P. Lariccia

MEASUREMENT OF THE STANDARD MODEL PARAMETERS FROM A STUDY OF W AND Z BOSONS

Abstract A study has been made of the decays W → ev and Z → e + e − , using the UA2 detector at the CERN pp Collider. The data correspond to an integrated luminosity of 142 nb −1 at a centre-of-mass collision energy √ s =546 GeV, and 768 nb −1 at √ s =630 GeV. Measurements of the standard model parameters from samples of 251 W decay and 39 Z decay candidates are compared with expectations of the standard electroweak model.

Search for exotic processes at the CERN pp̄ collider

Abstract The total UA2 data sample at the CERN pp Collider corresponds to an integrated luminosity of 910 nb −1 . Limits on various hypothetical processes, such as production of excited electrons, additional charged or neutral vector bosons, or supersymmetric particles, are presented from the analysis of this sample.

Direct photon production from pions and protons at 200 GeV/c

Direct photon production has been studied by an experiment performed with the NA3 spectrometer at CERN, using incident negative and positive beams at 200 GeV/c interacting with an isoscalar Carbon target. Two different triggers have been used; one of them requires the photon conversion. The experiment is sensitive to direct photons produced with 3.0≦PT≦6 GeV/c and center-of-mass rapidity −0.4≦y*≦1.2. Inclusive cross sections are given for incident π± and protons, and compared with second order QCD predictions; finally an estimation of the gluon structure function of the nucleon is given.

Mass and lifetime limits on new long-lived particles in 300 GeV/c π− interactions

A sensitive search has been done for the production of new long-lived and penetrating particles by 300 GeV/c negative pions. No new state —decaying into at least two charged known particles —has been detected with mass above 1 GeV/c2 and lifetime in the range 5·10−11 s to 5·10−7s. We give upper limits on production cross sections, and consequences on the existence of heavy “axion-like” particles, heavy neutrinos and supersymmetric particles. In particular, this experiment excludes the existence of light gluinos with lifetime in the range 5·10−11 to 10−8s: this closes the last “window of opportunity” for gluinos withM<2 GeV/c2 and lifetime measurable in particle physics experiments.

MEASUREMENT OF THE STRONG COUPLING CONSTANT ALPHA-s FROM A STUDY OF W BOSONS PRODUCED IN ASSOCIATION WITH JETS

Abstract The UA2 experiment at the CERN p p Collider has identified a total sample of 251 W→eν events. Among this sample 221 events are found without jets and 29 with one jet. The yield of one-jet events relative to that of zero-jet events provides a measurement of the strong coupling constant: αs(Mw2)=0.13±0.03(stat)±0.03±(syst1)±0.02(syst2), where syst1 represents the experimental systematic error and syst2 is an estimate of the theoretical uncertainty.

Direct photon pair production from pions and protons at 200 GeV/c

Direct photon production has been studied by an experiment performed with the NA3 spectrometer at CERN, using incident negative and positive beams at 200 GeV/c interacting with an isoscalar Carbon target. Two different triggers have been used; one of them requires the photon conversion. The experiment is sensitive to direct photons produced with 3.0≦PT≦6 GeV/c and center-of-mass rapidity −0.4≦y*≦1.2. Inclusive cross sections are given for incident π± and protons, and compared with second order QCD predictions; finally an estimation of the gluon structure function of the nucleon is given.

Direct photon production in\(\bar pp\) in collisions at\(\sqrt s = 630\) GeV

AbstractA measurement of the direct production of photons with high transverse momentum fromn

Jet Measures and Hadronic Event Shapes at the {CERN}

bar pp