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No description provided.
No description provided.
A coupled channel analysis has been carried out using a new amplitude analysis of the K 0 s K 0 s system produced in the reaction π − p→K 0 s K 0 s n at 22 GeV/ c , which contained about 40 000 new events in the low- t region (| t − t min |<0.1 GeV 2 ). Here only the I G =0 + , J PC =2 ++ amplitude from this analysis is considered, together with available data from other experiments in channels with the same quantum numbers in order to determine which 2 ++ isoscalar mesons have significant pseudoscalar-pseudoscalar couplings. It is found that four poles, f(1270), f'(1525), θ(1690), and f r (1810), are needed, plus a smooth background in order to fit these data; the need for the θ(1690) depends on the J/ψ radiative decay alone, and the f r (1810) is seen only in hadronic production.
No description provided.
High-statistics data on the reaction π−p→ηπ+π−n at 8.06 GeV/c were obtained. An isobarmodel partial-wave analysis was performed for the ηππ system. The η(1275) meson was confirmed as a narrow IJPC=00−+ resonance. It decays through both δπ and εη. A narrow state with IJPC=00−+ was found in an ηππ decay channel at 1.42 GeV. It has a prominent peak in a δπ decay mode. No significant E(1420) signal with IJPC=01++ was found near the mass region of 1.42 GeV.
No description provided.
We present a new measurement of parity nonconservation in cesium. In this experiment, a laser excited the 6S→7S transition in an atomic beam in a region of static electric and magnetic fields. The quantity measured was the component of the transition rate arising from the interference between the parity nonconserving amplitude, scrEPNC, and the Stark amplitude, βE. Our results are ImscrEPNC/β=−1.65±0.13 mV/cm and C2p=-2±2, where C2p is the proton-axial-vector–electron-vector neutral-current coupling constant. These results are in agreement with previous less precise measurements in cesium and with the predictions of the electroweak standard model. We give a detailed discussion of the experiment with particular emphasis on the treatment and elimination of systematic errors. This experimental technique will allow future measurements of significantly higher precision.
Axis error includes +- 0.0/0.0 contribution (?////THE UNCERTAINTY IS DOMINATED BY THE PURELY STATISTICAL CONTRIBUTION).
Axis error includes +- 0.0/0.0 contribution (?////THE UNCERTAINTY IS DOMINATED BY THE PURELY STATISTICAL CONTRIBUTION).
Axis error includes +- 0.0/0.0 contribution (?////THE UNCERTAINTY IS DOMINATED BY THE PURELY STATISTICAL CONTRIBUTION).
This paper completes the detailed presentation of our PV experiment on the 6S1/2 - 7S1/2 transition in Cs. A detailed description of the data acquisition and processing is given. The results of two independent measurements made on ΔF = 0 and ΔF =1 hfs components agree, providing an important cross-check. After a complete reanalysis of systematics and calibration, the precision is slightly improved, leading to the weighted average Im Epv 1/β = - 1.52 ± 0.18 mV/cm. Later results from an independent group agree quite well. With the semi-empirical value β = (26.8 ± 0.8) a30, our result yields Epv1 = (- 0.79 ± 0.10) x 10-11 i |e|a0. Coupled with the atomic calculations, this implies that the weak nuclear charge of Cs is Qw = -68 ± 9. This value agrees with the standard electroweak theory and leads to a weak interaction angle sin2 θ W = 0.21 ± 0.04. The complementarity of these measurements with high energy experiments is illustrated.
Revision of the earlier experiment PL 117B, 358. (7s)2S1/2:F=4 --> (6s)2S1/2:F=4 transition.
Revision of the earlier experiment PL 134B, 463. (7s)2S1/2:F=3 --> (6s)2S1/2:F=4 transition.
Combined of the two above measurements following the philosophy: quadratic sum of the statistical and systematic uncertainties and weighting each result by the squared reciprocal of that uncertainty. (7s)2S1/2 --> (6s)2S1/2 transitions.
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No description provided.
In an experiment carried out at the CERN Proton Synchrotron and using the CERN polarized deuteron target, the reaction π+n↑→π+π−p has been measured in the region -t=0.1–1.0 (GeV/c)2 and m(π+π−)=0.36–1.04 GeV at incident momenta of 5.98 and 11.85 GeV/c. We present the m and t dependence of the measured 14 linearly independent spin-density-matrix elements and of the bounds on the moduli squared of the S- and P-wave recoil transversity amplitudes. The results show the presence of ‘‘A1’’ exchange in the unnatural nucleon-helicity-nonflip amplitudes. The natural ‘‘A2’’-exchange amplitudes dominate at large t. In the range 0.2≤-t≤0.4 (GeV/c)2 the mass dependence shows that the unnatural exchange amplitudes with transversity ‘‘down’’ are generally larger than those with transversity ‘‘up.’’ The opposite is true for the natural exchange. In this range of t and at the ρ0 mass, the P-wave unnatural amplitudes with both transversities contribute in equal amounts while the production by natural exchange proceeds entirely with transversity up. We observe rapid changes of the moduli within the ρ0 mass range and variations of the width and the position of the ρ0 peak in spin-averaged partial-wave cross sections. These structures have not been seen in previous polarization experiments and reveal spin dependence of ρ0 production. Our bounds cannot exclude an S-wave resonance in the range 700–800 MeV. The results emphasize the need for a better experimental and theoretical understanding of the mass dependence of the production mechanism.
No description provided.
'Y' components of RHO.
'X' components of RHO.
The reactionsK−p→π∓Σ(1385)± are studied at an incident laboratory momentum of 8.25 GeV/c using data from a high statistics (≃180 events/μb) bubble chamber experiment. In the case of the reactionK−p→π−Σ(1385)+ an amplitude analysis is performed and the complete Σ(1385)+ spin density matrix is extracted as a function oft′. The results are compared with the predictions of the additive quark model. In the case of the reactionK−p→π+Σ(1385)− the cross-sections for forward and backward production are determined.
No description provided.
No description provided.
No description provided.
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No description provided.
The parity violation induced by weak neutral currents is measured in a ΔF =1 hyperfine component of the 6S–7S transition of the Cs atom. The measured value ( Im E PV 1 β ) = −1.78 ± 0.26 (statistical rms deviation) ±0.12 (systematic uncertainty) mV/cm, agrees with our previous measurement in a ΔF =0 component, and constitutes an important cross-check. Our result excludes a parity violation induced by a purely axial hadronic neutral current.
(7s)2S1/2:F=3 --> (6s)2S1/2:F=4 transition.
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