The Experts below are selected from a list of 7449 Experts worldwide ranked by ideXlab platform
G Takacs - One of the best experts on this subject based on the ideXlab platform.
-
out of horizon correlations following a quench in a Relativistic quantum field theory
Journal of High Energy Physics, 2020Co-Authors: Ivan Kukuljan, Spyros Sotiriadis, G TakacsAbstract:One of the manifestations of Relativistic Invariance in non-equilibrium quantum field theory is the “horizon effect” a.k.a. light-cone spreading of correlations: starting from an initially short-range correlated state, measurements of two observers at distant space-time points are expected to remain independent until their past light-cones overlap. Surprisingly, we find that in the presence of topological excitations correlations can develop outside of horizon and indeed even between infinitely distant points. We demonstrate this effect for a wide class of global quantum quenches to the sine-Gordon model. We point out that besides the maximum velocity bound implied by Relativistic Invariance, clustering of initial correlations is required to establish the “horizon effect”. We show that quenches in the sine-Gordon model have an interesting property: despite the fact that the initial states have exponentially decaying correlations and cluster in terms of the bosonic fields, they violate the clustering condition for the soliton fields, which is argued to be related to the non-trivial field topology. The nonlinear dynamics governed by the solitons makes the clustering violation manifest also in correlations of the local bosonic fields after the quench.
Adam Bednorz - One of the best experts on this subject based on the ideXlab platform.
-
objective realism and freedom of choice in Relativistic quantum field theory
Physical Review D, 2016Co-Authors: Adam BednorzAbstract:Traditional Bell's argument shows that freedom of choice is inconsistent with quantum realism if lack of signaling and sufficiently fast choices and readouts are assumed. While no-signaling alone is a consequence of special relativity, this is not the case of spacetime location of choice and readout. Here we attempt to incorporate freedom of choice into quantum objective realism relying solely on Relativistic quantum field theory. We conclude that this is impossible without breaking Relativistic Invariance and put forward the possibility of signaling faster than light, which cannot be excluded if an ultimate theory violates relativity.
Ivan Kukuljan - One of the best experts on this subject based on the ideXlab platform.
-
out of horizon correlations following a quench in a Relativistic quantum field theory
Journal of High Energy Physics, 2020Co-Authors: Ivan Kukuljan, Spyros Sotiriadis, G TakacsAbstract:One of the manifestations of Relativistic Invariance in non-equilibrium quantum field theory is the “horizon effect” a.k.a. light-cone spreading of correlations: starting from an initially short-range correlated state, measurements of two observers at distant space-time points are expected to remain independent until their past light-cones overlap. Surprisingly, we find that in the presence of topological excitations correlations can develop outside of horizon and indeed even between infinitely distant points. We demonstrate this effect for a wide class of global quantum quenches to the sine-Gordon model. We point out that besides the maximum velocity bound implied by Relativistic Invariance, clustering of initial correlations is required to establish the “horizon effect”. We show that quenches in the sine-Gordon model have an interesting property: despite the fact that the initial states have exponentially decaying correlations and cluster in terms of the bosonic fields, they violate the clustering condition for the soliton fields, which is argued to be related to the non-trivial field topology. The nonlinear dynamics governed by the solitons makes the clustering violation manifest also in correlations of the local bosonic fields after the quench.
Roberto Longo - One of the best experts on this subject based on the ideXlab platform.
-
Relativistic Invariance and charge conjugation in quantum field theory
Communications in Mathematical Physics, 1992Co-Authors: Daniele Guido, Roberto LongoAbstract:We prove that superselection sectors with finite statistics in the sense of Doplicher, Haag, and Roberts are automatically Poincare covariant under natural conditions (e.g. split property for space-like cones and duality for contractible causally complete regions). The same holds for topological charges, namely sectors localized in space-like cones, providing a converse to a theorem of Buchholz and Fredenhagen. We introduce the notion of weak conjugate sector that turns out to be equivalent to the DHR conjugate in finite statistics. The weak conjugate sector is given by an explicit formula that relates it to the PCT symmetry in a Wightman theory. Every Euclidean convariant sector (possibly with infinite statistics) has a weak conjugate sector and the converse is true under the above natural conditions. On the same basis, translation covariance is equivalent to the property that sectors are sheaf maps modulo inner automorphisms, for a certain sheaf structure given by the local algebras. The construction of the weak conjugate, sector also applies to the case of local algebras onS1 in conformal theories. Our main tools are the Bisognano-Wichmann description of the modular structure of the von Neumann algebras associated with wedge regions in the vacuum sector and the relation between Jones index theory for subfactors and the statistics of superselection sectors.
Francesco Ravanini - One of the best experts on this subject based on the ideXlab platform.
-
irreversibility of the renormalization group flow in non unitary quantum field theory
Journal of Physics A, 2017Co-Authors: Olalla A Castroalvaredo, Benjamin Doyon, Francesco RavaniniAbstract:We show irreversibility of the renormalization group flow in non-unitary but PT -invariant quantum field theory in two space-time dimensions. In addition to unbroken PT -symmetry and a positive energy spectrum, we assume standard properties of quantum field theory including a local energy-momentum tensor and Relativistic Invariance. This generalizes Zamolodchikov’s ctheorem to PT -symmetric hamiltonians. Our proof follows closely Zamolodchikov’s arguments. We show that a function ceff(s) of the renormalization group parameter s exists which is nonnegative and monotonically decreasing along renormalization group flows. Its value at a critical point is the “effective central charge” entering the specific free energy. At least in rational models, this equals ceff = c − 24∆, where c is the central charge and ∆ is the lowest primary field dimension in the conformal field theory which describes the critical point.
-
irreversibility of the renormalization group flow in non unitary quantum field theory
arXiv: High Energy Physics - Theory, 2017Co-Authors: Olalla A Castroalvaredo, Benjamin Doyon, Francesco RavaniniAbstract:We show irreversibility of the renormalization group flow in non-unitary but ${\cal PT}$-invariant quantum field theory in two space-time dimensions. In addition to unbroken $\mathcal{PT}$-symmetry and a positive energy spectrum, we assume standard properties of quantum field theory including a local energy-momentum tensor and Relativistic Invariance. This generalizes Zamolodchikov's $c$-theorem to ${\cal PT}$-symmetric hamiltonians. Our proof follows closely Zamolodchikov's arguments. We show that a function $c_{\mathrm{eff}}(s)$ of the renormalization group parameter $s$ exists which is non-negative and monotonically decreasing along renormalization group flows. Its value at a critical point is the "effective central charge" entering the specific free energy. At least in rational models, this equals $c_{\mathrm{eff}}=c-24\Delta$, where $c$ is the central charge and $\Delta$ is the lowest primary field dimension in the conformal field theory which describes the critical point.
