Anomalous Gauge Boson Couplings in the e^+ e^- -> ZZ Process

We discuss experimental aspects related to the $\mathrm{e^+ e^-} \to \mathrm{Z}\mathrm{Z}$ process and to the search for anomalous ZZV couplings (V$= \mathrm{Z}, \gamma$) at LEP2 and future $\mathrm{e^+ e^-}$ colliders. We present two possible approaches for a realistic study of the reaction and discuss the differences between them. We find that the optimal method to study double Z resonant production and to quantify the presence of anomalous couplings requires the use of a complete four-fermion final-state calculation.Comment: 28 pages, 12 figures, final version for Phys. Rev.

Biomarkers of postharvest resilience: unveiling the role of abscisic acid in table grapes during cold storage

Table grapes are considered non-climacteric fruit, not showing a rapid increase in respiration rate and ethylene production during ripening. Previous research has suggested that abscisic acid (ABA) may have a more crucial role in grape postharvest behaviour. This study aimed to identify biomarkers of postharvest resilience and flavour life of imported table grapes. An experiment was designed to determine i) the role of ABA and catabolites on grape berry senescence; ii) the spatial distribution of these hormones within the grape berry, and iii) the effect of 1-MCP and storage temperature on its postharvest quality. Hence, the use of an ethylene inhibitor, 1-methylcyclopropane (1-MCP), during table grape storage was investigated. Table grapes (Vitis vinifera L.) cv. ‘Krissy’ were subjected to i) control (untreated); and ii) 1-MCP (1 µL L-1; 12 hours; 15°C) and stored under two scenarios: i) 15 days at 0.5°C, followed by five days at 5.5°C to simulate shelf-life; and ii) 20 days at 5.5°C to simulate a higher storage temperature followed by shelf-life. Physiological (i.e. mould incidence, skin colour, firmness, respiration rate) and biochemical analysis (i.e. individual sugars, organic acids, abscisic acid and catabolites) were performed. Grapes subjected to 5.5°C showed significantly higher mould incidence at the end of the shelf-life compared to 0.5°C storage temperature (12.6% vs. 3.1%). Also, and for the first time, the spatial distribution of ABA during the senescence of table grapes was profiled; the distal section had three times more ABA and metabolites than the proximal. We demonstrated that senescence processes were initiated after a significant increase in respiration rate (from 1 to 2.8 mL CO2 kg-1 h-1), and that ABA could be considered a biomarker for table grapes senescence, since an ABA peak preceded the increase in respiration rate, mould incidence, organic acids, and sucrose hydrolysis during postharvest storage; and coincided with a decrease in berry firmness. These findings are of significant importance for the industry as understanding how ABA regulates both senescence processes and quality changes during postharvest cold storage of tables grapes can improve the consistency and reduce waste and consumer complaints

The role of ethylene and 1-MCP in early-season sweet cherry ‘Burlat’ storage life

Sweet cherries (Prunus avium L.) are highly appreciated because of their bioactive compound content and attractive organoleptic characteristics; however, they are very perishable. The aim of this work was to investigate whether ethylene and its antagonist 1-MCP affect the postharvest quality of an early-season sweet cherry cultivar, allowing storage life extension. ‘Burlat’ sweet cherries were subjected to three treatments at 1 °C for one month: i) control (air); ii) continuous ethylene supplementation (10 μL L−1); and iii) 1-Methylcyclopropene (1-MCP; 1 μL L−1 for 24 h) followed by air. The incidence of postharvest physiological disorders, the evolution of physical and functional quality traits, and fruit senescence were evaluated at 0, 7, 14, 21, and 30 days. Results showed that sweet cherries were sensitive to both ethylene and 1-MCP treatments. Continuous ethylene exposure reduced abscisic acid accumulation, resulting in higher weight and firmness loss. Moreover, ethylene application decreased titratable acidity through storage, indicating an effect on sweet cherry senescence. No significant differences among treatments were found for soluble solids content and individual sugars. Conversely, 1-MCP preserved firmness during the first 7 days of storage, while reduced the incidence of physiological disorders at the end of storage life. Furthermore, 1-MCP delayed the accumulation of cyanidin-3-O-glucoside for 7 days compared to control and ethylene treated cherries. Taken together these results highlight the potential use of 1-MCP to extend the postharevst life of early season sweet cherry fruit

Non-destructive methods for mango ripening prediction: Visible and near-infrared spectroscopy (visNIRS) and laser Doppler vibrometry (LDV)

With up to 19% of mango fruit being lost during ripening, the need for non-destructive technologies to predict internal physiochemical traits is paramount. This study compared two non-destructive technologies, visible and near-infrared spectroscopy (visNIRS) and laser Doppler vibrometry (LDV), for predicting the ripeness of mango fruit in two cultivars, ‘Kent’ and ‘Keitt’. An internal quality index (IQI) in ‘Kent’ was predicted using visNIRS (RP2 = 0.729, RMSEP = 0.532) using partial least squares regression, which gave a single measure for ripeness incorporating firmness, sweetness, and pulp colour. This model was improved by using the sum of the individual sugar contents (glucose, sucrose, and fructose) over the conventional total soluble solids (TSS) measure. LDV provided poor predictions of firmness (R2 < 0.5) in both ‘Kent’ and ‘Keitt’ using least squares regression line. The resonant frequency, as measured by LDV, decreased linearly with time, while firmness quantified destructively (quasi-static) showed an exponential decrease, suggesting the vibrational and destructive firmness measure distinct characteristics, which would contribute to poor model performance. These results showed that LDV is not suitable for assessing mango ripening. While visNIRS models have been successful at predicting quality traits, our results suggested that using individual sugar content in place of TSS can improve the prediction of ripening. This understanding of the strengths and limitations of both visNIRS and LDV, and how they relate to destructive quality measurements, can be used to improve postharvest management practices whilst reducing commercial losses in the mango industry

Study of Spin and Decay-Plane Correlations of W Bosons in the e+e- -> W+W- Process at LEP

Data collected at LEP at centre-of-mass energies \sqrt(s) = 189 - 209 GeV are used to study correlations of the spin of W bosons using e+e- -> W+W- -> lnqq~ events. Spin correlations are favoured by data, and found to agree with the Standard Model predictions. In addition, correlations between the W-boson decay planes are studied in e+e- -> W+W- -> lnqq~ and e+e- -> W+W- -> qq~qq~ events. Decay-plane correlations, consistent with zero and with the Standard Model predictions, are measured

Ultrarelativistic sources in nonlinear electrodynamics

The fields of rapidly moving sources are studied within nonlinear electrodynamics by boosting the fields of sources at rest. As a consequence of the ultrarelativistic limit the delta-like electromagnetic shock waves are found. The character of the field within the shock depends on the theory of nonlinear electrodynamics considered. In particular, we obtain the field of an ultrarelativistic charge in the Born-Infeld theory.Comment: 10 pages, 3 figure

Measurement of the Cross Section for Open-Beauty Production in Photon-Photon Collisions at LEP

The cross section for open-beauty production in photon-photon collisions is measured using the whole high-energy and high-luminosity data sample collected by the L3 detector at LEP. This corresponds to 627/pb of integrated luminosity for electron-positron centre-of-mass energies from 189GeV to 209GeV. Events containing b quarks are identified through their semi-leptonic decay into electrons or muons. The e+e- -> e+e-b b~X cross section is measured within our fiducial volume and then extrapolated to the full phase space. These results are found to be in significant excess with respect to Monte Carlo predictions and next-to-leading order QCD calculations

Closed-Loop Recycling of Copper from Waste Printed Circuit Boards Using Bioleaching and Electrowinning Processes

International audienceIn the present study, a model of closed-loop recycling of copper from PCBs is demonstrated, which involves the sequential application of bioleaching and electrowinning to selectively extract copper. This approach is proposed as part of the solution to resolve the challenging ever-increasing accumulation of electronic waste, e-waste, in the environment. This work is targeting copper, the most abundant metal in e-waste that represents up to 20% by weight of printed circuit boards (PCBs). In the first stage, bioleaching was tested for different pulp densities (0.25–1.00% w/v) and successfully used to extract multiple metals from PCBs using the acidophilic bacterium, Acidithiobacillus ferrooxidans. In the second stage, the method focused on the recovery of copper from the bioleachate by electrowinning. Metallic copper foils were formed, and the results demonstrated that 75.8% of copper available in PCBs had been recovered as a high quality copper foil, with 99 + % purity, as determined by energy dispersive X-ray analysis and Inductively-Coupled Plasma Optical Emission Spectrometry. This model of copper extraction, combining bioleaching and electrowinning, demonstrates a closed-loop method of recycling that illustrates the application of bioleaching in the circular economy. The copper foils have the potential to be reused, to form new, high value copper clad laminate for the production of complex printed circuit boards for the electronics manufacturing industry. Graphic Abstract: [Figure not available: see fulltext.] © 2020, The Author(s)

A search for flaring Very-High-Energy cosmic-ray sources with the L3+C muon spectrometer

The L3+C muon detector at the Cern electron-position collider, LEP, is used for the detection of very-high-energy cosmic \gamma-ray sources through the observation of muons of energies above 20, 30, 50 and 100 GeV. Daily or monthly excesses in the rate of single-muon events pointing to some particular direction in the sky are searched for. The periods from mid July to November 1999, and April to November 2000 are considered. Special attention is also given to a selection of known \gamma-ray sources. No statistically significant excess is observed for any direction or any particular source

Study of Neutral-Current Four-Fermion and ZZ Production in e+e−e^+ e^- Collisions at s\sqrt{s}= 183 GeV

Study of Neutral--Current Four--Fermion and ZZ \\ Production in $\rm e^+ e^-$ Collisions at $\rm \sqrt{s}=$ 183 GeV A study of neutral--current four--fermion processes is performed using a data sample corresponding to 55.3~pb$^{-1}$ of integrated luminosity collected by the L3 detector at LEP at an average centre--of--mass energy of 183~\GeV. The neutral--current four--fermion cross sections for final states with a pair of charged leptons plus jets and with four charged leptons are measured to be consistent with the Standard Model predictions. Events with fermion pair masses close to the Z boson mass are selected in all observable final states and the ZZ production cross section is measured to be %\begin{center} $\rm \sigma_{ZZ} = 0.30 ^{+0.22\,\,+0.07}_{-0.16\,\,-0.03}\,\mathrm{pb},$ %\end{center} in agreement with the Standard Model expectation. No evidence for the existence of anomalous triple gauge boson ZZZ and ZZ$\gamma$ couplings is found and limits on these couplings are set