Measurement of Trilinear Gauge Couplings in e+e−e^+ e^- Collisions at 161 GeV and 172 GeV

Trilinear gauge boson couplings are measured using data taken by DELPHI at 161~GeV and 172~GeV. Values for $WWV$ couplings ($V=Z, \gamma$) are determined from a study of the reactions \eeWW\ and \eeWev, using differential distributions from the $WW$ final state in which one $W$ decays hadronically and the other leptonically, and total cross-section data from other channels. Limits are also derived on neutral $ZV\gamma$ couplings from an analysis of the reaction \eegi

Disease surveillance by artificial intelligence links eelgrass wasting disease to ocean warming across latitudes

Ocean warming endangers coastal ecosystems through increased risk of infectious disease, yet detection, surveillance, and forecasting of marine diseases remain limited. Eelgrass (Zostera marina) meadows provide essential coastal habitat and are vulnerable to a temperature-sensitive wasting disease caused by the protist Labyrinthula zosterae. We assessed wasting disease sensitivity to warming temperatures across a 3500 km study range by combining long-term satellite remote sensing of ocean temperature with field surveys from 32 meadows along the Pacific coast of North America in 2019. Between 11% and 99% of plants were infected in individual meadows, with up to 35% of plant tissue damaged. Disease prevalence was 3× higher in locations with warm temperature anomalies in summer, indicating that the risk of wasting disease will increase with climate warming throughout the geographic range for eelgrass. Large-scale surveys were made possible for the first time by the Eelgrass Lesion Image Segmentation Application, an artificial intelligence (AI) system that quantifies eelgrass wasting disease 5000× faster and with comparable accuracy to a human expert. This study highlights the value of AI in marine biological observing specifically for detecting widespread climate-driven disease outbreaks

Search for Supersymmetry with R-Parity violating couplings at LLE- = 183 GeV

0info:eu-repo/semantics/publishe

Search for heavy neutral Higgs bosons in 2-doublet models

A search for pair production of neutral heavy Higgs bosons decaying into has been carried out in a study of hadronic decays of the Z boson into four jet final states using data taken by DELPHI in 1991 and 1992. The two production mechanisms present in the two Higgs doublets scheme, bremsstrahlung production of hZ* and associated production of hA, may lead to four beauty jets well recognizable using the precise microvertex detector measurements. No evidence for a signal was found, leading to limits on BR(Z -->, hA --> 4b) from 3.5 to 5.5 x 10(-4) at 95% confidence level, depending on the mass of the ligthest Higgs. When combined with the results of the recent DELPHI standard Higgs search, this result allows the kinematical limit to be reached for the masses of h and A in the minimal supersymmetric extension of the Standard Model (MSSM) scheme. It also allows the tan beta less than or equal to 1 domain to be explored, and a region above the kinematic limit for direct hA production is constrained by considering virtual hA production. Results are also given in the general two-doublet scheme

Measurement of the partial decay width R(b)(0)=Gamma(b(b)over-bar)/Gamma(had) of the Z with the DELPHI detector at LEP

The partial decay width of the Z to quark pairs has been measured by the DELPHI detector at LEP. B-hadrons, containing b-quarks, were tagged by several methods using tracks with large impact parameters to the primary vertex complemented sometimes by event shape variables or using leptons with high transverse momentum relative to the hadron. In order to reduce the systematic uncertainties, in all methods the b-tagging efficiency has been extracted directly from the data. Combining all methods, the value: Gamma()/Gamma(had) = 0.2216 +/- 0.0016(stat.) +/- 0.0021(syst.) was found, where the production fraction was fixed to its Standard Model value

Two-dimensional analysis of the Bose-Einstein correlations in e(+)e(-) annihilation at the Z(0) peak

The study of the directional dependence of two-particle correlations in the hadronic decays of the Z(0) boson is performed using the data collected by the DELPHI experiment in the 1992-1995 running periods. The comparison between the transverse, R-perpendicular to, and longitudinal, R-parallel to, correlation radii confirms the string model prediction that the transverse correlation length is smaller than the longitudinal one, with the measured values of R-perpendicular to = 0.53 +/- 0.08 fm and R-parallel to = 0.85 +/- 0.08 fm, for selected Z(0) –> q (q) over bar events. (C) 2000 Published by Elsevier Science B.V. All rights reserved