W-propagator corrections to muon and tau leptonic decays

We derive the corrections induced by the W-boson propagator to the differential rates of the leptonic decay of a polarized muon and tau lepton. Results are presented both for decays inclusive of inner bremsstrahlung as well as for radiative ones, when a photon emitted in the decay process is measured. The numerical effect of these corrections is discussed. The definition of the Fermi constant is briefly reviewed.Comment: 5 pages, no figures, accepted for publicatio

Radiative μ\mu and τ\tau leptonic decays at NLO

We present the differential rates and branching ratios of the radiative decays $\tau \to l \bar{\nu} \nu \gamma$, with $l=e$ or $\mu$, and $\mu \to e \bar{\nu} \nu \gamma$ in the Standard Model at next-to-leading order. Radiative corrections are computed taking into account the full depencence on the mass $m_l$ of the final charged leptons, which is necessary for the correct determination of the branching ratios. Only partial agreement is found with previous calculations performed in the $m_l \to 0$ limit. Our results agree with the measurements of the branching ratios $\mathcal{B} (\mu \to e \bar{\nu} \nu \gamma)$ and $\mathcal{B} (\tau \to \mu \bar{\nu} \nu \gamma)$ for a minimum photon energy of 10 MeV in the $\mu$ and $\tau$ rest frames, respectively. Babar's recent precise measurement of the branching ratio $\mathcal{B} (\tau \to e \bar{\nu} \nu \gamma)$, for the same photon energy threshold, differs from our prediction by 3.5 standard deviations.Comment: 13 pages, 1 figure, results included as ancillary file

Higher QCD corrections for inclusive semileptonic B decays

In these proceedings we review the calculation of the total decay rate for inclusive $B→X_{c}ℓ \overline{ν}_{ℓ}$ decays to higher orders in perturbative QCD. The partonic rate is obtained via an asymptotic expansion around the limit $1−m_{c}/m_{b}≪1$. The same method can be used to compute kinematic moments in case no experimental cuts are applied, i.e.\ moments of the differential rate integrated over the whole phase space. We discuss the impact of the $O(α^3_{s})$ corrections on the total semileptonic decay rate and the moments of the dilepton invariant mass $q^{2}$

τ→ μμμ at a rate of one out of 10¹⁴ tau decays?

We present in a full analytic form the partial widths for the lepton flavour violating decays μ±→e±e+e− and τ±→ℓ±ℓ′+ℓ′−, with ℓ,ℓ′=μ,e, mediated by neutrino oscillations in the one-loop diagrams. Compared to the first result by Petcov (Sov J Nucl Phys 25:340, 1977), obtained in the zero momentum limit P≪mν≪MW, we retain full dependence on P, the momenta and masses of external particles, and we determine the branching ratios in the physical limit mν≪P≪MW. We show that the claim presented in Pham (Eur Phys J C8:513, 1999) that the τ→ℓℓ′ℓ′ branching ratios could be as large as 10−14, as a consequence of keeping the P dependence, is flawed. We find rates of order 10−55, even smaller than those obtained in the zero momentum limit, as the latter prediction contains an unphysical logarithmic enhancement

Clear-water scour at comparatively large cylindrical piers

New long-duration clear-water scour data were collected at single cylindrical piers with the objective of investigating the effect of sediment coarseness, Dp=D50 (Dp = pier diameter; D50 = median grain size) on the equilibrium scour depth and improving the scour depth time evolution modeling by making use of the exponential function suggested in the literature. Experiments were carried out for the flow intensity close to the threshold condition of initiation of sediment motion, imposing wide changes of sediment coarseness and flow shallowness, d=Dp (d = approach flow depth). The effect of sediment coarseness on the equilibrium scour depth was identified; existing predictors were modified to incorporate this effect for U=Uc ≈ 1.0; Dp=D50 > ≈60 and d=Dp ≥ 0.5; the complete characterization of a known scour depth time evolution model was achieved for U=Uc ≈ 1.0, 60 < Dp=D50 < 500 and 0.5 ≤ d=Dp ≤ 5.0

Exploring irrigation and water supply technologies for smallholder farmers in the Mediterranean region

Water security is a hot topic all over the world, due to global warming, climate change, natural calamities such as droughts and floods, overuse of water, and other factors. Water issues have been scientifically investigated from several perspectives, namely institutional, economic, social, environmental, managerial, and technological. However, the technological aspects of irrigation and water supply for smallholder farmers in the Mediterranean region have not been adequately addressed. This paper explores irrigation and water supply technologies for smallholder farmers in the selected Mediterranean countries (Egypt, Malta, Morocco, and Portugal). The methods of analysis are literature review, fieldwork, and observation. The literature survey reveals that Mediterranean countries share many common features in terms of climate, water and land resources, and development issues. Nevertheless, the selected countries in the Mediterranean region (Egypt, Malta, Morocco, and Portugal) differ in terms of type of crops, water management regulations, labor force availability, financial sustainability, and economic approaches. These remarks signal the need for applying a specific approach in selecting a technology for irrigation and water supply according to the regional context. Additionally, the financial and economic perspectives of the three key technologies (i.e., SLECI, desalination technology, and engineering constructed wetlands) require further analysis.This research carried out within the project MED-WET “Improving MEDiterranean irrigation and Water supply for smallholder farmers by providing Efficient, low-cost and nature-based Technologies and practices” (Project ID 1646) funded by Partnership for Research and Innovation in the Mediterranean Area (PRIMA) program.info:eu-repo/semantics/publishedVersio