5,880 research outputs found
Top Quark Mass Measurements
Preliminary results on the measurement of the top quark mass (mt) at the
Tevatron Collider are presented. In the dilepton decay channel, the CDF
Collaboration measures mt=175.0(+17.4)(-16.9)(stat.)+/-8.4(syst.) GeV/c2, using
a sample of ~126 pb-1 of proton-antiproton collision data at sqrt(s)=1.96 TeV
(Run II). In the lepton plus jets channel, the CDF Collaboration measures
177.5(+12.7)(-9.4)(stat.)+/-7.1(syst.) GeV/c2, using a sample of ~102 pb-1 at
sqrt(s)=1.96 TeV. The D0 Collaboration has newly applied a likelihood technique
to improve the analysis of ~125 pb-1 of proton-antiproton collisions at
sqrt(s)=1.8 TeV (Run I), with the result: mt=180.1+/-3.6(stat.)+/-3.9(syst.)
GeV/c2. The latter is combined with all the measurements based on the data
collected in Run I to yield the most recent and comprehensive experimental
determination of the top quark mass: mt=178.0+/-2.7(stat.)+/-3.3(syst.) GeV/c2Comment: Contribution to the proceedings of the XXXIXth Rencontres de Moriond,
"QCD and High Energy Hadronic Interactions", March 200
Measurements of vector boson plus jets at the Tevatron
We present preliminary measurements of Z/γ∗+jets, W + c and
Z + b + X at the Tevatron, and review recent measurements of vector boson plus inclusive and heavy-flavor jets production. All measurements are in agreement with
next-to-leading-order QCD calculations within the experimental and theoretical uncertainties. We also point to comparisons of the production rate and kinematics of the data with several Monte Carlo simulation programs of vector boson + jets processes
The forward-backward asymmetry of top quark production at the Tevatron in warped extra dimensional models
The CDF and D0 experiments have reported on the measurement of the
forward-backward asymmetry of top quark pair production at the Tevatron and the
result is that it is more than 2 standard deviations above the predicted value
in the Standard Model. This has to be added to the longstanding anomaly in the
forward-backward asymmetry for bottom quark production at LEP which is 3
standard deviations different from the Standard Model value. The discrepancy in
the bottom asymmetry can be accounted for by the contributions of Kaluza-Klein
excitations of electroweak gauge bosons at LEP in warped extra dimensional
models in which the fermions are localized differently along the extra
dimension so that the gauge interactions of heavy third generation fermions are
naturally different from that of light fermions. In this paper, we show that it
is more difficult to elaborate a model generating a significant top asymmetry
in a similar way -- through exchanges of Kaluza-Klein gluons at the Tevatron --
due to the indirect constraints originating from precision electroweak data.Comment: 4 pages, 1 figure, published versio
Thermodynamics of the BCS-BEC crossover
We present a self-consistent theory for the thermodynamics of the BCS-BEC
crossover in the normal and superfluid phase which is both conserving and
gapless. It is based on the variational many-body formalism developed by
Luttinger and Ward and by DeDominicis and Martin. Truncating the exact
functional for the entropy to that obtained within a ladder approximation, the
resulting self-consistent integral equations for the normal and anomalous Green
functions are solved numerically for arbitrary coupling. The critical
temperature, the equation of state and the entropy are determined as a function
of the dimensionless parameter , which controls the crossover from the
BCS-regime of extended pairs to the BEC-regime of tightly bound molecules. The
tightly bound pairs turn out to be described by a Popov-type approximation for
a dilute, repulsive Bose gas. Even though our approximation does not capture
the critical behaviour near the continuous superfluid transition, our results
provide a consistent picture for the complete crossover thermodynamics which
compare well with recent numerical and field-theoretic approaches at the
unitarity point.Comment: published versio
Reading children's teeth to reconstruct life history and the evolution of human cooperation and cognition: The role of dental enamel microstructure and chemistry
Studying infants in the past is crucial for understanding the evolution of human life history and the evolution of cooperation, cognition, and communication. An infant's growth, health, and mortality can provide information about the dynamics and structure of a population, their cultural practices, and the adaptive capacity of a community. Skeletal remains provide one way of accessing this information for humans recovered prior to the historical periods. Teeth in particular, are retrospective archives of information that can be accessed through morphological, micromorphological, and biogeochemical methods. This review discusses how the microanatomy and formation of teeth, and particularly enamel, serve as archives of somatic growth, stress, and the environment. Examining their role in the broader context of human evolution, we discuss dental biogeochemistry and emphasize how the incremental growth of tooth microstructure facilitates the reconstruction of temporal data related to health, diet, mobility, and stress in past societies. The review concludes by considering tooth microstructure as a biomarker and the potential clinical applications
Multiparametric Dynamic Ultrasound Approach for Differential Diagnosis of Primary Liver Tumors
A correct differentiation between hepatocellular carcinoma (HCC) and intracellular cholangiocarcinoma (ICC) is essential for clinical management and prognostic prediction. However, non-invasive differential diagnosis between HCC and ICC remains highly challenging. Dynamic contrast-enhanced ultrasound (D-CEUS) with standardized software is a valuable tool in the diagnostic approach to focal liver lesions and could improve accuracy in the evaluation of tumor perfusion. Moreover, the measurement of tissue stiffness could add more information concerning tumoral environment. To explore the diagnostic performance of multiparametric ultrasound (MP-US) in differentiating ICC from HCC. Our secondary aim was to develop an US score for distinguishing ICC and HCC. Between January 2021 and September 2022 consecutive patients with histologically confirmed HCC and ICC were enrolled in this prospective monocentric study. A complete US evaluation including B mode, D-CEUS and shear wave elastography (SWE) was performed in all patients and the corresponding features were compared between the tumor entities. For better inter-individual comparability, the blood volume-related D-CEUS parameters were analyzed as a ratio between lesions and surrounding liver parenchyma. Univariate and multivariate regression analysis was performed to select the most useful independent variables for the differential diagnosis between HCC and ICC and to establish an US score for non-invasive diagnosis. Finally, the diagnostic performance of the score was evaluated by receiver operating characteristic (ROC) curve analysis. A total of 82 patients (mean age +/- SD, 68 +/- 11 years, 55 men) were enrolled, including 44 ICC and 38 HCC. No statistically significant differences in basal US features were found between HCC and ICC. Concerning D-CEUS, blood volume parameters (peak intensity, PE; area under the curve, AUC; and wash-in rate, WiR) showed significantly higher values in the HCC group, but PE was the only independent feature associated with HCC diagnosis at multivariate analysis (p = 0.02). The other two independent predictors of histological diagnosis were liver cirrhosis (p < 0.01) and SWE (p = 0.01). A score based on those variables was highly accurate for the differential diagnosis of primary liver tumors, with an area under the ROC curve of 0.836 and the optimal cut-off values of 0.81 and 0.20 to rule in or rule out ICC respectively. MP-US seems to be a useful tool for non-invasive discrimination between ICC and HCC and could prevent the need for liver biopsy at least in a subgroup of patients
Automated Synthesis of Tableau Calculi
This paper presents a method for synthesising sound and complete tableau
calculi. Given a specification of the formal semantics of a logic, the method
generates a set of tableau inference rules that can then be used to reason
within the logic. The method guarantees that the generated rules form a
calculus which is sound and constructively complete. If the logic can be shown
to admit finite filtration with respect to a well-defined first-order semantics
then adding a general blocking mechanism provides a terminating tableau
calculus. The process of generating tableau rules can be completely automated
and produces, together with the blocking mechanism, an automated procedure for
generating tableau decision procedures. For illustration we show the
workability of the approach for a description logic with transitive roles and
propositional intuitionistic logic.Comment: 32 page
A detailed map of Higgs boson interactions by the ATLAS experiment ten years after the discovery
The standard model of particle physics1-4 describes the known fundamental particles and forces that make up our Universe, with the exception of gravity. One of the central features of the standard model is a field that permeates all of space and interacts with fundamental particles5-9. The quantum excitation of this field, known as the Higgs field, manifests itself as the Higgs boson, the only fundamental particle with no spin. In 2012, a particle with properties consistent with the Higgs boson of the standard model was observed by the ATLAS and CMS experiments at the Large Hadron Collider at CERN10,11. Since then, more than 30 times as many Higgs bosons have been recorded by the ATLAS experiment, enabling much more precise measurements and new tests of the theory. Here, on the basis of this larger dataset, we combine an unprecedented number of production and decay processes of the Higgs boson to scrutinize its interactions with elementary particles. Interactions with gluons, photons, and W and Z bosons-the carriers of the strong, electromagnetic and weak forces-are studied in detail. Interactions with three third-generation matter particles (bottom (b) and top (t) quarks, and tau leptons (τ)) are well measured and indications of interactions with a second-generation particle (muons, μ) are emerging. These tests reveal that the Higgs boson discovered ten years ago is remarkably consistent with the predictions of the theory and provide stringent constraints on many models of new phenomena beyond the standard model
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