Institutionen för fysik och astronomi

# An integrable Lorentz-breaking deformation of two-dimensional CFTs

2017-11-24

Authors: Monica Guica

Preprint number: UUITP-45/17

It has been recently shown that the deformation of an arbitrary two-dimensional conformal field theory by the composite irrelevant operator  $T \bar T$, built from the components of the stress tensor, is solvable; in particular, the finite-size spectrum of the deformed theory can be obtained from that of the original CFT through a  universal formula. We study a  similarly universal, Lorentz-breaking deformation of  two-dimensional  CFTs that posess a conserved $U(1)$ current, $J$. The deformation takes the schematic form $J \bar T$ and is interesting because it preserves an $SL(2,\mathbb{R}) \times U(1)$ subgroup of the original global conformal symmetries. For the case of a purely (anti)chiral current, we find the finite-size spectrum of the deformed theory and study its thermodynamic properties. We test our predictions in a simple example involving deformed free fermions.