High-energy hadron spin-flip amplitude at small momentum transfer and new A<Subscript><Emphasis Type="Italic">N</Emphasis></Subscript> data from RHIC

In the case of elastic high-energy hadron-hadron scattering, the impact of the large-distance contributions on the behaviour of the slopes of the spin-non-flip and of the spin-flip amplitudes is analysed. It is shown that the long tail of the hadronic potential in impact parameter space leads to a value of the slope of the reduced spin-flip amplitude larger than that of the spin-non-flip amplitude. This effect is taken into account in the calculation of the analysing power in proton-nucleus reactions at high energies. It is shown that the preliminary measurement of A _N for p ¹²C obtained by the E950 Collaboration indeed favours a spin-flip amplitude with a large slope. Predictions for A _N at GeV/c are given.Received: 9 January 2004, Revised: 17 March 2004, Published online: 14 September 2004PACS: 13.85.Dz Elastic scattering - 13.85.Lg Total cross sections - 13.85.-t Hadron-induced high- and super-high-energy interactions (energy > 10 GeV)O.V. Selyugin: On leave from the Bogoliubov Laboratory of Theoretical Physics, JINR, 141980, Dubna, Moscow Region, Russia;     

Final-state interaction effects in semi-exclusive DIS off the deuteron

The effects of the final-state interaction (FSI) in semi-exclusive deep inelastic scattering of electrons off the deuteron are analyzed paying particular attention to two extreme kinematical regions: i) the one where FSI effects are minimized, so that the quark distribution of bound nucleons could be investigated, and ii) the one where the re-interaction of the produced hadrons with the spectator nucleon is maximized, which would allow one to study the mechanism of hadronization of highly virtual quarks. It is demonstrated that when the recoiling spectator nucleon is detected in the backward hemisphere with low momentum, the effects from the FSI are negligible, whereas at large transverse momenta of the spectator, FSI effects are rather large. Numerical estimates show that the FSI corrections are sensitive to the theoretical models of the hadronization mechanism.Received: 14 July 2003, Published online: 18 December 2003PACS: 24.85. + p Quarks, gluons, and QCD in nuclei and nuclear processes - 25.10. + s Nuclear reactions involving few-nucleon systems - 25.30.Fj Inelastic electron scattering to continuumL.P. Kaptari: On leave from the Bogoliubov Laboratory of Theoretical Physics, 141980, JINR, Dubna, Russia.B.Z. Kopeliovich: Also at Dzhelepov Laboratory of Nuclear Problems, 141980, JINR, Dubna, Russia.     

Baryon number transfer in hadronic interactions

The process of baryon number transfer due to string junction propagation in rapidity space is analyzed. It has a significant effect on the net baryon production in pp collisions at mid-rapidities and an even larger effect in the forward hemisphere in the cases of and interactions. The results of numerical calculations in the framework of the quark-gluon string model are in reasonable agreement with the data. Received: 14 December 2001 / Revised version: 24 April 2002 Published online: 16 October 2002 RID="a" ID="a" Permanent address: Yerewan Physics Institute, Armenia and JINR, Dubna, Russia e-mail: argev@jerewan1.yerphi.am RID="b" ID="b" e-mail: Alphonse.Capella@th.u-psud.fr RID="c" RID="d"     

Hidden Symmetries and Integrable Hierarchy of the $${\mathcal{N}}$$ = 4 Supersymmetric Yang-Mills Equations

We describe an infinite-dimensional algebra of hidden symmetries of supersymmetric Yang-Mills (SYM) theory. Our derivation is based on a generalization of the supertwistor correspondence. Using the latter, we construct an infinite sequence of flows on the solution space of the SYM equations. The dependence of the SYM fields on the parameters along the flows can be recovered by solving the equations of the hierarchy. We embed the SYM equations in the infinite system of the hierarchy equations and show that this SYM hierarchy is associated with an infinite set of graded symmetries recursively generated from supertranslations. Presumably, the existence of such nonlocal symmetries underlies the observed integrable structures in quantum SYM theory. On leave from Bogoliubov Laboratory of Theoretical Physics, JINR, Dubna, Russia. Address after October 1st, 2006: Theoretical Physics Group, The Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BW, United Kingdom.     

Exclusive charge exchange reaction pD↦n(pp) within the Bethe-Salpeter formalism

The exclusive charge exchange reaction pD↦n(pp) at intermediate and high energies is studied within the Bethe-Salpeter formalism. The final-state interaction in the detected pp pair at nearly zero excitation energy is described by the ¹ S ₀ component of the Bethe-Salpeter amplitude. Results of numerical calculations of polarization observables and differential cross-section persuade that, as in the non-relativistic case, this reaction i) can be utilized as a “relativistic deuteron polarimeter” and ii) delivers further information about the elementary nucleon-nucleon charge exchange amplitude. Received: 26 November 2002 / Accepted: 30 January 2003 / Published online: 29 April 2003     

Theoretical Optimization of Neutron and Physical Characteristics of a Multiplying Pulsed Neutron Source Based on a Proton Accelerator

Physics of Particles and Nuclei Letters - The neutron source operating at the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research (JINR, Dubna, Russia), based on an IBR-2M...     

The maximal randomness principle in d-dimensional turbulence

A set of self-consistent equations in one-loop approximation in a statistical model of fully developed homogeneous isotropic turbulence, which is based on the maximal randomness principle of the incompressible velocity field with stationary energy spectral flux, is obtained. Thanks to the applied principle the model statistics becomes essentially non Gaussian. The set of equations does not possess the infrared and ultraviolet divergences near the obtained Kolmogorov spectral exponents. The solution of these equations leads to the Kolmogorov exponents, but its amplitude proportional to the Kolmogorov constantC _k is negative for Euclidean dimensiond=3. Systematic investigation is made of (inertial) steady state scaling solutions for dimensions 2<d<2.55695,where constantC _k (d) becomes positive. Considered in this way, the model stability is discussed in the context of widely studied fractal aspects of turbulence.We have greatly benefited from discussions with Dr. Altaisky from JINR Dubna. The authors (M.H. and M.S.) are grateful to D. I. Kazakov and to director D. V. Shirkov for hospitality at the Laboratory of Theoretical Physics, JINR, Dubna.This work was supported by Fundamental Research Russian Fund, International Scientific Fund (grant R-63000) and by Slovak Grant Agency for Science (grant 2/550/93).     

Polarization effects in dispersion relations for photoproduction of π-mesons on deuterons

The photoproduction amplitude of ⁰-mesons on deuterons is calculated for different cases of polarization of the spin of deuterons by means of impulse approximation. The calculations carried out in the two-nucleon approximation in the Breit system are valid up to a maximum photon energy 236 MeV. In the unobservable region only a free proton and a free neutron contribute to the continuous part of the spectrum.The dispersion relations are given for all cases of deuteron-spin polarization.This paper is a continuation of the author's papsr elaborated in the Laboratory of Theoretical Physics of the Joint Institute of Nuclear Research, Dubna USSR, published in Nuclear Physics26 (1961), 681, which is hereafter referred to as I.     

Spallation neutron spectrum on a massive lead/paraffin target irradiated with 1 GeV protons

The gamma-ray spectra emitted by decaying of residual nuclei produced by spallation neutrons in (n, xn), (n, xnyp), (n, p), (n, ) reactions with activation threshold detectors, i.e. ²⁰⁹Bi, ¹⁹⁷Au, ⁵⁹Co, ¹¹⁵In, ²³²Th, were measured in the Laboratory of Nuclear Problems (LNP), JINR, Dubna, Russia. Spallation neutrons were generated by bombarding a 20 cm long cylindrical lead target with 8 cm diameter surrounded by a 6 cm thick layer of paraffin moderator with 1 GeV proton beam from the NUCLOTRON accelerator. Reaction rates and a spallation neutron spectrum were measured and compared with CASCADE code calculations.     

b-tagging in DELPHI at LEP

The numbers of events suitable for the determination of the gluon distribution function f ^p _g (x,Q ²) in a proton at the LHC for various intervals of x and Q ² are estimated. The contributions of background events of different sources are studied and estimated in the considered intervals of x and Q ². The PYTHIA event generator was used to produce physical events for this analysis.Received: 17 June 2003, Revised: 8 July 2004, Published online: 24 August 2004N.B. Skachkov: Present address: Joliot-Curie 6, JINR, 141980, Dubna, Moscow region, Russia     

Measuring the cross sections of heavy-metal spallation induced by deuterons with energies of 2, 2.94, and 3.5 GeV per nucleon

The cross sections for the spallation of the heavy-metal nuclei ¹⁸¹Ta, ¹⁹⁷Au, ²⁰⁷Pb, ²⁰⁹Bi, ²³²Th, and ²³⁸U induced by relativistic deuterons with energies of 2, 2.94, and 3.5 GeV per nucleon are measured using the deuteron beam from the Nuclotron accelerator of the JINR Laboratory of High Energy Physics in Dubna, Russia. The cross-section measurements employ a combined experimental technique involving the solidstate nuclear-track detectors and the activation gamma spectrometry. Adding our measurements to the database of experimental nuclear data will make it possible to test the computer codes used for selecting the parameters of the ADS-type facilities.     

Energy level displacement of the excited $n\ell$ state of pionic hydrogen

The energy level displacements of the excited states of pionic hydrogen and the contribution of the transitions and the transitions of the pair, coupled by the attractive Coulomb field in the S-wave state with a continuous energy spectrum, to the shift of the energy level of the ground state of pionic hydrogen, caused by strong low-energy interactions, are calculated within a quantum field theoretic, relativistic covariant and model-independent approach.Received: 19 November 2003, Revised: 25 November 2003, Published online: 5 February 2004PACS: 13.75.Gx Pion-baryon interactions - 11.10.St Bound and unstable states; Bethe-Salpeter equations - 21.30.Fe Forces in hadronic systems and effective interactions - 31.15.Ar Ab initio calculationsPermanent address A.N. Ivanov: State Polytechnical University, Department of Nuclear Physics, 195251 St. Petersburg, Russian Federation;Permanent address N.I. Troitskaya: State Polytechnical University, Department of Nuclear Physics, 195251 St. Petersburg, Russian Federation.     

Measurement of delayed-neutron yield from <Superscript>237</Superscript>Np fission induced by thermal neutrons

The delayed-neutron yield from thermal-neutron-induced fission of the ²³⁷Np nucleus was measured using a sample periodically exposed to a pulsed neutron beam with subsequent detection of neutrons during the time intervals between pulses. The experiment was realized on an Isomer-M setup mounted in the IBR-2 pulsed reactor channel equipped with a mirror neutron guide. The setup and the experimental procedure are described, the background sources are thoroughly analyzed, and the experimental data are presented. The total delayed-neutron yield from ²³⁷Np fission induced by thermal neutrons is ν _d = 0.0110 ± 0.0009. This study was performed at the Frank Laboratory of Neutron Physics (JINR, Dubna).     

Light-Ion Linear Accelerator for the NICA Project

Physics of Particles and Nuclei Letters - A joint team from the Joint Institute for Nuclear Research (JINR) (Dubna, Russia) and Bevatech GmbH (Frankfurt-am-Main, Germany) has been developing a new...     

Yield of delayed neutrons in the thermal-neutron-induced reaction <Superscript>245</Superscript>Cm(<Emphasis Type="Italic">n,f</Emphasis>)

The yield of delayed neutrons, v _d , from thermal-neutron-induced fission of ²⁴⁵Cm is measured. Experiments aimed at studying the properties of delayed neutrons from the fission of some reactor isotopes and initiated in 1997 were continued at the upgraded Isomer-M facility by a method according to which a periodic irradiation of a sample with a pulsed neutron beam from the IBR-2 reactor was accompanied by recording emitted neutrons in the intervals between the pulses. The accuracy of the resulting total delayed-neutron yield v _d = (0.64 ± 0.02)% is two times higher than that in previous measurements. This work was performed at the Frank Laboratory of Neutron Physics at the Joint Institute for Nuclear Research (JINR, Dubna).     

On the parallel dynamics of theQ-state Potts andQ-Ising neural networks

Using a probabilistic approach, the parallel dynamics of theQ-state Potts andQ-Ising neural networks are studied at zero and at nonzero temperatures. Evolution equations are derived for the first time step and arbitraryQ. These formulas constitute recursion relations for the exact parallel dynamics of the extremely diluted asymmetric versions of these networks. An explicit analysis, including dynamical capacity-temperature diagrams and the temperature dependence of the overlap, is carried out forQ=3. Both types of models are compared.On leave of absence from the Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna 141980, Russia.     

Relativistic nuclear physics at the Joint Institute for Nuclear Research

The basic stages of the development of the Veksler and Baldin Laboratory of High Energies, Joint Institute for Nuclear Research, in Dubna are described briefly. Some experiments on the investigation of cumulative particle production and the new direction of investigation of the processes of hadron-nuclear and nuclear-nuclear interaction in which the quark structure of nuclei can be manifested—relativistic nuclear physics—are considered. Basic methodical and experimental results obtained at the synchrophasotron and Nuclotron are presented, ideas produced in collaboration with theoreticians of the Bogoliubov Laboratory of Theoretical Physics are discussed. An overview of investigations in the field of relativistic nuclear physics planned at the Nuclotron is given.     

Supersymmetry in superspace: 35 years of the research activity in LTP

This is an overview of the all-years research activity in supersymmetry in the Markov-Ogievetsky group at the Bogoliubov Laboratory of Theoretical Physics. It started shortly after the discovery of supersymmetry and is lasting for more than 30 years. In this survey the main emphasis is made on the superspace geometric approaches and unconstrained superfield formulations. Alongside such milestones as the geometric formulation of supergravity and the harmonic superspace approach to extended supersymmetry, some other developments largely contributed by the Dubna theorists are briefly accounted for. The text was submitted by the author in English.     

Determination of microelement distribution in different components of soil-plant systems

The leaves, stem, and roots of two types of shrubs (tea (Camellia sinensis) and sweet leaf (Sauropus androgynus)) and two types of herbs (vetiver grass (Vetiveria zizanioides L. Nash) and maize (Zea mays L)) and the Thucuc soil where the plants were growing were collected to be studied. The contents of 22 elements in the samples were determined by three methods: X-Ray fluorescence analysis (XRFA), gamma activation analysis (GAA), and the tracking method to study the distribution of these elements in plants and the soil-plant relationship. This study was carried out at the Flerov Laboratory of Nuclear Reactions (FLNR), Joint Institute for Nuclear Research (JINR), Dubna, Russia. The distribution of the elements in the soil-plant system was studied.     

Enhancements observed in the two-proton invariant mass distribution in the pionless deuteron breakup at 3.3 GeV/c

A sample of “non-spectator” events in the pionless deuteron breakup at a 3.3 GeV/c momentum has been investigated by means of a 1 m HBC at the JINR, Dubna. The two-proton invariant mass spectrum in the charge exchange channel exhibits two enhancements for masses of 2,010 MeV/c² and 2,160 MeV/c². Theoretical calculations taking into account one-pion exchange diagrams and virtual pion absorption by the deuteron have been carried out. It has been shown that the enhancement atM _pp=2,010 MeV/c² can be explained if some kind of singularity near theN-N threshold is required. The observed maximum atM _pp=2,160 MeV/c² is caused mainly by intermediate Δ production and pion absorption on the deuteron.