Fabrizio Fabbri

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The perturbative QCD approach to multiparticle production predicts a characteristic suppression of particle multiplicity in a heavy quark jet as compared to a light quark jet. In the Modified Leading Logarithmic Approximation (MLLA) the multiplicity difference δQl between heavy and light quark jets is derived in terms of a few other experimentally measured(More)
February 2006 | Volume 3 | Issue 2 | e43 The term “globalization” was popularized by Marshall McLuhan in War and Peace in the Global Village . In the book, McLuhan described how the global media shaped current events surrounding the Vietnam War [1] and also predicted how modern information and communication technologies would accelerate world progress(More)
Bose-Einstein Correlations (BEC) of three identical charged pions were studied in 4× 106 hadronic Z0 decays recorded with the OPAL detector at LEP. The genuine three-pion correlations, corrected for the Coulomb effect, were separated from the known two-pion correlations by a new subtraction procedure. A significant genuine three-pion BEC enhancement near(More)
A search for pair produced scalar fermions with couplings that violate R-parity has been performed using a data sample corresponding to an integrated luminosity of 56 pb at a centre-of-mass energy of √ s = 183 GeV collected with the OPAL detector at LEP. An important consequence of R-parity breaking interactions is that the lightest supersymmetric particle(More)
Production of events with hadronic and leptonic final states has been measured in e+e− collisions at centre-of-mass energies of 130–172 GeV, using the OPAL detector at LEP. Cross-sections and leptonic forward-backward asymmetries are presented, both including and excluding the dominant production of radiative Zγ events, and compared to Standard Model(More)
G. Abbiendi, C. Ainsley, P. F. Åkesson, G. Alexander, J. Allison, P. Amaral, G. Anagnostou, K. J. Anderson, S. Asai, D. Axen, G. Azuelos, I. Bailey, E. Barberio, T. Barillari, R. J. Barlow, R. J. Batley, P. Bechtle, T. Behnke, K. W. Bell, P. J. Bell, G. Bella, A. Bellerive, G. Benelli, S. Bethke, O. Biebel, O. Boeriu, P. Bock, M. Boutemeur, S. Braibant, L.(More)
New measurements are presented of the photon structure function F 2 (x; Q 2) at four values of Q 2 between 9 and 59 GeV 2 based on data collected with the OPAL detector at centre-of-mass energies of 161?172 GeV, with a total integrated luminosity of 18.1 pb ?1. The evolution of F 2 with Q 2 in bins of x is determined in the Q 2 range from 1.86 to 135 GeV 2(More)
Gluon jets are identified in ee hadronic annihilation events by tagging two quark jets in the same hemisphere of an event. The gluon jet is defined inclusively as all the particles in the opposite hemisphere. Gluon jets defined in this manner have a close correspondence to gluon jets as they are defined for analytic calculations, and are almost independent(More)
A search for decays of the Bc meson was performed using data collected from 1990–1995 with the OPAL detector on or near the Z peak at LEP. The decay channels B+c → J/ψπ , B+c → J/ψa + 1 and B+c → J/ψl ν were investigated, where l denotes an electron or a muon. Two candidates are observed in the mode B+c → J/ψπ , with an estimated background of (0.63± 0.20)(More)
Searches for a scalar top quark and a scalar bottom quark have been performed using a data sample of 438 pb−1 at centreof-mass energies of √ s = 192–209 GeV collected with the OPAL detector at LEP. No evidence for a signal was found. The 95% confidence level lower limit on the scalar top quark mass is 97.6 GeV if the mixing angle between the supersymmetric(More)