41 research outputs found

    Measurement of prompt D0^{0} and D‟\overline{D}0^{0} meson azimuthal anisotropy and search for strong electric fields in PbPb collisions at root SNN\sqrt{S_{NN}} = 5.02 TeV

    Get PDF
    The strong Coulomb field created in ultrarelativistic heavy ion collisions is expected to produce a rapiditydependent difference (Av2) in the second Fourier coefficient of the azimuthal distribution (elliptic flow, v2) between D0 (uc) and D0 (uc) mesons. Motivated by the search for evidence of this field, the CMS detector at the LHC is used to perform the first measurement of Av2. The rapidity-averaged value is found to be (Av2) = 0.001 ? 0.001 (stat)? 0.003 (syst) in PbPb collisions at ?sNN = 5.02 TeV. In addition, the influence of the collision geometry is explored by measuring the D0 and D0mesons v2 and triangular flow coefficient (v3) as functions of rapidity, transverse momentum (pT), and event centrality (a measure of the overlap of the two Pb nuclei). A clear centrality dependence of prompt D0 meson v2 values is observed, while the v3 is largely independent of centrality. These trends are consistent with expectations of flow driven by the initial-state geometry. ? 2021 The Author. Published by Elsevier B.V. This is an open access article under the CC BY licens

    Measurement of the CP-violating phase ϕs_{s} in the B0^{0}s_{s}→J/ψ φ(1020) →ΌâșΌ⁻KâșK⁻ channel in proton-proton collisions at √s = 13 TeV

    Get PDF

    Observation of electroweak production of Wγ with two jets in proton-proton collisions at √s = 13 TeV

    Get PDF
    A first observation is presented for the electroweak production of a W boson, a photon, and two jets in proton-proton collisions. The W boson decays are selected by requiring one identified electron or muon and an imbalance in transverse momentum. The two jets are required to have a high dijet mass and a large separation in pseudorapidity. The measurement is based on data collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb−1^{-1}. The observed (expected) significance for this process is 4.9 (4.6) standard deviations. After combining with previously reported CMS results at 8 TeV, the observed (expected) significance is 5.3 (4.8) standard deviations. The cross section for the electroweak Wγjj_{γjj} production in a restricted fiducial region is measured as 20.4 +/- 4.5 fb and the total cross section for Wγ_{γ} production in association with 2 jets in the same fiducial region is 108 +/- 16 fb. All results are in good agreement with recent theoretical predictions. Constraints are placed on anomalous quartic gauge couplings in terms of dimension-8 effective field theory operators

    Measurements of production cross sections of polarized same-sign W boson pairs in association with two jets in proton-proton collisions at s=13 TeV

    Get PDF
    The first measurements of production cross sections of polarized same-sign W±W±boson pairs in proton-proton collisions are reported. The measurements are based on a data sample collected with the CMS detector at the LHC at a center-of-mass energy of 13TeV, corresponding to an integrated luminosity of 137fb−1. Events are selected by requiring exactly two same-sign leptons, electrons or muons, moderate missing transverse momentum, and two jets with a large rapidity separation and a large dijet mass to enhance the contribution of same-sign W±W±scattering events. An observed (expected) 95% confidence level upper limit of 1.17 (0.88)fbis set on the production cross section for longitudinally polarized same-sign W±W±boson pairs. The electroweak production of same-sign W±W±boson pairs with at least one of the Wbosons longitudinally polarized is measured with an observed (expected) significance of 2.3 (3.1) standard deviations.SCOAP

    Evolution and biogeography of Alectryon (Sapindaceae)

    No full text
    Phylogenetic analysis of nucleotide sequences from four plastid loci (matK, partial trnK–matK introns, rps16 intron) and one nuclear locus (the internal transcribed spacer of rDNA; ITS-1) was conducted for 14 species of Alectryon and five related genera in Sapindaceae. Both matK and rps16 intron provide few informative characters within Alectryon, whereas ITS-1 provides the largest number of parsimony-informative characters and has the greatest sequence divergence between taxa. Support for branches in cladograms produced in PAUP increased markedly upon inclusion of ITS-1 data to matK and rps16 intron data. Analyses of each region alone or combined produced congruent results, suggesting that the regions are complementary. Phylogenetic analysis indicates that there are two main lineages within Alectryon, with A. subcinereus sister to the remaining sampled Alectryon taxa. Two morphological characters, presence/absence of petals and aril patterning, are congruent with the molecular phylogeny. One robustly supported clade is characterized by smooth arils and petals, in contrast to the taxa in the other major clade which have patterned arils and an absence of petals. These analyses also support a number of revised subgeneric groupings for Alectryon. The decision to submerge Heterodendrum in Alectryon is supported, although taxa belonging to Heterodendrum do not form a clade. The majority of the Australian Alectryon appear to belong to the tropical monsoonal/arid flora with species from both lineages being found in representative vine thickets across northern Australia. It appears that the seasonally dry rainforest communities comprise a number of elements that do not share common evolutionary histories within this genus

    Divergence, diversity and species of the Australasian Callitris (Cupressaceous) and allied genera: evidence from ITS sequence data

    No full text
    Callitris Vent. is the most speciose of the Southern Hemisphere genera of Cupressaceae, occupying a diverse range of habitats within Australia and New Caledonia and is closely allied to Actinostrobus Miq. and the monotypic New Caledonian genus Neocallitropsis Florin. Results of phylogenetic analyses of 18S–26S rDNA internal transcribed spacer region sequences for representatives of 12 of the 18 currently recognised species of Callitris, two of the three Actinostrobus species and the single known species of Neocallitropsis help to clarify major lineages and relationships in this group. ITS data provide strong evidence against the monophyly of Callitris as currently circumscribed, with the strongest evidence being for the inclusion of the New Caledonian monotypic species Neocallitropsis pancheri (Carriere) de Laubenfels. This species shares a close relationship with C. sulcata (Parl.) Schltr. Three representatives of Actinostrobus are monophyletic and are placed in a polytomy with C. drummondii (Parl.) F.Muell., although indels provide some support for the early divergence of Actinostrobus in this group. Remaining sampled members of Callitris form a weakly supported clade, with C. macleayana (F.Muell.) F.Muell. sister to a highly robust core Callitris. Relationships within this core Callitris are unresolved; however, the following seven lineages are supported: C. rhomboidea R.Br. ex Rich.; C. muelleri (Parl.) F.Muell., C. oblonga Rich. and C. endlicheri (Parl.) F.M. Bailey; C. gracilis R.T. Baker, C. glaucophylla Thompson & Johnson and C. tuberculata R.Br. ex R.T. Baker & Smith; C. intratropica Baker & Smith; and C. columellaris F.Muell. There has been a marked increase in the rate of divergence of ITS sequences during the evolution of those populations assigned to C. intratropica, which perhaps reflects speciation processes within this widely distributed group

    Familiar concepts and relationships in the conifers based on rbcL and matK sequence comparisons

    No full text
    Analysis of sequence data for the chloroplast encoded genes rbcL and matK for 40 taxa representing all conifer families and subfamilies, rooted on Ginkgo biloba, provides robust support for the family concepts of Araucariaceae, Cupressaceae sensu lato, Pinaceae and Sciadopilyaceae. Whereas Phyllocladus and Cephalotaxus are robustly linked with, but separated from Podocarpaceae sensu stricto and Taxaceae, respectively, these distinctions decay at far fewer steps (+3.7 and +1.7 steps, respectively) than do any of the other families (>25 steps). It is argued that neither of these monogeneric families, Phyllocladaceae and Cephalotaxaceae, is warranted, and that recognition of a more broadly defined Podocarpaceae and Taxaceae is more informative of the relationships among conifers. The analysis provides strong support for Wollemia being sister to Agathis, rather than it being the first diverging lineage within the family. It also strongly supports sister relationships between Araucariaceae and Podocarpaceae, between Cupressaceae sensu lato and Taxaceae sensu lato, and between the latter clade and Sciadopityaceae. Pinaceae are strongly supported as the first lineage of extant conifers to diverge

    Seasonal resource availability and use by an endangered tropical mycophagous marsupial

    No full text
    This study highlights the importance of considering how seasonality of rainfall affects availability of resources and consequently species distributions within tropical ecosystems. The endangered northern bettong, Bettongia tropica Wakefield is thought to be restricted to habitats where seasonal availability of hypogeous fungi, their principal food resource, remains high. To test this hypothesis fungal abundance was quantified in the early wet, late wet, early dry and late dry seasons within known bettong habitat. A relationship was found between precipitation and fungal availability, with the abundance of hypogeous fungi being significantly lower in the late dry season. Fungal availability correlated strongly with the seasonal rainfall pattern determined from 74-year monthly means. This contrasts with a previous study where mycophagy, measured by faecal analysis, remained high across seasons presumably because of aseasonal rainfall during that study period. Alloteropsis semialata R.Br. (cockatoo grass) use by bettongs increased significantly during the period of low fungal availability. This suggests that the importance of cockatoo grass as an alternative food resource during annual and extended dry periods has previously been underestimated. With the frequency and intensity of drought expected to increase with global climate change, these findings have significant implications for bettong management. The important and possibly equivalent dependence of B. tropica on both hypogeous fungi and A. semialata helps to explain their habitat preference and identifies this species as a true ecotonal specialist

    Myrtaceae revisited: a reassessment of infrafamilial groups

    No full text
    Cladistic analyses are presented of matK sequence data as well as a nonmolecular database for an identical set of exemplar species chosen to represent the core genera or groups of genera in Myrtaceae. Eleven robust clades are recognized on the molecular data. Polyphyly of the previously recognized Metrosideros and Leptospermum alliances is confirmed, and several smaller informal taxonomic groupings are recognized from among the members of the former alliance, i.e., the Tristania, Tristaniopsis, Metrosideros, and Lophostemon groups. The nonmolecular analysis provides only limited resolution of relationships. A degree of congruence exists between the two analyses in that two separate fleshy-fruited clades, the Acmena and Myrtoid groups, are identified, as are the Eucalypt and Tristania groups, and Psiloxylon and Heteropyxis are the first lineages to diverge in both analyses. A combined analysis recognized all 11 clades that received strong support from the molecular data. A high level of homoplasy is revealed in many of the nonmolecular characters when they are examined against the combined estimate of phylogeny

    Near infrared spectroscopy as a rapid, non-invasive method for sandalwood oil determination

    No full text
    Fourier Transform (FT) - near infra-red spectroscopy (NIRS) was investigated as a non-invasive technique for predicting -santalol content in sandalwood chip samples. The correlation between the NIR spectral data and the a-santalol content from the GC-MS analysis was very high (R2 = 0.93). The feasibility study indicates that it is possible to use FT-NIRS to predict -santalol content in sandalwood chip samples. The technique of utilising NIRS technology for sandalwood quality and quantity determination needs to be further developed to be utilised as a tool for commercial applications
    corecore