292 research outputs found
Measurement of the branching ratio of the decay
From the 2002 data taking with a neutral kaon beam extracted from the
CERN-SPS, the NA48/1 experiment observed 97 candidates with a background contamination of events.
From this sample, the BR() is measured to be
Recent NA48/2 and NA62 results
The NA48/2 Collaboration at CERN has accumulated and analysed unprecedented
statistics of rare kaon decays in the modes: () and ()
with nearly one percent background contamination. It leads to the improved
measurement of branching fractions and detailed form factor studies. New final
results from the analysis of 381 rare decay
candidates collected by the NA48/2 and NA62 experiments at CERN are presented.
The results include a decay rate measurement and fits to Chiral Perturbation
Theory (ChPT) description.Comment: Prepared for the Proceedings of "Moriond QCD and High Energy
Interactions. March 22-29 2014." conferenc
Measurement of K^0_e3 form factors
The semileptonic decay of the neutral K meson, KL -> pi e nu (Ke3), was used
to study the strangeness-changing weak interaction of hadrons. A sample of 5.6
million reconstructed events recorded by the NA48 experiment was used to
measure the Dalitz plot density. Admitting all possible Lorentz-covariant
couplings, the form factors for vector (f_+(q^2)), scalar (f_S) and tensor
(f_T) interactions were measured. The linear slope of the vector form factor
lambda_+ = 0.0284+-0.0007+-0.0013 and values for the ratios |f_S/f_+(0)| =
0.015^{+0.007}_{-0.010}+-0.012 and |f_T/f_+(0)| = 0.05^{+0.03}_{-0.04}+-0.03
were obtained. The values for f_S and f_T are consistent with zero. Assuming
only Vector-Axial vector couplings, lambda_+ = 0.0288+-0.0004+-0.0011 and a
good fit consistent with pure V-A couplings were obtained. Alternatively, a fit
to a dipole form factor yields a pole mass of M = 859+-18 MeV, consistent with
the K^*(892) mass.Comment: 16 pages, 7 figures. submitted to Phys. Lett.
Observation of the rare decay K_S -> pi^0mu^+mu^-
A search for the decay K_S -> pi^0mu^+mu^- has been made by the NA48/1
Collaboration at the CERN SPS accelerator. The data were collected during 2002
with a high-intensity K_S beam. Six events were found with a background
expectation of 0.22^+0.18_-0.11 event. Using a vector matrix element and unit
form factor, the measured branching ratio is B(K_S ->
pi^0mu^+mu^-)=[2.9^+1.5_-1.2(stat)+/-0.2(syst)]x10^{-9}.Comment: 19 pages, 8 figures, 4 tables. To be published in Physics Letters
First observation and branching fraction and decay parameter measurements of the weak radiative decay Xi0 --> Lambda e+e-
The weak radiative decay Xi0 --> Lambda e+e- has been detected for the first
time. We find 412 candidates in the signal region, with an estimated background
of 15 +/- 5 events. We determine the branching fraction B(Xi0 --> Lambda e+e-)
= [7.6 +/- 0.4(stat) +/- 0.4(syst) +/- 0.2(norm)] x 10^{-6}, consistent with an
internal bremsstrahlung process, and the decay asymmetry parameter
alpha_{XiLambdaee} = -0.8 +/- 0.2, consistent with that of Xi0 --> Lambda
gamma. The charge conjugate reaction Xi0_bar --> Lambda_bar e+e- has also been
observed.Comment: 20 pages, 5 figures, 4 tables; revised: 19 pages, 4 figures, 4
tables, after reviewers' comments: 1 figure removed, 1 figure corrected,
minor editorial changes; to be published in Phys. Lett.
Measurement of K0e3 form factors
The semileptonic decay of the neutral K meson, K0L → π± e∓ ν (Ke3 ), was used to study the strangeness-changing weak interaction of hadrons. A sample of 5.6 million reconstructed events recorded by the NA48 experiment was used to measure the Dalitz plot density. Admitting all possible Lorentz-covariant couplings, the form factors for vector (f+(q2)), scalar (fS) and tensor (fT) interactions were measured. The linear slope of the vector form factor λ+ = 0.0284 ± 0.0007 ± 0.0013 and values for the ratios |fS/f+(0)| = 0.015 +0.007-0.010 ± 0.012 and |fT/f+(0)| = 0.05 +0.03-0.04 ± 0.03 were obtained. The values for fS and fT are consistent with zero. Assuming only vector–axial-vector couplings, λ+ = 0.0288 ± 0.0004 ± 0.0011 and a good fit consistent with pure V–A couplings were obtained. Alternatively, a fit to a dipole form factor yields a pole mass of M = 859 ± 18 MeV, consistent with the K∗(892) mass
Measurement of the radiative Ke3 branching ratio
We present a measurement of the relative branching ratio of the decay K0 → π± e± νγ (Ke3γ) with respect to K0 → π± e± ν (Ke3 + Ke3γ ) decay. The result is based on observation of 19 000 Ke3γ and 5.6 × 10^6 Ke3 decays. The value of the branching ratio is BR(K0e3γ , E∗γ > 30 MeV, θ∗eγ > 20◦)/ Br(K0e3 ) = (0.964 ± 0.008+0.011-0.009)%. This result agrees with theoretical predictions but is at variance with a recently published result
Experience of road and other trauma by the opiate dependent patient: a survey report
Background: Trauma plays an important role in the experience of many patients with substance use disorder, but is relatively under-studied particularly in Australia. The present survey examined the lifetime prevalence of various forms of trauma including driving careers in the context of relevant medical conditions. Methods: A survey was undertaken in a family medicine practice with a special interest in addiction medicine in Brisbane, Australia. Results: Of 350 patients surveyed, 220 were substance dependent, and 130 were general medical patients. Addicted patients were younger (mean ± S.D. 33.72 ± 8.14 vs. 44.24 ± 16.91 years, P < 0.0001) and had shorter driving histories (15.96 ± 8.50 vs. 25.54 ± 15.03 years, P < 0.0001). They had less driving related medical problems (vision, spectacle use, diabetes) but more fractures, surgical operations, dental trauma and assaults. Addicted patients also had significantly worse driving histories on most parameters measured including percent with driving suspensions (O.R. = 7.70, C.I. 4.38-13.63), duration of suspensions (1.71 ± 3.60 vs. 0.11 ± 0.31 years, P < 0.0001), number of motor vehicle collisions (2.00 ± 3.30 vs. 1.10 ± 1.32, P = 0.01), numbers of cars repaired (1.73 ± 3.59 vs. 1.08 ± 1.60, P = 0.042), rear end collisions (O.R. = 1.90, CI 1.13-3.25), running away after car crashes (O.R. = 26.37, CI 4.31-1077.48), other people hospitalized (O.R. = 2.00, C.I. 0.93-4.37, P = 0.037) and people killed (17 vs. 0 P = 0.0005). Upon multivariate analysis group membership was shown to be a significant determinant of both cars repaired and cars hit when controlled for length of driving history. Hence use of all types of drugs (O.R. = 10.07, C.I. 8.80-14.72) was more common in addicted patients as were general (O.R. = 3.64, C.I. 2.99-4.80) and road (O.R.= 2.73, C.I. 2.36-3.15) trauma. Conclusion: This study shows that despite shorter driving histories, addicted patients have worse driving careers and general trauma experience than the comparison group which is not explained by associated medical conditions. Trauma is relevant to addiction management at both the patient and policy levels. Substance dependence policies which focus largely on prevention of virus transmission likely have too narrow a public health focus, and tend to engender an unrealistically simplistic and trivialized view of the addiction syndrome. Reduction of drug driving and drug related trauma likely require policies which reduce drug use per se, and are not limited to harm reduction measures alone
A new measurement of direct CP violation in two pion decays of the neutral kaon
The NA48 experiment at CERN has performed a new measurement of direct CP violation, based on data taken in 1997 by simultaneously collecting KL and KS decays into pi0 pi0 and pi+ pi-. The result for the CP violating parameter Re(epsilon'/epsilon) is (18.5 +- 4.5(stat.) +- 5.8(syst.)) x 10^-4
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