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Semi-classical formula beyond the Ehrenfest time in
Semi-classical formula beyond the Ehrenfest time in

... Localized regime: After that time, the coherent state spreads more and more. But its width is still of microscopic size if ∆t  1, i.e. t  12 tE . In more precise terms, the semi-classical measure of ψ (t) is still a Dirac measure at x (t) in that range of time. In our example 21 tE = 3.6. At a tim ...
Holographic quantum error-correcting code
Holographic quantum error-correcting code

... such simple entanglement constructions which with EPR ...
Black-hole/near-horizon-CFT duality and 4 dimensional classical
Black-hole/near-horizon-CFT duality and 4 dimensional classical

... limit for three and four dimensions black holes. The near horizon CFT assumes the two dimensional black hole solutions that were first introduced by Christensen and Fulling (1977 Phys. Rev. D 15 2088104) and later expanded to a greater class of black holes via Robinson and Wilczek (2005 Phys. Rev. L ...
A Kinetic Theory Approach to Quantum Gravity
A Kinetic Theory Approach to Quantum Gravity

... In the last decade a statistical mechanics description of particles, fields and spacetime based on the concept of quantum open systems and the influence functional formalism has been introduced. It reproduces in full the established theory of quantum fields in curved spacetime [1–6] and contains als ...
Comparing Dualities and Gauge Symmetries - Philsci
Comparing Dualities and Gauge Symmetries - Philsci

... (specifically: diffeomorphisms) which are asymptotically non-trivial (i.e. do not tend to the identity at spacelike infinity), and which can thus change the state of a system relative to its environment.3 These sketches are enough to suggest that for any theory, or for any theory and its duals, dual ...
Functional-Integral Representation of Quantum Field Theory {functint
Functional-Integral Representation of Quantum Field Theory {functint

... in (14.56). In the euclidean formulation of the theory to be discussed in Section 14.5, it makes Z[0] equal to the thermodynamic partition function of the system. For free fields, Z[0] is equal to the partition function of a set of harmonic oscillators of frequencies ω(k) for all momenta k. This sta ...
Elements of QFT in Curved Space-Time
Elements of QFT in Curved Space-Time

... lines of matter fields and external limes of both matter and metric. In practice, one can consider gµν = ηµν + hµν . Is it possible to get EA for an arbitrary background in this way? Perhaps not. But it is sufficient to explore renormalization! An important aspect is that the general covariance in t ...
The Philosophy behind Quantum Gravity
The Philosophy behind Quantum Gravity

... physicists, is the construction of a quantum theory of gravity. The so far unsuccessful attempt to construct such a theory is an attempt to unify Einstein's general theory of relativity with quantum theory (or quantum field theory). While quantum gravity aims to describe everything in the universe i ...
Conformal Bootstrap Approach to O(N) Fixed Points in Five
Conformal Bootstrap Approach to O(N) Fixed Points in Five

... It has long been suspected that there are interacting conformal field theories in dimensions higher than 4. Yet, their existence were not clearly identified and even worse no theoretically satisfactory approach for systematic study of them was not developed. Recently, sparked by the suggestion from ...
What can string theory teach us about condensed matter physics?
What can string theory teach us about condensed matter physics?

... • Consider an infinite, continuum, translationally-invariant quantum system with a globally conserved U(1) charge Q (the “electron density”) in spatial dimension d > 1. • Describe zero temperature phases where d�Q�/dµ �= 0, where µ (the “chemical potential”) which changes the Hamiltonian, H, to H − ...
7. Low Energy Effective Actions
7. Low Energy Effective Actions

... we will need to develop new methods to solve it. Notice that strong coupling in α′ is hard, but the problem is at least well-defined in terms of the worldsheet path integral. This is qualitatively different to the question of strong coupling in gs for which, as discussed in Section 6.4.5, we’re real ...
General formula for symmetry factors of Feynman diagrams
General formula for symmetry factors of Feynman diagrams

... that in calculating S-factors, we can classify all well-known fields into two classes. The first class comprises self-conjugate fields for which the particle is the same as the antiparticle, such as the real Higgs scalar σ in the Standard Model, the photon and the Z boson. We will often refer to thi ...
Stability and dynamical property for two
Stability and dynamical property for two

... initial state 共za , zb兲 = 共1 , −1兲 is quite different. As shown in Fig. 4, the fixed point An approaches the unstable region II as Jef f increases from zero. However, it will not enter that region when J ⬍ Jc1. When Jef f decreases, the system returns to its initial state as shown in Fig. 6共b兲. When ...
A Critique of Pure String Theory: Heterodox Opinions of Diverse
A Critique of Pure String Theory: Heterodox Opinions of Diverse

... by compactifying one field theory and taking a limit, but this is not what we usually mean by a theory having multiple vacua. It is also significant that the cosmological constant in these theories is a discretely tunable, fundamental parameter which encodes properties of the fundamental UV theory, ...
The Effective Action for Local Composite Operators Φ2(x) and Φ4(x)
The Effective Action for Local Composite Operators Φ2(x) and Φ4(x)

... this reason the AO is frequently used as a testing ground for approximation methods in quantum field theory. The field-theoretical perturbation method enables us to calculate Green’s functions and their generating functionals to an arbitrary order in the coupling constant λ. Within this approach the ...
Janiszewski_washington_0250E_13369
Janiszewski_washington_0250E_13369

... Holography is a powerful theoretical duality that relates quantum gravitational theories to non-gravitational theories in one less dimension. The most explored example of this tool is the correspondence between general relativity on five dimensional Anti-de Sitter space and a four dimensional supers ...
Introduction to loop quantum gravity
Introduction to loop quantum gravity

... background independent way. This section introduces the reader to the ideas behind loop quantum gravity. Why must one quantise? Quantum mechanics has an external time variable, t in the Schrödinger equation, or alternatively in quantum field theory a fixed non-dynamical background. On the other han ...
Effective field theory methods applied to the 2-body
Effective field theory methods applied to the 2-body

... showing that in this class of gauges all gravity components satisfy a wave-like equation. However we will see later in this section that working with gauge invariant variables (though non-local) shows that only 2 degrees of freedom are physical and radiative, 4 more are physical and non-radiative an ...
Towards UV Finiteness of Infinite Derivative Theories of Gravity and
Towards UV Finiteness of Infinite Derivative Theories of Gravity and

... gravity is ultraviolet (UV) finite at 1-loop order [4]. That is, at 1-loop order, oneloop counterterms vanish on mass-shell. Now, at 2-loop order, pure gravity has a UV divergence [4, 5, 6]. Since infinitely many local counterterms would be required to eliminate the divergences, pure gravity is said ...
Quantum field theory and the Jones polynomial
Quantum field theory and the Jones polynomial

... evidence for the existence of such a connection had to do with Floer's work on three manifolds [3] and the nature of the relation between Donaldson theory and Floer theory. Also, the "Donaldson polynomials" had an interesting formal analogy with quantum field theory correlation functions. It has tur ...
univERsity oF copEnhAGEn
univERsity oF copEnhAGEn

... Although it was not clear why the hypercubic lattice regularization did not work, the formalism known as dynamical triangulation (DT) was suggested as an alternative [2]. It discretized the independent intrinsic worldsheet geometry used in the Polyakov formulation of bosonic string theory [3] and th ...
Notes on 2d quantum gravity and Liouville theory - lpthe
Notes on 2d quantum gravity and Liouville theory - lpthe

... 5.1.2 Adding the cosmological constant term . . . . . . . . . . . . . . . . 5.2 Derivation of the classical Liouville action . . . . . . . . . . . . . . . . . . 5.2.1 Integrating the conformal anomaly . . . . . . . . . . . . . . . . . . 5.2.2 Partition function and transformation properties . . . . ...
Infinite-randomness quantum Ising critical fixed points
Infinite-randomness quantum Ising critical fixed points

... Ω, each of the effective spins on its neighboring clusters— in more conventional terms the perturbatively modified wavefunctions that are labeled by the remaining effective spins—will acquire a component of the decimated cluster’s spin whose magnitude is of order J/Ω, with J the effective coupling t ...
Table des mati`eres 1 Technical and Scientific description of
Table des mati`eres 1 Technical and Scientific description of

... and the GSM is just the doubly indexed family (SΩ (n,k))(n,k)∈N2 . In the special case when there is only one annihilation, we can compute completely the GSM by means of one-parameter groups of substitution with prefunctions, i.e. of operators of the type f → fˆ(z) = g(z)f (φ(z)) with g(z) = 1 + · ...
Loop Quantum Gravity and Its Consistency
Loop Quantum Gravity and Its Consistency

... lattice momentum doubles the number of fermions in the theory (for each dimension that is put on the lattice). This is noted by the fact that the lattice propagator has an inappropriate number of singularities (and thus particles). Since this is not seen in reality, it can be considered to be incons ...
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Asymptotic safety in quantum gravity

Asymptotic safety (sometimes also referred to as nonperturbative renormalizability) is a concept in quantum field theory which aims at finding a consistent and predictive quantum theory of the gravitational field. Its key ingredient is a nontrivial fixed point of the theory's renormalization group flow which controls the behavior of the coupling constants in the ultraviolet (UV) regime and renders physical quantities safe from divergences. Although originally proposed by Steven Weinberg to find a theory of quantum gravity, the idea of a nontrivial fixed point providing a possible UV completion can be applied also to other field theories, in particular to perturbatively nonrenormalizable ones. In this respect, it is similar to Quantum triviality.The essence of asymptotic safety is the observation that nontrivial renormalization group fixed points can be used to generalize the procedure of perturbative renormalization. In an asymptotically safe theory the couplings do not need to be small or tend to zero in the high energy limit but rather tend to finite values: they approach a nontrivial UV fixed point. The running of the coupling constants, i.e. their scale dependence described by the renormalization group (RG), is thus special in its UV limit in the sense that all their dimensionless combinations remain finite. This suffices to avoid unphysical divergences, e.g. in scattering amplitudes. The requirement of a UV fixed point restricts the form of the bare action and the values of the bare coupling constants, which become predictions of the asymptotic safety program rather than inputs.As for gravity, the standard procedure of perturbative renormalization fails since Newton's constant, the relevant expansion parameter, has negative mass dimension rendering general relativity perturbatively nonrenormalizable. This has driven the search for nonperturbative frameworks describing quantum gravity, including asymptotic safety which — in contrast to other approaches—is characterized by its use of quantum field theory methods, without depending on perturbative techniques, however. At the present time, there is accumulating evidence for a fixed point suitable for asymptotic safety, while a rigorous proof of its existence is still lacking.
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