We study the dynamics of entanglement in scaling limit Ising spin chain presence both a longitudinal and transverse field. present analytical results for quench field critical which go beyond current lattice integrability techniques. test these against numerical simulation on corresponding model finding extremely good agreement. show that bound states spectrum theory leads to oscillations entropy suppresses its linear growth time scales accessible simulations. For small quenches, we exactly...

A bstract In this paper we study the non-unitary deformations of two-dimensional Tricritical Ising Model obtained by coupling its two spin ℤ 2 odd operators to imaginary magnetic fields. Varying strengths these fields and adjusting correspondingly constants even fields, establish presence universality classes infrared fixed points on critical surface. The first class corresponds familiar Yang-Lee edge singularity, while second tricritical version. We argue that are controlled conformal...

In the ferromagnetic phase of q-state Potts model, switching on an external magnetic field induces confinement domain wall excitations. For Ising model (q = 2) spectrum consists kink-antikink states which are analogues mesonic in QCD, while for q 3, depending sign field, may also contain three-kink bound baryons. recent years resulting "hadron" was described using several different approaches, such as quantum mechanics confining linear potential, WKB methods and Bethe-Salpeter equation. Here...

Quasinormal modes are characteristic oscillatory that control the relaxation of a perturbed physical system back to its equilibrium state. In this work, we calculate QNM frequencies and angular eigenvalues Kerr--de Sitter black holes using novel method based on conformal field theory. The spin-field perturbation equations background spacetime essentially reduce two Heun's equations, one for radial part part. We use accessory parameter expansion equation, obtained via isomonodromic...

We extend the branch point twist field approach for calculation of entanglement entropies to time-dependent problems in 1+1-dimensional massive quantum theories. focus on simplest example: a mass quench Ising theory from initial $m_0$ final $m$. The main analytical results are obtained perturbative expansion one-point function post-quench quasi-particle basis. expected linear growth R\'enyi at large times $mt\gg 1$ emerges second order. also show that and von Neumann entropies, infinite...

A bstract We study solutions of the Thermodynamic Bethe Ansatz equations for relativistic theories defined by factorizable S -matrix an integrable QFT deformed CDD factors. Such -matrices appear under generalized TTbar deformations special irrelevant operators. The TBA equations, course, determine ground state energy E ( R ) finite-size system, with spatial coordinate compactified on a circle circumference . limit attention to involving just one kind stable particles, and consider trivial...

We study the decay of false vacuum in scaling Ising and tricritical field theories using truncated conformal space approach compare numerical results to theoretical predictions thin wall limit. In case, are consistent with previous studies on quantum spin chain ${\ensuremath{\varphi}}^{4}$ theory; particular, we confirm that while get dependence bubble nucleation rate latent heat right, they off by a model-dependent overall coefficient. The model allows us other hand examine more exotic...

A bstract We study a novel class of Renormalization Group flows which connect multicritical versions the two-dimensional Yang-Lee edge singularity described by conformal minimal models $$ \mathcal{M} <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>M</mml:mi> </mml:math> (2 , 2 n + 3). The absence in these an order parameter implies that towards and between singularities are all related to spontaneous breaking \mathcal{PT} <mml:mi>PT</mml:mi> symmetry comprise pattern space...

A bstract We revisit and extend Fisher’s argument for a Ginzburg-Landau description of multicritical Yang-Lee models in terms single boson Lagrangian with potential φ 2 ( iφ ) n . explicitly study the cases = 1, by Truncated Hamiltonian Approach based on free massive perturbed PT symmetric deformations, providing clear evidence spontaneous breaking symmetry. For broken phases are separated critical point corresponding to minimal model $$ \mathcal{M}\left(2,5\right) <mml:math...

We study the leading and sub-leading magnetic perturbations of thermal E7 integrable deformation tricritical Ising model. In low-temperature phase, these lead to confinement kinks The resulting meson spectrum can be obtained using semi-classical quantisation, here extended include also mesonic excitations composed two different kinks. An interesting feature perturbation model is possibility swap role operators, i.e. consider as a A3 associated deformation. Due occurrence vacuum degeneracy...

We consider the field theory describing scaling limit of Potts quantum spin chain using a combination two approaches. The first is renormalized truncated conformal space approach (TCSA), while second one new thermodynamic Bethe Ansatz (TBA) system for excited state spectrum in finite volume. For TCSA we investigate and clarify several aspects renormalization procedure counter term construction. TBA verified by comparing its ultraviolet to infrared exact S-matrix predictions. then show that...

Weakly coupled Ising chains provide a condensed-matter realization of confinement. In these systems, kinks and antikinks bind into mesons due to an attractive interaction potential that increases linearly with the distance between particles. While single have been directly observed in experiments, role multiparticle continuum bound states excitation spectrum is far less clear. Using time-dependent density-matrix renormalization group methods, we study dynamical structure factors one-...

The thermal deformation of the critical point action 2D tricritical Ising model gives rise to an exact scattering theory with seven massive excitations based on exceptional E_7 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>E</mml:mi><mml:mn>7</mml:mn></mml:msub></mml:math> Lie algebra. high and low temperature phases this are related by duality. This duality guarantees that leading sub-leading magnetisation operators, \sigma(x)...

A bstract Classical conformal blocks appear in the large central charge limit of 2D Virasoro blocks. In AdS 3 / CFT 2 correspondence, they are related to classical bulk actions and used calculate entanglement entropy geodesic lengths. this work, we discuss identification Painlevé VI action showing how isomonodromic deformations naturally context. We recover accessory parameter expansion Heun’s equation from τ -function. also c = 1 -function leads a novel approach 4-point block.

We determine both analytically and numerically the entanglement between chiral degrees of freedom in ground state massive perturbations 1+1 dimensional conformal field theories quantised on a cylinder. Analytic predictions are obtained from variational Ansatz for terms smeared boundary states recently proposed by J. Cardy, which is validated numerical results Truncated Conformal Space Approach. also extend scope resolving degeneracies exploiting operator product expansion. The entropy...

This work considers entropy generation and relaxation in quantum quenches the Ising 3-state Potts spin chains. In absence of explicit symmetry breaking we find universal ratios involving Rényi growth rates magnetisation for small quenches. We also demonstrate that rate provides an observable signature “dynamical Gibbs effect” which is a recently discovered characteristic non-monotonous behaviour linked to changes quasi-particle spectrum.

Abstract Integrable Quantum Field Theories can be solved exactly using bootstrap techniques based on their elastic and factorisable S -matrix. While knowledge of the scattering amplitudes reveals exact spectrum particles on-shell dynamics, expression matrix elements various operators allows reconstruction off-shell quantities such as two-point correlation functions with a high level precision. In this review, we summarise results relevant to contact point between theory experiment providing...

We revisit and extend Fisher's argument for a Ginzburg-Landau description of multicritical Yang-Lee models in terms single boson Lagrangian with potential $\varphi^2 (i \varphi)^n$. explicitly study the cases $n=1,2$ by Truncated Hamiltonian Approach based on free massive perturbed $\boldsymbol P\boldsymbol T$ symmetric deformations, providing clear evidence spontaneous breaking P \boldsymbol symmetry. For $n=1$, broken phases are separated critical point corresponding to minimal model...

We study a novel class of Renormalization Group flows which connect multicritical versions the two-dimensional Yang-Lee edge singularity described by conformal minimal models M(2,2n+3). The absence in these an order parameter implies that towards and between Lee-Yang singularities are all related to spontaneous breaking PT symmetry comprise pattern space symmetric theories consistent with c-theorem counting relevant directions. Additionally, we find while part phase diagram domains unbroken...