many‐body systems the relations of these structure functions to the usual structure functions of the deep inelastic lepton hadron interaction are obtained. A hypothesis is put forward on the scale invariance of structure functions with respect to the ξ‐variable which is some complicated dimensionless combination of kinematic invariants.