Quantum black holes and effective quantum gravity approaches
This is the text of the invited talk I have given at the Karl Schwarzschild Meeting in Frankfurt in 2013.
gr-qc↗
arXiv subjects
Xavier Calmet
Publications and source records attributed to Xavier Calmet.
Virtual Black Holes, Remnants and the Information Paradox
We revisit the question of the contributions of Planckian quantum black holes in general and of remnants in particular to low energy physics observables. As long as quantum gravity preserves the symmetries of the low energy effective field theory, we find that the bounds on the number of quantum black holes or remnants are very weak. Typically we rule out using data on the anomalous magnetic moment of the muon that there are more than $10^{32}$ quantum black holes coupled to the standard model particles gravitationally. Remnants thus remain a viable option as a solution to the information paradox of black holes.
gr-qc↗
Quantum Black Holes and their Lepton Signatures at the LHC with CalCHEP
We discuss a field theoretical framework to describe the interactions of non-thermal quantum black holes (QBHs) with particles of the Standard Model. We propose a non-local Lagrangian to describe the production of these QBHs which is designed to reproduce the geometrical cross section for black hole production. This model is implemented into CalcHEP package and is publicly available at the High Energy Model Database (HEPMDB) for simulation of QBH events at the LHC and future colliders. We present the first phenomenological application of the QBH@HEPMDB model with spin-0 neutral QBH giving rise the $e^+e^-$ and $eμ$ signatures at the LHC@8TeV and LHC@13TeV and produce the respective projections for the LHC in terms of limits on the reduced Planck mass and the number of the extra-dimensions.
hep-ph↗
Cosmological Evolution of Fundamental Constants: From Theory to Experiment
In this paper we discuss a possible cosmological time evolution of fundamental constants from the theoretical and experimental point of views. On the theoretical side, we explain that such a cosmological time evolution is actually something very natural which can be described by mechanisms similar to those used to explain cosmic inflation. We then discuss implications for grand unified theories, showing that the unification condition of the gauge coupling could evolve with cosmological time. Measurements of the electron-to-proton mass ratio can test grand unified theories using low energy data. Following the theoretical discussion, we review the current status of precision measurements of fundamental constants and their potential cosmological time dependence.
gr-qc↗
The Lightest of Black Holes
In this paper we consider general relativity in the large $N$ limit, where $N$ stands for the number of particles in the model. Studying the resummed graviton propagator, we propose to interpret its complex poles as black hole precursors. Our main result is the calculation of the mass and width of the lightest of black holes. We show that the values of the masses of black hole precursors depend on the number of fields in the theory. Their masses can be lowered down to the TeV region by increasing the number of fields in a hidden sector that only interacts gravitationally with the standard model.
hep-th↗
Self-healing of unitarity in Higgs inflation
We reconsider perturbative unitarity violation in the standard model Higgs inflation model. We show that the Cutkosky cutting rule implied by perturbative unitarity is fulfilled at one-loop. This is a strong indication that unitarity is restored order by order in perturbation theory. We then resum certain one-loop diagrams and show that the relevant dressed amplitude fulfills the Cutkosky rule exactly. This is an example of the self-healing mechanism. The original Higgs inflation model is thus consistent and does not require any new physics beyond the standard model at least up to the Planck scale.
hep-ph↗
Excursion into Quantum Gravity via Inflation
The discovery of B-modes, and their effect on the fit to inflationary parameters, opens a window to explore quantum gravity. In this paper we adopt an effective theory approach to study quantum gravity effects in inflation. We apply this approach to chaotic and $ϕ^4$ inflation, and find that BICEP2 constrains these new operators to values which are consistent with the effective theory approach. This result opens the possibility to study quantum gravity in a systematic fashion, including its effect on Higgs inflation and other Starobisnky-like models.
hep-ph↗
Back-to-Back Black Holes decay Signature at Neutrino Observatories
We propose a decay signature for non-thermal small black holes with masses in the TeV range which can be discovered by neutrino observatories. The black holes would result due to the impact between ultra high energy neutrinos with nuclei in water or ice and decay instantaneously. They could be produced if the Planck scale is in the few TeV region and the highly energetic fluxes are large enough. Having masses close to the Planck scale, the typical decay mode for these black holes is into two particles emitted back-to-back. For a certain range of angles between the emitted particles and the center of mass direction of motion, it is possible for the detectors to measure separate muons having specific energies and their trajectories oriented at a large enough angle to prove that they are the result of a back-to-back decay event.
hep-ph↗
Effective theory for quantum gravity
In this paper, we discuss an effective theory for quantum gravity and discuss the bounds on the parameters of this effective action. In particular we show that measurement in pulsars binary systems are unlikely to improve the bounds on the coefficients of the $R^2$ and $R_{μν} R^{μν}$ terms obtained from probes of Newton's potential performed on Earth. Furthermore, we argue that if the coefficients of these terms are induced by quantum gravity, they should be at most of order unity since $R^2$ and $R_{μν} R^{μν}$ are dimension four operators. The same applies to the non-minimal coupling of the Higgs boson to the Ricci scalar.
gr-qc↗
Frame Transformations of Gravitational Theories
We show how to map gravitational theories formulated in the Jordan frame to the Einstein frame at the quantum field theoretical level considering quantum fields in curved space-time. As an example, we consider gravitational theories in the Jordan frame of the type $F(ϕ,\, R)=f(ϕ)\, R-V(ϕ)$ and perform the map to the Einstein frame. Our results can easily be extended to any gravitational theory. We consider the Higgs inflation model as an application of our results.
gr-qc↗
Non-thermal quantum black holes with quantized masses
In this paper we discuss non-thermal quantum black holes with a discrete mass spectrum and their possible new signatures at the LHC. We calculate the inclusive cross sections for the production of quantum black holes with discrete masses at the LHC as well as some exclusive cross sections for particularly interesting decay modes.
hep-ph↗
Bounds on the Nonminimal Coupling of the Higgs Boson to Gravity
We derive the first bound on the value of the Higgs boson non-minimal coupling to the Ricci scalar. We show that the recent discovery of the Higgs boson at the Large Hadron Collider at CERN implies that the non-minimal coupling is smaller than $2.6\times 10^{15}$.
hep-ph↗
Quantum Black Holes from Cosmic Rays
We investigate the possibility for cosmic ray experiments to discover non-thermal small black holes with masses in the TeV range. Such black holes would result due to the impact between ultra high energy cosmic rays or neutrinos with nuclei from the upper atmosphere and decay instantaneously. They could be produced copiously if the Planck scale is in the few TeV region. As their masses are close to the Planck scale, these holes would typically decay into two particles emitted back-to-back. Depending on the angles between the emitted particles with respect to the center of mass direction of motion, it is possible for the simultaneous showers to be measured by the detectors.
hep-ph↗
Observable Proton Decay from Planck Scale Physics
In the Standard Model, no dim-5 $ΔB \neq 0$ operators exist, so that Planck-scale-induced proton decay amplitudes are suppressed by at least $1/M^2_{P \ell}$. If the Standard Model is augmented by a light, color-non-singlet boson, then $O(1/M_{P \ell})$ proton-decay amplitudes are possible. These always conserve $B+L$, so that the dominant decay modes are $p \rightarrow Π^+ ν$ and $p \rightarrow Π^+ Π^+ \ell^-$, where $Π^+ = π^+$ or $K^+$.
hep-ph↗
Grand Unification without Higgs Bosons
We discuss how a model for the electroweak interactions without a Higgs could be embedded into a grand unified theory. The requirement of a non-trivial fixed point in the SU(2) sector of the weak interactions together with the requirement of the numerical unification of the gauge couplings leads to a prediction for the value of the SU(2) gauge coupling in the fixed point regime. The fixed point regime must be in the TeV region to solve the unitarity problem in the elastic scattering of W bosons. We find that the unification scale is at about 10^{14} GeV. Viable grand unified theories must thus conserve baryon number. We discuss how to build such a model without using Higgs bosons.
hep-ph↗
Non thermal small black holes
In this chapter we review the current theoretical state of the art of small black holes at the LHC. We discuss the production mechanism for small non thermal black holes at the LHC and discuss new signatures due to a possible discrete mass spectrum of these black holes.
hep-ph↗
On a Formulation of Qubits in Quantum Field Theory
Qubits have been designed in the framework of quantum mechanics. Attempts to formulate the problem in the language of quantum field theory have been proposed already. In this short note we refine the meaning of qubits within the framework of quantum field theory. We show that the notion of gauge invariance naturally leads to a generalization of qubits to QFTbits which are then the fundamental carriers of information from the quantum field theoretical point of view. The goal of this note is to stress the availability of such a generalized concept of QFTbits.
quant-ph↗
Brane World Models Need Low String Scale
Models with large extra dimensions offer the possibility of the Planck scale being of order the electroweak scale, thus alleviating the gauge hierarchy problem. We show that these models suffer from a breakdown of unitarity at around three quarters of the low effective Planck scale. An obvious candidate to fix the unitarity problem is string theory. We therefore argue that it is necessary for the string scale to appear below the effective Planck scale and that the first signature of such models would be string resonances. We further translate experimental bounds on the string scale into bounds on the effective Planck scale.
hep-ph↗