Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb^-1. The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final version published in European Physical Journal

Neuronal lysosomal dysfunction releases exosomes harboring APP C-terminal fragments and unique lipid signatures

Defects in endolysosomal and autophagic functions are increasingly viewed as key pathological features of neurodegenerative disorders. A master regulator of these functions is phosphatidylinositol-3-phosphate (PI3P), a phospholipid synthesized primarily by class III PI 3-kinase Vps34. Here we report that disruption of neuronal Vps34 function in vitro and in vivo impairs autophagy, lysosomal degradation as well as lipid metabolism, causing endolysosomal membrane damage. PI3P deficiency also promotes secretion of unique exosomes enriched for undigested lysosomal substrates, including amyloid precursor protein C-terminal fragments (APP-CTFs), specific sphingolipids, and the phospholipid bis(monoacylglycero)phosphate (BMP), which normally resides in the internal vesicles of endolysosomes. Secretion of these exosomes requires neutral sphingomyelinase 2 and sphingolipid synthesis. Our results reveal a homeostatic response counteracting lysosomal dysfunction via secretion of atypical exosomes eliminating lysosomal waste and define exosomal APP-CTFs and BMP as candidate biomarkers for endolysosomal dysfunction associated with neurodegenerative disorders.Fan Wang for the kind gift of the Pi3kc3flox/flox mice. We thank Basant Abdulrahman and Hermann Schaetzl for providing the gene-edited Atg5 KO N2a cells. We are also grateful to Zhenyu Yue, Ralph Nixon, and Jean Gruenberg for the kind gift of anti-Atg14L, Cathepsin D, and BMP antibodies, respectively. We thank Thomas Südhof for sharing Cre recombinase lentiviruses. We thank the OCS Microscopy Core of New York University Langone Medical Center for the support of the EM work and Rocio Perez-Gonzalez and Efrat Levy of New York University for their support during optimization of the brain exosome isolation technique. We thank Elizabeta Micevska for the maintenance and genotyping of the animal colony and Bowen Zhou for the preliminary lipidomic analysis of conditional Pi3kc3 cKO mice. We also thank Rebecca Williams and Catherine Marquer for critically reading the manuscript. This work was supported by grants from the Fundação para a Ciência e Tecnologia (PD/BD/105915/2014 to A.M.M.); the National Institute of Health (R01 NS056049 to G.D.P., transferred to Ron Liem, Columbia University; T32-MH015174 to Rene Hen (Z.M.L.)). Z.M.L. and R.B.C. received pilot grants from ADRC grant P50 AG008702 to S.A.S.info:eu-repo/semantics/publishedVersio

Pathway-Based Analysis of a Melanoma Genome-Wide Association Study: Analysis of Genes Related to Tumour-Immunosuppression

Systemic immunosuppression is a risk factor for melanoma, and sunburn-induced immunosuppression is thought to be causal. Genes in immunosuppression pathways are therefore candidate melanoma-susceptibility genes. If variants within these genes individually have a small effect on disease risk, the association may be undetected in genome-wide association (GWA) studies due to low power to reach a high significance level. Pathway-based approaches have been suggested as a method of incorporating a priori knowledge into the analysis of GWA studies. In this study, the association of 1113 single nucleotide polymorphisms (SNPs) in 43 genes (39 genomic regions) related to immunosuppression have been analysed using a gene-set approach in 1539 melanoma cases and 3917 controls from the GenoMEL consortium GWA study. The association between melanoma susceptibility and the whole set of tumour-immunosuppression genes, and also predefined functional subgroups of genes, was considered. The analysis was based on a measure formed by summing the evidence from the most significant SNP in each gene, and significance was evaluated empirically by case-control label permutation. An association was found between melanoma and the complete set of genes (pemp = 0.002), as well as the subgroups related to the generation of tolerogenic dendritic cells (pemp = 0.006) and secretion of suppressive factors (pemp = 0.0004), thus providing preliminary evidence of involvement of tumour-immunosuppression gene polymorphisms in melanoma susceptibility. The analysis was repeated on a second phase of the GenoMEL study, which showed no evidence of an association. As one of the first attempts to replicate a pathway-level association, our results suggest that low power and heterogeneity may present challenges

Search for Supersymmetry with Gauge-Mediated Breaking in Diphoton Events with Missing Transverse Energy at CDF II

accepted to Phys. Rev. LettWe present the results of a search for supersymmetry with gauge-mediated breaking and \NONE\to\gamma\Gravitino in the $\gamma\gamma$+missing transverse energy final state. In 2.6$\pm$0.2 \invfb of $p{\bar p}$ collisions at $\sqrt{s}$$=$1.96 TeV recorded by the CDF II detector we observe no candidate events, consistent with a standard model background expectation of 1.4$\pm$0.4 events. We set limits on the cross section at the 95% C.L. and place the world's best limit of 149\gevc on the \none mass at $\tau_{\tilde{\chi}_1^0}$$We present the results of a search for supersymmetry with gauge-mediated breaking and χ˜10→γG˜ in the γγ+missing transverse energy final state. In 2.6±0.2  fb-1 of pp̅ collisions at √s=1.96  TeV recorded by the CDF II detector we observe no candidate events, consistent with a standard model background expectation of 1.4±0.4 events. We set limits on the cross section at the 95% C.L. and place the world’s best limit of 149  GeV/c2 on the χ˜10 mass at τχ˜10≪1  ns. We also exclude regions in the χ˜10 mass-lifetime plane for τχ˜10≲2  ns.Peer reviewe

Measurements of branching fraction ratios and CP asymmetries in B+/- ->D_CP K+/- decays in hadron collisions

We reconstruct B+/- -> D K+/- decays in a data sample collected by the CDF II detector at the Tevatron collider corresponding to 1 fb-1 of integrated luminosity. We select decay modes where the D meson decays to either K- pi+ (flavor eigenstate) or K- K+, pi- pi+ (CP-even eigenstates), and measure the direct CP asymmetry A_CP+ = 0.39 +/- 0.17(stat) +/- 0.04(syst), and the double ratio of CP-even to flavor eigenstate branching fractions R_CP+ = 1.30 +/- 0.24(stat) +/- 0.12(syst). These measurements will improve the determination of the CKM angle gamma. They are performed here for the first time using data from hadron collisions.We reconstruct B±→DK± decays in a data sample collected by the CDF II detector at the Tevatron collider corresponding to 1  fb-1 of integrated luminosity. We select decay modes where the D meson decays to either K-π+ (flavor eigenstate) or K-K+, π-π+ (CP-even eigenstates), and measure the direct CP asymmetry ACP+=0.39±0.17(stat)±0.04(syst), and the double ratio of CP-even to flavor eigenstate branching fractions RCP+=1.30±0.24(stat)±0.12(syst). These measurements will improve the determination of the Cabibbo-Kobayashi-Maskawa angle γ. They are performed here for the first time using data from hadron collisions.Peer reviewe

Inclusive Search for Standard Model Higgs Boson Production in the WW Decay Channel using the CDF II Detector

We present a search for standard model (SM) Higgs boson production using ppbar collision data at sqrt(s) = 1.96 TeV, collected with the CDF II detector and corresponding to an integrated luminosity of 4.8 fb-1. We search for Higgs bosons produced in all processes with a significant production rate and decaying to two W bosons. We find no evidence for SM Higgs boson production and place upper limits at the 95% confidence level on the SM production cross section (sigma(H)) for values of the Higgs boson mass (m_H) in the range from 110 to 200 GeV. These limits are the most stringent for m_H > 130 GeV and are 1.29 above the predicted value of sigma(H) for mH = 165 GeV.We present a search for standard model (SM) Higgs boson production using pp̅ collision data at √s=1.96  TeV, collected with the CDF II detector and corresponding to an integrated luminosity of 4.8  fb-1. We search for Higgs bosons produced in all processes with a significant production rate and decaying to two W bosons. We find no evidence for SM Higgs boson production and place upper limits at the 95% confidence level on the SM production cross section (σH) for values of the Higgs boson mass (mH) in the range from 110 to 200 GeV. These limits are the most stringent for mH>130  GeV and are 1.29 above the predicted value of σH for mH=165  GeV.Peer reviewe

Measurement of the Lambda_b Lifetime in Lambda_b -> Lambda_c+ pi- Decays in p-pbar Collisions at sqrt(s) = 1.96 TeV

Submitted to Phys. Rev. LettWe report a measurement of the lifetime of the Lambda_b baryon in decays to the Lambda_C+ pi- final state in a sample corresponding to 1.1 fb^-1 collected in p-pbar collisions at sqrt(s) = 1.96 TeV by the CDF II detector at the Tevatron collider. Using a sample of about 3000 fully reconstructed Lambda_b events we measure tau(Lambda_b) = 1.401 +- 0.046 (stat) +- 0.035 (syst) ps (corresponding to c.tau(Lambda_b) = 420.1 +- 13.7 (stat) +- 10.6 (syst) um, where c is the speed of light). The ratio of this result and the world average B^0 lifetime yields tau(Lambda_b)/tau(B^0) = 0.918 +- 0.038 (stat and syst), in good agreement with recent theoretical predictions.We report a measurement of the lifetime of the Λb0 baryon in decays to the Λc+π- final state in a sample corresponding to 1.1  fb-1 collected in pp̅ collisions at √s=1.96  TeV by the CDF II detector at the Tevatron collider. Using a sample of about 3000 fully reconstructed Λb0 events we measure τ(Λb0)=1.401±0.046(stat)±0.035(syst)  ps (corresponding to cτ(Λb0)=420.1±13.7(stat)±10.6(syst)  μm, where c is the speed of light). The ratio of this result and the world average B0 lifetime yields τ(Λb0)/τ(B0)=0.918±0.038 (stat) and (syst), in good agreement with recent theoretical predictions.Peer reviewe

Measurement of the Top Quark Mass and ppbar -> ttbar Cross Section in the All-Hadronic Mode with the CDFII Detector

Submitted to Phys. Rev. DWe present a measurement of the top quark mass and of the top-antitop pair production cross section using p-pbar data collected with the CDFII detector at the Tevatron Collider at the Fermi National Accelerator Laboratory and corresponding to an integrated luminosity of 2.9 fb-1. We select events with six or more jets satisfying a number of kinematical requirements imposed by means of a neural network algorithm. At least one of these jets must originate from a b quark, as identified by the reconstruction of a secondary vertex inside the jet. The mass measurement is based on a likelihood fit incorporating reconstructed mass distributions representative of signal and background, where the absolute jet energy scale (JES) is measured simultaneously with the top quark mass. The measurement yields a value of 174.8 +- 2.4(stat+JES) ^{+1.2}_{-1.0}(syst) GeV/c^2, where the uncertainty from the absolute jet energy scale is evaluated together with the statistical uncertainty. The procedure measures also the amount of signal from which we derive a cross section, sigma_{ttbar} = 7.2 +- 0.5(stat) +- 1.0 (syst) +- 0.4 (lum) pb, for the measured values of top quark mass and JES.We present a measurement of the top quark mass and of the top-antitop (tt̅ ) pair production cross section using pp̅ data collected with the CDF II detector at the Tevatron Collider at the Fermi National Accelerator Laboratory and corresponding to an integrated luminosity of 2.9  fb-1. We select events with six or more jets satisfying a number of kinematical requirements imposed by means of a neural-network algorithm. At least one of these jets must originate from a b quark, as identified by the reconstruction of a secondary vertex inside the jet. The mass measurement is based on a likelihood fit incorporating reconstructed mass distributions representative of signal and background, where the absolute jet energy scale (JES) is measured simultaneously with the top quark mass. The measurement yields a value of 174.8±2.4(stat+JES)-1.0+1.2(syst)  GeV/c2, where the uncertainty from the absolute jet energy scale is evaluated together with the statistical uncertainty. The procedure also measures the amount of signal from which we derive a cross section, σtt̅ =7.2±0.5(stat)±1.0(syst)±0.4(lum)  pb, for the measured values of top quark mass and JES.Peer reviewe