We have studied the production of $\ensuremath{\rho}$ and $\ensuremath{\varphi}$ mesons from muon scattering on a liquidhydrogen target at 150 and 100 GeV. For the $\ensuremath{\rho}$ we observe a skewed mass distribution which becomes somewhat more normal with increasing ${Q}^{2}$ (the square of the four-momentum transferred from the muon), and an exponential distribution in $t$ (the square of the four-momentum transferred to the target proton) with a slope which is consistent with a slight decrease as ${Q}^{2}$ increases. The dependence of the cross section on ${Q}^{2}$ follows that of the square of the $\ensuremath{\rho}$ propagator with little contribution from longitudinal $\ensuremath{\rho}$ production. The angular distribution of the $\ensuremath{\rho}$ decay confirms the smallness of the contribution from longitudinal $\ensuremath{\rho}$ production at our energies. The cross section when extrapolated to ${Q}^{2}=0$ agrees with that measured in real photoproduction. The decay angular distribution of the $\ensuremath{\rho}$ decay shows that $s$-channel helicity is largely conserved, although we detect a helicity-single-flip contribution at the 10-15% level. Natural-parity exchange in the $t$ channel dominates, and the transverse and longitudinal amplitudes are found to be in phase. These characteristics are consistent with the diffractive nature of the vectordominance model. The $t$ distribution of $\ensuremath{\varphi}$ production is also exponential, although less steep than that for the $\ensuremath{\rho}$. We observe an elastically produced four-pion state at a mass of approximately 1600 MeV. We identify this state with the ${\ensuremath{\rho}}^{\ensuremath{'}}(1600)$, and find it to be produced with a distribution exponential in $t$.
Results on the protron structure function, ${F}_{2}$, are presented for $0.3<{q}^{2}<80.0$ Ge${\mathrm{V}}^{2}$ and $10<\ensuremath{\nu}<200$ GeV. The results support the conclusions of earlier work at 97 and 147 GeV that scaling is violated. A new value for $R=\frac{{\ensuremath{\sigma}}_{S}}{{\ensuremath{\sigma}}_{T}}=0.44\ifmmode\pm\else\textpm\fi{}0.25$ has been obtained using all the Fermilab proton measurements.
Absolute cross sections for the reactions $p+d\ensuremath{\rightarrow}{\mathrm{He}}^{3}+{\ensuremath{\pi}}^{0}$ and $p+d\ensuremath{\rightarrow}{\mathrm{H}}^{3}+{\ensuremath{\pi}}^{+}$ have been measured at several angles and energies. The experimental ${\mathrm{He}}^{3}$ and ${\mathrm{H}}^{3}$ momentum resolution has been computed and compared with the results obtained for these two reactions. By comparing experimental data on these reactions with the reaction $p+p\ensuremath{\rightarrow}d+{\ensuremath{\pi}}^{+}$ it has been possible to compute the impulse-approximation integral relating the processes. The results are in good agreement with other experiments.
We investigated mu(+) decays at rest produced at the ISIS beam stop target. Lepton flavor (LF) conservation has been tested by searching for nu(e) via the detection reaction p(nu(e),e(+))n. No nu(e) signal from LF violating mu(+) decays was identified. We extract upper limits of the branching ratio (BR) for the LF violating decay mu(+)-->e(+)+nu(e)+nu(-) compared to the standard model (SM) mu(+)-->e(+)+nu(e)+nu(mu) decay: BR<0.9(1.7) x 10(-3) (90% C.L.) depending on the spectral distribution of nu(e) characterized by the Michel parameter rho=0.75(0.0). These results improve earlier limits by one order of magnitude and restrict extensions of the SM in which nu(e) emission from mu(+) decay is allowed with considerable strength. The decay mu(+)-->e(+)+nu(e)+nu(mu) often proposed as a potential source for the nu(e) signal observed in the LSND experiment can be excluded.
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