Table of contents

Recent measurements of the deuteron electromagnetic structure functions A, B and T₂₀ extracted from high-energy elastic ed scattering, and the cross sections and asymmetries extracted from high-energy photodisintegration γ + d → n + p, are reviewed and compared with the theory. The theoretical calculations range from nonrelativistic and relativistic models using the traditional meson and baryon degrees of freedom, to effective field theories, to models based on the underlying quark and gluon degrees of freedom of QCD, including nonperturbative quark cluster models and perturbative QCD. We review what has been learned from these experiments, and discuss why elastic ed scattering and photodisintegration seem to require very different theoretical approaches, even though they are closely related experimentally.

We explore the factorization of hard and soft contributions into the hadronic decays of the B_c meson at large recoils in order to evaluate the decay rates into the S-, P- and D-wave charmonia associated with ρ and π. We discuss the constraints of the applicability of the approach and the uncertainties of numerical estimates. The mode with J/ψ in the final state is evaluated taking into account the cascade radiative electromagnetic decays of excited P-wave states, which enlarges the branching ratio by 20–25%.

The renormalization group (RG) flow for the two-dimensional sine-Gordon model is determined by means of Polchinski's RG equation at next-to-leading order in the derivative expansion. In this paper, we have two different goals, (i) to consider the renormalization scheme-dependence of Polchinski's method by matching Polchinski's equation with the Wegner–Houghton equation and with the real space RG equations for the two-dimensional dilute Coulomb-gas, (ii) to go beyond the local potential approximation in the gradient expansion in order to clarify the supposed role of the field-dependent wave-function renormalization. The well-known Coleman fixed point of the sine-Gordon model is recovered after linearization, whereas the flow exhibits strong dependence on the choice of the renormalization scheme when non-linear terms are kept. The RG flow is compared to those obtained in the Wegner–Houghton approach and in the dilute gas approximation for the two-dimensional Coulomb-gas.

We show that for osmium, platinum and mercury isotopes the α-particle preformation factors given by the standard shell model are not consistent with the barrier penetrabilities. The internal cluster formation amplitude and the outgoing Coulomb wavefunction should have the same logarithmic derivatives for the experimental Q-value. The usual shell model wavefunctions are not able to satisfy this condition along any isotopic chain. In order to correct this deficiency we use an effective procedure. We diagonalize the mean field using a single particle basis with two harmonic oscillator parameters, as proposed in a previous paper. In order to obtain correct tails of the wavefunctions, the second harmonic oscillator parameter should increase with the mass number. This is consistent with the suppression of α-clustering by increasing the proton–neutron asymmetry. A parabolic fit of this parameter versus the mass number enables us to ensure a consistency in experimental Q-values within a mean deviation of 300 keV.

We investigate the influence of spin-flip transitions on the formation of the spectral distribution of the radiation emitted by tens to hundreds GeV ultra-relativistic electrons incident along crystallographic axis in a single thin crystal. Both the formalism and the numerical data are presented. The calculated spectra for 35 to 243 GeV electrons in W crystals are compared with the dependences obtained experimentally (Kirsebom K et al 2001 Phys. Rev. Lett.87 054801).

The α-decay rates for the nuclides ^{168,170,171,172,173,174,176}Yb and ^{148,150,152,154}Gd have been estimated from transmission probabilities in a systematic α-nucleus potential and from an improved fit to α-decay rates in the rare-earth mass region. Whereas α-decay of ¹⁵²Gd in natural gadolinium is a severe obstacle for the use of gadolinium as a low-energy solar-neutrino detector, we show that α-decay does not contribute significantly to the background in a ytterbium detector. An extremely long α-decay lifetime of ¹⁶⁸Yb is obtained from calculation, which may be close to the sensitivity limit in a low-background solar-neutrino detector.

The theory behind a new, three-dimensional analysis technique for the measurement of time-integral, perturbed angular correlation (IPAC) functions is presented. The new technique is described in relation to existing methods and in terms of its specific application to a large, Ge-detector array. The effective application of the new technique is demonstrated with results from an experiment where the g factors of excited states in ²⁵²Cf, secondary fission fragments were determined. A ²⁵²Cf source, sandwiched between two iron foils and placed in a saturated magnetic field at the centre of the Gammasphere detector array, was used to make IPAC measurements of prompt γ rays in order to deduce Larmor precession angles of stopped fragments in iron. The g factor of the I^π = 2⁺ state in ¹⁰⁴Mo was thus measured to be g = +0.248(22). This new measurement shows a factor-of-5 improvement to the precision which has previously been attained in more conventional experiments.

Total ordinary muon capture (OMC) rates are calculated on the basis of the quasiparticle random phase approximation for several spherical nuclei from ⁹⁰Zr to ²⁰⁸Pb. It is shown that total OMC rates calculated with the free value of the axial-vector coupling constant g_A agree well with the experimental data for medium-size nuclei and considerably exceed the experimental rates for heavy nuclei. The sensitivity of theoretical OMC rates to the nuclear residual interactions is discussed.

We carefully examine bottomonia hadroproduction in colliders as a way of probing the gluon density in protons. To this end we develop some previous work, getting quantitative predictions and concluding that our proposal can be useful for performing consistency checks on the parametrization sets of different parton distribution functions.

Nuclei at both the neutron- and proton-drip lines are studied. In the cluster–core model, the halo structure of all the observed and proposed cases of neutron- or proton-halos is investigated in terms of simple potential energy surfaces calculated as the sum of binding energies, Coulomb repulsion, nuclear proximity attraction and the centrifugal potential for all the possible cluster+core configurations of a nucleus. The clusters of neutrons and protons are taken to be unbound, with additional Coulomb energy added for proton-clusters. The model predictions agree with the available experimental studies but show some differences with the nucleon separation energy hypothesis, particularly for proton-halo nuclei. Of particular interest are the halo structures of ¹¹N and ²⁰Mg. The calculated potential energy surfaces are also useful to identify the new magic numbers and molecular structures in exotic nuclei. In particular, N = 6 is a possible new magic number for very neutron-deficient nuclei, but N = 2, Z = 2 and Z = 8 seem to remain magic even for such nuclei, near the drip line.

Neutrino- and anti-neutrino-induced single charm production is particularly relevant to the study of the strange-quark parton distribution function and the threshold effect in the cross-section, associated with heavy quark production. Over the past 30 years, many experiments have been carried out using complementary techniques: calorimetry, bubble chambers and nuclear emulsions.

In this note, we review these data and combine them statistically to extract a world averaged single-charm production cross section for both neutrino and anti-neutrino.

Quasi-binary reaction of the deuteron breakup p + d → (pp) + n with the final proton–proton pair (pp) in the ¹S₀ state is analysed at initial energies 0.5–2 GeV in the kinematics of backward elastic pd-scattering pd → dp. On the basis of the main mechanisms of the pd → dp process, including initial and final state interactions, we show that unpolarized cross section and spin observables of this reaction exhibit important properties of the half-off-shell pp(¹S₀)-scattering amplitude, which are relevant to the nucleon–nucleon interaction at short distances.