35 research outputs found

    Measurement of forward charged hadron flow harmonics in peripheral PbPb collisions at √sNN = 5.02 TeV with the LHCb detector

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    Flow harmonic coefficients, v n , which are the key to studying the hydrodynamics of the quark-gluon plasma (QGP) created in heavy-ion collisions, have been measured in various collision systems and kinematic regions and using various particle species. The study of flow harmonics in a wide pseudorapidity range is particularly valuable to understand the temperature dependence of the shear viscosity to entropy density ratio of the QGP. This paper presents the first LHCb results of the second- and the third-order flow harmonic coefficients of charged hadrons as a function of transverse momentum in the forward region, corresponding to pseudorapidities between 2.0 and 4.9, using the data collected from PbPb collisions in 2018 at a center-of-mass energy of 5.02 TeV . The coefficients measured using the two-particle angular correlation analysis method are smaller than the central-pseudorapidity measurements at ALICE and ATLAS from the same collision system but share similar features

    Helium identification with LHCb

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    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

    Curvature-bias corrections using a pseudomass method

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    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→Ό + ÎŒ - 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→Ό + ÎŒ - mass resolution by roughly 18% and eliminates several pathological trends in the kinematic-dependence of the mean dimuon invariant mass

    Study of CP violation in B0 → DK⋆(892)0 decays with D → Kπ(ππ), ππ(ππ), and KK final states

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    A measurement of CP-violating observables associated with the interference of B0 → D0K⋆ (892)0 and B0 → DÂŻ 0K⋆ (892)0 decay amplitudes is performed in the D0 → K∓π ±(π +π −), D0 → π +π −(π +π −), and D0 → K+K− fnal states using data collected by the LHCb experiment corresponding to an integrated luminosity of 9 fb−1 . CP-violating observables related to the interference of B0 s → D0KÂŻ ⋆ (892)0 and B0 s → DÂŻ 0KÂŻ ⋆ (892)0 are also measured, but no evidence for interference is found. The B0 observables are used to constrain the parameter space of the CKM angle Îł and the hadronic parameters r DK⋆ B0 and ÎŽ DK⋆ B0 with inputs from other measurements. In a combined analysis, these measurements allow for four solutions in the parameter space, only one of which is consistent with the world average

    Effectiveness of teriparatide combined with the Ilizarov technique in septic tibial non-union

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    Aim The septic non-union is a common compliance in bone healing due to bone infection. Bone resection, associated with Ilizarov osteo-distraction technique, is commonly used in these cases. The aim of this study was to analyse clinical and radiological results of teriparatide in combination with the Ilizarov technique and to compare this treatment with the standard treatment. Methods Forty adult patients underwent surgery because of type C of the Association for the Study and Application of Methods of Ilizarov (ASAMI) classification non-union were enrolled. The patients were divided in two groups: those treated with Ilizarov technique (Norm group) and those treated with Ilizarov technique combined with teriparatide injection (Teri group). Surgical duration, complication rate, bone healing status, clinical and functional outcomes were assessed according to the A.S.A.M.I. classification in the mean follow-up of 12 months. The subjective quality of life was assessed by the Short Form Survey (SF)-12. Results Teri group showed less time wearing Ilizarov's frame (p <0.05) than the Norm group and a statistical significance in the inter-rater reliability Cohen's k (p>0.05) respect to Norm according the score between the bone healing and clinical outcome results. There was no statistically significant difference between the two groups in other parameters that were assessed. Conclusion A benefit of teriparatide was found as adjuvant in the treatment of septic non-union

    Romidepsin Plus Cyclophosphamide, Doxorubicin, Vincristine, and Prednisone Versus Cyclophosphamide, Doxorubicin, Vincristine, and Prednisone in Patients With Previously Untreated Peripheral T-Cell Lymphoma: Final Analysis of the Ro-CHOP Trial.

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    Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.The primary analysis of the Ro-CHOP phase III randomized controlled trial (ClinicalTrials.gov identifier: NCT01796002) established that romidepsin (Ro) plus cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP) did not yield an increased efficacy compared with CHOP alone as first-line treatment of peripheral T-cell lymphoma. We report the planned final analysis 5 years after the last patient enrolled. With a median follow-up of 6 years, median progression-free survival (PFS) was 12.0 months compared with 10.2 months (hazard ratio [HR], 0.79 [95% CI, 0.62 to 1.005]; P = .054), while median overall survival was 62.2 months (35.7-86.6 months) and 43.8 months (30.1-70.2 months; HR, 0.88 [95% CI, 0.68 to 1.14]; P = .324) in the Ro-CHOP and CHOP arms, respectively. In an exploratory analysis, the median PFS in the centrally reviewed follicular helper T-cell lymphoma subgroup was significantly longer in the Ro-CHOP arm (19.5 v 10.6 months, HR, 0.703 [95% CI, 0.502 to 0.985]; P = .039). Second-line treatments were given to 251 patients with a median PFS2 and OS2 after relapse or progression of 3.3 months and 11.5 months, respectively. Within the limits of highly heterogeneous second-line treatments, no specific regimen seemed to provide superior disease control. However, a potential benefit was observed with brentuximab vedotin in association with chemotherapy even after excluding anaplastic large-cell lymphoma subtype or after adjusting for histology and international prognostic index in a multivariate model (HR for PFS, 0.431 [95% CI, 0.238 to 0.779]; P = .005)

    High Throughput Screening Identifies Novel Lead Compounds with Activity against Larval, Juvenile and Adult Schistosoma mansoni

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    An estimated 600 million people are affected by the helminth disease schistosomiasis caused by parasites of the genus Schistosoma. There is currently only one drug recommended for treating schistosomiasis, praziquantel (PZQ), which is effective against adult worms but not against the juvenile stage. In an attempt to identify improved drugs for treating the disease, we have carried out high throughput screening of a number of small molecule libraries with the aim of identifying lead compounds with balanced activity against all life stages of Schistosoma. A total of almost 300,000 compounds were screened using a high throughput assay based on motility of worm larvae and image analysis of assay plates. Hits were screened against juvenile and adult worms to identify broadly active compounds and against a mammalian cell line to assess cytotoxicity. A number of compounds were identified as promising leads for further chemical optimization

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

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    The longitudinal polarization fraction of the D∗D^* meson is measured in B0→D∗−τ+ΜτB^0 \to D^{* -}\tau^+\nu_{\tau} decays, where the τ\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^{-1}. The D∗D^* polarization fraction FLD∗F_L^{D^*} is measured in two q2q^2 regions, below and above 7 GeV2^2/c4^4, where q2q^2 is defined as the squared invariant mass of the τΜτ\tau\nu_{\tau} system. The FLD∗F_L^{D^*} values are measured to be 0.51±0.07±0.030.51 \pm 0.07 \pm 0.03 and 0.35±0.08±0.020.35 \pm 0.08 \pm 0.02 for the lower and higher q2q^2 regions, respectively. The first uncertainties are statistical and the second systematic. The average value over the whole q2q^2 range is: FLD∗=0.43±0.06±0.03.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∗D^{*} meson is measured in B0→D∗−τ+ΜτB^0\to D^{*-}\tau^{+}\nu_{\tau} decays, where the τ\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^{-1}. The D∗D^{*} polarization fraction FLD∗F_{L}^{D^{*}} is measured in two q2q^{2} regions, below and above 7 GeV2/c4^{2}/c^{4}, where q2q^{2} is defined as the squared invariant mass of the τΜτ\tau\nu_{\tau} system. The FLD∗F_{L}^{D^{*}} values are measured to be 0.51±0.07±0.030.51 \pm 0.07 \pm 0.03 and 0.35±0.08±0.020.35 \pm 0.08 \pm 0.02 for the lower and higher q2q^{2} regions, respectively. The first uncertainties are statistical and the second systematic. The average value over the whole q2q^{2} range is: FLD∗=0.43±0.06±0.03.F_{L}^{D^{*}} = 0.43 \pm 0.06 \pm 0.03. These results are compatible with the Standard Model predictions

    Observation of Ξb0→Ξc+Ds−\Xi_b^0 \rightarrow \Xi_c^+ D_s^- and Ξb−→Ξc0Ds−\Xi_b^- \rightarrow \Xi_c^0 D_s^- decays

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    International audienceThe Ξb0→Ξc+Ds−\Xi_b^0 \rightarrow \Xi_c^+ D_s^- and Ξb−→Ξc0Ds−\Xi_b^- \rightarrow \Xi_c^0 D_s^- decays are observed for the first time using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of s=13TeV\sqrt{s}=13\mathrm{TeV}, corresponding to an integrated luminosity of 5.1fb−15.1\mathrm{fb}^{-1}. The relative branching fractions times the beauty-baryon production cross-sections are measured to be \begin{align*} \mathcal{R}\left(\frac{\Xi_b^0}{\Lambda_b^0}\right) \equiv \frac{\sigma\left(\Xi_b^0\right)}{\sigma\left(\Lambda_b^0\right)} \times \frac{\mathcal{B}\left(\Xi_b^0 \rightarrow \Xi_c^+ D_s^-\right)}{\mathcal{B}\left(\Lambda_b^0 \rightarrow \Lambda_c^0 D_s^-\right)} =(15.8\pm1.1\pm0.6\pm7.7)\%, \mathcal{R}\left(\frac{\Xi_b^-}{\Lambda_b^0}\right) \equiv \frac{\sigma\left(\Xi_b^-\right)}{\sigma\left(\Lambda_b^0\right)} \times \frac{\mathcal{B}\left(\Xi_b^- \rightarrow \Xi_c^0 D_s^-\right)}{\mathcal{B}\left(\Lambda_b^0 \rightarrow \Lambda_c^0 D_s^-\right)} =(16.9\pm1.3\pm0.9\pm4.3)\%, \end{align*} where the first uncertainties are statistical, the second systematic, and the third due to the uncertainties on the branching fractions of relevant charm-baryon decays. The masses of Ξb0\Xi_b^0 and Ξb−\Xi_b^- baryons are measured to be mΞb0=5791.12±0.60±0.45±0.24MeV/c2m_{\Xi_b^0}=5791.12\pm0.60\pm0.45\pm0.24\mathrm{MeV}/c^2 and mΞb−=5797.02±0.63±0.49±0.29MeV/c2m_{\Xi_b^-}=5797.02\pm0.63\pm0.49\pm0.29\mathrm{MeV}/c^2, where the uncertainties are statistical, systematic, and those due to charm-hadron masses, respectively
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