G. Otter

Test of lepton-flavour conservation in μ → e conversion on titanium☆

Abstract A search for μ → e conversion in muonic atoms is being performed at PSI with the SINDRUM II spectrometer. A first measurement on Ti gives upper limits on the branching ratios for the ground-state transitions of Γ(μ − Ti → e − Ti g.s. ) Γ(μ − Ti capture ) −12 and Γ(μ − Ti → e + Ca g.s. ) Γ(μ − Ti capture ) −12 (90% confidence ) . With the assumption of a giant resonance excitation of the Ca nucleaus the limit on the total rate for μ − → e + conversion is Γ(μ − Ti → e + Ca ∗ ) Γ(μ − Ti capture ) −11 .

Improved limit on the branching ratio of μ−→e+ conversion on titanium

Abstract The SINDRUM II spectrometer at PSI is used in searches for μ → e conversion in muonic atoms. Here we report on a search for the charge-changing μ − → e + conversion on titanium. The measurements yielded the new upper limits Γ ( μ − Ti → e + Ca GS )/ Γ ( μ − Ti capture) −12 (90% CL) for the ground state transition and Γ ( μ − Ti → e + Ca GDR )/ Γ ( μ − Ti capture) −11 (90% CL) for a giant dipole resonance excitation with both a mean energy and a width of 20 MeV. These results improve on our previous best limits by a factor of 2.5.

Measurement of the decay π+→e+νee+e− and search for a light Higgs boson

Abstract The radiative pion decay π + →e + ν e e + e − has been measured and values for the weak form factors F V , F A and R have been obtained. The measured branching ratio is Λ ( π + →e + ν e e + e − )/ Λ ( π + → μ + ν μ )=(3.2±0.5)×10 −9 . A light Higgs boson h with standard couplings to quarks is excluded in the mass range 10 MeV/ c 2 ⩽ m h ⩽110 MeV/ c 2 at 90% CL.

First observation of the decay π+ → e+νe+e− and a determination of the form factors FV, FA, R☆

Abstract The radiative pion decay π+ → e+νe+e- has been observed for the first time. Information on the form factors was obtained from the kinematical distribution of 79 events. The vector form factor has the same sign as the pion decay constant fπ. The ratios of axial-vector form factors to the vector form factor are γ = F A F V = 0.7 ± 0.5 and ξ = R F V = 2.3 ± 0.6. The value for γ is in agreement with the small positive value (0.53 ± 0.06) and excludes the large negative value (−2.49 ± 0.06) of γ obtained in π+ → e+νγ experiments.

Limits for short-lived neutral particles emitted in μ+ or π+ decay

Abstract In the data taken for the μ + → e + e + e - and π + → e + ν e + e - experiments a search was made for neutral particles φ produced in the decay μ + → e + φ or π + → e + νφ with subsequent decay φ → e + e - . No candidates were found, Upper limits for the branching ratios are given as a function of their masses and lifetimes. For lifetimes below 10 −10 s limits down to 2 × 10 −12 are obtained.

Search for Muon - Electron Conversion on Gold

Duringtheyear2000theSindrumIIcollaborationatthePaul-ScherrerInsti- tute,Switzerland(PSI)performedanalruninasearchforcoherent !e conversion on gold. An improvementin sensitivity by two ordersof magnitude wasachieved, but no candidate events for the conversionprocess have been seen.

A Partial Wave Analysis of the (

Abstract A partial wave analysis of the non-diffractively produced ( K 0 π + π - system has been performed. The system was produced in the reaction K - p→ K 0 π + π - n at 10 GeV/c, measured in the CERN Omega spectrometer. Besides the well-known K∗(1420) resonance, we find good evidence for the production of Q2(1400) and some indication for Q1(1290) production in JP=1+. In addition we clearly observe a bump in the 1800 MeV region, the properties of which are discussed.

\bar{K}0 \pi^+ \pi^-

Abstract A partial wave analysis of the non-diffractively produced ( K 0 π + π - system has been performed. The system was produced in the reaction K - p→ K 0 π + π - n at 10 GeV/c, measured in the CERN Omega spectrometer. Besides the well-known K∗(1420) resonance, we find good evidence for the production of Q2(1400) and some indication for Q1(1290) production in JP=1+. In addition we clearly observe a bump in the 1800 MeV region, the properties of which are discussed.

) System Produced in

Abstract A partial wave analysis of the non-diffractively produced ( K 0 π + π - system has been performed. The system was produced in the reaction K - p→ K 0 π + π - n at 10 GeV/c, measured in the CERN Omega spectrometer. Besides the well-known K∗(1420) resonance, we find good evidence for the production of Q2(1400) and some indication for Q1(1290) production in JP=1+. In addition we clearly observe a bump in the 1800 MeV region, the properties of which are discussed.