15 research outputs found

    Beam Spin Asymmetries in DVCS with CLAS at 4 .8 GeV

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    We report measurements of the beam spin asymmetry in Deeply Virtual Compton Scattering (DVCS) at an electron beam energy of 4.8 GeV using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The DVCS beam spin asymmetry has been measured in a wide range of kinematics, 1(GeV/c)2^2 <Q2<2.8<Q^2<2.8(GeV/c)2^2, 0.12<xB<0.480.12<x_B<0.48, and 0.1 (GeV/c)2^2 <t<0.8<-t<0.8(GeV/c)2^2, using the reaction \pEpX. The number of H(e,eγp)(e,e^{\prime}\gamma p) and H(e,eπ0p)(e,e^{\prime}\pi^0 p) events are separated in each (Q2,xB,t)(Q^2,x_B,t) bin by a fit to the line shape of the H(e,ep)X(e,e^{\prime}p)X Mx2M_x^2 distribution. The validity of the method was studied in detail using experimental and simulated data. It was shown, that with the achieved missing mass squared resolution and the available statistics, the separation of DVCS-BH and π0\pi^0 events can reliably be done with less than 5% uncertainty. The Q2Q^2- and tt-dependences of the sinϕ\sin\phi moments of the asymmetry are extracted and compared with theoretical calculations

    Search for jet extinction in the inclusive jet-pT spectrum from proton-proton collisions at s=8 TeV

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    Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published articles title, journal citation, and DOI.The first search at the LHC for the extinction of QCD jet production is presented, using data collected with the CMS detector corresponding to an integrated luminosity of 10.7  fb−1 of proton-proton collisions at a center-of-mass energy of 8 TeV. The extinction model studied in this analysis is motivated by the search for signatures of strong gravity at the TeV scale (terascale gravity) and assumes the existence of string couplings in the strong-coupling limit. In this limit, the string model predicts the suppression of all high-transverse-momentum standard model processes, including jet production, beyond a certain energy scale. To test this prediction, the measured transverse-momentum spectrum is compared to the theoretical prediction of the standard model. No significant deficit of events is found at high transverse momentum. A 95% confidence level lower limit of 3.3 TeV is set on the extinction mass scale

    Searches for electroweak neutralino and chargino production in channels with Higgs, Z, and W bosons in pp collisions at 8 TeV

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    Searches for supersymmetry (SUSY) are presented based on the electroweak pair production of neutralinos and charginos, leading to decay channels with Higgs, Z, and W bosons and undetected lightest SUSY particles (LSPs). The data sample corresponds to an integrated luminosity of about 19.5 fb(-1) of proton-proton collisions at a center-of-mass energy of 8 TeV collected in 2012 with the CMS detector at the LHC. The main emphasis is neutralino pair production in which each neutralino decays either to a Higgs boson (h) and an LSP or to a Z boson and an LSP, leading to hh, hZ, and ZZ states with missing transverse energy (E-T(miss)). A second aspect is chargino-neutralino pair production, leading to hW states with E-T(miss). The decays of a Higgs boson to a bottom-quark pair, to a photon pair, and to final states with leptons are considered in conjunction with hadronic and leptonic decay modes of the Z and W bosons. No evidence is found for supersymmetric particles, and 95% confidence level upper limits are evaluated for the respective pair production cross sections and for neutralino and chargino mass values

    Comparative study of seven commercial kits for human DNA extraction from urine samples suitable for DNA biomarker-based public health studies.

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    &lt;p&gt;Human genomic DNA extracted from urine could be an interesting tool for large-scale public health studies involving characterization of genetic variations or DNA biomarkers as a result of the simple and noninvasive collection method. These studies, involving many samples, require a rapid, easy, and standardized extraction protocol. Moreover, for practicability, there is a necessity to collect urine at a moment different from the first void and to store it appropriately until analysis. The present study compared seven commercial kits to select the most appropriate urinary human DNA extraction procedure for epidemiological studies. DNA yield has been determined using different quantification methods: two classical, i.e., NanoDrop and PicoGreen, and two species-specific real-time quantitative (q)PCR assays, as DNA extracted from urine contains, besides human, microbial DNA also, which largely contributes to the total DNA yield. In addition, the kits giving a good yield were also tested for the presence of PCR inhibitors. Further comparisons were performed regarding the sampling time and the storage conditions. Finally, as a proof-of-concept, an important gene related to smoking has been genotyped using the developed tools. We could select one well-performing kit for the human DNA extraction from urine suitable for molecular diagnostic real-time qPCR-based assays targeting genetic variations, applicable to large-scale studies. In addition, successful genotyping was possible using DNA extracted from urine stored at -20°C for several months, and an acceptable yield could also be obtained from urine collected at different moments during the day, which is particularly important for public health studies.&lt;/p&gt;</p

    Anatomical Versus Atypical Liver Resections - Advantages and Disadvantages

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    Background: Liver resections (LR) are a daily practice rather than exception with the aim of radicalism (sometimes `radicalism` is the excuse and justification of the surgeon). From a different point of view, an aggressive approach may predispose to specific post-resection complications (SPRC). There still are debates about the most proper procedure - anatomical versus atypical LRs. Aim: The aim of this article is an analysis of the structure and rate of SPRC (acute liver failure=ALF, biliary leakage, bleeding) with a focus on a possible correlation to the surgical technique. Materials and Methods: 344 liver resections in total were performed at the authors` institution from January 1, 2007 to December 31, 2015. All the procedures were indicated by benign tumors as well as by primary and metastatic malignancies. The study design was single-center, retrospective and randomized. Inclusion criteria were the following: (1) Age ≤ 70 years; (2) Presence of ≤ 3 cormobid conditions; (3) Major LR, i.e. removal of ≥ 2 segments or ≥ 30% of liver parenchyma; (4) No synchronous (Н1) liver metastases or metachronous metastases + local recurrence necessitating a single-stage multivisceral resections. We collected all the data from the medical records. Finally, 102 cases were selected according to the above-formulated criteria and they were divided into 2 groups: (A) Anatomical LR (AnatLR) - 44 patients; (B) Atypical LR (AtypLR) - 58 patients. The incidence rate and other characteristics of SPRC were analyzed and a possible correlation between SPRC and the group affiliation was investigated. Results: The early mortality and SPRC rates were 2.8% (3 cases) and 19.4% (21 complications in 20 patients), respectively. Fatal outcome was caused by ALF after right hepatectomy (2 cases) and sepsis leading to MODS and MOF (1 case). Four patients (3.7%) received reoperation due to biliary leakage and/or bleeding from the resection surface. The remaining 17 SPRCs were overcome by conservative treatment. There was no statistically significant difference in mortality and morbidity rates in group A and group B. Conclusions: A successful outcome after a major LR depends on many factors: preserved preoperatively liver function, definitive bilio- and hemostasis on the resection surface, as minimal as possible blood loss and prevention of postoperative biliary hypertension. In our study, we found that an AnatLR is an aggressive and risky procedure for acute liver failure, while a precise AtypLR may guarantee also a low rate of SPCR. The advantages and disadvantages of both techniques must be researched based on late results in oncologic cases

    First observation of the Λ(1405) line shape in electroproduction

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    We report the first observation of the line shape of the Λ(1405) from electroproduction, and show that it is not a simple Breit-Wigner resonance. Electroproduction of K+Λ(1405) off the proton was studied by using data from CLAS at Jefferson Lab in the range 1.0&#60;Q2&#60;3.0 (GeV/c)2. The analysis utilized the decay channels Σ+π− of the Λ(1405) and pπ0 of the Σ+. Neither the standard Particle Data Group resonance parameters, nor free parameters fitting to a single Breit-Wigner resonance represent the line shape. In our fits, the line shape corresponds approximately to predictions of a two-pole meson-baryon picture of the Λ(1405), with a lower mass pole near 1368 MeV/c2 and a higher mass pole near 1423 MeV/c2. Furthermore, with increasing photon virtuality the mass distribution shifts toward the higher mass pole

    First Observation of Large Missing-Momentum (e,e'p) Cross-Section Scaling and the onset of Correlated-Pair Dominance in Nuclei

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    International audienceWe report the first measurement of xBx_B-scaling in (e,ep)(e,e'p) cross-section ratios off nuclei relative to deuterium at large missing-momentum of 350pmiss600350 \leq p_{miss} \leq 600 MeV/c. The observed scaling extends over a kinematic range of 0.7xB1.80.7 \leq x_B \leq 1.8, which is significantly wider than 1.4xB1.81.4 \leq x_B \leq 1.8 previously observed for inclusive (e,e)(e,e') cross-section ratios. The xBx_B-integrated cross-section ratios become constant (i.e., scale) beginning at pmisskFp_{miss}\approx k_F, the nuclear Fermi momentum. Comparing with theoretical calculations we find good agreement with Generalized Contact Formalism calculations for high missing-momentum (>375> 375 MeV/c), suggesting the observed scaling results from interacting with nucleons in short-range correlated (SRC) pairs. For low missing-momenta, mean-field calculations show good agreement with the data for pmisskFp_{miss}\le k_F, and suggest that contributions to the measured cross-section ratios from scattering off single, un-correlated, nucleons are non-negligible up to pmiss350p_{miss}\approx 350 MeV/c. Therefore, SRCs become dominant in nuclei at pmiss350p_{miss}\approx 350 MeV/c, well above the nuclear Fermi Surface of kF250k_F \approx 250 MeV/c

    Design of the ECCE Detector for the Electron Ion Collider

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    International audienceThe EIC Comprehensive Chromodynamics Experiment (ECCE) detector has been designed to address the full scope of the proposed Electron Ion Collider (EIC) physics program as presented by the National Academy of Science and provide a deeper understanding of the quark-gluon structure of matter. To accomplish this, the ECCE detector offers nearly acceptance and energy coverage along with excellent tracking and particle identification. The ECCE detector was designed to be built within the budget envelope set out by the EIC project while simultaneously managing cost and schedule risks. This detector concept has been selected to be the basis for the EIC project detector

    Search for the associated production of the Higgs boson with a top-quark pair

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