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

Momentum scale calibration of the LHCb spectrometer

For accurate determination of particle masses accurate knowledge of the momentum scale of the detectors is crucial. The procedure used to calibrate the momentum scale of the LHCb spectrometer is described and illustrated using the performance obtained with an integrated luminosity of 1.6 fb-1 collected during 2016 in pp running. The procedure uses large samples of J/ψ → μ + μ - and B+ → J/ψ K + decays and leads to a relative accuracy of 3 × 10-4 on the momentum scale

Curvature-bias corrections using a pseudomass method

Momentum measurements for very high momentum charged particles, such as muons from electroweak vector boson decays, are particularly susceptible to charge-dependent curvature biases that arise from misalignments of tracking detectors. Low momentum charged particles used in alignment procedures have limited sensitivity to coherent displacements of such detectors, and therefore are unable to fully constrain these misalignments to the precision necessary for studies of electroweak physics. Additional approaches are therefore required to understand and correct for these effects. In this paper the curvature biases present at the LHCb detector are studied using the pseudomass method in proton-proton collision data recorded at centre of mass energy √(s)=13 TeV during 2016, 2017 and 2018. The biases are determined using Z→μ + μ - decays in intervals defined by the data-taking period, magnet polarity and muon direction. Correcting for these biases, which are typically at the 10-4 GeV-1 level, improves the Z→μ + μ - mass resolution by roughly 18% and eliminates several pathological trends in the kinematic-dependence of the mean dimuon invariant mass

A century of trends in adult human height

Being taller is associated with enhanced longevity, and higher education and earnings. We reanalysed 1472 population-based studies, with measurement of height on more than 18.6 million participants to estimate mean height for people born between 1896 and 1996 in 200 countries. The largest gain in adult height over the past century has occurred in South Korean women and Iranian men, who became 20.2 cm (95% credible interval 17.5-22.7) and 16.5 cm (13.3-19.7) taller, respectively. In contrast, there was little change in adult height in some sub-Saharan African countries and in South Asia over the century of analysis. The tallest people over these 100 years are men born in the Netherlands in the last quarter of 20th century, whose average heights surpassed 182.5 cm, and the shortest were women born in Guatemala in 1896 (140.3 cm; 135.8-144.8). The height differential between the tallest and shortest populations was 19-20 cm a century ago, and has remained the same for women and increased for men a century later despite substantial changes in the ranking of countries

Efecto de Pseudomonas syringae subsp. syringae en el rendimiento y distribución de biomasa en trigo

The effect of Pseudomonas syringae subsp. syringae on seed yield, aerial biomass production and partitioning in wheat (Triticum aestivum L.) is unknown. A field experiment was carried out in two locations of the Mexican Highlands (Montecillo and Chapingo) to evaluate the response of two wheat cultivars (‘Seri M82’ and ‘Rebeca F2000’) to four inoculum rates (106, 8, 10 cfu mL–1, plus a control without inoculum). Disease incidence and severity, seed yield, seed number and seed size were measured. At flowering and seed physiological maturity, aerial biomass production and distribution of main stem, secondary stems and total plant were recorded. Source-sink relationships during the grain filling period were estimated. Higher values of disease incidence and severity were observed at Chapingo; the same traits were also greater in ‘Seri’ than in ‘Rebeca’ at both sites (p < 0.05). Seed yield, seed number and seed size of ‘Rebeca’ were higher (p < 0.05) than that of ‘Seri’. The pathogen reduced (p < 0.05) plant height, seed yield, seed yield components, and biomass production of most organs of main and secondary stems. The magnitude of the reductions was similar in both cultivars at both sites. The effect of the bacteria at each location was higher (p < 0.05) at greater doses affecting seed number more than seed weight. Stems prevailed as sink organs, while laminae, sheaths, spikes, and other vegetative parts predominated as source organs. Plant disease records should complement crop physiological variables to evaluate and to explain bacterial disease effectsEl efecto de Pseudomonas syringae subsp. syringae en el rendimiento de semilla y en la producción y distribución de biomasa aérea en trigo (Triticum aestivum L.) es desconocido. Se sembró un experimento en dos localidades de los Valles Centrales de México (Montecillo y Chapingo) para evaluar la respuesta de dos cultivares de trigo (‘Seri M82’ y ‘Rebeca F2000’) a cuatro dosis de inóculo (106, 8, 10 cfu mL–1, más un testigo sin inóculo). Se registraron datos de incidencia y severidad, rendimiento de semilla y número y tamaño de semilla. En la floración y madurez fisiológica de semilla, se registró la producción y distribución de biomasa aérea de tallos, vainas, limbos y espigas de tallos principales, secundarios y total por planta. Se estimaron las relaciones fuente-demanda durante el periodo de llenado de grano. La incidencia y severidad de la enfermedad fueron mayores en Chapingo, y en ‘Seri’ respecto a ‘Rebeca’ en ambas localidades (p < 0,05). El rendimiento de semilla, así como el número y tamaño, fue mayor (p < 0,05) en ‘Rebeca’ que en ‘Seri’. El patógeno redujo (p < 0,05) la altura de la planta, el rendimiento y sus componentes, y la producción de biomasa de la mayoría de los órganos de los tallos principales y secundarios; sin embargo, la magnitud de las reducciones fue similar en ambos cultivares. El efecto de la bacteria en cada localidad fue mayor (p < 0,05) a dosis mayores al afectar al número de semillas más que al peso de las mismas. Los tallos prevalecieron como órganos de demanda, mientras que limbos, vainas, espigas, y otras partes vegetativas predominaron como órganos fuente. Los reportes de enfermedades de las plantas podrían complementarse con variables fisiológicas del cultivo para evaluar y explicar los efectos de las enfermedades bacteriana

Effect of pseudomonas syringae subsp. syringae on yield and biomass distribution in wheat [Efecto de pseudomonas syringae subsp. syringae en el rendimiento y distribuci�n de biomasa en trigo]

The effect of Pseudomonas syringae subsp. syringae on seed yield, aerial biomass production and partitioning in wheat (Triticum aestivum L.) is unknown. A field experiment was carried out in two locations of the Mexican Highlands (Montecillo and Chapingo) to evaluate the response of two wheat cultivars ('Seri M82' and 'Rebeca F2000') to four inoculum rates (106,8,10 cfu mL-1, plus a control without inoculum). Disease incidence and severity, seed yield, seed number and seed size were measured. At flowering and seed physiological maturity, aerial biomass production and distribution of main stem, secondary stems and total plant were recorded. Source-sink relationships during the grain filling period were estimated. Higher values of disease incidence and severity were observed at Chapingo; the same traits were also greater in 'Seri' than in 'Rebeca' at both sites (p < 0.05). Seed yield, seed number and seed size of 'Rebeca' were higher (p < 0.05) than that of 'Seri'. The pathogen reduced (p < 0.05) plant height, seed yield, seed yield components, and biomass production of most organs of main and secondary stems. The magnitude of the reductions was similar in both cultivars at both sites. The effect of the bacteria at each location was higher (p < 0.05) at greater doses affecting seed number more than seed weight. Stems prevailed as sink organs, while laminae, sheaths, spikes, and other vegetative parts predominated as source organs. Plant disease records should complement crop physiological variables to evaluate and to explain bacterial disease effects

Effect of pseudomonas syringae subsp. syringae on yield and biomass distribution in wheat [Efecto de pseudomonas syringae subsp. syringae en el rendimiento y distribución de biomasa en trigo]

The effect of Pseudomonas syringae subsp. syringae on seed yield, aerial biomass production and partitioning in wheat (Triticum aestivum L.) is unknown. A field experiment was carried out in two locations of the Mexican Highlands (Montecillo and Chapingo) to evaluate the response of two wheat cultivars ('Seri M82' and 'Rebeca F2000') to four inoculum rates (106,8,10 cfu mL-1, plus a control without inoculum). Disease incidence and severity, seed yield, seed number and seed size were measured. At flowering and seed physiological maturity, aerial biomass production and distribution of main stem, secondary stems and total plant were recorded. Source-sink relationships during the grain filling period were estimated. Higher values of disease incidence and severity were observed at Chapingo; the same traits were also greater in 'Seri' than in 'Rebeca' at both sites (p < 0.05). Seed yield, seed number and seed size of 'Rebeca' were higher (p < 0.05) than that of 'Seri'. The pathogen reduced (p < 0.05) plant height, seed yield, seed yield components, and biomass production of most organs of main and secondary stems. The magnitude of the reductions was similar in both cultivars at both sites. The effect of the bacteria at each location was higher (p < 0.05) at greater doses affecting seed number more than seed weight. Stems prevailed as sink organs, while laminae, sheaths, spikes, and other vegetative parts predominated as source organs. Plant disease records should complement crop physiological variables to evaluate and to explain bacterial disease effects

Measurement of the D∗D^* longitudinal polarization in B0→D∗−τ+ντB^0 \to D^{* -}\tau^+\nu_{\tau} decays

The longitudinal polarization fraction of the $D^*$ meson is measured in $B^0 \to D^{* -}\tau^+\nu_{\tau}$ decays, where the $\tau$ lepton decays to three charged pions and a neutrino, using proton-proton collision data collected by the LHCb experiment at center-of-mass energies of 7, 8 and 13 TeV and corresponding to an integrated luminosity of 5 fb$^{-1}$. The $D^*$ polarization fraction $F_L^{D^*}$ is measured in two $q^2$ regions, below and above 7 GeV$^2$/c$^4$, where $q^2$ is defined as the squared invariant mass of the $\tau\nu_{\tau}$ system. The $F_L^{D^*}$ values are measured to be $0.51 \pm 0.07 \pm 0.03$ and $0.35 \pm 0.08 \pm 0.02$ for the lower and higher $q^2$ regions, respectively. The first uncertainties are statistical and the second systematic. The average value over the whole $q^2$ range is: $$F_L^{D^*} = 0.43 \pm 0.06 \pm 0.03.$$ These results are compatible with the Standard Model predictions.The longitudinal polarization fraction of the $D^{*}$ meson is measured in $B^0\to D^{*-}\tau^{+}\nu_{\tau}$ decays, where the $\tau$ lepton decays to three charged pions and a neutrino, using proton-proton collision data collected by the LHCb experiment at center-of-mass energies of 7, 8 and 13 TeV and corresponding to an integrated luminosity of 5 fb$^{-1}$. The $D^{*}$ polarization fraction $F_{L}^{D^{*}}$ is measured in two $q^{2}$ regions, below and above 7 GeV$^{2}/c^{4}$, where $q^{2}$ is defined as the squared invariant mass of the $\tau\nu_{\tau}$ system. The $F_{L}^{D^{*}}$ values are measured to be $0.51 \pm 0.07 \pm 0.03$ and $0.35 \pm 0.08 \pm 0.02$ for the lower and higher $q^{2}$ regions, respectively. The first uncertainties are statistical and the second systematic. The average value over the whole $q^{2}$ range is: $$F_{L}^{D^{*}} = 0.43 \pm 0.06 \pm 0.03.$$ These results are compatible with the Standard Model predictions

Measurement of the D∗D^{*} longitudinal polarization in B0→D∗−τ+ντB^0\to D^{*-}\tau^{+}\nu_{\tau} decays

International audienceThe longitudinal polarization fraction of the $D^{*}$ meson is measured in $B^0\to D^{*-}\tau^{+}\nu_{\tau}$ decays, where the $\tau$ lepton decays to three charged pions and a neutrino, using proton-proton collision data collected by the LHCb experiment at center-of-mass energies of 7, 8 and 13 TeV and corresponding to an integrated luminosity of 5 fb$^{-1}$. The $D^{*}$ polarization fraction $F_{L}^{D^{*}}$ is measured in two $q^{2}$ regions, below and above 7 GeV$^{2}/c^{4}$, where $q^{2}$ is defined as the squared invariant mass of the $\tau\nu_{\tau}$ system. The $F_{L}^{D^{*}}$ values are measured to be $0.51 \pm 0.07 \pm 0.03$ and $0.35 \pm 0.08 \pm 0.02$ for the lower and higher $q^{2}$ regions, respectively. The first uncertainties are statistical and the second systematic. The average value over the whole $q^{2}$ range is: $$F_{L}^{D^{*}} = 0.43 \pm 0.06 \pm 0.03.$$ These results are compatible with the Standard Model predictions