B c and $$b\bar bc\bar c$$ at theZ 0-boson pole

The cross-section for the production of quarks ine ⁺ e ^– annihilation, that proves to be at a level of for is calculated within the frames of the QCD perturbation theory. The cross sections for the associated production of 1S-and 2S-wave states ofB _c-meson in the reaction were calculated in the nonrelativistic model of a heavy quarkonium. The number of _bc -hyperons to be expected at LEP is estimated on the basis of the assumption on quark-hadron duality.     

Signals of left-right supersymmetry ine + e − collisions

We study chargino and neutralino pair production at the Next Linear e⁺ e⁻ Collider in a supersymmetric left-right model. We investigateon- and off-resonance signals via the processes: and . These reactions could lead to observable signals as they compare with the background signal from W^± -pair production.     

\bar v_e e^ - -Annihilation and supersymmetric particles

In the framework of a minimal supersymmetric (s) extension of the standard Glashow-Weinberg-Salam theory, creation of s-partners of known leptons and gauge bosons in the -annihilation is studied. The angle distributions and total cross sections of s-particle creation are investigated in detail. The comparison with similar processes with the participation of known particles is performed. The possibility of an experimental identification of s-particles in the -annihilation is analyzed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 68–74, October, 1989.The authors thank I. M. Zheleznykh for useful discussions.     

The nature of the {\bar p} metastability in helium

A new interpretation of the nature of the metastable states of antiprotons in helium is proposed. The first step is the formation of an ion ( ), which shall be called “ioncule”. After its decay a neutral “atomcule” ( ) is formed which was observed in the experiments on metastable antiprotonic helium. This model explains the experiments in a natural way, in particular the quenching by atomic and molecular admixtures and the pressure dependence of quenching in pure helium. At high helium densities the ioncule creates a vacuum bubble in helium. It is shown that the annihilation of slowed-down can be suppressed at helium pressures of ∼ 10 000 bar. This revised version was published online in August 2006 with corrections to the Cover Date.     

Theoretical analysis of collisional shift and broadening of antiprotonic helium spectral lines

Effect of medium density on shift and broadening of ( ) spectral lines is considered in the framework of binary-collision approximation with an effective ( )–He potential including the long-range attraction and short-range repulsion. Quantum calculations of the scattering phase shifts at reasonable values of the potential parameters allow to explain the main features of the observed density effect on the shape of ( ) spectral lines in low-temperature helium. This revised version was published online in August 2006 with corrections to the Cover Date.     

Measurement of the forward-backward asymmetry of charm and bottom quarks at theZ pole usingD*± mesons

The forward-backward asymmetries for the processes and at theZ resonance are measured using identifiedD ^*± mesons. In 905,000 selected hadronic events, taken in 1991 and 1992 with the DEL-PHI detector at LEP, 4757D ^*+D ⁰⁺ decays are reconstructed. Thec andb quark forward-backward asymmetries are determined to be:

Higgss-channel production ine + e − collisions below theW + W − threshold

The cross section for direct neutral Higgs production in the reaction is calculated in theE _CM energy range of 40 to 160 GeV and compared to the corresponding Electro-Weak (EW) process . Neglecting radiation effects, a signal of the order of 10^–4 to 10^–3 over the EW can be expected outside theZ ⁰ region for the Minimal Standard Model Higgs in its decay to a state. For \sqrt s - M_Z $$ " align="middle" border="0"> , thes-channel Higgs formation can surpass the Bjorken Bremsstrahlung process and thus may afford at LEP 2 a realistic search method for high mass, say 100 GeV Higgs, given enough luminosity. For a non-Standard Model Higgs, in some cases, significantly higher signals are expected. The effects of initial state radiation and-machine energy resolution are evaluated and the gain in using longitudinal polarized electron beams is discussed.Supported in part by the Israel Ministry for Science and Technology     

Radiative production of the lightest neutralino in e + e − annihilation

The production of the lightest stable neutralino in the process including general mixing of gauginos and Higgsinos is studied. General formulas for the differential cross section are presented. The dependence of the differential cross section on the photon energy spectrum and also the dependence of the total cross section on the beam energies for three different mixing scenarios are illustrated. The text was submitted by the author in English.     

One-loop electroweak factorizable correctionsfor the Higgsstrahlung at a linear collider

We present standard model predictions for the four-fermion reaction being one of the best detection channels of a low-mass Higgs boson produced through the Higgsstrahlung mechanism at a linear collider. We include leading virtual and real QED corrections due to initial state radiation and a modification of the Higgs- Yukawa coupling, caused by the running of the b-quark mass, for . The complete electroweak corrections to Z-Higgs production and to the Z-boson decay width, as well as the remaining QCD and EW corrections to the Higgs decay width, as can be calculated with the program HDECAY, are taken into account in the double-pole approximation. Received: 17 March 2005, Revised: 30 March 2005, Published online: 30 August 2005 Work supported in part by the Polish State Committee for Scientific Research in years 2004-2006 as a research grant, by the European Community's Human Potential Program under contracts HPRN-CT-2000-00149 Physics at Colliders and CT-2002-00311 EURIDICE, and by DFG under Contract SFB/TR 9-03.     

Radioactive Production of the Lightest Neutralino in the Process of <Emphasis Type="Italic">e</Emphasis><Superscript>+</Superscript><Emphasis Type="Italic">e</Emphasis><Superscript>−</Superscript> Annihilation

The production of the lightest stable neutralino in the reaction with general mixing of the higgsino and gaugino is studied. General formulas for differential cross sections are presented. The dependence of the effective differential cross section on the photon energy spectrum and electron mass is illustrated together with the dependence of the effective total cross section on the beam energy for three different scenarios. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 48–57, June, 2005.     

Effect of a magnetic field on the yield point of NaCl crystals

A constant magnetic field is found to have a substantial effect on the macroplasticity of NaCl crystals when they are being actively strained at a constant rate during magnetic treatment. We have measured the dependence of the yield point σ _y on the magnetic induction B=0–0.48 T and the strain rate . It is shown that this magnetic effect has a threshold character and is observed only for B>B _c , where B _c grows with increasing as . The lower the strain rate , the larger the relative decrease in the yield point σ _y (B)/σ _y (0) at fixed field B>B _c . At small enough strain rates the threshold field B _c ceases to depend on and goes constant. A theoretical model is proposed which is in good agreement with the observed regularities. The model is based on the competition between thermally activated and magnetically stimulated depinning of dislocations from paramagnetic impurity centers. Zh. éksp. Teor. Fiz. 115, 951–958 (March 1999)     

Present and future experiments in nonequilibrium reactor antineutrino energy spectrum

Considerable efforts that have been undertaken in recent years in low-energy antineutrino experiments require further systematic investigations in line of reactor antineutrino spectroscopy as a metrological basis of these experiments. We consider some effects associated with the nonequilibrium of reactor radiation and residual emission from spent reactor fuel in contemporary experiments. The text was submitted by the authors in English.     

SU(1, 1) Perturbations of the s-Wave Morse Potential Problem

A purely algebraic perturbation theory based on deforming the generators of the dynamical group SU(1, 1) is applied to the l = 0 Morse potential problem with . In particular, perturbations of the form and are treated explicitly.     

Low Temperature Hydrogen Antihydrogen Interactions

In view of current interest in the trapping of antihydrogen ( ) atoms at low temperatures [1–3], we have carried out a full four-body variational calculation to determine s-wave elastic phase shifts for hydrogen antihydrogen scattering, using the Kohn Variational Principle. Terms outside the Born–Oppenheimer approximation have been taken into account using the formalism of Kołos and Wolniewicz [4]. As far as we are aware, this is the first time that these terms have been included in an H scattering calculation. This is a continuation of earlier work on H– interactions [5–7]. Preliminary results differ substantially from those calculated using the Born–Oppenheimer approximation [8–10]. A method is outlined for reducing this discrepancy and taking the rearrangement channel into account. This revised version was published online in August 2006 with corrections to the Cover Date.     

Antihydrogen synthesis: A progress report

The main suggested routes for atomic antihydrogen ( ) formation will be reviewed in a pedestrian fashion. These are the following reactions: , and (iii) . The present status of the projects related to these reactions, as well as the projects' experimental scope, will also be discussed or referred to. Some speculations will be made regarding the physics that can be yielded by an antihydrogen probe.     

RareB-decays and heavy to light semileptonic transitions in the Isgur and Wise limit

From the experimental braching ratios for and one finds, in the heavy quark limit of HQET, |V _bu|=(8.1±1.7)×10^–3, larger but consistent with the actual quoted range (2–7)×10^–3. In the same framework one predicts forR(BK ^*)=(2±2)10^–2.     

Weak carrier localization on the (10\bar 10) tellurium surface

A theory of weak localization responsible for the negative magnetoresistance effect is developed for quantum wells at the tellurium surface, which retains, in contrast to the surface considered earlier, a trigonal spectrum distortion with opposite signs near the M and P extrema, with the latter playing the part of states with opposite spins. It is shown that as a result of the motion in momentum and spin spaces being correlated the spin relaxation due to this distortion is smaller than that for the (0001) surface. Fiz. Tverd. Tela (St. Petersburg) 39, 1659–1664 (September 1997)     

Production and decay of neutralinos in the Next-to-Minimal Supersymmetric Standard Model

Within the framework of the Next-to-Minimal Supersymmetric Standard Model (NMSSM) we study neutralino production (i,j=1, …, 5) at center-of-mass energies between 100 and 600 GeV and the decays of the heavier neutralinos into the LSP plus a fermion pair, a photon or a Higgs boson. For representative gaugino/higgsino mixing scenarios, where the light neutralinos have significant singlet components, we find some striking differences between the NMSSM and the minimal supersymmetric model. Since in the NMSSM neutralino and Higgs sector are strongly correlated, the decay of the second lightest neutralino into a Higgs boson and the LSP often is kinematically possible and even dominant in a large parameter region of typical NMSSM scenarios. Also, the decay rates into final states with a photon may be enhanced.