Finn Ravndal

• Ravndal, Finn (2012). Symmetric and conserved energy-momentum tensors in moving media. Europhysics letters. ISSN 0295-5075. 99(5). doi: 10.1209/0295-5075/99/50002.
• Alnes, Håvard; Olaussen, Kåre; Ravndal, Finn; Ravndal, Finn & Wehus, Ingunn Kathrine (2007). Resolution of an apparent inconsistency in the electromagnetic Casimir effect. Journal of Physics A: Mathematical and Theoretical. ISSN 1751-8113. 40, p. F315–F320. doi: 10.1088/1751-8113/40/17/F01.
• Alnes, Håvard; Ravndal, Finn & Wehus, Ingunn Kathrine (2007). Black-body radiation with extra dimensions. Journal of Physics A: Mathematical and Theoretical. ISSN 1751-8113. 40, p. 14309–14316. doi: 10.1088/1751-8113/40/47/018.
• Wehus, Ingunn Kathrine & Ravndal, Finn (2007). Gravity coupled to a scalar field in extra dimensions. Journal of Physics: Conference Series (JPCS). ISSN 1742-6588. 66. doi: 10.1088/1742-6596/66/1/012024.
• Johansen, Nils Voje & Ravndal, Finn (2006). On the discovery of Birkhoff's theorem. General Relativity and Gravitation. ISSN 0001-7701. 38, p. 537–540.
• Alnes, Håvard; Olaussen, Kåre; Ravndal, Finn & Wehus, Ingunn Kathrine (2006). Electromagnetic Casimir energy with extra dimensions. Physical Review D. Particles and fields. ISSN 0556-2821. 74. doi: 10.1103/PhysRevD.74.105017.
• Koivisto, T; Kurki-Suonio, H & Ravndal, Finn (2005). CMB spectrum in Cardassian models. Physical Review D. Particles and fields. ISSN 0556-2821. 71.
• Callin, Petter & Ravndal, Finn (2005). Lagrangian formalism of gravity in the Randall-Sundrum model. Physical Review D. Particles and fields. ISSN 0556-2821. 72. doi: 10.1103/PhysRevD.72.064026.
• Wehus, Ingunn Kathrine & Ravndal, Finn (2004). Dynamics of the scalar field in 5-dimensional Kaluza-Klein theory. International Journal of Modern Physics A. ISSN 0217-751X. 19(27), p. 4671–4685. doi: 10.1142/S0217751X04020609. Show summary

  Using the language of differential forms, the Kaluza�Klein theory in 4+1 dimensions is derived. This theory unifies electromagnetic and gravitational interactions in four dimensions when the extra space dimension is compactified. Without any ad hoc assumptions about the five-dimensional metric, the theory also contains a scalar field coupled to the other fields. By a conformal transformation the theory is transformed from the Jordan frame to the Einstein frame where the physical content is more manifest. Including a cosmological constant in the five-dimensional formulation, it is seen to result in an exponential potential for the scalar field in four dimensions. A similar potential is also found from the Casimir energy in the compact dimension. The resulting scalar field dynamics mimics realistic models recently proposed for cosmological quintessence.

• Callin, Petter & Ravndal, Finn (2004). Higher order corrections to the Newtonian potential in the Randall-Sundrum model. Physical Review D. Particles and fields. ISSN 0556-2821. 70. Show summary

  The general formalism for calculating the Newtonian potential in fine-tuned or critical Randall-Sundrum braneworlds is outlined. It is based on using the full tensor structure of the graviton propagator. This approach avoids the brane-bending effect arising from calculating the potential for a point source. For a single brane, this gives a clear understanding of the disputed overall factor 4/3 entering the correction. The result can be written on a compact form which is evaluated to high accuracy for both short and large distances.

• Tor, Haugset; Haugerud, Hårek & Ravndal, Finn (1998). Thermodynamics of a weakly interacting Bose–Einstein gas. Annals of Physics. ISSN 0003-4916. 266(1), p. 27–62. doi: 10.1006/aphy.1998.5795.
• Haugerud, Hårek; Tor, Haugset & Ravndal, Finn (1997). A more accurate analysis of Bose-Einstein condensation in harmonic traps. Physics Letters A. ISSN 0375-9601. 225(1-3), p. 18–22. doi: 10.1016/S0375-9601(96)08842-1. Show summary

  Using the Euler-Maclaurin summation we calculate analytically the internal energy for non-interacting bosons confined within a harmonic oscillator potential. The specific heat shows a sharp λ-like peak indicating a condensation into the ground state at a well-defined transition temperature. Full agreement is obtained with direct numerical calculation of the same quantities. When the number of trapped particles is very large and at temperatures near and above the transition temperature, the results also agree with previous approximate calculations. At extremely low temperatures both the specific heat and the number of particles excited from the condensate are exponentially suppressed.

• Haugerud, Hårek & Ravndal, Finn (1995). The two‐dimensional harmonic oscillator at finite temperature and nonzero chemical potential. American Journal of Physics (AJP). ISSN 0002-9505. 63(9), p. 839–844. doi: 10.1119/1.17809.
• Haugerud, Hårek; Ravndal, Finn & Uimin, Gennadi (1993). Interacting holes in CuO cyclic chains. Journal of Physics: Condensed Matter. ISSN 0953-8984. 5(37).
• Haugerud, Hårek & Ravndal, Finn (1990). Finite-temperature Gaussian effective potential from a variational principle. Physical Review D. ISSN 1550-7998. 43, p. 2736–2738. doi: 10.1103/PhysRevD.43.2736. Show summary

  Writing the partition function for a scalar quantum field theory as a functional integral, it follows that the finite-temperature Gaussian effective potential is an upper limit to the free energy of the system. Explicit results are given for the anharmonic oscillator at finite temperature.

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• Ravndal, Finn (2014). How i got to work with Feynman on the covariant quark model. International Journal of Modern Physics A. ISSN 0217-751X. 30:1530009. doi: 10.1142/S0217751X15300094.
• Ravndal, Finn (2009). Comment on "Casimir energies: Temperature dependence, dispersion, and anomalies". Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. ISSN 1539-3755. 79(5). doi: 10.1103/PhysRevE.79.053101.
• Ravndal, Finn & Kong, Xinwei (2000). Proton-proton fusion in effective field theory. nucl-th/0004038. Show summary

  Raten for proton-proton fusion beregnet ved bruk av effektiv feltteori inkludert foerste ordens korreksjoner

• Ravndal, Finn (2000). Problems with the Casimir Vacuum Energy. Show summary

  Beregning av staraalingskorreksjoner til Casimir-energien ved bruk av effektiv feltteori

• Ravndal, Finn (1999). Corrections to the Pionium Lifetime. Show summary

  Beregning av relativistisk korreksjon til levetiden for pionium ved bruk av effektiv kvantefeltteori.

• Wehus, Ingunn Kathrine & Ravndal, Finn (2006). Dark energy from scalar fields and conformal invariance in extra dimensions. Unipub forlag.
• Alnes, Håvard & Ravndal, Finn (2006). An inhomogeneous alternative to dark energy. Unipub forlag.
• Callin, Petter & Ravndal, Finn (2006). Gravitational effects from extra dimensions. Unipub forlag.

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