arXiv subjects

Davide Polvara

Publications and source records attributed to Davide Polvara.

16 recordsLinked to original sources

arXiv2026

Deriving the $\text{AdS}_3\times\text{S}^3\times \text{T}^4$ Quantum Spectral Curve I: Y-system and discontinuity relations

The mirror Thermodynamic Bethe Ansatz (TBA) describes the spectrum of $\text{AdS}_3\times\text{S}^3\times \text{T}^4$ superstrings supported by a mixture of Ramond-Ramond (RR) and Neveu-Schwarz-Neveu-Schwarz (NSNS) flux. In recent years, a conjecture was put forward regarding the Quantum Spectral Curve (QSC) formulation in the Ramond-Ramond case. In this paper, we initiate the derivation of the Ramond-Ramond QSC from the mirror TBA equations. We describe the Y-system underlying the TBA and its discontinuity relations for pure-RR backgrounds. This provides the foundation for the derivation of the T-system and the Quantum Spectral Curve, which will be presented in a follow-up paper.

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arXiv2026

Relativistic limit on the $AdS_3 \times S^3 \times S^3 \times S^1$ string worldsheet

We study the relativistic limit of the worldsheet S matrix of $AdS_3 \times S^3 \times S^3 \times S^1$ strings in the presence of mixed Ramond-Ramond (RR) and Neveu-Schwarz-Neveu-Schwarz (NS-NS) flux, and complete the S-matrix bootstrap including the dressing factors for fundamental particles and bound states. Our results agree with the relativistic limit of the recent proposal arXiv:2512.07721.

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arXiv2025

Thermodynamics of integrable N=2 theories, squared

In arXiv:2306.17553 a new supersymmetric integrable QFT was constructed from the relativistic limit of the worlsdheet theory of AdS$_3 \times$ S$^3\times $T$^4$ superstrings with mixed Ramond-Ramond and Neveu-Schwarz-Neveu-Schwarz flux. The model is closely reminiscent of one previously considered by Fendley and Intriligator, though it enjoys twice as many supersymmetries. In this paper we study its finite-volume and finite-temperature properties. We formulate the string hypothesis for the Bethe--Yang equations, write down the thermodynamic Bethe ansatz equations, and simplify them in the form of a Y-system. We obtain three decoupled sectors associated with massive, massless-chiral and massless-antichiral particles, for which we compute the UV central charge. We illustrate the similarities and differences between this model and the one of Fendley and Intriligator.

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arXiv2025

Dressing Factors and Mirror Thermodynamic Bethe Ansatz for mixed-flux AdS3/CFT2

We complete the derivation of the dressing factors for the $AdS_3\times S^3\times T^4$ S matrix with mixed Ramond--Ramond and Neveu-Schwarz-Neveu-Schwarz flux, in the "string" and "mirror" kinematics. Using these, we propose the mirror Thermodynamic Bethe Ansatz equations which describe the spectrum of the model at any string tension.

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arXiv2025

Exchange relations and crossing

We discuss the scattering matrix of two-dimensional integrable QFTs whose fields obey non-trivial exchange relations. We show that crossing equations for such models have to be modified, and propose their consistent modification. This modification opens the way to constructing new integrable S~matrices. As a check, we consider the crossing equations for the $SU(N)$ chiral Gross-Neveu model, and for the $Φ_{21}$ deformation of the tricritical Ising model, finding an agreement with the existing proposals. Finally, we reconsider the crossing equations for massless excitations of the mixed-flux $AdS_3\times S^3\times T^4$ light-cone gauge superstring sigma model, and conjecture that the massless excitations satisfy non-trivial exchange relations. This changes the crossing equations and leads to a simpler massless dressing factor.

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arXiv2025

One-loop integrability with shifting masses

We investigate the perturbative integrability of two-dimensional massive quantum field theories with polynomial-like interactions and show that any theory of such class which is purely elastic at the tree level is also purely elastic at one loop. To preserve the elasticity, the physical renormalized masses of the theory must differ from the classical ones by quantum corrections carried by one-loop bubble diagrams. After the masses are corrected in this manner we show that one-loop inelastic processes vanish and integrability is preserved under one-loop effects. Relying on this fact we show that the closed expression for one-loop S-matrices in terms of tree S-matrices obtained in arXiv:2402.12087 extends to models that do not preserve the mass ratios at one loop. We test our results on the full class of nonsimply-laced affine Toda theories and find exact match with the S-matrices bootstrapped in the past.

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arXiv2025

Massive dressing factors for mixed-flux AdS$_3$/CFT$_2$

We follow up on our proposal for dressing factors for the mixed-flux $AdS_3\times S^3\times T^4$ background presented in arXiv:2402.11732. We discuss in detail the analytic properties of the dressing factors in the string and mirror kinematics for fundamental massive particles and bound states. We prove that the dressing factors are unitary and CP-invariant in the string kinematics, parity invariant in the mirror, and solve the crossing equations in both kinematics. In the limit of pure Ramond-Ramond flux they reduce to the known ones. Finally, we present their expansion at strong tension, as well as in the (small-RR-flux) relativistic limit, finding agreement with the literature.

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arXiv2025

Dressing Factors for Mixed-Flux $AdS_3\times S^3\times T^4$ Superstrings

We propose the dressing factors for the scattering of massive particles on the worldsheet of mixed-flux $AdS_3\times S^3\times T^4$ superstrings, in the string and mirror kinematics. The proposal passes all self-consistency checks in the both kinematics, including for bound states. It matches with perturbative and semiclassical computations from the string sigma model, and with its relativistic limit.

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arXiv2024

On the worldsheet S matrix of the AdS3/CFT2 mixed-flux mirror model

String on $AdS_3\times S^3\times T^4$ backgrounds are known to be classically integrable in the presence of a mixture of Ramond-Ramond and Neveu-Schwarz-Neveu-Schwarz fluxes. It is expected that this results in the existence of a well-defined factorised worldsheet S matrix. In order to use integrability to compute the string spectrum we need such a factorised S matrix to exist also for the "mirror" model, obtained by a double Wick rotation of the original worldsheet theory. In the mixed-flux case the mirror model has a complex Hamiltonian, which raises questions on its well-definedness. In the paper we study the worldsheet tree-level S matrix of the original and mirror model and discuss some necessary conditions for the integrability and reality of the spectrum.

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arXiv2024

One-loop elastic amplitudes from tree-level elasticity in 2d

In this paper we extend the study initiated in arXiv:2302.04709v2 [hep-th] to the computation of one-loop elastic amplitudes. We consider 1+1 dimensional massive bosonic Lagrangians with polynomial-like potentials and absence of inelastic processes at the tree level; starting from these assumptions we show how to write sums of one-loop diagrams as products and integrals of tree-level amplitudes. We derive in this way a universal formula for the one-loop two-to-two S-matrices in terms of tree S-matrices. We test our results on different integrable theories, such as sinh-Gordon, Bullough Dodd and the full class of simply-laced affine Toda theories, finding perfect agreement with the bootstrapped S-matrices known in the literature. We show how Landau singularities in amplitudes are naturally captured by our universal formula while they are lost in results based on unitarity-cut methods implemented in the past arXiv:1304.1798v3 [hep-th], arXiv:1405.7947v2 [hep-th].

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arXiv2023

From tree- to loop-simplicity in affine Toda theories II: higher-order poles and cut decompositions

Recently we showed how, in two-dimensional scalar theories, one-loop threshold diagrams can be cut into the product of one or more tree-level diagrams arXiv:2206.09368. Using this method on the ADE series of Toda models, we computed the double- and single-pole coefficients of the Laurent expansion of the S-matrix around a pole of arbitrary even order, finding agreement with the bootstrapped results. Here we generalise the cut method explained in arXiv:2206.09368 to multiple loops and use it to simplify large networks of singular diagrams. We observe that only a small number of cut diagrams survive and contribute to the expected bootstrapped result, while most of them cancel each other out through a mechanism inherited from the tree-level integrability of these models. The simplification mechanism between cut diagrams inside networks is reminiscent of Gauss's theorem in the space of Feynman diagrams.

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arXiv2023

On mixed-flux worldsheet scattering in AdS3/CFT2

Strings on AdS3xS3xT4 with mixed Ramond-Ramond and Neveu-Schwarz-Neveu-Schwarz flux are known to be classically integrable. This is a crucial property of this model, which cannot be studied by conventional worldsheet-CFT techniques. Integrability should carry over to the quantum level, and the worldsheet S matrix in the lightcone gauge is known up to the so-called dressing factors. In this work we study the kinematics of mixed-flux theories and consider a relativistic limit of the S matrix whereby we can complete the bootstrap program, including the dressing factors for fundamental particles and bound states. This provides an important test for the dressing factors of the full worldsheet model, and offers new insights on the features of the model when the amount of NSNS flux is low.

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arXiv2023

One-loop inelastic amplitudes from tree-level elasticity in 2d

We investigate the perturbative integrability of different quantum field theories in 1+1 dimensions at one loop. Starting from massive bosonic Lagrangians with polynomial-like potentials and absence of inelastic processes at the tree level, we derive a formula reproducing one-loop inelastic amplitudes for arbitrary numbers of external legs. We show that any one-loop inelastic amplitude is equal to its tree-level version, in which the masses of particles and propagators are corrected by one-loop bubble diagrams. These amplitudes are nonzero in general and counterterms need to be added to the Lagrangian to restore the integrability at one loop. For the class of simply-laced affine Toda theories, we show that the necessary counterterms are obtained by scaling the potential with an overall multiplicative factor, proving in this way the one-loop integrability of these models. Even though we focus on bosonic theories with polynomial-like interactions, we expect that the on-shell techniques used in this paper to compute amplitudes can be applied to several other models.

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arXiv2022

From tree- to loop-simplicity in affine Toda theories I: Landau singularities and their subleading coefficients

Various features of the even order poles appearing in the S-matrices of simply-laced affine Toda field theories are analysed in some detail. In particular, the coefficients of first- and second-order singularities appearing in the Laurent expansion of the S-matrix around a general $2N^{\rm th}$ order pole are derived in a universal way using perturbation theory at one loop. We show how to cut loop diagrams contributing to the pole into particular products of tree-level graphs that depend on the on-shell geometry of the loop; in this way, we recover the coefficients of the Laurent expansion around the pole exploiting tree-level integrability properties of the theory. The analysis is independent of the particular simply-laced theory considered, and all the results agree with those obtained in the conjectured bootstrapped S-matrices of the ADE series of theories.

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arXiv2021

Tree level integrability in 2d quantum field theories and affine Toda models

We investigate the perturbative integrability of massive (1+1)-dimensional bosonic quantum field theories, focusing on the conditions for them to have a purely elastic S-matrix, with no particle production and diagonal scattering, at tree level. For theories satisfying what we call `simply-laced scattering conditions', by which we mean that poles in inelastic $2$ to $2$ processes cancel in pairs, and poles in allowed processes are only due to one on-shell propagating particle at a time, the requirement that all inelastic amplitudes must vanish is shown to imply the so-called area rule, connecting the $3$-point couplings $C^{(3)}_{abc}$ to the masses $m_a$, $m_b$, $m_c$ of the coupled particles in a universal way. We prove that the constraints we find are universally satisfied by all affine Toda theories, connecting pole cancellations in amplitudes to properties of the underlying root systems, and develop a number of tools that we expect will be relevant for the study of loop amplitudes.

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arXiv2019

Quantum anomalies in A^{(1)}_r Toda theories with defects

We study quantum integrability of affine Toda theories with a line of defect. In particular, we focus on the problem of constructing quantum higher-spin conserved currents in models defined by two A_r^{(1)} Toda theories separated by a non-trivial type-I defect. For a suitable choice of the defect potential these theories are known to be classically integrable, that is they possess an infinite set of higher-spin conserved charges in involution. Studying the corresponding conservation laws at quantum level we discover that anomalies arise, which we compute exactly at all orders in the coupling constant. While for the stress-energy tensor these anomalies can be cancelled by a finite renormalization of the defect potential, we find that from the first non-trivial higher-spin current this is no longer possible. This opens the question whether these theories are indeed integrable at quantum level.

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