From hard thermal loops to Langevin dynamics

May, 1999
45 pages
Published in:
  • Nucl.Phys.B 559 (1999) 502-538
e-Print:
Report number:
  • NBI-HE-99-13

Citations per year

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Abstract:
In hot non-Abelian gauge theories, processes characterized by the momentum scale g2Tg^2 T (such as electroweak baryon number violation in the very early universe) are non-perturbative. An effective theory for the soft (pg2T|\vec{p}|\sim g^2 T) field modes is obtained by integrating out momenta larger than g2Tg^2 T. Starting from the hard thermal loop effective theory, which is the result of integrating out the scale TT, it is shown how to integrate out the scale gTgT in an expansion in the gauge coupling gg. At leading order in gg, one obtains Vlasov-Boltzmann equations for the soft field modes, which contain a Gaussian noise and a collision term. The 2-point function of the noise and the collision term are explicitly calculated in a leading logarithmic approximation. In this approximation the Boltzmann equation is solved. The resulting effective theory for the soft field modes is described by a Langevin equation. It determines the parametric form of the hot baryon number violation rate as Γ=κg10log(1/g)T4\Gamma = \kappa g^{10} \log(1/g) T^4, and it allows for a calculation of κ\kappa on the lattice.
Note:
  • 42 pages, 2 figures, uses elsart.sty; explanatory paragraph added to the introduction, 4 references added, a few quotations added; to appear in Nucl. Phys. B Report-no: NBI-HE-99-13
  • 11.10.Wx
  • 11.15.Kc
  • 11.30.Fs
  • Finite temperature
  • Gauge theory
  • Non-Abelian
  • Real time
  • Non-perturbative
  • Hot sphaleron rate
  • Lattice