I. Peruzzi

Properties of anomalous eμ events produced in e+e− annihilation☆☆☆

Abstract We present the properties of 105 events of the form e + + e − → e +- + μ ∓ + missing energy, in which no other charged particles or photons are detected. The simplesthypothesis compatible with all the data is that these events come from the production of a pair of heavy leptons, the mass of the lepton being in the range 1.6 to 2.0 GeV/ c 2

D and D meson production near 4 GeV in e+e− annihilation

Abstract We have studied momentum spectra for D0 ( D 0) and D± mesons produced near 4 GeV in e+e− annihilation and find that production is dominated by two-body reactions involving D and D∗ states where the D∗ (charged and neutral) have masses near 2.01 GeV/c2. A detailed study of D momentum spectra near Ecm = 4.028 GeV allows determination of masses and branching ratios of D and D∗ states. Lastly we find that events containing a D0 meson conserve strangeness, thus establishing upper limits on D0- D 0 mixing and on the effects of charm changing neutral currents.

K° production in e+e- annihilation

Abstract The production of enutral kaons in e + e − annihilation has been measured for c.m. energies between 3.4 GeV and 7.6 GeV. Near 4 GeV the inclusive K S cross section shows an increase and structure similar to total hadron production. Roughly 40–45% of all hadronic final states contain kaons, except at 4.028 GeV and 4.415 GeV, where a significantly larger kaon fraction is observed.

Properties of the proposed τ charged lepton

Abstract The anomalous eμ and 2-prong μx events produced in e + e − annihilation are used to determine the properties of the proposed τ charged lepton. We find the τ mass is 1.90 ± 0.10 GeV/ c 2 ; the mass of the associated neutrino, ν τ , is less than 0.6 GeV/ c 2 with 95% confidence; V - A coupling is favored over V + A coupling for the τ − ν τ current; and the leptonic branching ratios are 0.186 ± 0.010 ± 0.028 from the eμ events and 0.175 ± 0.027 ± 0.030 from the μx events where the first error is statistical and the second is systematic.

Inclusive production of D-mesons in e+e− annihilation at 7 GeV☆

Abstract Inclusive momentum and energy spectra of neutral and charged D-mesons produced in e+e− annihilation at energies near 7 GeV are presented. The slope of the energy spectrum is similar to the charged pion spectrum at the same energy. The inclusive cross section σ(e+e−→ D or D + anything) at 7 GeV is 4.8±1.3 nb.

Inclusive

We have measured inclusive ..gamma.. and ..pi../sup 0/ production in multiprong events produced by e/sup +/e/sup -/ annihilation in the center-of-mass energy range 4.9 to 7.4 GeV. We find that ..pi../sup 0/ inclusive cross section to be consistent in shape and normalization with half the charged-..pi.. cross section between chi = 0.15 and 0.60, with an integrated inclusive cross-section ratio of sigma (..pi../sup 0/)/ vertical-bar (sigma (..pi../sup +/) + sigma (..pi../sup -/) vertical-bar = 0.47 +- 0.10.

\gamma

Abstract We have observed events of the form e + +e − → e + +e − and e + +e − → μ + + μ − in which there are no other detected particles and there is substantial missing energy; and which cannot be explained by conventional electromagnetic interactions. We show that these events can be explained as the decay products from the pair production, e + +e − → τ + + τ − , of a new charged lepton, τ ± , of mass ≈1800 MeV/ c 2 . Some properties of these events are presented. In particular, this production cross section is inconsistent with the τ being an electron-related paralepton.

and

Abstract Decay modes of the charmed mesons, D 0 and D + , are studied in e + e − annihilation data at 4.03 and 4.41 GeV c.m. energy. The products of cross section times branching ratio are measured for the K − π + , K − π + π + π − , K S π + π − and K − π + π + final states. Upper limits are established for the Cabibbo forbidden decays via π + π − , K + K − , K + K − π + , K + π + π − and π + π − π + . The K − π + π + π − final state is shown to be dominated by K − π + ρ 0 .

\pi^0

Abstract We have searched for relativistic, highly-interacting fractionally-charged particles using the free-quark detector at the e + e − storage ring PEP. No convincing events were seen. For an assumed interaction cross section with matter of 100 times geometric, 90% confidence level upper limits on their production relative to e + e − → μ + μ − are between 0.025 and 0.49 depending on quark mass (up to 13 GeV/ c 2 ) and reaction type. These are the first published limits on the production of fractionally charged particles with interaction cross sections of 100 times geometric or larger.

Production in

We have measured inclusive ..gamma.. and ..pi../sup 0/ production in multiprong events produced by e/sup +/e/sup -/ annihilation in the center-of-mass energy range 4.9 to 7.4 GeV. We find that ..pi../sup 0/ inclusive cross section to be consistent in shape and normalization with half the charged-..pi.. cross section between chi = 0.15 and 0.60, with an integrated inclusive cross-section ratio of sigma (..pi../sup 0/)/ vertical-bar (sigma (..pi../sup +/) + sigma (..pi../sup -/) vertical-bar = 0.47 +- 0.10.