The NA48/2 experiment at CERN reports the first observation of the $K^± → π^0π^0μ^±$ν decay based on a sample of 2437 candidates with 15% background contamination collected in 2003–2004. The decay ...branching ratio in the kinematic region of the squared dilepton mass above 0.03 GeV2/c4 is measured to be (0.65 ± 0.03) × 10–6. The extrapolation to the full kinematic space, using a specific model, is found to be (3.45 ± 0.16) × 10–6, in agreement with chiral perturbation theory predictions.
A
bstract
The NA48/2 experiment at CERN reports the first observation of the
K
±
→
π
0
π
0
μ
±
ν
decay based on a sample of 2437 candidates with 15% background contamination collected in 2003–2004. ...The decay branching ratio in the kinematic region of the squared dilepton mass above 0.03 GeV
2
/
c
4
is measured to be (0.65 ± 0.03) × 10
−
6
. The extrapolation to the full kinematic space, using a specific model, is found to be (3.45 ± 0.16) × 10
−
6
, in agreement with chiral perturbation theory predictions.
Retrospective studies in hematological unit have suggested that single red blood cell (1-RBC) unit transfusion policy may reduce the number of RBC used without negative clinical impact.
Acute ...leukemia patients requiring intensive chemotherapy or patients receiving autologous or allogeneic transplantation were randomly assigned to receive either single RBC (1-RBC arm) or double RBC (2-RBC arm) per transfusion with a hemoglobin trigger of 8 g/dL. The primary composite endpoint was the percentage of patients experiencing serious complications, such as a non-hematological adverse event grade ≥ 3 or intensive care admission or death.
A total of 981 and 592 RBC transfusions were required in the 1-RBC arm (n = 125) and the 2-RBC arm (n = 120), respectively. The mean pre-transfusion hemoglobin levels were 7.49 ± 0.83 g/dL in the 1-RBC arm and 7.46 ± 0.67 g/dL in the 2-RBC arm (p = 0.275). The predefined non-inferiority criteria was achieved with 28/125 patients reaching the primary endpoint in the 1-RBC arm (22.4 %) and 28/120 patients in the 2-RBC arm (23.3 %) (Risk difference 0.009; 95 %, Confidence interval −0.0791 to 0.0978, p = 0.021). The median (IQR) of RBC units transfused per patient was 7 (4–12) in the 1-RBC arm and 8 (4–12) in 2-RBC arm. Hemoglobin levels at discharge were also comparable in both arms.
The results of this trial indicate that a single RBC transfusion policy is not inferior to a double RBC transfusion policy for patients receiving a bone marrow transplant or intensive chemotherapy in a hematological intensive care unit. However, the single RBC transfusion policy did not reduce the number of RBC units transfused per stay.
This trial was funded by a grant from the French Ministry of Health
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•Randomisation between 1-RBC arm and 2-RBC arm in hematological intensive care unit patient with hb>8g/dL.•Primary endpoint: percentage of patients who developed grade≥ 3 complications including death and ICU admission.•1-RBC transfusion policy was non-inferior to the 2-RBC transfusion policy.•No difference in quality of life assessment.•No reduction in RBC transfused with the 1-RBC strategy.
When video-based motion analysis systems are used to measure segmental kinematics, the major source of error is the displacement of skin-fixed markers relative to the underlying skeletal structure. ...Such displacements cause the marker representation of the segment to deform, thereby decreasing the accuracy of subsequent three-dimensional kinematic calculations. We have developed a two-step solidification procedure to address this problem. First, the mean rigid shape is computed which best represents the time-varying marker configuration of each segment. Second, a least-squares minimization is used to replace the measured marker coordinates with those corresponding to the best-fit mean rigid shape. Rigid body theory can then be applied unambiguously to perform kinematic analyses.
To evaluate this approach, we defined an unperturbed three-dimensional reference movement using kinematic data from the swing phase of gait. After perturbing the marker coordinates with artificial noise, the rotation matrix and translation vector (absolute and relative movement) between each pair of successive images were computed using (1) reference frames fixed directly to the perturbed marker coordinates, (2) a least-squares minimization procedure found in the literature, and (3) the proposed solidification procedure. The least-squares and solidification procedures produced extremely similar results which, relative to the direct calculation, reduced kinematic errors on average by 20–25% when the maximum distance between markers was small (e.g. < 15 cm). The solidification methodology therefore combines the numerical benefits of the least-squares method with the conceptual benefits of a rigid body method.
Recent QCD results from the NA48/2 experiment Anzivino, Giuseppina; Anzivino, G.; Arcidiacono, R. ...
Nuclear and particle physics proceedings,
07/2018, Letnik:
300-302
Journal Article
Recenzirano
The NA48/2 experiment collected data in 2003 and 2004 with the main purpose to study direct CP violation in charged kaons decaying in three pions. Thanks to the huge statistics collected, other ...studies are also possible. In this paper two recent results, in the framework of QCD studies, are reported: the measurement of the K± → π0e±ν Form Factors and the first observation of the rare decay K± → π±π0e+e−.
The distribution of the K±→π±π+π− decays in the Dalitz plot has been measured by the NA48/2 experiment at the CERN SPS with a sample of 4.71×108 fully reconstructed events. With the standard Particle ...Data Group parameterization the following values of the slope parameters were obtained: g=(−21.134±0.017)%, h=(1.848±0.040)%, k=(−0.463±0.014)%. The quality and statistical accuracy of the data have allowed an improvement in precision by more than an order of magnitude, and are such as to warrant a more elaborate theoretical treatment, including pion–pion rescattering, which is in preparation.
A sample of more than one million K +/- ? p + p - e +/- ? (K e 4) decay candidates with less than one percent background contamination has been collected by the NA48/2 experiment at the CERN SPS in ...2003-2004, allowing a detailed study of the decay properties. The branching ratio, inclusive of K e 4 gamma decays, is measured to be BR (K e 4) = (4.257 +/- 0.016 exp +/- 0.031 ext) X 10 - 5 with a total relative error of 0.8 % . This measurement complements the study of S- and P-wave hadronic form factors by assigning absolute values to the relative hadronic form factors obtained earlier in a simultaneous analysis of the pp scattering lengths conducted on the same data sample. The overall form factor normalization f s = 5.705 +/- 0.017 exp +/- 0.031 ext is obtained with a total relative precision of 0.6 % .
A measurement of the form factors of charged kaon semileptonic decays is presented, based on 4.4 × 106K± → π0e±νe (K e3 ± ) and 2.3 × 106K± → π0μ±νμ (K μ3 ±) decays collected in 2004 by the NA48/2 ...experiment. The results are obtained with improved precision as compared to earlier measurements. The combination of measurements in the K e3 ± and K μ3 ± modes is also presented.
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