scispace - formally typeset
Search or ask a question

Showing papers in "Nuovo Cimento Della Societa Italiana Di Fisica A-nuclei Particles and Fields in 1985"


Journal ArticleDOI
TL;DR: In this article, the existence of a nontrivial continuum QED with a fixed bare coupling constant is analyzed and a simple physical interpretation of the results of the computer simulations in lattice QED is given.
Abstract: The phase diagram in the coupling constant in QED and its connection with the spontaneous chiral symmetry breaking are discussed. The mechanism of such a breaking connected with the collapse phenomenon is considered and a simple physical interpretation of the recent results of the computer simulations in lattice QED is given. The problem of the existence of the nontrivial continuum QED is analysed and, as a result, the following hypothesis is considered: in the Landau-Pomeranchuk-Fradkin « zero-charge » situation (the renormalization constantZ 3=0) theS-matrix of continuum QED with a fixed bare coupling constant,α (0)=α c∼1, is nontrivial. The physical content of such a hypothetical continuum theory is revealed.

239 citations


Journal ArticleDOI
TL;DR: In this article, a new statistical approach is adopted which, through a suitable analysis of light clusters emitted in heavy-ion collisions, allows us to evaluate temperature and free-nucleon densities of the emission source.
Abstract: A new statistical approach is adopted which, through a suitable analysis of light clusters emitted in heavy-ion collisions, allows us to evaluate temperature and free-nucleon densities of the emission source. All known data concerning the emission of2H,3H,3He,4He measured in a common experiment are used. These data refer to 19 heavy-ion reactions studied at projectile energies between 26 and 2100 MeV per nucleon. Analysed events are only those attributable to the equilibrium component through carefully adopted selections. Among the results, a correlation is observed between temperatureT and total free-nucleon density ϱt F of the emission source. A nuclear-matter model is formulated in order to compare its quantitative predictions with the observed (T, ϱ t F) correlation. A good agreement is found by this comparison.

182 citations


Journal ArticleDOI
TL;DR: In this article, the authors formulate anomalous chiral and related Ward-Takahashi identities in supersymmetric-gauge theories, by generalizing Fujikawa's functionalintegral method to superspace.
Abstract: We formulate anomalous chiral and related Ward-Takahashi identities in supersymmetric-gauge theories, by generalizing Fujikawa’s functional-integral method to superspace. Our approach provides a manifestly supersymmetric and gauge-covariant treatment of the superspace Abelian anomalies, and is applicable to chiral- as well as to left-right symmetric theories. Non-Abelian anomalies are also discussed briefly. Superspace Abelian anomalies imply that particular composite operators,i.e. those containing the associatedU1 currents as a component, exhibit an anomalous supermultiplet structure. We discuss how this leads to various exact relations between scalar and gauge fermion condensates, thereby imposing strong constraints on possible chiral-symmetry realizations in supersymmetric-confining theories.

160 citations


Journal ArticleDOI
TL;DR: Miyazawa's supersymmetric generalization of the approximate SU 6/21 symmetry of hadrons is shown to hold in the same approximation for which SU 6 is a good symmetry, provided a diquark structure emerges through an effective string interaction as mentioned in this paper.
Abstract: Miyazawa's supersymmetric generalization of the approximateSU 6 symmetry of hadrons, namelyU 6/21, is shown to arise within the frame of the standard theory of quarks interacting through gluons. The supersymmetry is found to hold in the same approximation for whichSU 6 is a good symmetry, provided a diquark structure emerges through an effective string interaction. The spin independence of the confining force of the strong-coupling regime then explains the near parallelism of the leading Regge trajectories for baryons and mesons. Symmetry breaking is due to mass differences of the constituents and spin-dependent forces caused by gluon exchange. TheU 6/21 algebra is also shown to be embedded in a larger octonionic algebra which puts mesons and baryons, exotic mesons, quarks and diquarks in the same multiplet. The experimental evidence for the existence of qq and $$qq\overline {qq} $$ systems is briefly discussed.

69 citations



Journal ArticleDOI
TL;DR: In this article, the existence of extreme breathing nuclear states is predicted in the framework of coherent density fluctuation model, where the nuclear size is considerably larger in the excited states than in the ground state.
Abstract: The existence of extreme breathing nuclear states is predicted in the framework of coherent density fluctuation model. The energies of these states are comparable with the nuclear binding energies. The nuclear size is considerably larger in the excited states than in the ground state. There exists a threshold with respect to the mass numberA for the appearance of the breathing vibrations. The extreme nuclear states are discussed in relation with the collective mechanism in deep inelastic proton-nuclei scattering, in which a formation of highly excited system is suggested.

32 citations


Journal ArticleDOI
TL;DR: Schwinger's action principle for transition amplitudes, in quantum mechanics and field theory, is derived for long-range interactions by using the unescapable fact that a scattering out-(in-) state when translated forward (backward) in time for large positive (negative) times may stilldepend on the quantum-mechanical coupling parameter.
Abstract: Schwinger’s action (dynamical) principle for transition amplitudes, in quantum mechanics and field theory, is derived for long-range interactions by using the unescapable fact that a scattering out-(in-) state when translated forward (backward) in time for large positive (negative) times may stilldepend on the quantum-mechanical coupling parameter. For such interactions, the dynamical principle is different from the conventional one used extensively historically in the literature. As a corollary to our main result we show that the integrand in the Feynman path integral formulation is not simply given by exp [i[Action]]. Applications of the derived results are then given to the specific cases for the Coulomb interaction and to quantum electrodynamics.

28 citations


Journal ArticleDOI
TL;DR: In this article, it was shown that in the framework of quantum field theory with non-Euclidean momentum space there exist several equally acceptable expressions for the Dirac wave operator, which depend parametrically on the fundamental mass.
Abstract: It is demonstrated that in the framework of quantum field theory with non-Euclidean momentum space there exist several different equally acceptable expressions for the Dirac wave operator, which depend parametrically on the fundamental massM. As a result there appears the necessity to consider fermion fields of different types, includingexotic fields which increase in the flat limitM→∞ as √M. The description of all fermionic fields is made along the lines accepted in the previous article of this series. The main feature of the developed approach —the locality of the theory in configuration space of five dimensions— is conserved.

22 citations


Journal ArticleDOI
Y. Hoshino1
TL;DR: In this article, the Schwinger-Dyson equation for the quark propagator is solved numerically and an infra-red nonsingular solution is found, which gives the finite vacuum expectation value 〈\(\bar \psi \)ψ〉0.
Abstract: Schwinger-Dyson equation for the quark propagator is solved numerically. Because of the gluon mass, an infra-red nonsingular solution is found. This solution gives the finite vacuum expectation value 〈\(\bar \psi \)ψ〉0. By studying the effective potential to the two-loop order, chiral symmetry is suggested to break spontaneously even in two dimensions. But the Goldstone boson becomes massive through the interaction determined by nonlinearσ-model.

19 citations


Journal ArticleDOI
TL;DR: In this article, the authors provide a general, co-ordinate-free geometrical presentation of ideas advanced before in coordinate language with reference to specific instances, which generalizes to non-Abelian fields results of extant "geometrical quantization".
Abstract: The aim of this paper is to provide a general, co-ordinate-free geometrical presentations of ideas advanced before in co-ordinate language with reference to specific instances. This approach generalizes to non-Abelian fields results of extant “geometrical quantization»; it also permits a natural connection between quantum mechanics and information theory, as discussed elsewhere.

18 citations


Journal ArticleDOI
TL;DR: In this paper, the theory of the free electromagnetic field and the Yang-Mills field is developed adequately by taking into account the non-Euclidean character of the momentum 4-space.
Abstract: SummaryThe present paper is the second of a new series of our publications on quantum field theory with the fundamental mass. Here the theory of the free electromagnetic field and the Yang-Mills field is developed adequately by taking into account the non-Euclidean character of the momentum 4-space. Similarly to the scalar model this scheme allows a specific local formulation in the five-dimensional configuration space. It is remarkable that the symmetry of the theory with respect to gauge transformations within this formulation looks like a broken local gauge symmetry in five dimensions, the breaking mechanism being of universal form.RiassuntoQuesto lavoro è il secondo di una nuova serie di pubblicazioni nostre sulla teoria quantistica di campi con massa fondamentale. La teoria del campo elettromagnetico libero e del campo di Yang-Mills è qui sviluppata adeguatamente considerando il carattere non euclideo del quadrispazio degli impulsi. Analogamente al modello scalare questo schema ammette una specifica formulazione locale nello spazio delle configurazioni a cinque dimensioni. Si nota che la simmetria della teoria rispetto alle transformazioni di gauge nell'ambito di questa formulazione assomiglia ad una simmetria di gauge locale rotta in cinque dimensioni, essendo il meccanismo di rottura di forma universale.РезюмеРабота является второй публикацией в рамках нового цикла наших исследований по квантовой теории поля с фундаментальной массой. В ней развита калибровочная теория свободнго электромагнитного поля и поля Янга-Миллса, адекватно учитывающая неевклидов характер импульсного 4-пространства. Подобно скалярной модели, данная схема допускает своеобразную локальную формулировку в пятимерном конфитурационном пространстве. Замечательно, что в этой формулировке симметрия теории относителЯно калибровочных преобразований принимает облик нарушенной локальной симметрии в пяти измерениях, причем механизм нарушения имеет универсальный характер.

Journal ArticleDOI
TL;DR: The notion of covariance and propagation in quantum space-times constituting such fiber bundles is investigated in this paper, which gives rise in a natural manner to certain realizations of relativistic canonical commutation relations in terms of covariant derivatives involving internal as well as external degrees of freedom of space-time excitons.
Abstract: Quantum geometries whose points are stochastic and serve as seats for quantum space-time excitons are formulated as fibre bundles over base spaces of mean values with a Minkowski or general relativistic structure. The fibres contain the proper wave functions of all exciton states in a given model. The notion of covariance and propagation in quantum space-times constituting such fibre bundles is investigated. Maxwell and Yang-Mills gauge degrees of freedom are introduced by appropriately enlarging the structure group, which in all cases contains phase-space representations of the Poincare group corresponding to the exciton wave function sample space specific to a given model. It is shown that these formulations give rise in a natural manner to certain realizations of the relativistic canonical commutation relations in terms of covariant derivatives involving internal as well as external degrees of freedom of space-time excitons.

Journal ArticleDOI
TL;DR: In this article, the masses of multiquark hadrons were estimated by using simplified string, bag and NR potential models, and the results turn out to be qualitatively similar in all these models.
Abstract: The use of basis states described as hadronic (or hadron-hadron) or hidden-colour (or colour-colour) for a system of quarks does not necessarily imply that connected exotic multiquark hadrons do exist. Antisymmetrization of quark wave functions tends to make these descriptions ill defined. It appears necessary to have stable collective structures called strings or bags to provide the physical connections required by quark confinement. The masses of multiquark hadrons can then be estimated by using simplified string, bag and NR potential models. The results turn out to be qualitatively similar in all these models. The stability problem for multiquark strings is briefly discussed.

Journal ArticleDOI
TL;DR: In this article, the relativistic canonical communication relations for a massive particle with spin are determined by the requirements that the set of Poincare group generators form a covariant tensor operator, and that a certain covariance condition be satisfied.
Abstract: It is shown how the relativistic canonical communication relations (RCCRs) for a massive particle with spin are essentially uniquely determined by the requirements that the set of Poincare group generators form a covariant tensor operator, and that a certain covariance condition be satisfied An outline of the connection between stochastic-phase-space representations of the Poincare group and realizations of the RCCRs is presented, and the possibility of generalization to curved space-times with internal gauge symmetry is considered

Journal ArticleDOI
TL;DR: In this paper, a scalar coupling model of the Higgs and fermion is considered, and the Julia-Zee dyon's ansatz is not complete, but the closed equations of the radial wave functions of the Fermion are obtained.
Abstract: A scalar coupling model ofSU2 Higgs and fermion is considered. It is shown that 1) the Julia-Zee dyon's ansatz is not complete. But, if we treat the Julia-Zee dyon as external potential, the closed equations of the radial wave functions of the fermion are obtained. 2) The asymptotic solutions of the fermion's radial wave functions at infinity and near the origin are solved. 3) The necessary condition of the fermion's bound state is qualitatively discussed, which shows that for the dyon case in which the scalar coupling approaches zero, the existence of the fermion's bound states is possible, but for the monopole case in which the scalar coupling approaches zero the fermion's bound states do not exist.

Journal ArticleDOI
TL;DR: In this paper, the relation between five-dimensional quantum field theory and conventional quantum electrodynamics is also elucidated by taking discrete mass states for field operators, and it is shown that the quantization in terms of the invariant time is equivalent to the conventional quantization of the ordinary time.
Abstract: Five-dimensional quantum field theory is formulated by employing the invariant times as a useful parameter for quantizing field operators. It is shown that the quantization in terms of the invariant time is equivalent to the conventional quantization in terms of the ordinary time. The relation between five-dimensional quantum field theory and conventional quantum electrodynamics is also elucidated by taking discrete mass states for field operators.

Journal ArticleDOI
TL;DR: A class of irreducible finite-dimensional representations of the Lie superalgebragln/m, which are constructed in terms of creation and annihilation operators acting in certain Fock superspaces, were investigated in this article.
Abstract: We investigate a class of irreducible finite-dimensional representations of the Lie superalgebragln/m, which are constructed in terms of creation and annihilation operators acting in certain Fock superspaces. For these representations we calculate the highest weights relative to representatives of all (n+m)!/n!m! conjugacy classes of Borel subalgebras ofgln/m.

Journal ArticleDOI
TL;DR: In this paper, a variational formulation of nuclear fluid dynamics is presented, which is valid both for zero and for finite temperatures, and equations for small-amplitude oscillations around a stationary state are derived.
Abstract: A variational formulation of nuclear fluid dynamics is presented, which is valid both for zero and for finite temperatures The equations for small-amplitude oscillations around a stationary state are derived As an example of the variational approach, a fluid-dynamical calculation which avoids the so-called scaling approximation but takes into account distortions of the Fermi surface is briefly discussed

Journal ArticleDOI
TL;DR: The bola model as discussed by the authors is a phenomenological model with the aim of affording easy and reliable computations of meson and baryon mass spectra for given interactions.
Abstract: Relativistically covariant quantum mechanics with direct interaction is used to construct a model of several confined particles. Suggested by the three-gluon vertex of QCD this model is characterized by an interaction center and therefore called «the bola model». It is a phenomenological model with the aim of affording easy and reliable computations of meson and baryon mass spectra for given interactions. The presentation is preceded by a corresponding classical relativistic dynamics.

Journal ArticleDOI
TL;DR: In this paper, a method for simplifying the evaluation of the infinite parts of Feynman diagrams is presented, based on the observation that counterterms are local functions, and all integrals are reduced to logarithmically divergent ones with no masses or external momenta.
Abstract: A method for simplifying the evaluation of the infinite parts of Feynman diagrams is presented. It is based on the observation that counterterms are local functions. All integrals are reduced to logarithmically divergent ones with no masses or external momenta. The method is particularly useful for many-point Green's functions at more than one loop. Here a pedagogical approach is taken, using the example of a massiveϕ3 theory in six dimensions.

Journal ArticleDOI
TL;DR: In this article, a measurement made with a Ge (Li) detector and nine NaI detectors in a 4π geometry is reported, and the following limits have been obtained after 1079 hours.
Abstract: Neutrinoless double beta decays of76Ge (Jπ=0+) leading to the excited states (Jπ=21+,E=559.1 keV andJπ=02+,E=1122.3 keV) of76Se have been investigated. After some theoretical considerations about the information one can extract from the experimental data, we report on a measurement made with a Ge (Li) detector and nine NaI detectors in a 4π geometry. The following limits have been obtained after 1079 hours, of statisticsT1/2(0+→21+)≥5.5·1021 y andT1/2(0+→02+)≥2.3·1021 y (at 68% confidence level).

Journal ArticleDOI
TL;DR: In this article, the Skyrme chiral soliton model of the nucleon is generalized to the case of u, d, s flavours of quarks and applied to the baryon octet and decimet representations of SU3-flavour.
Abstract: The Skyrme chiral soliton model of the nucleon is generalized to the case of u, d, s flavours of quarks and applied to the baryon octet and decimet representations ofSU3-flavour. We recall that the physical basis of the model is a topological interpretation of baryon number conservation and a representation of baryons as the solitons of an extended nonlinear mesonicσ-model for chiralSU3-flavour. The chiral Lagrangian consists of the standard quadratic coupling in the meson fields, of the commutatorlike quartic coupling and of the additional couplings specified by the correspondence with the underlying dynamics of QCD, namely the Wess-Zumino-Witten action and the coupling terms responsible for the breaking of the flavour, isospin andUA,1 symmetries. Computations are carried out for the mass spectra of the baryon octet and decimet, the mass splittings and the low-energy single-current observables. Predictions match with observations at a level of 20%.

Journal ArticleDOI
TL;DR: In this paper, the expansion coefficients for fundamental bases of a quantum circular oscillator are calculated and the values of these coefficients are tabulated for some particular cases, such as the case when the oscillator has a polar base and a Cartesian base.
Abstract: Expansion coefficients for fundamental bases of a quantum circular oscillator are calculated. Formulae are found for the coefficients of expansions of the elliptic bases over the polar and Cartesian ones. The values of these coefficients are tabulated for some particular cases.

Journal ArticleDOI
TL;DR: In this article, a pair of coupled Dirac equations for the quark-antiquark system with equal or unequal masses were proposed, and when the coupling terms are carefully chosen, the equations are mutually compatible, and lead by iteration to a relativistic harmonic-oscillator equation.
Abstract: We write a pair of coupled Dirac equations for the quark-antiquark system (with equal or unequal masses). When the coupling terms are carefully chosen, the equations are mutually compatible, and lead by iteration to a relativistic harmonic-oscillator equation, plus complementary conditions on the timelike oscillator and on the spinors. The coupling terms contain phenomenological parameters, which are adjusted on the experimental meson spectrum.

Journal ArticleDOI
TL;DR: In this paper, the role played by composite vector supermultiplets is studied in detail in the context of general supersymmetric confining theories, and the structure of the low-energy effective action involving these vector super multiplets is determined by use of the chiral WT identities.
Abstract: The role played by composite vector supermultiplets is studied in detail in the context of general supersymmetric confining theories. The structure of the low-energy effective action involving these vector supermultiplets is determined by use of the chiral WT identities. One of the most interesting outcome is the universal appearance of an effective gauge symmetry structure. Another is the emergence of a generationlike structure among the composite « matter » multiplets under this effective gauge symmetry.


Journal ArticleDOI
TL;DR: In this paper, the elastic-scattering data were analyzed in the framework of the R-matrix theory and six resonances have been observed and their parameters determined, and three other resonances were identified in the 19F(p, α) reactions.
Abstract: Absolute differential cross-sections for19F(p, p) elastic scattering and19F(p, ∝0-π), (p, ∝1-3)reactions were measured forEp=(1.5÷ ÷2.1) MeV. The elastic-scattering19F(p, p) data were analysed in the framework of theR-matrix theory. Six resonances have been observed and their parameters determined. Three other resonances have been identified in the19F(p, α) reactions. The 0+, 14.47 MeV state in20Ne has been identified as aT=1 state and is suggested to be the isobaric analogue state of the 4.315 MeV state in20F.

Journal ArticleDOI
TL;DR: In this paper, the problem of chiral symmetry breaking on the basis of an ansatz for the vertex functions which incorporates the transverse parts was examined and a broken-symmetry solution with interesting properties was presented.
Abstract: We investigate the Dyson equations and Ward identities satisfied by the flavor current vertex functions in continuum QCD. We examine the problem of chiral symmetry breaking on the basis of an ansatz for the vertex functions which incorporates the transverse parts. We exhibit a broken-symmetry solution with interesting properties. This solutions leads to an entire function for the quark propagator indicative of confinement. It is also gauge invariant.

Journal ArticleDOI
TL;DR: In this paper, a total of 1.8·106 photograms of the 180 litre xenon bubble chamber exposed to a K+ beam with 0.85 GeV/c momentum were measured and the ratio of theCP-violating to the CP-conserving amplitudes was measured.
Abstract: In a total of 1.8·106 photograms of the 180 litre xenon bubble chamber exposed to a K+ beam with 0.85 GeV/c momentum, 409 identified K0→π+π−π0 decays were selected and the ratio of theCP-violating to theCP-conserving amplitudes η+−0=A(K S o →π+π−π0)/A (K L 0 →π+π−π0) was measured. The results are: η+−0=(−0.002 ±, 0.23) +i(−0.14±0.35), and assuming Re η+−0=0, |η+−0|2<0.2 and Г(K S 0 →π+π−π0)/Г(K S 0 →all)<5.5·10−5 at the 90% c.l. Moreover, combining the present results with those of a previous experiment performed and analysed in a similar way, corresponding to a total of 601 events, η+−0=(0.05±0.17)+i(0.15±0.33);|η+−0|2<0.23 and Г(K S 0 → π+π−π0)/Г(K S 0 →all)<4.9·10−5 were obtained.

Journal ArticleDOI
TL;DR: The Faddeev-Popov charge-zero and charge-one sectors of the cohomology space of the differential operator δΓc1L were studied in this article.
Abstract: We study the Faddeev-Popov charge-zero and charge-one sectors of the cohomology space of the differential operator δΓc1L which induces general co-ordinate transformations in four-dimensional space-time. We shall use, with some modification, a technique introduced some years ago by Dixon. In this paper we show that the cohomology of the operator δΓc1L on the local functional space is isomorphic to the cohomology of the operatorS=δΓc1L−Cλ(x∂λ−∂λCλ(x) on the domain of local polynomial functions.