P. W. Balm

Direct search for charged Higgs bosons in decays of top quarks

We present a search for charged Higgs bosons in decays of pair-produced top quarks in pp collisions at sqrt[s] = 1.8 TeV recorded by the D0 detector at the Fermilab Tevatron collider. With no evidence for signal, we exclude most regions of the ( M(H+/-),tan(beta)) parameter space where the decay t--> H(+)b has a branching fraction >0.36 and B(H+/--->tau(nu)(tau)) is large.

Search for large extra dimensions in the monojet + missing E(T) channel at D0

We present a search for large extra dimensions (ED) in p-pbar collisions at a center-of-mass energy of 1.8 TeV using data collected by the D0 detector at the Fermilab Tevatron in 1994-1996. Data corresponding to 78.8 +/- 3.9 pb^-1 are examined for events with large missing transverse energy, one high-p_T jet, and no isolated muons. With no excess beyond the background prediction from the standard model, we place limits on the fundamental Planck scale of 1 TeV (0.6 TeV) for 2 (7) ED.

Search for new particles in the two-jet decay channel with the DO detector

We present the results of a search for the production of new particles decaying into two jets in p p collisions at sqrt[s]=1.8 TeV, using the DO 1992–1995 data set corresponding to 109 pb-1. We exclude at the 95% confidence level the production of excited quarks (q*) with masses below 775 GeV/c2, the most restrictive limit to date. We also exclude standard-model-like W′ (Z′) bosons with masses between 300 and 800 GeV/c2 (400 and 640 GeV/c2). A W′ boson with mass <786 GeV/c2 has been excluded by previous measurements, and our lower limit is therefore the most stringent to date.

Ratio of isolated photon cross sections in p(p)over-bar collisions at root s=630 and 1800 GeV

The inclusive cross section for production of isolated photons has been measured in \pbarp collisions at

Subjet multiplicity of gluon and quark jets reconstructed with the k(perpendicular to) algorithm in p(p)over-bar collisions

\sqrt{s} = 630

Direct measurement of the W boson decay width

GeV with the \D0 detector at the Fermilab Tevatron Collider. The photons span a transverse energy (

t(t)over-bar production cross section in p(p)over-bar collisions at root s=1.8 TeV

E_T

Multiple jet production at low transverse energies in p(p)over-bar collisions at root s=1.8 TeV

) range from 7-49 GeV and have pseudorapidity

The inclusive jet cross section in

|\eta| < 2.5

p\bar{p}

. This measurement is combined with to previous \D0 result at