Excitations in a Bose-Condensed Liquid Book

	Preface
1	Theory of excitations in superfluid [superscript 4]He: an introduction	1
1.1	Landau-Feynman picture	3
1.2	Role of the Bose condensate and field-theoretic analysis	14
1.3	Outline of book	20
2	Dynamic response of Helium atoms to thermal neutrons	25
2.1	Response functions: general properties and sum rules	25
2.2	Density fluctuation spectrum of superfluid [superscript 4]He	31
2.3	High momentum transfer and the impulse approximation	39
3	Bose broken symmetry and its implications	47
3.1	Bose broken symmetry in a liquid	49
3.2	Single-particle Green's functions for a Bose-condensed fluid	53
3.3	S(Q,[omega]) in the Bogoliubov approximation	61
3.4	Mean-field analysis	64
4	High-momentum scattering and the condensate fraction	67
4.1	Condensate-induced changes in the momentum distribution	69
4.2	Impulse approximation using a Green's function formulation	75
4.3	Measurement of the atomic momentum distribution	77
4.4	Extraction of the condensate fraction	86
5	Dielectric formalism for a Bose fluid	92
5.1	Dielectric formalism	93
5.2	RPA or zero-loop approximation	105
5.3	One-loop approximation for regular quantities	112
5.4	Gavoret-Nozieres analysis	116
5.5	The collective vs. single-particle scenarios	123
6	Response functions in the low-frequency, long-wavelength limit	127
6.1	Zero-frequency sum rules and the normal fluid density	128
6.2	Hydrodynamic (two-fluid) limit	132
6.3	The nature of phonons in Bose fluids	141
7	Phonons, maxons and rotons	153
7.1	S(Q,[omega]): neutron-scattering data	154
7.2	S(Q,[omega]): theoretical interpretation	177
8	Sum-rule analysis of the different contributions to S(Q,[omega])	195
8.1	The Wagner-Wong-Gould f-sum rules	195
8.2	Woods-Svensson two-fluid ansatz for S(Q, [omega])	200
8.3	Superfluid and normal fluid f-sum rules	203
9	Variational and parameterized approaches	208
9.1	Variational theories in coordinate space	209
9.2	Polarization potential theory	218
9.3	Memory function formalism	225
10	Two-particle spectrum in Bose-condensed fluids	231
10.1	Two-particle Green's function	232
10.2	Evidence for the two-excitation spectrum in neutron scattering	239
10.3	Raman scattering from superfluid [supercript 4]He	249
11	Relation between excitations in liquid and solid [supercript 4]He	257
11.1	Phonons as poles of the displacement correlation function	258
11.2	Phonons vs. density fluctuations in solid [supercript 4]He	263
11.3	Relation between S(Q,[omega]) in superfluid and solid [supercript 4]He	266
12	The new picture: some unsolved problems	270
12.1	Comments on the development of the new picture	270
12.2	Dielectric formalism for superfluid [superscript 3]He-[superscript 4]He mixtures	277
12.3	Suggestions for future research	282
	References	285
	Author index	295
	Subject index	299