Formalism for dilepton production via virtual photon bremsstrahlung in hadronic reactions

We derive a set of new formulas for various distributions in dilepton production via virtual photon bremsstrahlung from pseudoscalar mesons and unpolarized spin-one-half fermions. These formulas correspond to the leading and sub-leading terms in the Low-Burnett-Kroll expansion for real photon bremsstrahlung. The relation of our leading-term formulas to previous works is also shown. Existing formulas are examined in the light of Lorentz covariance and gauge invariance. Numerical comparison is made in a simple example, where an "exact" formula and real photon data exist. The results reveal large discrepancies among different bremsstrahlung formulas. Of all the leading-term bremsstrahlung formulas, the one derived in this work agrees best with the exact formula. The issues of M_T-scaling and event generators are also addressed.Comment: 37 pages, RevTeX, epsf.sty, 10 embedded figure

Neutral K*(890) and [rho]0 meson production in e+e- annihilation at

The production of neutral K*(890) and [rho]0 mesons was studied in e+e- annihilation at using the High Resolution Spectrometer at PEP. Differential cross sections are presented as a function of the scaled energy variable z and compared to [pi]0 and K0 production. The measured multiplicities are 0.84+/-0.08 [varrho]0 mesons and 0.57+/-0.09 K*0(890) mesons per event for a meson momentum greater than 725 MeV/c. The ratios of vector meson to pseudoscalar meson production for (u,d), s and c quark are compared to predictions of the Lund model.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25574/3/0000116.pd

Measurement of the lifetime of hadrons containing the b-quark

Data collected with the High Resolution Spectrometer at PEP, corresponding to an integrated luminosity of 200 pb-1 of e+e- annihilation at 29 GeV, were used to measure the mean lifetime of hadrons containing the bottom quark. The lifetime was determined using the impact parameter method on events containing a high-transverse-momentum electron. The result, based on a sample of 301 events, is [tau]B = 1.02 +/-0.390.42 ps, where the indicated errors include both statistics and systematics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26581/1/0000120.pd

Measurement of the D 0 → K - Π + Branching Fraction a

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72296/1/j.1749-6632.1988.tb51529.x.pd

Charged particle multiplicity distributions in e + e − annihilation at 29 GeV: a comparison with hadronic data

The charged particle multiplicity distributions for two-jet events in e + e − annihilation at 29 GeV have been measured using the High Resolution Spectrometer at PEP. A Poisson distribution describes the data for both the complete event and for the single jets. In addition, no correlation is observed between the multiplicities in the two jets of an event. For fixed values of the prong number of the complete event, the multiplicity sharing between the two jets is in good agreement with a binomial distribution. The rapidity gap distribution is exponential with a slope equal to the mean rapidity density. These observations, which are consistent with a picture of independent emission of single particles, are contrasted to the results from soft hadronic collisions and conclusions are drawn about the nature of clusters.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47881/1/10052_2005_Article_BF01570767.pd

Experimental limits on monojet production in e+e- annihilation at 29 GeV

A search was made for e+e--->X1X2 where X1 consists of one or more light unobservable particles and X2 decays promptly to a visible jet of particles. One event was found for an integrated luminosity of 176 pb-1, a rate consistent with known backgrounds. This result places a significant constraint on a number of theoretical models.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25641/3/0000191.pd

First measurements of hadronic decays of the Z boson

We have observed hadronic final states produced in the decays of Z bosons. In order to study the parton structure of these events, we compare the distributions in sphericity, thurst, aplanarity, and number of jets to the predictions of several QCD-based models and to data from lower energies. The data and models agree within the present statistical precision

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/c^2, 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

Studies of jet production rates in e + e − annihilation at E cm =29 GeV

Production rates of multijet hadronic final states are studied in e + e − annihilation at 29 GeV center of mass energy. QCD shower model calculations with exact first order matrix element weighting at the first gluon vertex are capable of reproducing the observed multijet event rates over a large range of jet pair masses. The method used to reconstruct jets is well suited for directly comparing experimental jet rates with parton rates calculated in perturbative QCD. Evidence for the energy dependene of α s is obtained by comparing the observed production rates of 3-jet events with results of similar studies performed at higher center of mass energies.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47886/1/10052_2005_Article_BF01506527.pd