Table of contents

The constraint of a progressive decrease in residual renormalization scale dependence with increasing loop order is developed as a method for obtaining bounds on unknown higher-order perturbative corrections to renormalization-group-invariant quantities. This technique is applied to the inclusive semileptonic process b → u_ℓℓ⁻ (explicitly known to two-loop order) in order to obtain bounds on the three- and four-loop perturbative contributions that are not accessible via the renormalization group. Combining this technique with the principle of minimal sensitivity, we obtain an estimate for the perturbative contributions to Γ(b → u_ℓℓ⁻) that incorporates theoretical uncertainty from as-yet-undetermined higher-order QCD corrections.

The FELIX collaboration had proposed the construction of a full-acceptance detector for the LHC. The primary mission of FELIX was the study of QCD: to provide comprehensive and definitive observations of a very broad range of strong-interaction processes. This document contains an extensive discussion of this physics menu. In a further paper the FELIX detector will be reviewed.

We consider the dynamical stability of a static brane model that incorporates a three-index antisymmetric tensor field and has recently been proposed [1, 2] as a possible solution to the cosmological constant problem. Ultimately, we are able to establish the existence of time-dependent, purely gravitational perturbations. As a consequence, the static solution of interest is 'dangerously' located at an unstable saddle point. This outcome is suggestive of a hidden fine tuning in what is an otherwise self-tuning model.

We give a complete analytical computation of three-point one-loop integrals with one heavy propagator, up to the third tensor rank, for arbitrary values of external momenta and masses.

The recently proposed stabilization mechanism of the Randall–Sundrum metric gives rise to a scalar radion, which couples universally to matter with a weak interaction (≃1 TeV) scale. Demanding that gauge boson scattering as described by the effective low-energy theory be unitary up to a given scale leads to significant constraints on the mass of such a radion.

We present new results of measurements of the isotopic cross sections of ¹²C fragmentation in the energy region of a few GeV/n. The experiment has been performed at the Dubna synchrophasotron using the magnetic spectrometer ANOMALON, equipped with Cherenkov counters. In this experiment ¹²C is the projectile and liquid hydrogen is a target. The isotopic cross sections obtained in the measurement are compared with the values predicted by the models: semi-empirical (Silberberg and Tsao) and parametric (Webber, Kish and Schrier). This work is a continuation of the previous one where similar results, but at 3.66 GeV/n, are presented.

We study a formulation of the translationally invariant coupled cluster method in coordinate space for finite nuclei. The new formulation remedies convergence problems that plagued previous calculations in configuration space. The method is applied to light nuclei using semi-realistic central interactions.

A simple criterion for the ΔI = 4 bifurcation is applied to 22 superdeformed bands in the A ∼ 150 mass region. An analysis confirms the configuration dependence effect and allows us to discriminate between single-particle states that are active and inactive for staggering. The consideration is based on additivity of the nonaxial quadrupole and hexadecapole moments. The analysis shows the correlation between the nonaxial hexadecapole moment of single-particle orbitals involved in the configurations of superdeformed bands and their staggering behaviour.

The Lund fragmentation model implemented through Monte Carlo FRITIOF is used to analyse the data from pion–emulsion interactions in a strong pulsed magnetic field at P_Lab = 50 GeV/c. The model is based on the concept of classical strings and uses the longitudinal excitation as a means of string formation. The subsequent string fragmentation follows the Lund fragmentation scheme. Detailed inclusive studies based on rapidity, momenta, transverse momenta, etc of the fast pions produced in such interactions are undertaken. The analysis is motivated by the fact that such inclusive studies have not been performed earlier and to make detailed tests of the model to establish correctness of the procedures relating to the dynamics involved in the particle production. This also gives interesting comparison between the data and the model predictions.

The measurements of partial production cross-sections of the multiple helium fragments emitted at 14.6 A GeV ²⁸Si–emulsion interactions are reported. The production rate of helium fragments due to fragmentation of ²⁸Si ions is studied and compared with that obtained from different projectiles at various energies. The dependence of ⟨N_α⟩ on the mass number of the incident beams is formulated. The multiplicity distributions of the helium fragments produced in 14.6 A GeV and 3.7 A GeV ²⁸Si aswell as 200 A GeV ³²S exhibit KNO scaling. The characteristics of He-multiplicity events associated with and without projectile fragments of charge Z ⩾ 3 are investigated.

Theoretical results representing further development of scaling formalism for the lateral distribution of electrons in atmospheric cascade showers are reported in this paper. A detailed study of the root mean square radius of extensive air shower electrons—the basic parameter of the lateral distribution function (LDF)—has been carried out. Comparisons of our predictions with CORSIKA simulation results and also KASCADE and AGASA experimental data are presented. A new method for cosmic ray primary composition deduction from the shape of electron LDF, applicable in wide primary energy range with weak sensitivity to hadronic interaction model, is introduced.

We show that assuming a simple cosmic ray (CR) acceleration scenario, where all the pulsar rotational energy is transformed into CR particles of the highest available energy at a given moment, one obtains particle fluxes of the order of the observed ones. We derive the energy spectrum of the produced particles assuming that the pulsar magnetic field decays with time. The slope of the spectrum for E > 10¹⁶ eV is determined by a power-law distribution of the pulsar initial periods and the knee in the spectrum at ∼3 × 10¹⁵ eV by the decay of the pulsar magnetic fields. Moreover, the pulsar parameters at birth, fitted to describe the CR energy spectrum, reconstruct reasonably well their present equilibrium population.

We investigate the ωσγ-vertex and estimate the coupling constant g_ωσγ in the framework of the light cone QCD sum rules. We compare our result with the values of this coupling constant deduced from a phenomenological analysis of ω → ππγ decays.

A recently developed quark model approach to pseudoscalar meson photoproduction is extended to the electroproduction process for the η meson in the kinematics of momentum transfer Q² ≤ 4 (GeV/c)² and total centre of mass energy W ≤ 1.6 GeV. Existing data are well reproduced and the roles of the S₁₁ (1535) and D₁₃ (1520) resonances are closely investigated. In the study of the longitudinal excitation of the S₁₁ (1535) resonance, a reliable constraint on the S₁₁ (1535) properties is obtained by cleanly removing the electromagnetic transition from the γ_(v)p → S₁₁ (1535) → ηp amplitude. Thus, the fitted quantities can be determined with an uncertainty of about 15%. This could be the first direct constraint on the S₁₁ (1535) properties in theory.

In the present work we apply the lowest order Brueckner theory of infinite nuclear matter to obtain nucleon–nucleus optical potential for p-⁴⁰Ca elastic scattering at 200 MeV using Urbana V14 soft core internucleon potential. We have investigated the effect of target density on the calculated nucleon–nucleus optical potential. We find that the calculated optical potentials depend quite sensitively on the density distribution of the target nucleus. The important feature is that the real part of calculated central optical potential for all densities shows a wine-bottle-bottom type behaviour at this energy. We also discuss the effect of our new radial dependent effective mass correction. Finally, we compare the prediction of our calculated nucleon optical potential using V14 with the prediction using older hard core Hamada–Johnston internucleon potential for p-⁴⁰Ca elastic scattering at 200 MeV.

Recoil protons from the β-decay of unpolarized neutrons are stored in a cryogenic ion trap formed by the superposition of an axisymmetric electrostatic field on a coaxial magnetic field, which varies uniformly in space between regions of high (∼4.30 T) and low (∼0.61 T) homogeneous field. Protons generated in the high field region are adiabatically focused onto a 'mirror' electrode in the low field region. The integrated energy spectrum is determined by counting the number of stored protons as a function of mirror potential. Violation of the exact adiabatic conditions is corrected for by carrying out alternate measurements at trapping times which differ by a factor of 2. The results: a₀ = −0.1054 ± 0.0055, |λ| = 1.271 ± 0.018 are in agreement with previous measurements of these quantities.

Pion–pion scattering amplitude obtained from one-loop chiral perturbation theory (ChPT) is crossing symmetric, however, the corresponding partial wave amplitudes do not respect exact unitarity relation. There are different approaches to get unitarized partial wave amplitudes from ChPT. Here we consider the inverse amplitude method (IAM) that is often used to fit pion–pion phase shifts to experimental data. We measure the amount of crossing symmetry violation (CSV) in this case and we show that crossing symmetry is badly violated by the IAM unitarized ChPT amplitude in the resonance region. Important CSV also occurs when all free parameters are set equal to zero.

Ultra high energy (UHE) particles coming from discrete extragalactic sources are potential candidates for EAS events above a few tens of EeV. In particular, galaxies with huge infrared luminosity triggered by collision and merging processes are possible sites of UHECR acceleration. Here we check whether this could be the case. Using the PSCz catalogue of IR galaxies we calculate a large scale anisotropy of UHE protons originating in the population of the luminous infrared galaxies (LIRGs). Small angle particle scattering in weak irregular extragalactic magnetic fields as well as deflection by regular galactic field are taken into account. We give analytical formulae for deflection angles with included energy losses on cosmic microwave background (CMB). The hypotheses of the anisotropic and isotropic distributions of the experimental data above 40 EeV from AGASA are checked, using various statistical tests. The tests applied for the large scale data distribution are not conclusive in distinguishing between isotropy and our origin scenario for the available small data sample. However, we show that on the basis of the small scale clustering analysis there is a much better correlation of the UHECRs data below GZK cut-off with the predictions of the LIRG origin than with those of isotropy. We derive analytical formulae for a probability of a given number of doublets, triplets and quadruplets for any density distribution of independent events on the sky. The famous AGASA UHE triple event is found to be very well correlated on the sky with the brightest extragalactic infrared source within 70 Mpc—merger galaxies Arp 299 (NGC 3690 + IC 694).

An exclusive study of the characteristics of the interactions accompanied by the backward emission (θ_Lab ≥ 90°) of relativistic and fast hadrons in the collisions of 4.5 A GeV/c³²S beam with emulsion nuclei is carried out. The experimental multiplicity distributions of different particles emitted in the forward (θ_Lab < 90°) and backward hemispheres due to the interactions with the two emulsion components (CNO, AgBr) are presented and analysed. The correlations between the multiplicities of the different emitted particles are also investigated. This study reveals that there are signatures for a collective mechanism, which plays a role in the production of particles in the backward hemisphere. Hence, the backward multiplicity distribution of the emitted shower or grey particles at 4.5 A GeV/c incident momentum can be represented by a decay exponential law formula independent of the projectile size. The exponent of the power was found to increase with decreasing target size. The experimental data favour the idea that the backward particles were emitted due to the decay of the system in the latter stage of the reaction. While the mean values of the shower particles emitted in the forward hemisphere ⟨n^f_s⟩ are strongly dependent on the projectile size and incident energy, the mean value of the multiplicity of the shower particles flying into the backward hemisphere ⟨n^b_s⟩ are found to be only a function of the target size (i.e. impact parameter). Therefore, the results yield quite interesting information regarding the mechanism of the backward particle production in heavy ion interactions. The present data are believed to support the mechanism, which considers the backward particle production as a consequence of the isotropic decay of a highly excited target system, in its rest frame, after the forward particle emission.

Following the re-establishment of the σ(500) and the κ(900), the light scalar mesons a₀(980) and f₀(980) together with the σ(500) and the κ(900) are considered as the chiral scalar partner of pseudoscalar nonet in SU(3) chiral symmetry, and the high mass scalar mesons a₀(1450), K*₀(1430), f₀(1370) and f₀(1710) turned out to be considered as the L = 1 q scalar mesons. We assume that the high mass of the L = 1 q scalar mesons is caused by the mixing with the light scalar mesons. For the structure of the light scalar mesons, we adopted the qq model in order to explain the 'scalar meson puzzle'. The inter-mixing between the light scalar nonet and the high mass L = 1 q nonet and the intra-mixing among each nonet are analysed by including the glueball into the high mass scalar nonet.

The possible transverse polarization of the τ-lepton, which is T-odd and can be used to measure CP-violation, is estimated precisely in the radiative decay mode B_c → τ_τγ with possible parameters for the multi Higgs doublet model and the R-parity violating supersymmetric model. We find that the up-bound of the transverse polarization with possible parameters in the models is at very different levels, i.e. it can be ≤15 ∼ 23% for the former but ≤0.1% for the latter, and it will be accessible experimentally soon.

High-spin states in the neutron-deficient isotope ¹⁰⁴Cd were populated using the ⁵⁰Cr(⁵⁸Ni,4p)¹⁰⁴Cd reaction at a beam energy of 250 MeV. The level scheme has been extended using triple γ-ray coincidences to a spin of 29ℏ and an excitation energy of 18.2 MeV. Several collective structures involving the excitation of h_11/2 neutrons have been observed to spins approaching 30ℏ. The high-spin structure has been compared to the results of cranked Nilsson–Strutinsky calculations.

We study here a nuclear system consisting of n nucleons in a (2j+1)-fold degenerate shell, interacting through a pure pairing force. On the background of the seniority scheme, we introduce an alternative formulation based on doubly deformed (qp) operators. By mapping onto qp boson space we postulate a qp Hamiltonian to describe the pairing correlations among this system. We have calculated the neutron pair separation energy based on this formulation. A fit to experimental data of Sn isotopes shows a good agreement.

We study the β-vibrational spectrum of the putative double magic superheavy nucleus ²⁹²120, as predicted by the relativistic mean-field (RMF) model in a phenomenological collective approach and compare it with the one of the well-known double magic heavy nuclei ²⁰⁸Pb. Results are also presented for the elements ³⁰⁰120 and ²⁹⁸114. We use a selection of different mean-field forces and discuss their different predictions and the consequences for the collective modes.

In the framework of the macroscopic model for giant resonances we compute the transition densities of the isoscalar monopole, quadrupole and octupole, and isovector dipole modes for the superheavy element ²⁹²120, whose ground state density is determined from the RMF model. The results are also compared to those of ²⁰⁸Pb.

The low energy part of the reactor neutrino spectra has not been measured experimentally. Its uncertainties limit the sensitivities in certain reactor neutrino experiments. This paper discusses the origin of these uncertainties and examines their effects on the measurements of neutrino interactions with electrons and nuclei. The discrepancies between previous results and the standard model expectations can be explained by the underestimation of the reactor neutrino spectra at low energies. To optimize the experimental sensitivities, measurements for _e–e cross-sections should focus on events with large (>1.5 MeV) recoil energy while those for neutrino magnetic moment searches should focus on events <100 keV. The merits and attainable accuracies for neutrino–electron scattering experiments using artificial neutrino sources are discussed.

This paper proposes a new concept for generating controlled, high-flux pulses of neutrinos. Laser-induced generation of relativistic protons, followed by pion production and decay, provides the neutrino source. By conservative estimate, the source will yield nanosecond-range pulses of muon–neutrinos, with fluxes of ∼10¹⁹ ν_μ s⁻¹ sr⁻¹ and energies of ∼20 MeV or higher. Concept feasibility depends upon further progress in high-intensity lasers; the process assumes a driving laser with pulse energy ∼8 kJ, providing an irradiance of ∼9 × 10²² W cm⁻². The study of the KARMEN time anomaly and neutrino oscillations would be the possible applications of the source.

Using data from oscillation analyses, the ranges of the neutrino mixing matrix and the Majorana mass matrix are calculated. It is investigated whether observable effects apart from neutrinoless double beta decay can be expected. Branching ratios and cross sections for a variety of high and low energy lepton number violating processes are estimated. Direct and indirect limits on all entries of the Majorana mass matrix are defined and compared. Only neutrinoless double beta decay, depending on the ee element of the mass matrix, provides a realistic chance for observation. The consequences of this fact for determination of the complete mass matrix are discussed. A similar analysis is performed for effects of heavy Majorana neutrinos, where a different matrix is used and unitarity allows us to set lower limits on the respective processes.

Within the framework of the Pierre Auger project, it was necessary to identify suitable places for the observatory sites and to characterize them in order to make a final selection. 'Pampa Amarilla' in the province of Mendoza, Argentina and Millard County, State of Utah, USA have been chosen for the southern and northern sites, respectively. Atmospheric, meteorological, soil and topography studies were performed at those sites.

Attention is drawn to the fact that results of the model obtained by Rodríguez-Frías et al are in conflict with both the straightforward physical consideration and the results of other models of charge-changing acceleration in solar flares. The numerical code given by Rodríguez-Frías et al generates an erroneous result that charge states of ions accelerated to few thermal energies can significantly differ from the equilibrium thermal ion charge state. However a straightforward calculation indicates that modification of the ion charge is possible only at much higher energies. We also provide a number of references to works on energy-dependent charge states of cosmic ray ions, which have been published for over 20 years, disproving a statement by Rodríguez-Frías et al that 'it is usually assumed that the charge state of cosmic rays corresponds to the ionization equilibrium of the plasma where they undergo acceleration'.

There is a typographical error in the penultimate sentence of section 4.2 (p 723) of the above paper. The value `8.99' should read `1.99' so the correct sentence is `This has to be compared with the measured value of 1.99 ± 0.13 |_stat ± 0.17 |_syst % [16].'