Letters in Mathematical Physics最新文献

We construct a class of fixed-time models in which the commutations relations of a Dirac field with a bosonic field are non-trivial and depend on the choice of a given distribution (“twisting factor”). If the twisting factor is fundamental solution of a differential operator, then applying the differential operator to the bosonic field yields a generator of the local gauge transformations of the Dirac field. Charged vectors generated by the Dirac field define states of the bosonic field which in general are not local excitations of the given reference state. The Hamiltonian density of the bosonic field presents a non-trivial interaction term: besides creating and annihilating bosons, it acts on momenta of fermionic wave functions. When the twisting factor is the Coulomb potential, the bosonic field contributes to the divergence of an electric field and its Laplacian generates local gauge transformations of the Dirac field. In this way, we get a fixed-time model fulfilling the equal time commutation relations of the interacting Coulomb gauge.

The Kerr-star spacetime is the extension over the horizons and in the negative radial region of the slowly rotating Kerr black hole. It is known that below the inner horizon, there exist both timelike and null (lightlike) closed curves. Nevertheless, we prove that null geodesics can be neither closed nor even contained in a compact subset of the Kerr-star spacetime.

Quantum states over time are a spatiotemporal generalization of density operators which were first introduced to give a more even-handed treatment of space and time in quantum theory. In particular, quantum states over time encode not only spatial, but also causal correlations associated with the dynamical evolution of a quantum system, and the association of quantum states over time with the dynamical flow of quantum information is in direct analogy with spacetime and its relation to classical dynamics. In this work, we further such an analogy by formulating a notion of general covariance for the theory of quantum states over time. We then associate a canonical state over time with a density operator which is to evolve under a sequence of quantum processes modeled by completely positive trace-preserving (CPTP) maps, and we show that such a canonical state over time satisfies such a notion of covariance. We also show that the dynamical quantum Bayes’ rule transforms covariantly with respect to quantum states over time, and we conclude with a discussion of what it means for a physical law to be generally covariant when formulated in terms of quantum states over time.

We construct combinatorial analogs of 2d higher topological quantum field theories. We consider triangulations as vertices of a certain CW complex (Xi ). In the “flip theory,” cells of (Xi _textrm{flip}) correspond to polygonal decompositions obtained by erasing the edges in a triangulation. These theories assign to a cobordism (Sigma ) a cochain Z on (Xi _textrm{flip}) constructed as a contraction of structure tensors of a cyclic (A_infty ) algebra V assigned to polygons. The cyclic (A_infty ) equations imply the closedness equation ((delta +Q)Z=0). In this context, we define combinatorial BV operators and give examples with coefficients in (mathbb {Z}_2). In the “secondary polytope theory,” (Xi _textrm{sp}) is the secondary polytope (due to Gelfand–Kapranov–Zelevinsky) and the cyclic (A_infty ) algebra has to be replaced by an appropriate refinement that we call an (widehat{A}_infty ) algebra. We conjecture the existence of a good Pachner CW complex (Xi ) for any cobordism, whose local combinatorics is described by secondary polytopes and the homotopy type is that of Zwiebach’s moduli space of complex structures. Depending on this conjecture, one has an “ideal model” of combinatorial 2d HTQFT determined by a local (widehat{A}_infty ) algebra.

Joyce structures were introduced by T. Bridgeland in the context of the space of stability conditions of a three-dimensional Calabi–Yau category and its associated Donaldson–Thomas invariants. In subsequent work, T. Bridgeland and I. Strachan showed that Joyce structures satisfying a certain non-degeneracy condition encode a complex hyperkähler structure on the tangent bundle of the base of the Joyce structure. In this work we give a definition of an analogous structure over an affine special Kähler (ASK) manifold, which we call a special Joyce structure. Furthermore, we show that it encodes a real hyperkähler (HK) structure on the tangent bundle of the ASK manifold, possibly of indefinite signature. Particular examples include the semi-flat HK metric associated to an ASK manifold (also known as the rigid c-map metric) and the HK metrics associated to certain uncoupled variations of BPS structures over the ASK manifold. Finally, we relate the HK metrics coming from special Joyce structures to HK metrics on the total space of algebraic integrable systems.

We study 3d (mathcal {N}=2) U(1) Chern–Simons-Matter QFT on a cylinder (Ctimes mathbb {R}). The topology of C gives rise to BPS sectors of low-energy solitons known as kinky vortices, which interpolate between (possibly) different vacua at the ends of the cylinder and at the same time carry magnetic flux. We compute the spectrum of BPS vortices on the cylinder in an isolated Higgs vacuum, through the framework of warped exponential networks, which we introduce. We then conjecture a relation between these and standard vortices on (mathbb {R}^2), which are related to genus-zero open Gromov–Witten invariants of toric branes. More specifically, we show that in the limit of large Fayet–Iliopoulos coupling, the spectrum of kinky vortices on C undergoes an infinite sequence of wall-crossing transitions and eventually stabilizes. We then propose an exact relation between a generating series of stabilized CFIV indices and the Gromov–Witten disk potential and discuss its consequences for the structure of moduli spaces of vortices.

We show that the wave operators for Schrödinger scattering in (mathbb {R}^4) have a particular form which depends on the existence of resonances. As a consequence of this form, we determine the contribution of resonances to the index of the wave operator.

We analyse the ergodic properties of quantum channels that are covariant with respect to diagonal orthogonal transformations. We prove that the ergodic behaviour of a channel in this class is essentially governed by a classical stochastic matrix. This allows us to exploit tools from classical ergodic theory to study quantum ergodicity of such channels. As an application of our analysis, we study dual unitary brickwork circuits which have recently been proposed as minimal models of quantum chaos in many-body systems. Upon imposing a local diagonal orthogonal invariance symmetry on these circuits, the long-term behaviour of spatio-temporal correlations between local observables in such circuits is completely determined by the ergodic properties of a channel that is covariant under diagonal orthogonal transformations. We utilize this fact to show that such symmetric dual unitary circuits exhibit a rich variety of ergodic behaviours, thus emphasizing their importance.

According to Zuo and an unpublished work of Bertola, there is a two-index series of Dubrovin–Frobenius manifold structures associated to a B-type Coxeter group. We study the relations between these structures for the different values of these indices. We show that part of the data of such Dubrovin–Frobenius manifold indexed by (k, l) can be recovered by the ((k+r,l+r)) Dubrovin–Frobenius manifold.Continuing the program of Basalaev et al. (J Phys A: Math Theor 54:115201, 2021) we associate an infinite system of commuting PDEs to these Dubrovin–Frobenius manifolds and show that these PDEs extend the dispersionless BKP hierarchy.

In Gérard et al. (Ann Sci Ecole Norm Sup 56:127–196, 2023), the Unruh state for massless fermions on a Kerr spacetime was constructed and the authors showed its Hadmard property in the case of very slowly rotating black holes ({left| a right| }ll M). In this note, we extend this result to the full non extreme case ({left| a right| }<M).