![]() ![]() ![]() Zichichi, “Search for the timelike structure of the proton,” Physics Letters 5 (1963) 195. Zichichi, “A large-acceptance and high-efficiency neutron detector for missing-mass studies,” Nuovo Cimento 61A (1969) 125. Zichichi, “Range measurements for muons in the GeV region,” Nuovo Cimento 35 (1965) 759.ĭ. Zichichi, “Range measurements for muons in the GeV region,” CERN Report 64–31, 24 June 1964.Ī. ![]() Zichichi “A large electromagnetic shower detector with high rejection power against pions,” Nuclear Instruments and Methods 101 (1972) 433.Ī. à haute rejection des pions,” Revue de Physique Appliquée 4 (1969) 108. Zichichi, “A new electron detector with high rejection power against pions,” Nuovo Cimento 39 (1965) 464.ĭ. Zichichi, “A telescope to identify electrons in the presence of pion background,” CERN 63–25, 27 June 1963. Zichichi, “Measurement of the anomalous magnetic moment of the muon,” Physical Review Letters 6 (1961) 128. Zichichi., “A proposal to search for leptonic quarks and heavy leptons produced by ADONE,” INFN/AE-67/3, 20 March 1967. Perl et al., “Evidence for Anomalous Lepton Production in e +-e - Annihilation,” Physical Review Letters, 35 (1975) 1489. This process is experimental and the keywords may be updated as the learning algorithm improves. These keywords were added by machine and not by the authors. These original contributions started in 1960 at CERN with the construction of the first large solid-angle detector able to simultaneously detect electrons and muons with high rejection power against pions, thus allowing, already in 1964, to establish the validity of the (ℯ ± μ ∓) method as the best one to detect Heavy Lepton pair production. These contributions include: i) the idea of a new lepton in the GeV mass range, carrying its own leptonic number ii) the search for the best production process: ℯ +ℯ -→ HL + HL - iii) the invention of the acoplanar (ℯ ± μ ∓) method with the associated technology and the proof that it works iv) the implementation of the large solid-angle detector needed to establish the first upper limit on the HL mass at Frascati v) the promotion of the HL searches at energies higher than ADONE. arXiv: 2212.The original contributions of the Bologna-CERN-Frascati (BCF) group to the discovery - via the acoplanar (ℯ ± μ ∓) method - of the Heavy Lepton ( HL, now called τ) are described. Measurement of lepton universality parameters in B +→K +ℓ +ℓ − and B 0→K *0ℓ +ℓ − decays. Test of lepton universality in b→sℓ +ℓ − decays. “These results are compatible with the expectation of our theory.” “The results shown today are the product of a comprehensive study of the two main modes using our full data sample and applying new, more robust techniques.” “Measurements of the ratios of rare B-meson decays to electrons and muons have generated much interest in recent years because they are theoretically ‘clean’ and show consistency with a pattern of anomalies seen in other flavor processes,” said LHCb Collaboration spokesperson Professor Chris Parkes, a physicist at the University of Manchester and CERN. The results, which supersede previous comparisons, are in excellent agreement with the principle of lepton flavor universality. In addition, the two decay modes are measured in two different mass regions, thus yielding four independent comparisons of the decays. It considers two different B-meson decay modes simultaneously for the first time and provides better control of the background processes that can mimic the decays of B-mesons to electrons. The new LHCb analysis, which has been ongoing for the past five years, is more comprehensive. Interest in the ‘flavor anomalies’ peaked in March 2021, when LHCb presented new results comparing the rates at which certain B mesons, composite particles that contain beauty quarks, decay into muons and electrons.Īccording to the theory, decays involving muons and electrons should occur at the same rate, once differences in the leptons’ masses are accounted for.īut the LHCb results hinted that B mesons decay into muons at a lower rate than predicted, as indicated by the results’ statistical significance of 3.1 standard deviations from the Standard Model prediction. In recent years, however, an accumulation of results from LHCb and experiments in Japan and the United States have suggested that this might not be the case, generating cautious excitement among physicists that a more fundamental theory - perhaps one that sheds light on the Standard Model’s mysterious flavor structure - might reveal itself at the LHC. Lepton flavor universality states that the fundamental forces are blind to the generation to which a lepton belongs. Image credit: CERN.Ī central mystery of particle physics is why the 12 elementary quarks and leptons are arranged in pairs across three generations that are identical in all but mass, with ordinary matter comprising particles from the first, lightest generation. ![]()
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