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

Plantas com possível atividade hipolipidêmica: uma revisão bibliográfica de livros editados no Brasil entre 1998 e 2008 Plants with possible hypolipidemic activity: a review of books published in Brazil between 1998 and 2008

O objetivo deste trabalho foi realizar levantamento sobre as plantas medicinais indicadas para o tratamento da hiperlipidemia, hipercolesterolemia e/ou aterosclerose. Este estudo foi feito a partir da pesquisa bibliográfica em 32 livros publicados no Brasil entre 1998 e 2008, resultando em lista de 85 espécies distribuídas em 53 famílias, principalmente Asteraceae e Fabaceae, com 54 espécies exóticas e 31 nativas. As espécies mais citadas foram Allium sativum (Alliaceae), Cynara scolymus (Asteraceae), Curcuma longa (Zingiberaceae), Allium cepa (Alliaceae), Echinodorus grandiflorus (Alismataceae), Taraxacum officinale (Asteraceae), Vernonia condensata (Asteraceae), Cuphea carthagenensis (Lythraceae) e Curcuma zedoaria (Zingiberaceae). As espécies nativas, citadas em pelo menos 2 livros, foram investigadas para alguma evidencia científica relacionada a possíveis efeitos hipolipidêmico, hipocolesterolêmico e/ou contra aterosclerose. Somente foram encontrados estudos científicos, relacionados a estes efeitos, para as espécies nativas Cuphea carthagenensis e Echinodorus grandiflorum, indicando a necessidade de pesquisas que possam garantir a segurança e a eficácia do uso destas espécies.<br>The aim of this study was to survey medicinal plants indicated for the treatment of hyperlipidemia, hypercholesterolemia and/or atherosclerosis. This study was performed from a review of 32 books published in Brazil between 1998 and 2008, resulting in a list of 85 species belonging to 53 families, especially Asteraceae and Fabaceae, with 54 exotic and 31 native species. The species most often cited were Allium sativum (Alliaceae), Cynara scolymus (Asteraceae), Curcuma longa (Zingiberaceae), Allium cepa (Alliaceae), Echinodorus grandiflorus (Alismataceae), Taraxacum officinale (Asteraceae), Vernonia condensata (Asteraceae), Cuphea carthagenensis (Lythraceae) and Curcuma zedoaria (Zingiberaceae). Native species cited in at least 2 books were investigated for some scientific evidence related to possible hypolipidemic and hypocholesterolemic effects and/or action against atherosclerosis. Scientific studies related to these effects were found only for the native species Cuphea carthagenensis and Echinodorus grandiflorum, indicating the need for studies capable of assuring the safety and the efficacy as to the use of these species

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