Conveners
Quantum field theory in curved spacetimes and perturbative quantum gravity: Monday block 1
- Sebastián Franchino-Viñas (Universität Heidelberg - Universidad Nacional de La Plata)
- Markus B. Fröb (ITP, Universität Leipzig)
Quantum field theory in curved spacetimes and perturbative quantum gravity: Monday block 2
- Sebastián Franchino-Viñas (Universität Heidelberg - Universidad Nacional de La Plata)
- Markus B. Fröb (ITP, Universität Leipzig)
Quantum field theory in curved spacetimes and perturbative quantum gravity: Thursday block 1
- Sebastián Franchino-Viñas (Universität Heidelberg - Universidad Nacional de La Plata)
- Markus B. Fröb (ITP, Universität Leipzig)
Quantum field theory in curved spacetimes and perturbative quantum gravity: Thursday block 2
- Markus B. Fröb (ITP, Universität Leipzig)
- Sebastián Franchino-Viñas (Universität Heidelberg - Universidad Nacional de La Plata)
Description
The theory of quantum field theory in curved spacetimes and the perturbative (effective field theoretic) approach to quantum gravity provide one of the most effective and developed joint descriptions of matter and gravity. This session is devoted to the discussion of their formal aspects and their applications to describe phenomena in cosmology and astrophysics, including (but not limited to) the energy-momentum tensor and the semiclassical Einstein equations, symmetries and anomalies, QFT in de Sitter space, effective actions and the renormalization group.
Even classical scalar fields, non-minimally coupled with the curvature, can violate energy conditions such as the null energy condition. In the context of quantum field theory, non-minimally coupled scalars can obey lower bounds, known as quantum energy inequalities, but these are always state dependent. In this talk I will discuss classical and quantum bounds on the null energy and consider...
We construct boson star configurations in quantum field theory using the semiclassical gravity approximation. Restricting our attention to the static case, we show that the semiclassical Einstein-Klein- Gordon system for a single real quantum scalar field whose state describes the excitation of N identical particles, each one corresponding to a given energy level, can be reduced to the...
In this talk we show that the relevant physical information in the construction of a vacuum state is encoded in the selection of a Lagrangian subspace of the space of complexified solutions. In particular we show the existence of a one-to-one correspondence between vacuum states for qft in curved spacetime and Lagrangian subspace. This result implies a unification of a general notion of...
Conformal Field Theory in momentum space allows to investigate effective actions related to the Trace Anomaly of the Stress energy Tensor in great detail. The resulting action is nonlocal and can be investigated in general metric backgrounds. The method of reconstruction of the action is worked out, in our analysis, both around flat spacetime and for general backgrounds, by comparing the...
The trace anomaly is the breaking of Weyl ($\sim$ scale) invariance upon quantisation of a theory, and occurs in a gauge and/or gravitational background. The presence of the parity violating Pontryagin densities $R\tilde R$ and $F\tilde F$ in the trace anomaly could have far reaching phenomonological consequences, and have been the subject of debates over the past decade.
In our latest work...
Functional flow equations based on proper-time (PT) regulators have attracted much interest in recent years because of their effectiveness in various non-perturbative situations, for example the exploration of the ordered phase in a scalar theory or non-perturbarive quantum gravity. In this talk in particular we study the flow of the non-local truncation in quantum gravity and we focus in...
We present an approach to field quantization in curved spacetime which is based on the De Donder-Weyl Hamiltonian theory where space and time dimensions are treated on an equal footing. This leads to a description in terms of Clifford algebra valued wave functions on the bundle of field variables an spacetime variables, and a Dirac-like analog of the Schroedinger equation for this universal...
This talk presents a new avenue to black hole evaporation using a heat-kernel approach in the context of effective field theory analogous to deriving the Schwinger effect. Applying this method to an uncharged massless scalar field in a Schwarzschild spacetime, we show that spacetime curvature takes a similar role as the electric field strength in the Schwinger effect. We interpret our results...
We study the spontaneous breaking of diffeomorphism invariance using the proper-time non-perturbative flow equation in quantum gravity. In particular, we analyze the structure of the UV critical manifold of conformally reduced Einstein-Hilbert theory and study the occurrence of a non-trivial minimum for the conformal factor at Planckian energies. We argue that our result can be interpreted as...
We develop a non-conventional description of the vacuum energy in quantum field theory in terms of quantum entropy. Precisely, we show that the vacuum energy of any non-interacting quantum field at zero temperature is proportional to the quantum entropy of the qubit degrees of freedom associated with virtual fluctuations. We prove this for fermions first and then extend the derivation to...
Quantum entanglement harvesting (EH) in the relativistic setup has recently attracted much attention. The formulation studies the possibility of two uncorrelated Unruh-DeWitt detectors getting entangled over time due to the effects of quantum vacuum fluctuations, depending on the motion and the background spacetimes. We investigate the effects of field temperature $T^{(f)}$ on EH between two...
The propagation of electromagnetic waves in vacuum is commonly modeled within the geometric optics approximation according to which light rays follow null geodesics. This is a sensible model whenever the wavelength is much smaller than the characteristic length scale of the medium through which it propagates since distinct wave phenomena such as diffraction are negligible in this case....
In this talk, I will describe a theory for scalar QED near the black hole event horizon. In particular, I will show how to compute the electromagnetic eikonal S-matrix from elastic 2 → 2 scattering of charged particles exchanging soft photons in the black hole eikonal limit. The resulting ladder resummation agrees perfectly with the result from the first quantised formalism developed by ’t...
The knowledge of what entered them is completely lost as black holes evaporate. This contradicts the unitarity principle of quantum mechanics and is referred to as the information loss paradox. Understanding the end stages of black hole evaporation is key to resolving this paradox. As a first step, we need to have exact models that can mimic 4-D black holes in General relativity in classical...
Black holes are fascinating objects in nature. Although they are introduced as classical solutions in general relativity, their intrinsic nature should be quantum, which manifests during the black hole formation and evaporation processes. If string theory is claimed to be a quantum gravity candidate, it should be able to provide a consistent picture and elucidate some perspectives for black...
We review some recent advances in connection with the energy-momentum tensor and the semiclassical Einstein equations, symmetries and anomalies, effective actions, the renormalization group and other questions in the context of quantum field theory in curved spacetime.
Inspired by the pioneering 1968 work of L Parker, demonstrating matter quanta production in a dynamical spacetime background, we consider production of scalar quanta in a gravitational wave background. Choosing the spacetime to be a flat spacetime perturbed linearly by a linear gravitational wave, we show that scalar particles may indeed be produced in a perturbative manner. Our formulation is...
