Search

We have studied the time distribution of semi-leptonic decays of the neutral K meson produced in a hydrogen bubble chamber in the reaction K+p → Kopπ+ with K+ momenta between 1.2 and 1.7 GeV/c. We have identified 306 πev decays and 74 πμv decays of known lepton charge with proper times between 0.04 and 20 KS lifetimes. The results are compatible with no violation of the ΔS = ΔQ rule. For the ratio x of the ΔS = −ΔQ amplitude to the ΔS = ΔQ amplitude we find the values +0.06+0.13inKe3decays:Re⁡xe=0.05inKμ3decays:Re⁡xμ=0.10−0.07−0.16+0.06+0.16Im⁡xe=0.08Im⁡xμ=−0.03−0.07,−0.18. Assuming ΔS = ΔQ we find the rate Γ(KoL → πev + πμv) = (12.4 ± 0.7) × 106 s−1.

From a study of 70 000 K° decays in the CERN 2m hydrogen bubble chamber, we have estimated the rate for KS0 → π+π−γ for different cuts in the γ momentum. The results are in good agreement with inner bremsstrahlung on KS0 → π+π−. For γ momentum in the K° c.m. greater than 50 MeV/c, we obtain the branching ratio: Γ(KS → π+π−γ, k>50 MeV/c)/Γ(KS→π+π−)=(2.8. ± 0.6)×10−3. This leads to an estimate for the direct γ emission process: Γ(KS→π+π−γ direct)/Γ(KS → π+π−)=(0.3 ± 0.6) × 10−3.

We have studied the time distribution of π + π − π o decays of the neutral K meson produced in the reaction K + p → K o pπ + with K + momenta at 1.4 and 1.7 GeV/ c . Within our fiducial volume we have 98 uniquely identified π + π − π o decays with proper times between 0.04 and 20 K s lifetimes. For the ratio η +− o of the amplitude K s → π + π − π o to the amplitude K L → π + π − π o , it is found that: Re η +−0 = 0.01 ± 0.22 0.20 , Im η +−o = 0.33 ± 0.42 0.50 . This result is consistent with no CP -violation. Assuming η +− o = 0, we find the rate Г( K L → π + π − π o ) = (2.5 ± 0.3) 10 6 sec −1 .

We present the results on total channel cross-sections obtained in the Saclay 180 l HBC exposed to a separated K− beam at Nimrod. The cross-sections for each channel are given at 13 incident K− momenta between 1.26 and 1.84 GeV/c.

We have measured theKSO mean life using a sample of 50 000 KO → π+π− decays in a hydrogen bubble chamber. We obtain τ = (0.8958 ± 0.0045) × 10−10 s. This value is significantly higher than the present world average of τ = (0.862 ± 0.006) × 10−10 s.

The observation of 70 000 K0 pπ+ events produced with K+ incident momenta of 1.21, 1.29, 1.38 and 1.69 GeV/c allows a detailed description of the production and decay of the Δ(1236) and K∗(892) resonances which dominate the K0pπ+ final state. No striking variations with energy are observed. The associated production of Δ and K∗ near threshold shows striking similarities with the same production at higher energy.

Surgical investigations of the scrotom were carried out on six infants born by breech presentation. Three of them exhibited clinically significant oedema of the scrotum with haematic infiltration. In two others a bilateral haematoma of the scrotum and of the distal extremity of the penis was noted. In the remaining infant the scrotum was normal at birth but a few hours later an increase in volume and an induration were noted on one side. During surgery the authors noted an intravaginal torsion of the testicle with necrosis confirmed histologically. In four cases there was infiltration of blood into the testicle and the spermatic cord histological examination showing separation of the seminiferous tubules by an effusion of blood, the vegetative cells and the gonocytes being intact. In the last case the testicles and the spermatic cords were normal. The indications for operation on the scrotum were based on opacity to transillumination. The prognosis varies in relation to the lesions discovered. Atrophy of the testicles follows after six hours in cases of torsion while the evolution appears to be better in cases of haematic infiltrations. Breech presentation leads, in a certain number of cases, to haematic infiltration of the testicles and spermatic cords and seems to be a factor leading to torsion of the testicles. Detailed and repeated examinations of the scrotum are thus indicated after births of this type.