Meson theory of nuclear forces

Wolfgang Pauli

The institute for advanced study, Princeton, New Jersey, and federal polytechnicum Zurich, Switzerland.

Second edition 1948

Interscience publishers, Inc. New York

Interscience publishers, Ltd. London

Copy right, 1946, 1948, by Interscience publishers, Inc. 215 Fourth Avenue, New York 3,N.Y

Printed in the United States of America by Mack Printing Company, Easton, Pa

First Edition, 1946

Second Edition, 1948

All right reserved

This book or any part thereof must not be reproduced in any form without permission of the publisher in writing.

This applies specifically to photostatic and microfilm reproductions.

Preface to the second edition

Since the publication of the last edition some of the older experiments( particularly those on angular distribution

In proton-neutron scattering ) have been rendered absolved by more recent work. In addition, some consequences of the strong coupling theory have been clarified. In this respect, improvements have been introduced into the text.

On the other hand , the provisional state of meson theory has become still more obvious as a result of the experimental discovery of at least two kinds of mesons by C.F.Powell and G.P.S.Occhialini, and by the absence of negative meson capture by the lighter nuclei by M.Conversi , E.Pancini, and O.Piccioni. In view of the failure of all present theories in explaining there new facts, the author saw no possibility of making an essential improvement in the substance of this book. But the recent success of C.M.G.Lattes and E.Dardner in producing meson artificially will presumably bring forth a great change of the whole situation in the near future.

Zurich, Switzerland

June, 1948

Wolfgang Pauli

Preface to the First Edition

The purpose of this volume is to make accessible to a larger number of readers the lectures which I gave in the autumn of 1944 at the Massachusetts Institute of Technology. Without pretending to contain anything essentially new, they may serve to give to students and research workers a first orientation in the more recent literature on the theory of the interaction of mesons with protons and neutrons( nucleons ) and the interactions between nucleons derived from it. Despite the imperfections of my lectures, the original notes written by Dr. J.F.Carlson and Dr. A.J.F.Siegert have been amended only slightly , to preserve the informed character of the lectures and to emphasize the very provisional state of the problems in question, to which new experiments may in the future make important contributions . Special thanks are extended to Dr. S.T.Ma for reading and checking the proofs.

Princeton, New Jersey

February, 1946

Wolfgang Pauli

Contents

Preface

Chapter I

Various Types of Meson Fields

Scalar Charged Meson Field

Pseudoscalar Symmetric Theory

Vector-Fields Theory

Chapter II

Theory of Extended Source

Chapter III

Scattering of Mesons

Magnetic Moment in the Strong Coupling Case

Magnetic Moment in the Weak Coupling Case

Chapter IV

Quantum Theory of Scattering

Theory of Radiation Damping

Heisenberg’s “ Observable Quantities ”

Proof that S in Unitary

Chapter V

Theory of Neutron-Proton Scattering

Chapter VI

Strong Coupling Theory of the Two-Nucleon System

Concluding Remarks

Appendix

Chapter　I

　The meson theory of nuclear forces has been developed in analogy to the theory of the Coulomb force, which arise from the interaction of charged particles with the electromagnetic field. The short range of the nuclear forces is obtained by letting the particles corresponding to the photons have a rest mass ^⑴,the range of forces arising from a field of particles of rest mass μ being ｈ/μc. From experiments on scattering of neutrons by proton the range of nuclear forces is known to be ～ 2 x 10 ⁻¹³ cm, which leads to a rest mass ～ 200 electron masses. Charged particles of this rest mass have subsequently been discovered in cosmic rays.

Another difference between the meson field and the electromagnetic field lies in the fact that mesons have charge and spin.

The main experimental data to be explained by the meson theory of nuclear forces are:

(a) the binding energy of the deuteron : E₀ = 2.17 Mev,

(b) the cross section for neutron-proton scattering : σ = ( 21 ± 0.7 ) x 10⁻²⁴ cm²

(c) the quadruple moment of the deuteron : Q = 2.73 x 10⁻²⁷ cm²

(d) the analysis of the proton-proton scattering shows that in the singlet state the interaction energy of two protons is, in very good approximation, the same as that between a proton and a neutron.