Showing papers in "Nuovo Cimento Della Societa Italiana Di Fisica A-nuclei Particles and Fields in 1995"
TL;DR: In this paper, the authors prove perturbative unitarity of the S-matrix on the physical Hilbert space for Yang-Mills theories with matter fields in the causal approach.
Abstract: SummaryWe prove perturbative unitarity of theS-matrix on the physical Hilbert space for Yang-Mills theories with matter fields in the causal approach. Here unitarity is a direct consequence of gauge invariance. To establish the latter, we prove theC-number identities for gauge invariance (Cg-identities).
46 citations
TL;DR: In this article, a generalized Kaup-Newell spectral problem is introduced, which corresponds to infinitely many hierarchies of soliton equations and two new hierarchical systems are derived from two reductive spectral problems.
Abstract: A generalized Kaup-Newell spectral problem is introduced. This spectral problem corresponds to infinitely many hierarchies of soliton equations. Further two reductions of the generalized Kaup-Newell spectral problem are discussed and two new hierarchies of associated soliton equations are derived. Through non-linearization of two reductive spectral problems, two new finite-dimensional integrable systems are engendered, which possess non-confocal involutive integrals of motion.
42 citations
TL;DR: In this article, a Lagrangian for the neutral-particle theory is proposed, which is an example of the Nigam-Foldy-Bargmann-Wightman-Wigner type quantum field theory based on the doubled representations of the extended Lorentz group.
Abstract: Equations describing self/anti-self-charge conjugate states, recently proposed by Ahluwalia, are re-written in covariant form. The corresponding Lagrangian for the neutral-particle theory is proposed. From a group-theoretical viewpoint the construct is an example of the Nigam-Foldy-Bargmann-Wightman-Wigner-type quantum field theory based on the doubled representations of the extended Lorentz group. Relations with the Sachs-Schwebel and Ziino-Barut concepts of relativistic quantum theory are discussed.
40 citations
TL;DR: In this paper, lower limits on neutrino masses were derived from necessary consistency conditions on a class of SO(10) GUT models with SU(4)PS⊗SU(2)L⊂SU(1)R or SU(3)C⊆SU(3), SU(2), L⊈SU(4), SU (2)R, U(1)-B−L intermediate gauge symmetry.
Abstract: In the last few years physicists have been looking atSO(10) GUT models with renewed attention because it has been realized that theSU(5) minimal model cannot unify the strong, electromagnetic and weak interactions in a way consistent with the experimental values of α(Mz),\(\sin ^2 \theta _W \left( {M_Z } \right)\) and\(\alpha _S \left( {M_Z } \right)\). In this paper we derive lower limits on neutrino masses, relevant for cosmology and for the solar-neutrino problem, from necessary consistency conditions on a class ofSO(10) models withSU(4)PS⊗SU(2)L⊗SU(2)R orSU(3)C⊗SU(2)L⊗SU(2)R⊗U(1)B−L intermediate gauge symmetry.
16 citations
TL;DR: In this paper, a modification of the Veltman condition based on the compensation of vacuum energies is developed to predict the top-quark and Higgs-boson masses.
Abstract: The fine-tuning principles are examined to predict the top-quark and Higgs-boson masses. The modification of the Veltman condition based on the compensation of vacuum energies is developed. It is implemented in the Standard Model and in its minimal extension with two Higgs doublets. The top-quark and Higgs-boson couplings are fitted in the SM for the lowest ultraviolet scale where the fine-tuning can be stable under rescaling. It yields the low-energy valuesmt≅≅ 175 GeV,mH≅210 GeV.
12 citations
TL;DR: A model to treat state-dependent short-range correlations in finite nuclei is developed to study the effects of the various correlation channels on the nuclear charge distribution.
Abstract: A model to treat state-dependent short-range correlations in finite nuclei is developed. The model is applied to study the effects of the various correlation channels on the nuclear charge distribution. Results for the208Pb nucleus are presented.
10 citations
TL;DR: In this paper, the 3.7A GeV32S ions in nuclear emulsion have been investigated and the multiplicities of charged particles emitted from both projectile and the target nuclei have been studied.
Abstract: The interactions of 3.7A GeV32S ions in nuclear emulsion have been investigated. The multiplicities of charged particles emitted from both projectile and the target nuclei have been studied. The data are compared with current results on the interactions of relativistic ions with emulsion nuclei. The variation of the characteristics of the nucleus-nucleus interactions with the projectile mass number is investigated. The correlations between various kinds of particles of multiple production in32S-Em collisions are presented.
9 citations
TL;DR: In this paper, the authors studied the effect of Coulomb interaction with the nuclear charge on the electron scattering off 16O,40Ar, 208Pb and 238U, including the distortion of the incoming and outgoing electron wave due to Coulomb interactions.
Abstract: The inclusive quasi-elastic electron scattering off16O,40Ar,208Pb and238U is studied including the distortion of the incoming and outgoing electron wave due to Coulomb interaction with the nuclear charge. The total cross-section, containing a new term due to the interference between the longitudinal and transverse structure functions, is discussed within the impulse approximation where final-state interaction and binding effects are included by using sum rules techniques. The quasi-elastic scattering induced by positrons is also investigated.
8 citations
TL;DR: In this article, the basic characteristics of singly, doubly and heavily charged fragments of the incident nucleus in inelastic interactions of relativistic 24Mg nuclei in nuclear emulsion are presented.
Abstract: We present the basic characteristics of singly, doubly and heavily charged fragments of the incident nucleus in inelastic interactions of relativistic24Mg nuclei in nuclear emulsion. The relationship between the charge of the incident projectile nuclei and those of the projectile fragments is studied. The result reflects the importance of the charge of the incident projectiles and consequently the electromagnetic interactions in the fragmentation processes.
8 citations
TL;DR: In this article, the characteristics of secondary particles produced in 4.5 GeV/c12C-nucleus reactions were investigated and the correlations of fast target protons with evaporated and shower particles emitted in 12C nucleus interactions have been thoroughly studied.
Abstract: An attempt has been made to investigate the characteristics of secondary particles produced in 4.5 GeV/c12C-nucleus reactions. The correlations of fast target protons with evaporated and shower particles emitted in12C-nucleus interactions have been thoroughly studied. The results reveal that /D increases withNg and is in fine agreement with the predictions of the simple independent particle model. Furthermore, the ratioD/ decreases withNg. This result is in marked disagreement with the predictions of collective tube model and supports the models which include repeated collisions. Finally our results are almost similar to those obtained in high-energy particle-nucleus collisions.
8 citations
TL;DR: In this paper, the a1→π(ππ)S-wave decay and the low-energy ππ-scattering are considered within current algebra at the quark level (CA)q and chiral perturbation theory (CHPT)q based on the extended Nambu-Jona-Lasinio model with linear realization of chiral U(3)×U(3)-symmetric symmetry.
Abstract: The a1→π(ππ)S-wave decay and the low-energy ππ-scattering are considered within current algebra at the quark level (CA)q and chiral perturbation theory at the quark level (CHPT)q based on the extended Nambu-Jona-Lasinio model with linear realization of chiralU(3)×U(3) symmetry. It is shown that low-energy interactions of a new kind, produced by convergent constituent-quark diagrams and being very useful for the theoretical understanding of experimental data on the processes under consideration, are very good blending with (CA)q and (CHPT)q. The contribution of these interactions is caused by the application of ordinary rules of quantum field theory. These interactions allow one to escape the problem of the quark condensate, vanishing in the chiral limit.
TL;DR: Fission fragment folding-angle technique has been used to separate the complete fusion-fission and the transfer-induced fission (TF) components in the reaction of19F on232Th for the first time in sub-barrier energies.
Abstract: Fission fragment folding-angle technique has been used to separate the complete fusion-fission (CFF) and the transfer-induced fission (TF) components in the reaction of19F on232Th for the first time in sub-barrier energies. The fragment folding-angle distributions were measured using two position-sensitive Breskin-type detectors and were compared with simulations based on the kinematics for complete fusion-fission and transfer-fission events. The results on the excitation function and angular distributions for the CFF, TF and total fission events have been simultaneously measured over the bombarding energy range of 78.5 MeV to 106.5 MeV for the above system.
TL;DR: In this paper, the modification of the scaling behavior of parton distributions due to quantum statistical effects is studied. But the authors do not consider the effect of the Boltzmann equation on the parton distribution.
Abstract: The phenomenological evidence of quantum statistical effects in parton physics is here briefly summarized, and the recent good results obtained by parameterizing the parton distributions in terms of Fermi-Dirac and Bose-Einstein statistical functions are discussed. In this framework we study the modification of the scaling behaviour of parton distributions due to quantum statistical effects. In particular, by following a well-known formal analogy which holds between the Altarelli-Parisi evolution equations, at leading-log approximation, and a set of Boltzmann equations, we suggest a generalization of evolution equations to take into account Pauli exclusion principle and gluon-induced emission.
TL;DR: In this paper, the authors showed that the magnitude and phase shift of the penguin amplitude can be determined only from the branching ratios of the SU(3) relations, and they showed that not only the magnitude but also the strong phase shift can be estimated only from branching ratios.
Abstract: A reliable prediction forCP violation in Bd0vs.\(B_d^0 {\mathbf{ }}vs.{\mathbf{ }}\bar B_d^0 \to \pi ^ + \pi ^ - \) suffers from the penguin-diagram induced uncertainty. With the help ofSU(3) relations, we show that not only the magnitude but also the strong phase shift of the penguin amplitude can be approximately determined only from the branching ratios of\(B_d^0 {\mathbf{ }}vs.{\mathbf{ }}\bar B_d^0 \to \pi ^ + \pi ^ - ,B_d^0 \to K^ + \pi ^ - \), and\(B_u^0 \to K^0 \pi ^ + \).
TL;DR: In this paper, the generalized three-particle Bargmann-Wigner equations are derived from a non-linear isospinor-spinor field equation and a special class of spin-1/2 bound states are calculated.
Abstract: Starting from a non-linear isospinor-spinor field equation, generalized three-particle Bargmann-Wigner equations are derived. In the strong-coupling limit, a special class of spin-1/2 bound states are calculated. These solutions which are antisymmetric with respect to all indices, have mixed symmetries in isospin-superspin space and in spin orbit space. As a consequence of this mixed symmetry, we get three solution manifolds. These solution manifolds are interpreted as the three generations of leptons and quarks. This interpretation will be justified in a forthcoming paper.
TL;DR: In this paper, the multiplicity distributions and the correlations of different types of slow particles produced in 200A GeV oxygen-induced interactions with emulsion nuclei are presented within the framework of the generalized Andersson-Otterlund-Stenlund (AOS) model.
Abstract: The multiplicity distributions and the correlations of different types of slow particles produced in 200A GeV oxygen-induced interactions with emulsion nuclei are presented. The experimental distributions are studied within the framework of the generalized Andersson-Otterlund-Stenlund (AOS) model for nucleus-nucleus interactions. The generalized (AOS) model fails to describe the present experimental data. Also a systematic comparison using the calculations of VENUS model is made. The grey-particles multiplicity is successfully reproduced by the theoretical multistring model VENUS, while the model is inadequate for explaining the distribution of black particles.
TL;DR: In this paper, a structural explanation of the coupling constants in the standard model, i.e., the fine-structure constant and the Weinberg angle, and of the gauge-fixing contributions is given in terms of symmetries and representation theory.
Abstract: A structural explanation of the coupling constants in the standard model,i.e. the fine-structure constant and the Weinberg angle, and of the gauge-fixing contributions is given in terms of symmetries and representation theory. The coupling constants are normalizations of Lorentz invariantly embedded little groups (spin and polarization) arising in a harmonic analysis of quantum vector fields. It is shown that the harmonic analysis of massless fields requires an extension of the familiar Fourier decomposition, containing also indefinite unitary non-decomposable time representations. This is illustrated by the non-probabilistic contributions in the electromagnetic field.
TL;DR: In this article, the authors consider the possibility of separating the opposite spin states of the (anti)protons belonging to a circulating beam via repetitive longitudinal Stern-Gerlach kicks.
Abstract: We consider the possibility of separating the opposite spin states of the (anti)protons belonging to a circulating beam via repetitive longitudinal Stern-Gerlach kicks. Comparisons are made with the already proposed method based upon reiterated transverse Stern-Gerlach kicks.
TL;DR: In this paper, a six-dimensional Wess-Zumino model is examined, where the component fields are quantized in such a way that the operator representing the supercharge is the generator of supersymmetry transformations.
Abstract: We examine a six-dimensional Wess-Zumino model. The equations of motion are of the fourth order, implying two modes of propagation; a normal bradyonic mode and a tachyonic mode. The conserved fermion current is constructed. The component fields are quantized in such a way that the operator representing the supercharge is the generator of supersymmetry transformations. The quantization is complemented by the definition of the vacuum for both modes. The evaluation of vacuum expectation values leads to a Feynman propagator for the normal mode and a half-advanced and half-retarded propagator for the tachyon mode. Convolutions between these propagators show consistency with unitarity.
TL;DR: In this article, the mean free path λ (m.f.p.) of 16O ions was calculated and found to be 12.81±0.39 cm, indicating a small energy transfer between target and fragment.
Abstract: This work mainly deals with the study of the He-fragmentation of16O nuclei as a result of their interactions with nuclear emulsion at 200A GeV. The data being analyzed consist of 1088 inelastic16O-Em collisions. The mean free path λ (m.f.p.) of16O ions was calculated and found to be 12.81±0.39 cm. A comparison of the percentage ratios for producing He-projectile fragments (p. f.’s) in16O-Em collisions at the present energies with the corresponding values at different energies enables to test the limiting fragmentation hypothesis. The multiplicity distribution of the He-p.f.’s exhibits a KNO scaling. The projected angular distribution of these fragments is typically Gaussian-shaped. The nuclear temperature of the emitting system is inferred from the projected angular distribution of theZ=2 p.f.’s and is approximately equal to the projectile nuclear binding energy, indicating a small energy transfer between target and fragment.
TL;DR: In this paper, the first non-mesonic decays of light hypernuclei Λ6He and Λ5He with identification of the final residual nuclei 24He and 13He were measured with the FINUDA detector at the DAΦNEΦ-Factory.
Abstract: Exclusive non-mesonic decays of light hypernucleiΛ6He andΛ5He, with identification of the final residual nuclei24He and13He, could be measured for the first time with the FINUDA detector at the DAΦNEΦ-Factory. This results could shed light on the ΔI=1/2 rule.
TL;DR: In this paper, the conditions for satisfying both the Lorentz and SU(2)_invariances were studied. But the conditions were not considered for the preon model, where particle and antiparticle construct the weak isospin doublet.
Abstract: To account forCP violation in β-decay of the nucleon, we seek the conditions for satisfying both the Lorentz andSU(2)_invariances. To this end, we consider the preon model in which particle and antiparticle construct theSU(2) weak isospin doublet.
TL;DR: In this article, the authors studied the shower particles multiplicity distribution produced in 60A GeV16O-Em collisions in the framework of an extended Glauber model in which terms higher than the first (optical limit) in the phase shift expansion are considered.
Abstract: The shower particles multiplicity distribution produced in 60A GeV16O-Em collisions is studied in the framework of an extended Glauber model in which terms higher than the first (optical limit) in the phase shift expansion are considered. These are the so-called eclipse correction terms. The calculated distribution shows satisfactory agreement with the present experimental data.
ENEA1
TL;DR: The quark mixing matrix is diagonalized and the use of the exponential parametrization leads to straightforward results, obtained in exact form, without simplifying assumptions.
Abstract: The quark mixing matrix is diagonalized. The use of the exponential parametrization leads to straightforward results, obtained in exact form, without simplifying assumptions. We define weak-interaction eigenstates in the sense of Fritzch and Planckl. The relevant mass matrices are derived and are shown to belong to Barnhill canonical forms. It is proven that, at lowest order, these matrices exhibit a democratic structure. The mechanism of democracy breaking is finally discussed.
TL;DR: The ratios of the K+ total cross-section on nuclei to that on deuteron,RT, are calculated in the Glauber approach, to demonstrate the antishadowing in double scattering.
Abstract: The ratios of the K+ total cross-section on nuclei to that on deuteron,RT, are calculated in the Glauber approach, to demonstrate the antishadowing in double scattering. The K+N amplitudes derived from the Bonn meson exchange potential are used as input parameters. TheRT is sensitive to K+ɛ total cross-section and the ratioɛ of the real to imaginary part of the elementary K+RT amplitude. TheRT depends on the mass numberA of the target nucleus. |ɛ|>1 is essential to give rise to the antishadowing effects for light nuclei.
TL;DR: In this paper, the dependence of the level density in the second potential well on the nuclear shape symmetry for actinide nuclei was investigated, and it was shown that the second well has a higher level density than the first well.
Abstract: We investigate the dependence of the level density in the second potential well on the nuclear shape symmetry for actinide nuclei. We compare statistical theory calculations with the experimental results deduced by observing the fission times of Pa and Np isotopes. In the weak-coupling approximation of the two classes of excited states we find that the level density in the second well, higher than the one in the first well, is related to a symmetry breakdown of the nuclear shape of the second saddle point.
TL;DR: In this paper, the observed scale of ΔI=1/2 enhancement is set by charmed quark or charmed D-meson W-mediated loops, and all four K→3π decay amplitudes are linked to the above K0→2π transitions via PCAC and the dominant pion pole part.
Abstract: We show in many chiral schemes how to relate consistently K→2π to K to vacuum transitions. Then we discuss how the observed scale of ΔI=1/2 enhancement is set by charmed quark or charmed D-meson W-mediated loops. Lastly we demonstrate that all four K→3π decay amplitudes are linked to the above K0→2π transitions via PCAC and the dominant pion pole part. We conclude that all six K0→2π, K→3π weak decays are compatible with data.
TL;DR: In this paper, the 11B,15N and 19F (α,7Li) reaactions have been studied atEα= =27.2MeV to investigate the cluster structure of the above target-nuclei.
Abstract: The11B,15N and19F(α,7Li) reaactions have been studied atE
α= =27.2MeV to investigate the cluster structure of the above target-nuclei. The measured7Lig.s. and7Li0.478 angular distributions are analyzed with the contributions coming from the statistical and direct processes. The spectroscopic factors of the studied cluster configuration for the target-nuclei were deduced. The results are compared with the ones deduced by other authors at various incident energies.
TL;DR: In this paper, the angular distribution of the 3He, 2H and 4He particles was analyzed by a near/far-side formalism using Fuller's model, and different characteristics of the rainbow effects and the shape of the angular distributions for various reaction mechanisms were observed.
Abstract: Nuclear-rainbow effects in elastic and inelastic scattering and transfer reactions by the3He+12C interaction atE(3He)=98 MeV are observed, analyzing the angular distributions of the3He,2H and4He particles. The data are analyzed by a near/far-side formalism using Fuller's model. We also observe the different characteristics of the rainbow effects and of the shape of the angular distributions for various reaction mechanisms.
TL;DR: In this paper, an improved formulation of low-energy nuclear-fusion reactions based on the optical theorem was proposed. But this formulation is much less model dependent than previous theoretical approaches.
Abstract: We describe a new improved formulation of low-energy nuclear-fusion reactions based on the optical theorem. Our formulation is much less model dependent than previous theoretical approaches. We obtain an analytic formula for the cross-section,σ(E), which exhibits explicitly the energy and charge dependence ofσ(E). The formula indicates that some of the anomalous effects observed in deuterated metals may be justified theoretically if the imaginary part of the effective nuclear interaction in the elastic channel has a very weak component with a long finite interaction range.