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Dispersive Techniques for $α_s$, $R_{had}$ and Instability of the Perturbative Vacuum

Y. Srivastava·S. Pacetti·G. Pancheri·A. Widom
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Abstract

Recent dispersive techniques developed by us are applied to discuss three problems: 1. A long standing discrepan-cy between the measurements of $R(s)$ for $\sqrt{s} = (5÷7.5)GeV$ by Crystal Ball and MARK I has been analyzed and its consequences analyzed for the number of contributing quarks. 2. Noting that the perturbative $α_s$ has the wrong analyticity, analytic models consistent with asymptotic freedom (AF) and confinement have been constructed and applied to discuss $τ$ decay. 3. It is shown that AF leads to a wrong sign for $\im\big(α(s)\big)$ which signals an instability of the perturbative QCD vacuum.

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Y. Srivastava, S. Pacetti, G. Pancheri, A. Widom. 2001-06-29. Dispersive Techniques for $α_s$, $R_{had}$ and Instability of the Perturbative Vacuum. https://arxiv.org/abs/hep-ph/0106005

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