87 research outputs found
Population dynamics of Pseudomonas savastanoi pv. phaseolicola in bean, throughout the epiphytic and pathogenic phases
Study of the lineshape of the chi(c1) (3872) state
A study of the lineshape of the chi(c1) (3872) state is made using a data sample corresponding to an integrated luminosity of 3 fb(-1) collected in pp collisions at center-of-mass energies of 7 and 8 TeV with the LHCb detector. Candidate chi(c1)(3872) and psi(2S) mesons from b-hadron decays are selected in the J/psi pi(+)pi(-) decay mode. Describing the lineshape with a Breit-Wigner function, the mass splitting between the chi(c1 )(3872) and psi(2S) states, Delta m, and the width of the chi(c1 )(3872) state, Gamma(Bw), are determined to be (Delta m=185.598 +/- 0.067 +/- 0.068 Mev,)(Gamma BW=1.39 +/- 0.24 +/- 0.10 Mev,) where the first uncertainty is statistical and the second systematic. Using a Flatte-inspired model, the mode and full width at half maximum of the lineshape are determined to be (mode=3871.69+0.00+0.05 MeV.)(FWHM=0.22-0.04+0.13+0.07+0.11-0.06-0.13 MeV, ) An investigation of the analytic structure of the Flatte amplitude reveals a pole structure, which is compatible with a quasibound D-0(D) over bar*(0) state but a quasivirtual state is still allowed at the level of 2 standard deviations
Measurement of the CKM angle in and decays with
A measurement of -violating observables is performed using the decays
and , where the meson is
reconstructed in one of the self-conjugate three-body final states and (commonly denoted ). The decays are analysed in bins of the -decay phase space, leading
to a measurement that is independent of the modelling of the -decay
amplitude. The observables are interpreted in terms of the CKM angle .
Using a data sample corresponding to an integrated luminosity of
collected in proton-proton collisions at centre-of-mass
energies of , , and with the LHCb experiment,
is measured to be . The hadronic
parameters , , , and ,
which are the ratios and strong-phase differences of the suppressed and
favoured decays, are also reported
Measurement of CP asymmetries and branching fraction ratios of B− decays to two charm mesons
The asymmetries of seven decays to two charm mesons are measured using data corresponding to an integrated luminosity of of proton-proton collisions collected by the LHCb experiment. Decays involving a or meson are analysed by reconstructing only the or decay products. This paper presents the first measurement of and , and the most precise measurement of the other five asymmetries. There is no evidence of violation in any of the analysed decays. Additionally, two ratios between branching fractions of selected decays are measured.The CP asymmetries of seven B decays to two charm mesons are measured using data corresponding to an integrated luminosity of 9 fb of proton-proton collisions collected by the LHCb experiment. Decays involving a D or meson are analysed by reconstructing only the D or decay products. This paper presents the first measurement of (B→D) and (B→D), and the most precise measurement of the other five CP asymmetries. There is no evidence of CP violation in any of the analysed decays. Additionally, two ratios between branching fractions of selected decays are measured.[graphic not available: see fulltext]The asymmetries of seven decays to two charm mesons are measured using data corresponding to an integrated luminosity of of proton-proton collisions collected by the LHCb experiment. Decays involving a or meson are analysed by reconstructing only the or decay products. This paper presents the first measurement of and , and the most precise measurement of the other five asymmetries. There is no evidence of violation in any of the analysed decays. Additionally, two ratios between branching fractions of selected decays are measured
Helium identification with LHCb
The identification of helium nuclei at LHCb is achieved using a method based on measurements of ionisation losses in the silicon sensors and timing measurements in the Outer Tracker drift tubes. The background from photon conversions is reduced using the RICH detectors and an isolation requirement. The method is developed using pp collision data at √(s) = 13 TeV recorded by the LHCb experiment in the years 2016 to 2018, corresponding to an integrated luminosity of 5.5 fb-1. A total of around 105 helium and antihelium candidates are identified with negligible background contamination. The helium identification efficiency is estimated to be approximately 50% with a corresponding background rejection rate of up to O(10^12). These results demonstrate the feasibility of a rich programme of measurements of QCD and astrophysics interest involving light nuclei
Study of the doubly charmed tetraquark T+cc
Quantum chromodynamics, the theory of the strong force, describes interactions of coloured quarks and gluons and the formation of hadronic matter. Conventional hadronic matter consists of baryons and mesons made of three quarks and quark-antiquark pairs, respectively. Particles with an alternative quark content are known as exotic states. Here a study is reported of an exotic narrow state in the D0D0π+ mass spectrum just below the D*+D0 mass threshold produced in proton-proton collisions collected with the LHCb detector at the Large Hadron Collider. The state is consistent with the ground isoscalar T+cc tetraquark with a quark content of ccu⎯⎯⎯d⎯⎯⎯ and spin-parity quantum numbers JP = 1+. Study of the DD mass spectra disfavours interpretation of the resonance as the isovector state. The decay structure via intermediate off-shell D*+ mesons is consistent with the observed D0π+ mass distribution. To analyse the mass of the resonance and its coupling to the D*D system, a dedicated model is developed under the assumption of an isoscalar axial-vector T+cc state decaying to the D*D channel. Using this model, resonance parameters including the pole position, scattering length, effective range and compositeness are determined to reveal important information about the nature of the T+cc state. In addition, an unexpected dependence of the production rate on track multiplicity is observed
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Confocal imaging of pseudomonas syringae pv. phaseolicola colony development in bean reveals reduced multiplication of strains containing the genomic island PPHGI-1.
Pseudomonas syringae pv. phaseolicola is the seed borne
causative agent of halo blight in the common bean Phaseolus
vulgaris. Pseudomonas syringae pv. phaseolicola race 4
strain 1302A contains the avirulence gene hopAR1 (located
on a 106-kb genomic island, PPHGI-1, and earlier named
avrPphB), which matches resistance gene R3 in P. vulgaris
cultivar Tendergreen (TG) and causes a rapid hypersensitive
reaction (HR). Here, we have fluorescently labeled selected
Pseudomonas syringae pv. phaseolicola 1302A and 1448A strains (with and without PPHGI-1) to enable confocal
imaging of in-planta colony formation within the apoplast of resistant (TG) and susceptible (Canadian Wonder [CW]) P. vulgaris leaves. Temporal quantification of fluorescent Pseudomonas syringae pv. phaseolicola colony development correlated with in-planta bacterial multiplication
(measured as CFU/ml) and is, therefore, an effective means of monitoring Pseudomonas syringae pv. phaseolicola endophytic colonization and survival in P. vulgaris. We
present advances in the application of confocal microscopy
for in-planta visualization of Pseudomonas syringae pv.
phaseolicola colony development in the leaf mesophyll to
show how the HR defense response greatly affects colony
morphology and bacterial survival. Unexpectedly, the presence of PPHGI-1 was found to cause a reduction of colony
development in susceptible P. vulgaris CW leaf tissue. We
discuss the evolutionary consequences that the acquisition
and retention of PPHGI-1 brings to Pseudomonas syringae
pv. phaseolicola in planta
Conspicuous eggs and colourful hypotheses: testing the role of multiple influences on avian eggshell appearance
The diversity of eggshell colours and patterning across different birds is a fascinating example of the extended avian phenotype. The avian egg's background colours range from light green/yellow to brilliant blue and intense maroon, and with the scrawling patterns comparable to the assortment of eggs found in an Easter Bunny's basket. Here we briefly introduce the diversity of eggshell appearance, its perplexingly narrow chemical basis, and clarify how the a priori assessment of assumptions and potential hypotheses can shape new eggshell research. In addition, we highlight some of the recent hypotheses developed outside the visual paradigm that has dictated the most influential hypotheses of eggshell appearance to date. Finally, we indicate priority areas for future comprehensive research on eggshells based on adaptations to ongoing changes in environmental conditions.Phillip Cassey, Golo Maurer, P. George Lovell and Daniel Hanle
Making climate change governable: accounting for carbon as sinks, credits and personal budgets
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