23,196 research outputs found

    From Sakata Model to Goldberg-Ne'eman Quarks and Nambu QCD Phenomenology and "Right" and "Wrong" experiments

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    The basic theoretical milestones were the Sakata SU(3) symmetry, the Goldberg-Ne'eman composite model with SU(3) triplets having baryon number (1/3) and the Nambu color gauge Lagrangian. The transition was led in right and wrong directions by experiments interpreted by phenomenology. A "good" experiment on pˉp\bar p p annihilation at rest showed that the Sakata model predictions disagreed with experiment. A "bad" experiment prevented the use of the Goldberg-Ne'eman triplet model to predict the existence and masses of the of the Ξ\Xi^* and Ω\Omega^-. More "good" experiments revealed the existence and mass of the Ξ\Xi^* and the Ω\Omega^- and the absence of positive strangeness baryon resonances, thus confirming the "tenfold way". Further "good experiments" revealed the existence of the vector meson nonet, SU(3) breaking with singlet-octet mixing and the suppression of the ϕρπ\phi \to \rho \pi decay. These led to the quark triplet model. The paradox of peculiar statistics then arose as the Δ++\Delta^{++} and Ω\Omega^- contained three identical spin-1/2 fermions coupled symmetrically to spin (3/2). This led to color and the Nambu QCD. The book "Lie Groups for Pedestrians" used the Sakata model with the name "sakaton" for the pnΛpn\Lambda triplet to teach the algebra of SU(3) to particle physicists in the U.S. and Europe who knew no group theory. The Sakata model had a renaissance in hypernuclear physics in the 1970's.Comment: 8 page

    The Problem of Personal Income Tax Avoidance

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    Reconnecting Young Black Men: What Policies Would Help?

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    The term "disconnected youth" refers to young people who have been out of school and out of work for considerable periods of time – like a year or more. They are not temporarily "idle" but are fully disconnected from the mainstream worlds of schooling and work. They may be incarcerated or on parole or probation; they might be aging out of foster care or still attached to their nuclear families. But, overwhelmingly, they come from low-income families and often grow up in poor and relatively segregated neighborhoods. Of all racial and gender groups, young black men are by far the most likely to become "disconnected" from school and work. In the year 2000 – when the labor market was very tight – over 17 percent of all young black men between the ages of 16 and 24 were disconnected, while the comparable percentages for other race/gender groups were much lower. Indeed, this figure implies that one out of every six young black men was disconnected from both school and work at that time
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