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B physics at the Z sup 0 pole
No full textThe SLC has been running at SLAC since April, and more than 100 Z{sup 0} events have been reconstructed. Shortly the new European facility at CERN-LEP-will also turn on, and by the end of the year we anticipate that more than 10,000 Z{sup 0} events will have been registered by each of the four LEP detectors. Most of the experimental facilities at these two machines are equipped with excellent particle tracking and identification. Some have close-in tracking devices which will provide unparalleled precision in trajectory reconstruction, and lead to the possibility of identifying a large proportion of the charmed and beauty particles. Not only does the Z{sup 0} pole offer a relatively large production cross section for e{sup +}e{sup {minus}} machines, but a large proportion of the events are b{bar b} pairs. One sees from this figure that a gain of six or more is obtained from running at the Z{sup 0}. An SLC producing 10{sup 5} events per year yields 20,000 b{bar b} events. Similarly, for LEP, over 200,000 b{bar b} events will become available per year. In addition, the planned upgrade for LEP will increase its luminosity by about an order of magnitude, and the SLC will run with polarized electron beams. The physics that may be studies from these event samples fall into two general categories: tests of the Standard Model; and studies of B mesons and B baryons, including lifetimes, mixing, spectroscopy, and CP violation. 8 refs., 8 figs., 1 tab
Charles-Louis de Secondat, baron de La Brède et de Montesquieu : Gravure de B. L. Henriquet, XVIIIe siècle
No full textMontesquieu (1689-1755) est l'auteur des Lettres persanes et de L'esprit des lois. On doit tenir compte de l'infinie variété des climats et des mours, mais la tyrannie est à condamner sous tous les cieux et l'idée de justice est commune à tous les hommes. "Je suis nécessairement homme et je ne suis Français que par hasard."téléchargeabl
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