Calculation of the differential and total cross sections of γπ interactions

The differential and total cross sections of the processes and 3 are calculated on the basis of the vector-dominance model and current algebra. Up to a photon energy of order 1 GeV, the cross sections of these processes are very small, and it is only in the region of the resonance that values 0.01–0.05 mb are reached.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 84–88, September, 1980.I am very grateful to Professor M. P. Rekalo for constant interest in the work.     

Luminescent Properties of Metal Porphyrin Reduction Products

We have investigated the luminescent properties of -anions in Zn and Pd complexes of octaethylporphin and etioporphyrin, and also of protonation products of -dianions (-monoanions of phlorins). It is established that the quantum yield of luminescence of -anion radicals in Zn complexes amounts to 2.9·10^–4. The lifetime of the lower excited (doublet) state is estimated to be 120 ± 25 nsec. We failed to reveal the luminescence of -dianions. In reducing the Pd porphyrins into -anion radicals and -dianions, a loss of the luminescent properties is observed. However, the -monoanion of phlorin in Pd octaethylporphin luminesces. The Zn complex of the phlorin anion also has the same properties. The spectral properties of Zn and Pd phlorin anions are similar: a large Stokes shift is observed at room temperature; on decrease in the temperature to 77 K the fluorescence spectrum becomes narrower, the maximum of the spectrum shifts strongly to the blue region, and the quantum yield of luminescence increases. The special features of the spectral properties of phlorin anions are explained by conformation changes in the excited state. It is found that in a solution at room temperature Pd phlorin anions quench the phosphorescence of neutral Pd porphyrins.     

Charged ±2π-twist Disclinations in Ferroelectric Liquid Crystals

The electrostatic charge of (±2)-twist disclinations in ferroelectric chiral smectic C liquid crystals is introduced as an approximation in order to simplify the evaluation of the electrostatic self-energy of disclination. As an example, electrostatic charges of (±2)-twist disclinations in an infinite sample are evaluated. Screening effects of free charges in a material and of the ferroelectric structure surrounding the disclination are taken into account by introducing a phenomenological depolarization factor.     

Scalar mesons in ππ and K¯K scattering

The s-wave pion scattering amplitude is analysed with the aim to clarify the mass spectrum of scalar mesons and to find evidence of lightest glueball. The S-matrix and K¯K coupled channel formalism is used. The existence of scalar mesons S^* and is implied by the data. The production K¯K and the elastic K¯KK¯K coupled amplitudes are predicted from the scattering data. The couplings c f S^* to and K¯K states are determined.     

A new approach to the problem of the anomalous magnetic moment of the electron

A heuristic model for deriving the anomalous magnetic moment of the electron is presented. A term /2 – 0.327(/)² is deduced, in better agreement with experiment than is the QED derivation of /2 – 0.328(/)². The result is strengthened by the recent non-QED account of the Lamb shift by Yu and Sachs.     

Three-pion resonances

We investigate the continuum three-pion problem within a relativistic three-body model that takes into account the S andP waves. The dynamical input of the two-body subsystem is given by separable potentials, which yield a good fit to the scattering data and resonance parameters up to a two-body invariant mass of 900MeV. We introduce a parameter expressing the ambiguity in the reduction of a fully relativistic theory to a three-dimensional one. The masses and widths of the ,a ₁(1260), and (1300) mesons, which decay predominantly into three pions, are reasonably well described by our model. Theh ₁(1170) meson, however, which also decays into three pions, cannot be explained as a three-pion resonance. Some Argand diagrams are shown in those channels where resonances exist.     

Note on the dispiration and 2π-disclination interaction in Sm C* phases of liquid crystal

The elastic interaction between the dispiration and the 2-disclination in Sm C^* phases of liquid crystal is estimated. It is shown that this interaction can influence the mobility of the 2-disclinations through the Sm C^* structure. The core energy of the twist-edge dispiration with the Burgers vector equal to the smectic layer thickness is estimated using the Peierls-Nabarro model.     

Constraints on πN threshold parameters and the sigma term from measuring the polarization

We discuss N polarizations and cross sections at low energies. Presently two conflicting solutions for the low energy amplitudes exist. The first one is based on low energy scattering data and disagrees with the chiral sigma term while the second one, based on mesic atoms level shifts, is consistent with chiral expectations. We show that the ^±p polarization atT _R = 51 MeV is able to distinguish these solutions. We also illustrate the sensitivity to the small P waves.Contributed paper to the symposium on Mesons and Light and Nuclei IV, Bechyn, Czechoslovakia, September 5–10, 1988.We would like to thank J. Gasser and H. Leutwyler for the stimulating collaboration on which this note is based. G. Höhler, R. Koch and H. M. Staudenmaier from the Karlsruhe group have generously supplied all conceivable information on their analysis.     

Off-shell effects inpp↔πd spin observables

We show that spin observables inppd are fairly sensitive to small changes in the off-shell N helicity amplitudes. This is illustrated at proton laboratory kinetic energies ofT _p=515 MeV andT _p=578 MeV. A reduction of the helicity-flip amplitude by 13% brings the predictions of the relativistic rescattering model much closer to experiment.     

Wedge-screw dispiration in nonchiral smectic O liquid crystals

Using the approximative expression for the elastic energy density of the smectic O liquid crystal the elastic self-energy of (, b)- and (3, b)-wedge-screw dispirations is estimated. Using the elastic self-energy of (3, b)-wedge-screw dispiration the stability of this defect is discussed.The author expresses his thanks to Professor A. Fukuda, Professor H. Takezoe and Dr. Y. Takanishi for discussions on their observations of (3, b)-wedge-screw dispirations in liquid crystals with antiferroelectric and anticlinic molecular ordering. This work was supported by the grant of Acad. Sci. of the Czech Rep. No. 19062 and also benefited by the grant No. 202/93/155 from the Grant Agency of the Czech Republic.     

Polarization of the secondary nucleons in thepp → ppπ 0 andpp→npπ+ reactions at 1000 MeV

The calculation of the secondary nucleons polarization in thepppp⁰ andppnp⁺ reactions at 1000 MeV is effected in the framework of the one-pion exchange model. It is shown that polarization is due to the interference of the resonant amplitude with the non-resonant amplitudes of theN virtual scattering. The angular dependence of the polarization is sensitive to the behaivour of theN scattering amplitudes off the mass shell.Submitted to the symposium Mesons and Light Nuclei, Liblice, Czechoslovakia, June 1981.     

A theoretical study of the spectra of ketones,acids, and esters

The long-wave * transitions and weak n * transitions are discussed for several compounds of practical importance. Wave functions are presented for aliphatic ketones, acids, and esters.     

Study of the πn → π<Superscript>{-}</Superscript>π<Superscript>{-}</Superscript>p reaction at 430 MeV energy

The total cross-section for the ^{-}n ^{-}{-}p reaction has been measured at a pion kinetic energy of 430MeV in a deuterium bubble chamber. The cross-section value was found to be 0.197±0.016mb that is much smaller than the predictions of the chiral perturbation theory. The differential spectra are compared with calculations made in the framework of the model of Bolokhov et al. 13.60.LeMeson production [:AND:]13.85.LgTotal cross-sections     

An Effective Field Theory Model to Describe Nuclear Matter in Heavy-Ion Collisions

Relativistic mean field theory with mesons , , and mediating interactions and nucleons as basic fermions has been very successful in describing nuclear matter and finite nuclei. However, in heavy-ion collisions, where the c. m. energy of two colliding nucleons will be in the hundreds of GeV region, nucleons are not expected to behave as point-like particles. Analyses of elastic pp and ¯pp scattering data in the relevant c. m. energy range show that the nucleon is a composite object—a topological soliton or Skyrmion embedded in a condensed quark-antiquark ground state. Against this backdrop, we formulate an effective field theory model of nuclear matter based on the gauged linear -model where quarks are the basic fermions, but the mesons still mediate the interactions. The model describes the nucleon as a Skyrmion and produces a q¯q ground state analogous to a superconducting ground state. Quarks are quasi-particles in this ground state. When the temperature exceeds a critical value, the scalar field in the ground state vanishes, quarks become massless, and a chiral phase transition occurs leading to chiral symmetry restoration. We explore the possibility of a first order phase transition in this model by introducing suitable self-interactions of the scalar field. Internal structures of the Skyrmions are ignored, and they are treated as point-like fermions.     

The formation of pseudoscalar mesons in neutrino-lepton interactions

The paper considers the processes of formation of pseudoscalar mesons by the interaction of an antineutrino with a leptonv _ll K, , K.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 139–143, August, 1974.     

Weakly model dependent pion form factor with physically interpretable parameters

Conclusion We have constructed the pion form factor model satisfying fundamental principles, providing some freedom for the asymptotic behaviour and depending only on the adjustable parameters with a definite physical interpretation. The explicit incorporation of the pion form factor left-hand cut from the second Riemann sheet into a model was carried out for the first time. As a result we have described (contrary to the previous attempts [18, 19]) the pion form factor data from the range of momenta –9·770 GeV² t 9·579 GeV² and data on theP-wave isovector phase shift in the elastic region simultaneously with the adjustable parameters acquiring very reasonable values. The asymptotic behaviour was enforced by the data to be consistent with the naive quark model prediction. The calculated values of the pion charge radius as well as theP-wave isovector scattering length coincide with the world averaged values. With regard to these positive features of our pion form factor model it can be employed for the reliable calculation (via unitarity) of theP-wave isovector scattering partial amplitude outside the physical region, which could be useful in a saturation of various sum rules in scattering physics.     

Spin-orbit coupling in the chlorobenzene molecule

The possible ways of drawing of the intensity of the S₀ T* transition in the chlorobenzene molecule are investigated. The effective spin-orbit coupling of either S* or S* states with the T* state leads to the out-of-plane polarized component of phosphorescence in the chlorobenzene. The in-plane polarized component cannot be explained by the mechanism under consideration — by drawing of intensity of the S₀ S₀* transitions through spin-orbit coupling of first order.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 134–138, August, 1974.     

Semiconducting structures and devices based on gallium arsenide with deep centers

We have examined the characteristics of nontraditional gallium arsenide -v-n type device structures, in which p-n junctions are formed by doping the semiconductor with deep centers. The properties of -v-n structures are established by processes of charge trapping at deep centers under the effect of an external bias or exposure to a wide spectral range of electromagnetic radiation. The nature of formation of S-type negative differential resistance for a reverse biased -v-n structure and the mechanism of high speed switching (with a switching time of (0.4–5)×10^–10 sec) were analyzed. The results of an investigation of the effects of optical radiation, x-rays, -radiation and high energy charged particles on the structures are discussed and the characteristics of new devices constructed using -v-n structures are presented. These devices include high speed avalanche S-diodes and triodes, wide spectral band photodiodes (=0.2–10 µm) and detectors for x-rays, -radiation, and relativistic electrons.V. D. Kuznetsov Siberian Physical-Technical Institute, State University, Tomsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 33–44, September, 1992.     

Wedge-screw dispiration in smectic liquid crystals with antiferroelectric order

Using the approximative expression for the elastic energy density of the antiferroelectric (AF) liquid crystal the elastic self-energy of (, b)-wedge-screw dispiration is estimated. Then the elastic interaction between (, b)-wedge-screw dispiration and (2)-wedge dischnation in AF liquid crystals is investigated. The attraction of dislocation part of dispiration with (2)-wedge disclination can lead to the formation of (3)-wedge-screw dispiration. When (2)-wedge disclination is trapped by (2d)-screw dislocation the resulting (2, 2d)-dispiration can dissociate into a pair of two (, d)-dispirations.The authors express their thanks to Professors A. Fukuda, H. Takezoe, Dr. Y. Takanishi and to Dr. K. Miyachi for discussions concerning their experimental observations of (3, d)-wedge-screw dispirations and (, d)-twist-edge dispirations in AF structures. This work was supported by the grant No. 19062 from Acad. Sci. Cz. R. and also benefited by the grant No.: 202/93/155 from the Grant Agency of the Czech Republic.