λ\lambda-Deformations in the upper-half plane

Mar 15, 2021
69 pages
Published in:
  • Nucl.Phys.B 968 (2021) 115451
  • Published: Jul, 2021
e-Print:

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Abstract: (Elsevier)
We formulate λ -deformed σ -models as QFTs in the upper-half plane. For different boundary conditions we compute correlation functions of currents and primary operators, exactly in the deformation parameter λ and for large values of the level k of the underlying WZW model. To perform our computations we use either conformal perturbation theory in association with Cardy's doubling trick, as well as meromorphicity arguments and a non-perturbative symmetry in the parameter space (λ,k) , or standard QFT techniques based on the free field expansion of the σ -model action, with the free fields obeying appropriate boundary conditions. Both methods have their own advantages yielding consistent and rich, compared to those in the absence of a boundary, complementary results. We pay particular attention, albeit not exclusively, to integrability preserving boundary conditions.
Note:
  • v1: 45 pages + 24 pages appendices, v2: NPB version
  • operator: primary
  • boundary condition
  • field theory
  • Wess-Zumino-Witten model
  • correlation function
  • perturbation theory
  • nonperturbative
  • integrability
  • deformation
  • conformal