120282404
A new multivariate technique for top quark search
Abstract We present a new multivariate event classifier, the PDE classifier, which can be used to identify rare signals in the presence of large backgrounds. The classifier is based on a discriminant function which uses kernel density estimates of the signal and background event densities. The PDE method offers the flexibility of a neural network but is conceptually simpler, theoretically better understood, and easier to optimize in practice. The technique is tested on Monte Carlo data using processes t t → e + E t + jets as signal and W + jets → e + Et + jets as background. The performance of the PDE classifier is similar to that of a neural network. Both methods outperform conventional analysis.
120544624
Triggering on high-transverse-momentum jets
We compare the characteristics of events selected by ''global'' and ''two-high'' triggers in large-transverse-energy hadron-hadron collisions. Using a QCD-based Monte Carlo model of Fox and collaborators, we find that the former is effectively a high-multiplicity trigger, the latter a high-planarity trigger favoring unusually clean jet events. Predictions of the model for both triggers are in good qualitative agreement with recent data.
119722876
Measurement of the dijet cross section in 400-GeV pp collisions
The invariant cross section for production of jet pairs in 400-GeV/c pp interactions has been measured as a function of p{tau} in the p{tau} range 4 to 9 GeV/c. The results are in good agreement with predictions of perturbative QCD models. 20 refs., 3 figs., 1 tab.
125525593
HADRON JETS IN 400-GeV p p COLLISIONS
198138883
Experimental information on the pion gluon distribution function
An experiment performed at Fermilab used double-arm calorimeter triggers to study di-jet production by 400 GeV protons and 200 GeVπ− mesons incident on liquid hydrogen. The observed ratio of positive to negative leading particles in the jets was compared forpp andπp production using a tree level parton scattering model. The results are moderately sensitive to the form of the pion gluon distribution function and yieldx g(x)⋍(1−x)2.75±0.40±0.75.
120365910
Modular TPCs for relativistic heavy-ion experiments☆
Abstract A description is given of a TPC system that operates in a relativistic heavy-ion beam and yields good track reconstruction efficiency in very-high-multiplicity events. The mechanical construction of the chamber is discussed. A set of custom hybrid circuits are used to build a very compact, cost-effective electronics system mounted directly on the chamber. Results from running in test beams and from preliminary experimental runs are given.
119905977
Quantum number transfer and overlap calculations
Abstract The relationship between Regge behaviour of two-body amplitudes and quantum number exchange in multiparticle production is analyzed. An exact bound on the elastic forward peak in terms of inclusive p ⊥ correlations is given. Another result is that one cannot obtain α ′ ϱ > α ′ P from overlap calculations, using only the present inclusive data as input.
119783273
Factorisation and inclusive photoproduction
Abstract Inclusive photoproduction cross sections for π ± and Λ in the fragmentation region of the proton are predicted via factorisation from hadron initiated reactions. Comparison with existing data is favourable.
121339748
MOMENTUM TRANSFER DEPENDENCE IN DIFFRACTION DISSOCIATION.
Abstract The mechanism of kinematic coupling between momentum transfers in producing a low mass two particle system with double-peripheral dynamics is studied theoretically and model calculations. A method of data analysis which eliminates the effects of this kinematic reflection is presented. The data of the reaction pp → pnπ + at 19 GeV/ c have been analyzed using this method. It is seen that the high production slope of the low mass ηπ + system observed in this process is not a cosequences of double-peripheral dynamics plus kinematics but must be explicitly present in the invariant matrix element.
121736887
Diffraction scattering and the parton structure of hadrons
We apply parton-model concepts to the ''soft'' (small-momentum- transfer) processes which make up the majority of the hadronic total cross section. Diffraction is calculated as the shadow of these soft processes. We obtain an attractive picture of the essential features of total, elastic, and diffractive-inelastic scattering. In particular, the rather large cross section for inelastic diffraction, which is observed experimentally, results from fluctuations in the distribution of the wee partons which initiate interactions. These fluctuations lead to diffractive production by the mechanism of Good and Walker. The observed peripheral character of diffraction as a function of impact parameter, the absence of a forward dip in dsigma/dt dm/sup 2/, the correct integrated cross section, and the correct small-t slope of diffraction all follow naturally in our approach.
120138835
FACTORIZATION AND EXCHANGE DEGENERACY OF SECONDARY TRAJECTORIES IN INCLUSIVE REACTIONS.
Abstract Some predictions following from factorization and exchange degeneracy of secondary trajectories in inclusive reactions are tested and discussed.