Precise calculation of coulomb binding energies of mesomolecules

The best variational energies obtained to date for the ground states of all -mesomolecules are presented. The results are of rather high accuracy and can serve as a theoretical basis for the experimental study of three-body systems. The energies of thee ^– e ⁺ e ^–,H^– and 1¹ S, 2³ S, 2³ P, 2³ P states ofHe are calculated using the same method.     

Search for contact interactions in the reactionse+e?→l+l? ande+e?→γγ

Contact interactions are searched for using the differential cross sections for the reactionse ⁺ e ^–e ⁺ e ^–,e ⁺ e ^–µ ⁺ µ ^–,e ⁺ e ^{– + –} ande ⁺ e ^– measured at 12 energies around theZ peak and corresponding to about 20 pb^–1 of cumulated luminosity. Four-fermion contact term models assuming various chiralities of lepton currents are fitted to the lepton data and lower limits on the energy scale of such terms are set at 95% c.l. The limits vary in the range 0.9–4.7 TeV, depending on the model and on the lepton flavour. Theee contact terms are searched for assuming various chiralities. Limits on the energy scale between 79 and 130 GeV are extracted from the data. The results are compared and combined with those reported at lower energies.Deceased     

The oscillator representation and the stability of three-body Coulomb systems

Within nonrelativistic quantum mechanics the Wick-ordering method, called the oscillator representation, is suggested for calculating the energy spectrum for a wide class of potentials allowing the existence of a bound state. As test cases, anharmonic (V(r)=r ²) and screened Coulomb potentials are considered. In particular, the method is applied to three-body Coulomb systems to obtain the dependence of the bound-state energy on the masses and charges of the particles. The calculations of the bound-state energies for the moleculesH ^–=(pee),H ₂ ⁺ =(ppe), (e ^–e^–e⁺) and (pp), (dd), (dt) prove the accuracy of the zeroth approximation to be better than one per cent. For the three-body Coulomb system with charges +, –, – and arbitrary masses the region of stability is determined. For the systems (pe ^–C⁺), (A ⁺e^–e⁺), and (pB ^–e^–) the critical masses are calculated to beM _c=1.945m_e,M _A=4.350m_e andM _B=1.575m_e. It turns out that the system (pe ^–e⁺) is unstable.     

Angular correlation of photons ine + e − collision in QED: Planar processes

The angular correlation for two monochromatic photons produced ine ⁺ e ^– collision has been calculated to lowest order in the fine-structure constant in QED for planar processes. The angular correlation is defined as the average of the cosine of the angle between the directions of momenta of the two photons. This is done by computing, in the process, thee ⁺ e ^–-spin-momentum-averaged,-polarization-averaged conditional probability. In particular, we learn that for energies of the photons above a certain critical value, the angular correlation is strictly positive, for planar processes, indicating that the photons tend to travel in the same direction in a statistical sense for such processes.On sabbatical leave from Royal Military College, Kingston, Ontario, K7K 5LO, Canada.     

Negative muon hyperfine transition rate in aluminum

The residual polarization of theF ^– hyperfine state of ^–27Al has been investigated as a function of applied transverse magnetic field strength using standard TD- ^–SR techniques. TheF ^– precession frequency is –0.2623(5) [theoretical value: –0.2622] times that of the free muon in the same field. The observed muon decay electron asymmetry in theF ^– state decreases with increasing magnetic field strength, due to initial precession in the opposite direction of theF ⁺ state, which most muon initially populate, followed by a rapid transition to theF ^– state. A fit of the data to this model indicates a transition rateR=41(9)s^–1, in good agreement with theoretical predictions. This method can be used to determineR experimentally in other cases where it is too fast to be observed directly.     

Trace norm convergence of exponential product formula

LetH andK be lower-bounded self-adjoint operators whose form sum is denoted byH K. We show the norm inequality (e^–rH/2 e^–rK e^–rH/2)^1/r forr > 0 and any symmetric norm . WhenH +K is essentially self-adjoint and e^–K is of trace class, we prove that (e^–rH/2e^–rK e^–rH/2)^1/r converges asr 0 to e^–(H+K) in the trace norm.     

Measurement of exclusive one-prong and inclusive three-prong branching ratios of the τ lepton

Using the ARGUS detector at thee ⁺ e ^– storage ring DORIS II at DESY, a study ofB ⁰ oscillations has been performed using three different techniques. Besides the standard dilepton method, charge correlations betweenD ^* mesons and one or two leptons have also been investigated. The mixing parameterr is determined to be (20.6±7.0)%.Supported by the German Bundesministerium für Forschung und Technologie, under contract number 054DO51P     

Production of hard photons in electron-positron annihilation into hadrons

Frequency of emission of prompt, hard photons radiated by the fast-moving quarks (antiquarks) ine ^– e ⁺ annihilation into hadrons is estimated for the string model. The differential probability of emission of such photons is obtained from a sum rule which takes for the initial state of the emitter a classical trajectory. It is found that the string models are quite effective in production of hard photons (i.e., photons whose energies are substantial fractions of the energies of the initiale ^– e ⁺ pair) associated with production of hadrons. For 100 GeVe ⁺ e ^– initial energy the frequency of emission,v, of 10 GeV<><40gev photons=" is=" estimated=" to=" be=">^–4v<>^–3.Supported in part by the Polish Ministry of Education, Grant DNS-P-04/215/90-2 and KBN Grant No 2-00054-91-01     

Limits on electron compositeness from Bhabha scattering

We have studied the reactione ⁺ e ^–e ⁺ e ^– using data taken by the CELLO detector at 35 GeV centre of mass energy with an integrated luminosity of 86 pb^–1. The differential cross section is found to agree with the Standard Model and is used to set limits on possible deviations from the pointlike structure of the electron. The lower limits obtained for the compositeness scale range from 0.8 to 6.0 TeV (95% C.L.), depending on the structure of the current.     

Probing the photon at γe-colliders

We investigate the feasibility of studying the photon structure function at a e-collider. We show that the deep inelastic probe of the real photon by a highly virtual photon in such a collider will extend significantly thex andQ ² range presently accessible ate ⁺ e ^– colliders. In addition, we study the production of large transverse momentum dijet final states to determine the sensitivity of these cross sections to different parametrisations of the quark and gluon distributions in the photon.     

The\bar pp \to e^ + e^ - reaction at rest and the hierarchy of the annihilation ranges

A new procedure is devised to evaluate the proton form-factor at the ¯pp threshold from experimental data on ¯ppe ⁺ e ^– annihilation at rest. Comparison of the ¯ppe ⁺ e ^– and¯pp ^+– processes reveals that annihilation ranges for various channels are ranked in line with quark dynamics.This work has been funded in part by the German Federal Minister for Research and Technology (BMFT) under the contract number 06HD756     

Exact solutions for stimulated emissions by external sources

The exact solutions for transition amplitudes are derived forstimulated emissions by external sources. More precisely, we obtain the exact expressions for transition amplitudes for the emission of an arbitrary number of particles by the sources when some particles are already present, in the process,prior to the switching on of the external sources. The solutions are given for an arbitrary number of particles with arbitrary configurations (of momenta, spin, etc.) and for particles of spin-0, spin-1/2, massive and massless (photons) spin-1 particles, and massless (gravitons) spin-2 particles. Applications are given as illustrations to the process Ø anything, and, in quantum electrodynamics, to the process e ⁺e^–+ any photons, in thepresence of external sources, where a (virtual) photon decays into the paire ⁺e^–.     

Four-quark and hybrid mixing in the light-quark vector sector

The data one ⁺ e ^– annihilation are shown to be incompatible with an interpretation of the observed vector mesons as excitations. It is necessary to consider mixing with some system. Two specific models are considered: either four-quark states or hybrid states mixing with the conventional quark-antiquark excitations. Both models are compatible with the presente ⁺ e ^– annihilation data. It is possible to incorporate the 1.3 GeVJ ^PC =1^–– state seen by LASS in the channel in the four-quark model, but this is not possible with the hybrid model.     

Photon-photon angular correlation ine +e− collision in QED

The angular correlation of two monochromatic photons produced ine ⁺e^– collision (annihilation), defined as the average of the cosine of the angle of separation between their outgoing momenta, is studied completely in momentum space to lowest order in the fine structure constant in QED. This is done from the expression of thee ⁺e^–-momentum-spin,-polarization-averaged conditional probability density for the angular distributions of the photons, given that the process has occurred. Although the density is in general nonvanishing for less than as well as greater than/2, the angular correlation is found to be strictly negative for all energies, indicating that the photons tend to travel in opposing directions in a statistical sense. The back-to-back motion, however, is very quickly unfavored as we move to higher energies.     

Electromagnetic form factor ofD * →D transition in the time-like region

The internal conversion processD ^* De ⁺ e ^–, andD ^* -pair production ine ⁺ e ^–-collisions,e ⁺ e ^– D ^* , which are described by the same electromagnetic form factor with time-like momentum transfer, have been analyzed. After carrying out a general analysis of the kinematical aspects of the one-photon mechanism has been performed and the predictions of the vector-dominance model for theD ^* D transition form factor are discussed. It is shown that use of the asymptotic behaviour of the form factors ofD ^*+,0 D ^+,0* and the theoretical values of constants ofD ^*+,0 D^+,0 radiative decay enables one to determine part of the unknown parameters of these form factors. The coefficient of the internal conversion forD ^* De ⁺ e ^– is calculated and is shown to be model independent.     

A possible way to promote antihydrogen formation via metastable antiprotonic helium atoms

A new way to promote antihydrogen formation via the recently discovered long-lived metastable states of antiprotonic helium atoms is discussed. Recombination processes such ase ^– ¯pHe⁺⁺ +e ⁺ e ^– e ⁺ ¯p + He⁰ are possible in this respect.Dedicated to Prof. Dr. P. Kienle on the occasion of his 60th birthday     

Characterization of vacancy-related defects introduced into silicon during heat treatment by deep-level transient spectroscopy and gamma-ray diffraction techniques

Vacancy-related defects introduced into n-Si during annealing or aluminium diffusion at high temperature (1000–1250°C) have been studied. Different ambients (argon, nitrogen, vacuum and chlorine-containing atmosphere) were used to create a vacancy supersaturation during heat treatments. Three deep-level centers whose formation is governed by the presence of vacancies have been identified. They were characterized by the following temperature dependences of the thermal emission rate:e3 = 7.92 × 10⁷ T ² × exp(– 0.455/kT),e ₅ = 2.64 × 10⁶ T ² × exp( – 0.266/kT),e ₇ = 7.26 × 10⁶ T ² × exp (– 0.192/kT). The influence of different factors, such as heat-treatment conditions, concentration of oxygen and doping level in initial crystals, on center formation was studied. An asymmetric diffuse-ray scattering was observed near the surface of a crystal irradiated by thermal neutrons and annealed in a chlorine-containing atmosphere. This scattering is related to the formation of structural defects of the vacancy type. In the same region of the crystal, the concentration of the E7 center was one order of magnitude higher than that of other deep-level centers. Comparison of the-ray diffraction and deeplevel transient spectroscopy (DLTS) data suggests that the formation of the center occurs under the conditions of Si supersaturation with vacancies.     

Determination of the parton distributions and structure functions of the proton from neutrino and antineutrino reactions on hydrogen and deuterium

The analytic expressions for the production cross sections of polarized bottom and top quarks ine ^* e ^– annihilation are explicitly derived at the one-loop order of strong interactions. Chirality-violating mass effects will reduce the longitudinal spin polarization for the light quark pairs by an amount of 3%, when one properly considers the massless limit for the final quarks. Numerical estimates of longitudinal spin polarization effects in the processese ^* e ^–b (g) ande ^* e ^–t (g) are presented.supported in part by the BMFT, Germany under contract 06MZ730     

Gluon and quark jets in deep-inelastic scattering of electrons by nucleons

The paper considers the formation of gluon and quark jets in the inelastic scattering of electrons by nucleons with large momentum transfers. It is assumed that these jets are created by the processes e^–+qe^–+q+g and e^–+ g e^–+q+q, where q is a quark and g is a gluon. The angular distributions of gluon and quark jets are calculated in the lowest order in the quark-gluon coupling constant. It is shown that after integration the processes e^–+qe^–+q+g and e^–+g e^–+q+¯q lead to violation of the scaling invariance of deep-inelastic scattering of electrons by nucleons.Translated from Izvestiya Vysshkikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 68–73, September, 1981.