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The CLEO Collaboration

Publications and source records attributed to The CLEO Collaboration.

25 records · Page 2Linked to original sources
arXiv1994

Two-Photon Production of Charged Pion and Kaon Pairs

A measurement of the cross section for the combined two-photon production of charged pion and kaon pairs is performed using 1.2~$\rm fb^{-1}$ of data collected by the CLEO~II detector at the Cornell Electron Storage Ring. The cross section is measured at invariant masses of the two-photon system between 1.5 and 5.0 GeV/$c^2$, and at scattering angles more than $53^\circ$ away from the $γγ$ collision axis in the $γγ$ center-of-mass frame. The large background of leptonic events is suppressed by utilizing the CsI calorimeter in conjunction with the muon chamber system. The reported cross section is compared with leading order QCD models as well as previous experiments. In particular, although the functional dependence of the measured cross section disagrees with leading order QCD at small values of the two-photon invariant mass, the data show a transition to perturbative behavior at an invariant mass of approximately 2.5 GeV/$c^2$. hardcopies with figures can be obtained by writing to to: Pam Morehouse preprint secretary Newman Lab Cornell University Ithaca, NY 14853 or by sending mail to: preprints@lns62.lns.cornell.edu

hep-ph↗
arXiv1994

Production and Decay of D_1(2420)^0 and D_2^*(2460)^0

We have investigated $D^{+}π^{-}$ and $D^{*+}π^{-}$ final states and observed the two established $L=1$ charmed mesons, the $D_1(2420)^0$ with mass $2421^{+1+2}_{-2-2}$ MeV/c$^{2}$ and width $20^{+6+3}_{-5-3}$ MeV/c$^{2}$ and the $D_2^*(2460)^0$ with mass $2465 \pm 3 \pm 3$ MeV/c$^{2}$ and width $28^{+8+6}_{-7-6}$ MeV/c$^{2}$. Properties of these final states, including their decay angular distributions and spin-parity assignments, have been studied. We identify these two mesons as the $j_{light}=3/2$ doublet predicted by HQET. We also obtain constraints on {\footnotesize $Γ_S/(Γ_S + Γ_D)$} as a function of the cosine of the relative phase of the two amplitudes in the $D_1(2420)^0$ decay.

hep-ph↗
arXiv1994

Study of the Decay $Λ_c \to Λl^+ ν_{l}

Using the CLEO II detector at CESR, we observe 500 $Λl^+$ pairs consistent with the semileptonic decay $Λ_c \to Λl^+ ν_{l}$. We measure $σ(e^+ e^- \to Λ_c X) \dot {cal B}(Λ_c^+ \to Λl ν_{l}) =4.77 \pm 0.25 \pm 0.66 $pb. Combining with the charm semileptonic width and the lifetime of the $Λ_c$, we also obtain ${\cal B}(Λ_c \to p K^- π^+)$. We find no evidence for $Λl^+ ν_{l}$ final states in which there are additional $Λ_c^+$ decay products. We measure the decay asymmetry parameter of $Λ_c \to Λl^+ ν_{l}$ to be $α_{Λ_c} =-0.89\pm{^{0.17}_{0.11}}\pm{^{0.09}_{0.06}}.

hep-ph↗
arXiv1994

Precision Measurement of the $D_s^{*+}- D_s^+$ Mass Difference

We have measured the vector-pseudoscalar mass splitting $M(D_s^{*+})-M(D_s^+) = 144.22\pm 0.47\pm 0.37 MeV$, significantly more precise than the previous world average. We minimize the systematic errors by also measuring the vector-pseudoscalar mass difference $M(D^{*0})-M(D^0)$ using the radiative decay $D^{*0}\rightarrow D^0γ$, obtaining $[M(D_s^{*+})-M(D_s^+)]-[M(D^{*0})-M(D^0)] = 2.09\pm 0.47\pm 0.37 MeV$. This is then combined with our previous high-precision measurement of $M(D^{*0})-M(D^0)$, which used the decay $D^{*0}\rightarrow D^0π^0$. We also measure the mass difference $M(D_s^+)-M(D^+)=99.5\pm 0.6\pm 0.3$ MeV, using the $ϕπ^+$ decay modes of the $D_s^+$ and $D^+$ mesons.

hep-ph↗
arXiv1994

Observation of a New Charmed Strange Meson

Using the CLEO-II detector, we have obtained evidence for a new meson decaying to $D^0 K^+$. Its mass is $2573.2^{+1.7}_{-1.6}\pm 0.8\pm 0.5$ {}~MeV/$c^2$ and its width is $16^{+5}_{-4}\pm 3$~MeV/$c^2$. Although we do not establish its spin and parity, the new meson is consistent with predictions for an $L=1$, $S=1$, $J_P=2^+$ charmed strange state.

hep-ph↗
arXiv1994

Measurement of Cabibbo Suppressed Decays of the $τ$ Lepton

Branching ratios for the dominant Cabibbo-suppressed decays of the $τ$ lepton have been measured by CLEO~II in $e^+ e^-$ annihilation at CESR ($\sqrt{s} \sim 10.6$~GeV) using kaons with momenta below $0.7\ \rm GeV/c$. The inclusive branching ratio into one charged kaon is $(1.60 \pm 0.12 \pm 0.19)\%$. For the exclusive decays, $B(τ\to K^-) = (0.66 \pm 0.07 \pm 0.09)\%$, $B(τ\to K^- π^0) = (0.51 \pm 0.10 \pm 0.07)\%$, and, based on three events, $B(τ\to K^- π^0 π^0) < 0.3\%$ at the 90\% confidence level. These represent significant improvements over previous results. $B(τ\to K^- π^0)$ is measured for the first time with exclusive $π^0$ reconstruction.

hep-ph↗