Weakly coupled neutral gauge bosons at future linear colliders

A weakly coupled new neutral gauge boson forms a narrow resonance that is hard to discover directly in e+e- collisions. However, if the gauge boson mass is below the center-of-mass energy, it can be produced through processes where the effective energy is reduced due to initial-state radiation and beamstrahlung. It is shown that at a high-luminosity linear collider, such a gauge boson can be searched for with very high sensitivity, leading to a substantial improvement compared to existing limits from the Tevatron and also extending beyond the expected reach of the LHC in most models. If a new vector boson is discovered either at the Tevatron Run II, the LHC or the linear collider, its properties can be determined at the linear collider with high precision, thus helping to reveal origin of the new boson.Comment: 21 p

Nonexotic Neutral Gauge Bosons

We study theoretical and experimental constraints on electroweak theories including a new color-singlet and electrically-neutral gauge boson. We first note that the electric charges of the observed fermions imply that any such Z' boson may be described by a gauge theory in which the Abelian gauge groups are the usual hypercharge along with another U(1) component in a kinetic-diagonal basis. Assuming that the observed quarks and leptons have generation-independent U(1) charges, and that no new fermions couple to the standard model gauge bosons, we find that their U(1) charges form a two-parameter family consistent with anomaly cancellation and viable fermion masses, provided there are at least three right-handed neutrinos. We then derive bounds on the Z' mass and couplings imposed by direct production and Z-pole measurements. For generic charge assignments and a gauge coupling of electromagnetic strength, the strongest lower bound on the Z' mass comes from Z-pole measurements, and is of order 1 TeV. If the new U(1) charges are proportional to B-L, however, there is no tree-level mixing between the Z and Z', and the best bounds come from the absence of direct production at LEPII and the Tevatron. If the U(1) gauge coupling is one or two orders of magnitude below the electromagnetic one, these bounds are satisfied for most values of the Z' mass.Comment: 26 pages, 2 figures. A comparison with the LEP bounds on sneutrino resonances is include

Prevalence and Antimicrobial-Resistance of Pseudomonas aeruginosa in Swimming Pools and Hot Tubs

Pseudomonas aeruginosa is an important opportunistic pathogen in recreational waters and the primary cause of hot tub folliculitis and otitis externa. The aim of this surveillance study was to determine the background prevalence and antimicrobial resistance profile of P. aeruginosa in swimming pools and hot tubs. A convenience sample of 108 samples was obtained from three hot tubs and eight indoor swimming pools. Water and swab samples were processed using membrane filtration, followed by confirmation with polymerase chain reaction. Twenty-three samples (21%) were positive for P. aeruginosa, and 23 isolates underwent susceptibility testing using the microdilution method. Resistance was noted to several antibiotic agents, including amikacin (intermediate), aztreonam, ceftriaxone, gentamicin, imipenem, meropenem (intermediate), ticarcillin/clavulanic acid, tobramycin (intermediate), and trimethoprim/sulfamethoxazole. The results of this surveillance study indicate that 96% of P. aeruginosa isolates tested from swimming pools and hot tubs were multidrug resistant. These results may have important implications for cystic fibrosis patients and other immune-suppressed individuals, for whom infection with multidrug-resistant P. aeruginosa would have greater impact. Our results underlie the importance of rigorous facility maintenance, and provide prevalence data on the occurrence of antimicrobial resistant strains of this important recreational water-associated and nosocomial pathogen

Louse flies in Azorean and mainland populations of four Passeriformes species_a new perspective to parasite Island syndromes

Environmental Sciences & Ecology ; ParasitologyHippoboscid flies, also known as louse flies, are obligate blood-feeders ectoparasites of birds and mammals. By studying louse fly parasites of four Passeriformes species, Eurasian blackbird (Turdus merula), Eurasian blackcap (Sylvia atricapilla), common chaffinch (Fringilla coelebs) and European robin (Erithacus rubecula), with dissimilar time of colonization of Azores islands, we tested whether: (i) island host populations have lower parasite richness than the mainland one; (ii) island host populations undergo higher parasite prevalence, mean intensities and mean abundance than the mainland one; (iii) island parasite diversity are composed exclusively by specific parasites and (iv) parasite richness is positively correlated with the island area and proximity to the continent. For these purposes, 775 birds were sampled for presence of louse flies, by modified fumigation chamber method, from Azores Islands (S˜ao Miguel, Terceira and Flores) and Portugal mainland. Insular and mainland parasite assemblages were statistically compared. We record for the first time to Azores, Ornithomya fringillina and Icosta minor from Portugal mainland. Louse flies had highest prevalence and abundance from Azores Islands compared to those observed in mainland birds, especially blackbirds. The insular parasite diversity of Azores blackbirds, blackcaps and chaffinches was richer than the one observed in mainland population. None of the hippoboscid flies observed on the islands and mainland were host-specific. Thus, our findings provide an upgrade of parasite island syndromes knowledge, in the context of the ectoparasites, namely to the ippoboscid flies case.info:eu-repo/semantics/publishedVersio

Isoprenoid emission in hygrophyte and xerophyte European woody flora: ecological and evolutionary implications

Aim The relationship between isoprenoid emission and hygrophily was investigated in woody plants of the Italian flora, which is representative of European diversity. Methods Volatile isoprenoids (isoprene and monoterpenes) were measured, or data collected from the literature, for 154 species native or endemic to the Mediterranean. The Ellenberg indicator value for moisture (EIVM) was used to describe plant hygrophily. Phylogenetic analysis was carried out at a broader taxonomic scale on 128 species, and then refined on strong isoprene emitters (Salix and Populus species) based on isoprene synthase gene sequences (IspS). Results Isoprene emitters were significantly more common and isoprene emission was higher in hygrophilous EIVM classes, whereas monoterpene emitters were more widespread and monoterpene emission was higher in xeric classes. However, when controlling for phylogeny, isoprene emission was not associated with EIVM, possibly due to the large presence of Salicaceae among hygrophilous isoprene emitters. Moreover, the distribution of isoprene emitters among EIVM classes was not related to IspS-based phylogenesis in Populus and Salix, suggesting that the gene has not undergone evolution linked to ecological pressure. In contrast, the monoterpene emission pattern is independent of phylogeny, suggesting that the evolution of monoterpenes is associated with transitions to more xeric habitats. Main conclusions Our results reveal an interesting ecological pattern linking isoprenoids and water availability. We suggest that isoprene is a trait that: (1) evolved in plants adapted to high water availability; (2) is replaced by more effective protection mechanisms, e.g. more stable isoprenoids, in plants adapting to more xeric environments; and (3) being strongly constrained by phylogeny, persists in Salicaceae adapted to more xeric environments

Evidence for muon neutrino oscillation in an accelerator-based experiment

We present results for muon neutrino oscillation in the KEK to Kamioka (K2K) long-baseline neutrino oscillation experiment. K2K uses an accelerator-produced muon neutrino beam with a mean energy of 1.3 GeV directed at the Super-Kamiokande detector. We observed the energy dependent disappearance of muon neutrino, which we presume have oscillated to tau neutrino. The probability that we would observe these results if there is no neutrino oscillation is 0.0050% (4.0 sigma).Comment: 5 pages, 4 figure

Search for coherent charged pion production in neutrino-carbon interactions

We report the result from a search for charged-current coherent pion production induced by muon neutrinos with a mean energy of 1.3 GeV. The data are collected with a fully active scintillator detector in the K2K long-baseline neutrino oscillation experiment. No evidence for coherent pion production is observed and an upper limit of $0.60 \times 10^{-2}$ is set on the cross section ratio of coherent pion production to the total charged-current interaction at 90% confidence level. This is the first experimental limit for coherent charged pion production in the energy region of a few GeV.Comment: 5 pages, 4 figure

General constraints on light resonances in a strongly coupled symmetry breaking sector

In this paper we consider the information that can be obtained about a strongly-interacting symmetry breaking sector from precision measurements of four-fermion processes at LEP2 or a (500 GeV) NLC . Using a ``Z-peak'' subtracted approach to describe four-fermion processes, we show that measurements of the cross section for muon production, the related forward-backward asymmetry, and the total cross section for the production of hadrons (except $t$'s) can place constraints on (or measure the effectsof) the lightest vector or axial resonances present in a strong symmetry breaking sector. We estimate that such effects will be visible at LEP2 for resonances of masses up to approximately 350 GeV, and at a 500 GeV NLC for resonances of masses up to approximately 800 GeV. Multiscale models, for example, predict the presence of light vector and axial mesons in this mass range and their effects could be probed by these measurements.Comment: 22 pages and 6 figures. e-mail: [email protected]