Measurement of scattering lengths using Kπ3 decay
Date
2000-01-01
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Journal ISSN
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ORCID
Type
Degree Level
Doctoral
Abstract
The determination of N-N and π π scattering lengths is of fundamental importance in the studies of hadron dynamics. A direct measurement of π π scattering lengths is impossible due to a lack of processes with just two pions in both the initial and final state. Therefore indirect methods must be used. In the past, π N → π π N and Kₑ₄ decay[1] have been employed. These analyses are complicated due to problems of (a) extrapolation to threshold, (b) contribution of higher multipoles, and (c) inelasticity effects. In this thesis we present a novel analysis of stopped K+π3 decays (K+→ π+π 0 π 0) to deduce the scattering lengths ( a00 and a20 ) in a nearly model independent way. The model of Sawyer and Wali[2], incorporating Chew and Mandelstam's[3] result for π π scattering, was used to analyze the data. The data is a kinematically complete determination of Kp3 decays, a byproduct of the T-violation experiment at KEK[4]. It is fit to an amplitude
At' s1,s2,s3 =-λ 2λπ 2λπ+12 t20s1 +t20 s2+13t0 0s3-t 20s3 0.1
where λ, λπ are the Kπ → π π and π π → π π coupling constants, 'si' are the center of mass energies of pion pairs and, tI (I = 0, 2) is the S wave scattering amplitude for isospin I given by the Roy equation: tI(s)=√s-4m2 eiδ(s) sin δ(s). Here δ(s) is phase shift which depends on the scattering length α. We deduce π+π⁰ (π⁰π⁰ ) scattering lengths to be α00 = 0.199 ± 0.003(stat) ± 0.002(syst) and α20 = -0.0285 ± 0.0008 stat+0.0012 -0.0007 (syst). This also is the first experimental determination of Weinberg's universal curve[5] W=2α20-5α2 0=0.540±0.007stat +0.005-0.007syst.
Description
Keywords
Kð3 decay, hadron dynamics, physics, ðð scattering
Citation
Degree
Doctor of Philosophy (Ph.D.)
Department
Physics and Engineering Physics
Program
Physics and Engineering Physics