Levinson's theorem and a bound state of a positron in electron gas

T. Taipaleenmäki, F. V. Kusmartsev, M. Saarela

Research output: Contribution to journalConference articlepeer-review


Positrons embedded in metals annihilate predominantly with conduction electrons. The annihilation rate reduces with decreasing density for the whole range of metallic densities. Controversial suggestions have been made on the annihilation rates at very low electron gas densities. We calculate the effective screened interaction between the positron impurity and electrons within a simplified jellium model where the electrons are treated as bosonic particles and show that the electrons attracted to the positron can form a bound cluster. The resonance states of the effective interaction are analysed by calculating the scattering phase-shifts. We find that the maximum of the phase-shift at zero energy approaches to π when rs ≈ 14. According to the Levinson's theorem this indicates a bound state.

Original languageBritish English
Pages (from-to)348-349
Number of pages2
JournalPhysica E: Low-Dimensional Systems and Nanostructures
Issue number1-3
StatePublished - May 2003
Event23rd International Conference on Low Temperature Physics - Hiroshima, Japan
Duration: 20 Aug 200227 Aug 2002


  • Bound state
  • Jastrow theory
  • Levinson's theorem
  • Positron impurity


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