arXiv subjects

Alexander Söderberg Rousu

Publications and source records attributed to Alexander Söderberg Rousu.

4 recordsLinked to original sources

arXiv2023

Fusion of conformal defects in interacting theories

We study fusion of two scalar Wilson defects. We propose that fusion holds at a quantum level by showing that bare one-point functions stay invariant. This is an expected result as the path integral stays invariant under fusion of the two defects. The difference instead lies in renormalization of local quantities on the defects. Those on the fused defect takes into account UV divergences in the fusion limit when the two defects approach eachother, in addition to UV divergences in the coincident limit of defect-local fields and in the near defect limits of bulk-local fields. At the fixed point of the corresponding RG flow the two conformal defects have fused into a single conformal defect.

hep-th↗

arXiv2023

The O(N)-flavoured replica twist defect

Replica twist defects are of codimension two and enter in quantum information when finding the Rényi entropy. In particular, they generate n replicas of the bulk conformal field theory. We study the monodromy of such defect and learn how a global O(N)-symmetry is broken. By applying the equation of motion to the bulk-defect operator-product expansion we are able to extract the anomalous dimension of defect-local fields.

hep-th↗

arXiv2023

The CW mechanism in a semi-definite system

We study the $ϕ^6 - \hatϕ^4$ model with $O(N)$-symmetry near three dimensions. This model has a sextic bulk-interaction and a quartic boundary-interaction. The bulk two-point correlator is found upto two-loops by solving the equation of motion and applying the boundary conditions. Finally we apply the Coleman-Weinberg mechanism to this model, which allows us to flow along the renormalization group to a first-ordered phase transition. At one-loop order only the boundary receives a non-trivial effective potential, giving the scalar on the boundary a vacuum expecation value. However, due to the boundary operator product expansion, the bulk one-point function is non-zero as well. This leads to a spontaneous symmetry breaking of the original $O(N)$-symmetry.

hep-th↗

arXiv2023

The discontinuity method in a BCFT

We consider a conformal field theory in the presence of a boundary, and explain how two-point correlators of mixed bulk-local operators can be bootstrapped by exploiting the analytical structure of the conformal blocks. This yields the operator product expansion coefficients in either bootstrap channel. We apply this bootstrap technique to an $O(N)$-model in $d = 4 - ε$ dimensions to find the $ϕ- ϕ^5$ bulk correlator and the corresponding operator product expansion coefficients upto $\mathcal{O}(ε)$. Parts of this paper was first presented in my thesis.

hep-th↗