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Clock shifts in a Fermi gas interacting with a minority component: A soluble model

Bruun, Georg LU ; Pethick, C. J. and Yu, Zhenhua (2010) In Physical Review A (Atomic, Molecular and Optical Physics) 81(3).
Abstract
We consider the absorption spectrum of a Fermi gas mixed with a minority species when majority fermions are transferred to another internal state by an external probe. In the limit when the minority species is much more massive than the majority one, we show that the minority species may be treated as static impurities and the problem can be solved in closed form. The analytical results bring out the importance of vertex corrections, which change qualitatively the nature of the absorption spectrum. It is demonstrated that large line shifts are not associated with resonant interactions in general. We also show that the commonly used ladder approximation fails when the majority component is degenerate for large mass ratios between the... (More)
We consider the absorption spectrum of a Fermi gas mixed with a minority species when majority fermions are transferred to another internal state by an external probe. In the limit when the minority species is much more massive than the majority one, we show that the minority species may be treated as static impurities and the problem can be solved in closed form. The analytical results bring out the importance of vertex corrections, which change qualitatively the nature of the absorption spectrum. It is demonstrated that large line shifts are not associated with resonant interactions in general. We also show that the commonly used ladder approximation fails when the majority component is degenerate for large mass ratios between the minority and majority species and that bubble diagrams, which correspond to the creation of many particle-hole pairs, must be taken into account. We carry out detailed numerical calculations, which confirm the analytical insights, and we point out the connection to shadowing phenomena in nuclear physics. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review A (Atomic, Molecular and Optical Physics)
volume
81
issue
3
publisher
American Physical Society (APS)
external identifiers
  • wos:000276262500170
  • scopus:77949760379
ISSN
1050-2947
DOI
10.1103/PhysRevA.81.033621
language
English
LU publication?
yes
id
c7ca3d2a-c007-40a5-a6d0-2010ed6139eb (old id 1586926)
date added to LUP
2010-04-27 12:21:00
date last changed
2018-05-29 10:48:06
@article{c7ca3d2a-c007-40a5-a6d0-2010ed6139eb,
  abstract     = {We consider the absorption spectrum of a Fermi gas mixed with a minority species when majority fermions are transferred to another internal state by an external probe. In the limit when the minority species is much more massive than the majority one, we show that the minority species may be treated as static impurities and the problem can be solved in closed form. The analytical results bring out the importance of vertex corrections, which change qualitatively the nature of the absorption spectrum. It is demonstrated that large line shifts are not associated with resonant interactions in general. We also show that the commonly used ladder approximation fails when the majority component is degenerate for large mass ratios between the minority and majority species and that bubble diagrams, which correspond to the creation of many particle-hole pairs, must be taken into account. We carry out detailed numerical calculations, which confirm the analytical insights, and we point out the connection to shadowing phenomena in nuclear physics.},
  articleno    = {033621},
  author       = {Bruun, Georg and Pethick, C. J. and Yu, Zhenhua},
  issn         = {1050-2947},
  language     = {eng},
  number       = {3},
  publisher    = {American Physical Society (APS)},
  series       = {Physical Review A (Atomic, Molecular and Optical Physics)},
  title        = {Clock shifts in a Fermi gas interacting with a minority component: A soluble model},
  url          = {http://dx.doi.org/10.1103/PhysRevA.81.033621},
  volume       = {81},
  year         = {2010},
}