arXiv subjects

R. Poutissou

Publications and source records attributed to R. Poutissou.

22 records · Page 2Linked to original sources

arXiv1997

Observation of the Decay K^+ --> pi^+ gamma gamma

The first observation of the decay K^+ --> pi^+ gamma gamma is reported. A total of 31 events was observed with an estimated background of 5.1 +- 3.3 events in the pi+ momentum range from 100 MeV/c to 180 MeV/c. The corresponding partial branching ratio, B(K+ -> pi+ gamma gamma, 100 MeV/c < P_pi^+ < 180 MeV/c), is (6.0 +- 1.5 (stat) +- 0.7 (sys)) x 10^{-7}. No K^+ --> pi^+ gamma gamma decay was observed in the pi^+ momentum region greater than 215 MeV/c. The observed pi^+ momentum spectrum is compared with the predictions of chiral perturbation theory.

hep-ex↗

arXiv1997

Observation of the Decay K+ --> pi+ mu+ mu-

We have observed the rare decay K+ --> pi+ mu+ mu- and measured the branching ratio Gamma(K+ --> pi+ mu+ mu-)/Gamma(K+ --> all) = (5.0 +/- 0.4 (stat.) +/- 0.7 (sys.) +/- 0.6 (theor.)) x 10^{-8}. We compare this result with predictions from chiral perturbation theory and estimates based on the decay K+ --> pi+ e+ e-.

hep-ex↗

arXiv1996

Radiative Muon Capture on Hydrogen and the Induced Pseudoscalar Coupling

The first measurement of the elementary process $μ^- p \rightarrow ν_μ n γ$ is reported. A photon pair spectrometer was used to measure the partial branching ratio ($2.10 \pm 0.22) \times 10^{-8}$ for photons of k > 60 MeV. The value of the weak pseudoscalar coupling constant determined from the partial branching ratio is $g_p(q^{2}=-0.88m_μ^2) = (9.8 \pm 0.7 \pm 0.3) \cdot g_a(0)$, where the first error is the quadrature sum of statistical and systematic uncertainties and the second error is due to the uncertainty in $λ_{op}$, the decay rate of the ortho to para $p μp$ molecule. This value of g_p is $\sim$1.5 times the prediction of PCAC and pion-pole dominance.

nucl-ex↗

arXiv1995

Search for the Decay $K^+ \to π^+ ν\overlineν$

An upper limit on the branching ratio for the decay $K^+ \! \rightarrow \! π^+ ν\overlineν$ is set at $2.4 \times 10^{-9}$ at the 90\% C.L. using pions in the kinematic region $214~{\rm MeV}/c < P_π< 231~{\rm MeV}/c$. An upper limit of $5.2 \times 10^{-10}$ is found on the branching ratio for decays $K^+ \! \rightarrow \! π^+ X^0$, where $X^0$ is any massless, weakly interacting neutral particle. Limits are also set for cases where $M_{X^0}>0$.

hep-ex↗