Spin Motion at and Near Orbital Resonance in Storage Rings with Siberian Snakes I: At Orbital Resonance.

In this paper, and in a sequel, we invoke the invariant spin field to provide an in-depth study of spin motion at and near low order orbital resonances in a simple model for the effects of vertical betatron motion in a storage ring with Siberian Snakes. This leads to a clear understanding, within the model, of the behaviour of the beam polarization at and near so-called snake resonances in proton storage rings

Influence of fabrication errors on wake function suppression in NC X-band accelerating structures for linear colliders

Wake function suppression is effected by ensuring that the mode frequencies of an X-band normal conducting (NC) accelerating structure of multiple cells are detuned and moderately damped by waveguide manifolds attached to the outer wall of the accelerator. We report on the dilution in the wake function suppression that occurs due to errors resulting from the fabrication process. After diffusion bonding 206 cells a non-uniform expansion in the cell geometry forces a substantial shift in the frequencies of select cells. We remap all circuit parameters to these shifted cell frequencies to predict the wake function. Experiments performed on the SLC at the SLAC National Accelerator Laboratory indicate that the wake function is well predicted by the circuit model. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft

Determination of alpha s from a differential-jet-multiplicity distribution in e+e- collisions at sqrt s =29 and 91 GeV.

We measured the differential jet-multiplicity distribution in e+e- annihilation with the Mark II detector. This distribution is compared with the second-order QCD prediction and s is determined to be 0.1230.0090.005 at ssSMZ (at the SLAC Linear Collider) and 0.1490.0020.007 at ss=29 GeV (at the SLAC storage ring PEP). The running of s between these two center-of-mass energies is consistent with the QCD prediction. © 1990 The American Physical Society

Upper limits on D+/- and B+/- decays to two leptons plus pi +/- or K+/-

Data taken by the Mark II detector at the SLAC e+e- storage ring PEP was used to search for exclusive decays of D and B mesons into two charged leptons plus a charged pion or kaon. All possible charge and lepton combinations consistent with charge conservation were considered and no evidence for any signals was found. We obtain upper limits for the various branching ratios ranging from 2.5×10-3 to 9.2×10-3, at a 90% confidence level. Some of these limits can be used to constrain leptoquark masses in various models. © 1990 The American Physical Society

Direct search for pair production of heavy stable charged particles in Z decays.

A search for pair production of stable charged particles from Z decay has been performed with the Mark II detector at the SLAC Linear Collider. Particle masses are determined from momentum, ionization energy loss, and time-of-flight measurements. A limit excluding pair production of stable fourth-generation charged leptons and stable mirror fermions with masses between the muon mass and 36.3 GeV/c2 is set at the 95% confidence level. Pair production of stable supersymmetric scalar leptons with masses between the muon mass and 32.6 GeV/c2 is also excluded. © 1990 The American Physical Society

Measurement of the B0-meson lifetime.

We report a measurement of the lifetime of the B0 meson based upon 29-GeV e+e- annihilation data taken with the Mark II detector at the SLAC storage ring PEP. The B0 mesons are tagged by their decays into D*- and D*+, where the D*- is tagged by its decay into -D 0. We reconstruct the decay vertices of 15 B0-meson candidates and measure the B0 lifetime to be 1.20-0.360.14+0.52+0.16 psec. © 1990 The American Physical Society

Measurements of Z-boson resonance parameters in e+e- annihilation.

We have measured the mass of the Z boson to be 91.14±0.12 GeV/c2, and its width to be 2.42-0.35+0.45 GeV. If we constrain the visible width to its standard-model value, we find the partial width to invisible decay modes to be 0.46±0.10 GeV, corresponding to 2.8±0.6 neutrino species, with a 95%-confidence-level upper limit of 3.9. © 1989 The American Physical Society