A1πγ vertex and pion scattering lengths from current algebra and Veneziano representation

1971 ◽  
Vol 4 (3) ◽  
pp. 575-587
Author(s):  
R. Acharya ◽  
L. Brink ◽  
R. P. Saxena
Keyword(s):  
Current Algebra ◽  
Pion Scattering ◽  
Scattering Lengths

scholarly journals Relative entropy in scattering and the S-matrix bootstrap

2020 ◽  
Vol 9 (5) ◽  
Author(s):  
Anjishnu Bose ◽  
Parthiv Haldar ◽  
Aninda Sinha ◽  
Pritish Sinha ◽  
Shaswat Tiwari
Keyword(s):  
Relative Entropy ◽  
Cross Sections ◽  
High Energy ◽  
Quantum Field Theories ◽  
Superstring Theory ◽  
Information Theoretic ◽  
Pion Scattering ◽  
S Matrix ◽  
Information Theoretic Measures ◽  
Scattering Lengths

We consider entanglement measures in 2-2 scattering in quantum field theories, focusing on relative entropy which distinguishes two different density matrices. Relative entropy is investigated in several cases which include \phi^4ϕ4 theory, chiral perturbation theory (\chi PTχPT) describing pion scattering and dilaton scattering in type II superstring theory. We derive a high energy bound on the relative entropy using known bounds on the elastic differential cross-sections in massive QFTs. In \chi PTχPT, relative entropy close to threshold has simple expressions in terms of ratios of scattering lengths. Definite sign properties are found for the relative entropy which are over and above the usual positivity of relative entropy in certain cases. We then turn to the recent numerical investigations of the S-matrix bootstrap in the context of pion scattering. By imposing these sign constraints and the \rhoρ resonance, we find restrictions on the allowed S-matrices. By performing hypothesis testing using relative entropy, we isolate two sets of S-matrices living on the boundary which give scattering lengths comparable to experiments but one of which is far from the 1-loop \chi PTχPT Adler zeros. We perform a preliminary analysis to constrain the allowed space further, using ideas involving positivity inside the extended Mandelstam region, and other quantum information theoretic measures based on entanglement in isospin.

On low-energy pion-pion scattering lengths

1969 ◽  
Vol 62 (1) ◽  
pp. 192-198
Author(s):  
C. S. Lai
Keyword(s):  
Low Energy ◽  
Pion Scattering ◽  
Scattering Lengths

scholarly journals Lattice QCD calculation of full pion scattering lengths

1993 ◽  
Vol 71 (15) ◽  
pp. 2387-2390 ◽  
Author(s):  
Y. Kuramashi ◽  
M. Fukugita ◽  
H. Mino ◽  
M. Okawa ◽  
A. Ukawa
Keyword(s):  
Lattice Qcd ◽  
Pion Scattering ◽  
Scattering Lengths
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