Searching for Z′Z' bosons decaying to gluons

The production and decay of a new heavy vector boson, a chromophilic $Z'$ vector boson, is described. The chromophilic $Z'$ couples only to two gluons, but its two-body decays are absent, leading to a dominant decay mode of $Z'\rightarrow q\bar{q}g$. The unusual nature of the interaction predicts a cross-section which grows with $m_{Z'}$ for a fixed coupling and an accompanying gluon with a coupling that rises with its energy. We study the $t\bar{t}g$ decay mode, proposing distinct reconstruction techniques for the observation of an excess and for the measurement of $m_{Z'}$. We estimate the sensitivity of current experimental datasets.Comment: For submission to PR

Le référentiel taxonomique Florical et les caractéristiques de la flore vasculaire indigène de la Nouvelle-Calédonie

The taxonomic reference base Florical and characteristics of the native vascular flora of New Caledonia. The floristic inventory presented here comprises the evolving computerised database Florical (http://www.botanique.nc/herbier/florical). As of the date of publication, it lists all native vascular plant species (as well as infraspecific taxa) present in the territory of New Caledonia, whether validly published or in press, along with their basionym, organised according to the most recent classifications systems (APG III 2009 for the angiosperms, Smith et at [2006] for the ferns and lycophytes, and Mabberley [2009] for the gymnosperms), accompanied by their status (native or endemic) and the various vegetation types in which they occur. After a brief historical review of our knowledge of New Caledonian botany, the characteristics (richness, composition and endemism) of the different taxonomic groups (ferns and lycophytes, gymnosperms and then angiosperms -mono- and dicotyledons) are analyzed, followed by an assessment of the distribution of these groups among the vegetation types. The vascular flora of New Caledonia is characterised by its high level of richness (3371 species, including 3099 for the flowering plants alone), despite the absence or under-representation of some taxa that are abundantly represented elsewhere in the tropics, and especially by its remarkable distinctiveness (with endemism at the species level reaching 74,7%, and 77.8% for the flowering plants). The flora stands out by the presence of several relictual taxa and a high level of speciation among certain groups, despite the fact that the island was re-colonised relatively recently following the total submersion of its much older basement during the Paleocene and the Oligocene. Details of the measures taken to conserve this extraordinary natural heritage show that only 3.4% of the territory's total surface area is effectively protected. Despite the undeniable progress made in recent years by the authorities concerned, significant work remains to be done, especially in the northern Province

Functional polymorphisms in genes of the Angiotensin and Serotonin systems and risk of hypertrophic cardiomyopathy: AT1R as a potential modifier

<p>Abstract</p> <p>Background</p> <p>Angiotensin and serotonin have been identified as inducers of cardiac hypertrophy. DNA polymorphisms at the genes encoding components of the angiotensin and serotonin systems have been associated with the risk of developing cardiovascular diseases, including left ventricular hypertrophy (LVH).</p> <p>Methods</p> <p>We genotyped five polymorphisms of the <it>AGT</it>, <it>ACE</it>, <it>AT1R</it>, <it>5-HT2A</it>, and <it>5-HTT </it>genes in 245 patients with Hypertrophic Cardiomyopathy (HCM; 205 without an identified sarcomeric gene mutation), in 145 patients with LVH secondary to hypertension, and 300 healthy controls.</p> <p>Results</p> <p>We found a significantly higher frequency of <it>AT1R </it>1166 C carriers (CC+AC) among the HCM patients without sarcomeric mutations compared to controls (p = 0.015; OR = 1.56; 95%CI = 1.09-2.23). The <it>AT1R </it>1166 C was also more frequent among patients who had at least one affected relative, compared to sporadic cases. This allele was also associated with higher left ventricular wall thickness in both, HCM patients with and without sarcomeric mutations.</p> <p>Conclusions</p> <p>The 1166 C <it>AT1R </it>allele could be a risk factor for cardiac hypertrophy in patients without sarcomeric mutations. Other variants at the <it>AGT</it>, <it>ACE</it>, <it>5-HT2A </it>and <it>5-HTT </it>did not contribute to the risk of cardiac hypertrophy.</p

Simultaneous measurement of the ratio B(t->Wb)/B(t->Wq) and the top quark pair production cross section with the D0 detector at sqrt(s)=1.96 TeV

We present the first simultaneous measurement of the ratio of branching fractions, R=B(t->Wb)/B(t->Wq), with q being a d, s, or b quark, and the top quark pair production cross section sigma_ttbar in the lepton plus jets channel using 0.9 fb-1 of ppbar collision data at sqrt(s)=1.96 TeV collected with the D0 detector. We extract R and sigma_ttbar by analyzing samples of events with 0, 1 and >= 2 identified b jets. We measure R = 0.97 +0.09-0.08 (stat+syst) and sigma_ttbar = 8.18 +0.90-0.84 (stat+syst)} +/-0.50 (lumi) pb, in agreement with the standard model prediction.Comment: submitted to Phys.Rev.Letter

Search for charged Higgs bosons decaying to top and bottom quarks in ppbar collisions

We describe a search for production of a charged Higgs boson, q \bar{q'} -> H^+, reconstructed in the t\bar{b} final state in the mass range 180 <= M_{H^+} <= 300 GeV. The search was undertaken at the Fermilab Tevatron collider with a center-of-mass energy sqrt{s} = 1.96 TeV and uses 0.9 fb^{-1} of data collected with the D0 detector. We find no evidence for charged Higgs boson production and set upper limits on the production cross section in the Types I, II and III two-Higgs-doublet models (2HDMs). An excluded region in the (M_{H^+},tan\beta) plane for Type I 2HDM is presented.Comment: Submitted to Phys. Rev. Letter

Search for R-parity Violating Supersymmetry in Dimuon and Four-Jets Channel

We present results of a search for R-parity-violating decay of the neutralino chi_1^0, taken to be the Lightest Supersymmetric Particle. It is assumed that this decay proceeds through one of the lepton-number violating couplings lambda-prime_2jk (j=1,2; k=1,2,3). This search is based on 77.5 pb-1 of data, collected by the D0 experiment at the Fermilab Tevatron in ppbar collisions at a center of mass energy of 1.8 TeV in 1992-1995.Comment: 10 pages, 3 figure

Measurement of the forward-backward charge asymmetry and extraction of sin^2Theta^{eff}_W in ppbar -> Z/\gamma^{*}+X -> e+e+X events produced at \sqrt{s}=1.96 TeV

We present a measurement of the forward-backward charge asymmetry ($A_{FB}$) in $p\bar{p} \to Z/\gamma^{*}+X \to e^+e^-+X$ events at a center-of-mass energy of 1.96 TeV using 1.1 fb$^{-1}$ of data collected with the D0 detector at the Fermilab Tevatron collider. $A_{FB}$ is measured as a function of the invariant mass of the electron-positron pair, and found to be consistent with the standard model prediction. We use the $A_{FB}$ measurement to extract the effective weak mixing angle $sin^2Theta^{eff}_W = 0.2327 \pm 0.0018 (stat.) \pm 0.0006 (syst.)$.Comment: 7 Pages, 1 Figure, 3 Tables, Accepted by Phys. Rev. Let

Search for anomalous \boldmath{Wtb} couplings in single top quark production

In 0.9 fb$^{-1}$ of $p \bar p$ collisions, D0 has observed an excess of events with an isolated lepton, missing transve rse momentum, and two to four jets. This excess is consistent with single top quark production. We examine these data to study the Lorentz structure of the $Wtb$ coupling. The standard model predicts a left-handed vector coupling at the $Wt b$ vertex. The most general lowest dimension, CP-conserving Lagrangian admits right-handed vector and left- or right-h anded tensor couplings as well. We find that the data prefer the left-handed vector coupling and set upper limits on the anomalous couplings. These are the first direct constraints on a general $Wtb$ interaction and the first direct limits on left- and right-handed tensor couplings.Comment: 7 pages, 4 figure