Abstract

Assuming that the pion-pion scattering amplitude and its absorptive part are analytic inside an ellipse in $t$- plane with foci $t=0$, $u=0$ and right extremity $t=4 m_{\pi}^2 +\epsilon $, ($\epsilon > 0$), except for cuts prescribed by Mandelstam representation for $t\geq 4 m_{\pi}^2$, $u\geq 4 m_{\pi}^2$ , and bounded by $s^N$ on the boundary of this domain, we prove that for $s\rightarrow \infty$, \sigma_{inel} (s) > \frac{Const}{s^{5/2} }\exp {[-\frac{\sqrt{s}}{4} (N+5/2) \ln {s} ]}.

Highlights

  • It is well known that if there is no inelasticity, the scattering amplitude must be zero

  • Assuming that the pion-pion scattering amplitude and its absorptive part are analytic inside an ellipse in the complex t plane with foci t 1⁄4 0, u 1⁄4 0 and right extremity t 1⁄4 4m2π þ ε, (ε > 0)—except for cuts prescribed by the Mandelstam representation for t ≥ 4m2π, u ≥ 4pmffi 2π, and bounded by sN on the boundary of this domain—we prove that for s const s5=2 exp

  • Since we shall use the dominance of the nearest singularities for large angular momenta, we state at the same time the assumption he needs and our assumption

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Summary

INTRODUCTION

It is well known that if there is no inelasticity, the scattering amplitude must be zero. If we use the standard Mandelstam variables s, t, u and choose units such that the pion mass mπ 1⁄4 1, we need fixed-energy analyticity in an ellipse with foci at t 1⁄4 0 and u 1⁄4 0 and right extremity at t 1⁄4 4 þ ε, minus the obvious cuts t ≥ 4, u ≥ 4 for the amplitude, and t ≥ 4 þ 64= ðs − 16Þ, u ≥ 4 þ 64=ðs − 16Þ for the absorptive part (see Fig. 1). We seek a lower bound on its imaginary part Imfl, for which we need a bound on the discontinuity of the absorptive part which is nothing but the Mandelstam double spectral function This is what was missing in the work of Dragt [3].

Domain of positivity of the double spectral function and a lower bound
LOWER BOUND ON INELASTICITY
Estimates of f lðsÞ and Imf lðsÞ
LOWER BOUND ON THE DOUBLE SPECTRAL FUNCTION
REAL PIONS OF ISOTOPIC SPIN 1
New results
Upper bound
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