4,519 research outputs found
Fitting and selecting scattering data
The main purpose of scattering experiments is to unveil the underlying
structure of the colliding particles and their interaction. Typically one
measures scattering observables (cross sections and polarizations) at discrete
angles and energies and mutually consistent data may validate or falsify
proposed theories or models. However, the accumulation of data from different
laboratories while potentially improves the statistical significance it may
sometimes generate mutually inconsistent data as a side-effect. Thus, some
decision has to be made on what are the maximal amount of data which are
mutually compatible. We show elastic and scattering as prominent
examples where this selection is called for. We discuss how it can be done in a
self-consistent manner invoking a principle of maximal consensus of the
database and with the help of a sufficiently flexible model involving a minimal
number of theoretical assumptions. In the NN case this has become possible with
a combination of long distance field theoretical constraints at the hadronic
level such as pion exchanges and electromagnetic effects and a coarse graining
of the unknown interaction over the shortest de Broglie wavelength being probed
in the scattering process.Comment: 7 pages, 5 figures, talk presented by ERA at XVII International
Conference on Hadron Spectroscopy and Structure - Hadron2017, Salamanca,
25-29 September 201
Uncertainty quantification and falsification of Chiral Nuclear Potentials
Are chiral theories at present describing experimental NN scattering data
satisfactorily ?. Will the chiral approach offer a framework where fitting and
selecting the existing np and pp data can be done without theoretical bias ?.
While predictive power in theoretical nuclear physics has been a major concern
in the study of nuclear structure and reactions, the Effective Field Theory
(EFT) based on chiral expansions has emerged after Weinberg as a model
independent hierarchy for many body forces and much progress has been achieved
over the last decades. We review some of the issues involved which point to
being close to the solution, but also that work remains still to be done to
validate the theory. We analyze several examples including zero energy NN
scattering and perturbative counterterm -- free peripheral scattering where one
would expect these methods to work best and unveil relevant systematic
discrepancies when a fair comparison to the Granada-2013 NN-database and
partial wave analysis (PWA) based on coarse graining the interaction is
undertaken.Comment: Prepared for the special issue of "The tower of effective (field)
theories and the emergence of nuclear phenomena"; 20 pages, 7 figure
Uncertainty quantification of transition operators in the empirical shell model
While empirical shell model calculations have successfully described
low-lying nuclear data for decades, only recently has significant effort been
made to quantify the uncertainty in such calculations. Here we quantify the
statistical error in effective parameters for transition operators in empirical
calculations in the (--) valence space,
specifically the quenching of Gamow-Teller transitions, effective charges for
electric quadrupole (E2) transitions, and the effective orbital and spin
couplings for magnetic dipole (M1) transitions. We find the quenching factor
for Gamow-Teller transitions relative to free-space values is tightly
constrained and that the isoscalar coupling of E2 is much more tightly
constrained than the isovector coupling. For effective M1 couplings, we found
isovector components more constrained than isoscalar, but that to get any
sensible result we had to fix one of four couplings. This detailed
quantification of uncertainties, while highly empirical, nonetheless is an
important step towards interpretation of experiments
Risk factors for one-year mortality in hospitalized adults with severe covid-19 comment
As the body''s immunity declines with age, elderly-hospitalized patients due to COVID-19 might be at higher mortality risk. Therefore, the aim of this prospective study was to examine the possible risk factors (demographic, social or comorbidities) most associated with mortality one-year after diagnosis of COVID-19. Routine data were collected from a cohort of hospitalized adults with severe COVID-19. The primary endpoint was mortality at one-year after diagnosis of COVID-19. We used a Cox proportional hazard model to estimate the hazard ratios (HRs) for both all-cause and specific cardiorespiratory mortality. A fully adjusted model included sex, socioeconomic status, institutionalization status, disability, smoking habit, and comorbidities as confounders. A total of 368 severe cases hospitalized on average 67.3 +/- 15.9 years old were included. Participants aged >= 71 years had significantly higher HRs for all-cause mortality (adjusted HRs = 2.86, 95%CI: 2.01-4.07) and cardiorespiratory mortality (adjusted HRs = 2.86, 95%CI: 1.99-4.12). The association between age and mortality after diagnosis of COVID-19 due to both all-causes and cardiorespiratory mortality showed a consistent dose-response fashion. Institutionalization, disability, and socioeconomic status also showed a significant association with mortality. In conclusion, aging itself was the most important risk factor associated with mortality one year after diagnosis of COVID-19. People with disabilities, institutionalized or low socioeconomic status are significantly more likely to die after COVID-19
Efficacy of chemotherapy for malignant pleural mesothelioma according to histology in a real-world cohort
Cancer therapy; MesotheliomaTerapia del cáncer; MesoteliomaTeràpia del càncer; MesoteliomaCheckMate 743 trial demonstrated survival benefit of immunotherapy in first line in MPM with some differences in the efficacy of chemotherapy according to histology. The objective of this study is to characterize the impact of chemotherapy according to histology in patients diagnosed with MPM at our institution. Clinical records of all MPM patients diagnosed at Vall d’Hebron University Hospital between November 2002 and April 2020 were reviewed. Associations between clinical variables and outcomes were assessed with Cox regression models. Survival data were calculated by the Kaplan–Meier method. 189 patients were included with 76% of tumors classified as epithelioid subtype. First line chemotherapy was offered to 85% of patients. Median survival in overall population was 21.3 months (95% CI 17.2–24.3). We found that patients with epithelioid tumors had better overall survival (OS) and progression free survival (PFS). Median OS of epithelioid patients treated with first line chemotherapy was 26.7 months versus 15.0 months in non-epithelioid patients (HR 2.25 CI 95% 1.4–3.4; p < 0.001). Median PFS for patients with epithelioid tumors treated with chemotherapy was 4.8 months versus 3.6 months in non-epithelioid (HR 1.5 CI 95% 1.0–2.3; p = 0.03). The improvement of outcomes in patients with epithelioid histology was detected in patients treated with cisplatin or carboplatin. Histology was not a predictive factor for the platinum agent sensitivity (p of interaction PFS = 0.09, p of interaction OS = 0.65). In our series, patients with non-epithelioid tumors presented worse prognosis. Although epithelioid tumors exposed to cisplatin had higher PFS, histology was not a clear predictor of chemotherapy efficacy
Precise measurement of the W-boson mass with the CDF II detector
We have measured the W-boson mass MW using data corresponding to 2.2/fb of
integrated luminosity collected in proton-antiproton collisions at 1.96 TeV
with the CDF II detector at the Fermilab Tevatron collider. Samples consisting
of 470126 W->enu candidates and 624708 W->munu candidates yield the measurement
MW = 80387 +- 12 (stat) +- 15 (syst) = 80387 +- 19 MeV. This is the most
precise measurement of the W-boson mass to date and significantly exceeds the
precision of all previous measurements combined
Search for Neutral Higgs Bosons in Events with Multiple Bottom Quarks at the Tevatron
The combination of searches performed by the CDF and D0 collaborations at the
Fermilab Tevatron Collider for neutral Higgs bosons produced in association
with b quarks is reported. The data, corresponding to 2.6 fb-1 of integrated
luminosity at CDF and 5.2 fb-1 at D0, have been collected in final states
containing three or more b jets. Upper limits are set on the cross section
multiplied by the branching ratio varying between 44 pb and 0.7 pb in the Higgs
boson mass range 90 to 300 GeV, assuming production of a narrow scalar boson.
Significant enhancements to the production of Higgs bosons can be found in
theories beyond the standard model, for example in supersymmetry. The results
are interpreted as upper limits in the parameter space of the minimal
supersymmetric standard model in a benchmark scenario favoring this decay mode.Comment: 10 pages, 2 figure
- …