We introduce soft colour interactions as a novel mechanism to understand the observed events with large rapidity gaps in ep collisions at HERA. Colour exchanges between produced partons and colour-charges in the proton remnant modifies the colour structure for hadronization, such that colour singlet systems may appear well separated in rapidity. Our explicit model show characteristics of diffracti

We discuss how the renormalization scheme ambiguities in QCD can be fixed, when two observables are related, by requiring the coefficients in the perturbative expansion relating the two observables to have their conformal limit values, i.e., to be independent of the [Formula presented] function of the renormalized coupling. We show how the next-to-leading order BLM automatic scale-fixing method ca

The deep inelastic scattering 2+1 jet cross-section is a useful observable for precision tests of QCD, e.g. measuring the strong coupling constant αs. A consistent analysis requires a good understanding of the theoretical uncertainties and one of the fundamental ones in QCD is due to the renormalisation scheme and scale ambiguity. Different methods, which have been proposed to resolve the scale am

We analyze some of the different determinations of αs(mτ 2) that can be found in the literature and the numerical impact of their possible weaknesses with the publicly available non-strange spectral function from ALEPH tau decays. We also introduce some novel approaches. We find very stable results and uncertainties dominated by the perturbative part. Our final value is αs(mτ 2)=0.328±0.013.

Heavy Majorana neutrinos (N), predicted in various extensions of the standard model, are examined with respect to the present limits on their masses and mixings with ordinary leptons resulting in explicit examples of allowed values of interest for present and planned accelerator energies. The decay N→Zv is added to the previously available formalism and all dominating branching ratios are calculat

We present a comprehensive study of the determination of the strong coupling from τ decay, using the most recent release of the experimental ALEPH data. We critically review all theoretical strategies used in previous works and put forward various novel approaches which allow one to study complementary aspects of the problem. We investigate the advantages and disadvantages of the different methods

Although the projected changes in the climate include considerable uncertainties, especially with downscaling, there is irrefutable evidence that the climate is changing at an unprecedented and alarming rate. In recent studies, some of the potential climate-change risks on bridges have been identified. The sheer number of these potential risks provokes two questions. Firstly, for a certain risk of

The strong coupling from ALEPH tau decays. We use the publically available non-strange spectral function from ALEPH tau decays to critically analyze the different determinations of αs(mτ2) that can be found in the literature and the numerical impact of their possible weaknesses. We also introduce some novel approaches. We find that perturbative uncertainties dominate. Our results with different ap

The early modern era sees critical changes in the relations between individual and society, home and community, self and other. The notion of privacy, both as a potential threat against communal welfare and stability, and as something worthy of protection, is gradually emerging and can be traced in politics, religious practices, ideas on family and personal relations, as well as in architecture an

Using the most recent release of the ALEPH τ decay data, we present a very detailed phenomenological update of the αs(mτ 2) determination. We have exploited the sensitivity to the strong coupling in many different ways, exploring several complementary methodologies. All determinations turn out to be in excellent agreement, allowing us to extract a very reliable value of the strong coupling. We fin

In a previous paper, one of us pointed out that the anomalous dimension matrices for all physical processes that have been calculated to date are complex symmetric, if stated in an orthonormal basis. In this paper we prove this fact and show that it is only true in a subset of all possible orthonormal bases, but that this subset is the natural one to use for physical calculations.

Using the updated ALEPH V-. A spectral function from τ decays, we determine the lowest spectral moments of the left-right correlator and extract dynamical information on order parameters of the QCD chiral symmetry breaking. Uncertainties associated with violations of quark-hadron duality are estimated from the data, imposing all known short-distance constraints on a resonance-based parametrization

The most common modules for ultrafiltration (UF) and nanofiltration (NF) are spiral wound elements due to their low investment, easy replacement and high packing density. Operating at high temperatures greater than 70°C, the use of spiral wound modules is, however, often limited. In the past ceramic membranes have been considered as the only viable option to operate at these temperatures. However,

We analyze the lowest spectral moments of the left-right two-point correlation function, using all known short-distance constraints and the recently updated ALEPH V-A spectral function from τ decays. This information is used to determine the low-energy couplings L10 and C87 of chiral perturbation theory and the lowest-dimensional contributions to the operator product expansion of the left-right co

The hadronic final state in deep-inelastic ep scattering at HERA is influenced by colour coherence effects in QCD. Three different models for initial- and final-state multi-parton emission and soft hadronization, as implemented in the Monte Carlo programs LEPTO, ARIADNE and HERWIG, are compared in this respect both at the parton and hadron level (with experimental conditions taken into account).