Abstract
The first part of this paper is devoted to investigating the static response functions of superfluid helium in the hydrodynamic region which results in obtaining a new sum rule. Sum rules are then specialized to zero temperature and exploited to determine matrix elements of the particle creation and annihilation operators between the ground state and the one quasiparticle state in the long wavelength limit. We examine the particle distribution function and besides calculating the leading term, we are able to give a lower limit to the next one in the expansion for small wave numbers.
Резюме
Первая часть данной работы посвящена исследованию функций статической реакции сверхтекучего ге лия в гидродинамической области, которое результирует в выходе новое правило сумм. Правила сумм затем специализированы к нулевой температуре и использованы при определении матричных элементов операторов рождения и уничтожения частиц между основным и одним квазичастичным состоянием в пределе большой длины волны. Проводилось исследование функции распределения частиц и кроме вычисления начального члена, удалось определить низшую границу следующего члена в выражении для маленьких волновых чисел.
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References
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Dedicated to Prof.P. Gombás on his 60th birthday.
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Szépfalusy, P. Sum rules and their application in the theory of superfluid helium. Acta Physica 27, 299–307 (1969). https://doi.org/10.1007/BF03156754
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DOI: https://doi.org/10.1007/BF03156754