Semiclassical S-matrix and black hole entropy in dilaton gravity

We use complex semiclassical method to compute scattering amplitudes of a point particle in dilaton gravity with a boundary. This model has nonzero minimal black hole mass $M_{cr}$. We find that at energies below $M_{cr}$ the particle trivially scatters off the boundary with unit probability. At higher energies the scattering amplitude is exponentially suppressed. The corresponding semiclassical solution is interpreted as formation of an intermediate black hole decaying into the final-state particle. Relating the suppression of the scattering probability to the number of the intermediate black hole states, we find an expression for the black hole entropy consistent with thermodynamics. In addition, we fix the constant part of the entropy which is left free by the thermodynamic arguments. We rederive this result by modifying the standard Euclidean entropy calculation.Comment: 33 pages, 9 figure

Light-shining-through-wall cavity setups for probing ALPs

We discuss the aspects of axion-like-particles (ALPs) searches with Light-Shining-through-Wall (LSW) experimental setups consisted of two radio-frequency cavities. We compare the efficiencies of three setups which involve the cavity pump modes and external magnetic fields. Additionally, we discuss the sensitivity dependence both on the relative position of two cylindrical cavities and on their radius-to-length ratio.Comment: 9 pages, 6 figures, 1 table. Revised version, accepted to JETP Letter

Preface: “Quarks-2016”, 19th International Seminar on High Energy Physics

The highlights of the most recent CMS results with 13 TeV data will be presented in this overview. The Standard Model precision measurements, including the top quark production, will be shown first. This will be followed by the presentation of Higgs boson studies with the early 13 TeV data. Then the focus will shift to searches for physics beyond the Standard Model, including the searches for several Supersymmetric scenarios, using different analysis techniques. The talk will conclude with searches for the exotic resonances, with an emphasis on studies of the high-mass diphoton production

Black bounces and remnants in dilaton gravity

We propose a family of dilaton gravity models possessing bouncing solutions with interiors connecting separate asymptotically flat regions. We demonstrate that inner Cauchy horizons are stable given certain initial conditions. We study causal structure and evaluate thermodynamic properties of black bounces using Euclidean methods. Extremal bounces have zero temperature and can be considered as remnants. We speculate that quantum fluctuations can dissolve event horizons in case of black bounces providing a possible resolution to the information paradox.Comment: 17 pages, 5 figure

Failure of mean-field approximation in weakly coupled dilaton gravity

We investigate black hole evaporation in a weakly coupled model of two-dimensional dilaton gravity paying a particular attention to the validity of the semiclassical mean-field approximation. Our model is obtained by adding a reflecting boundary to the celebrated RST model describing N gravitating massless scalar fields to one-loop level. The boundary cuts off the region of strong coupling. Although our model is explicitly weakly coupled, we find that the mean field approximation inevitably fails at the end of black hole evaporation. We propose an alternative semiclassical method aiming at direct calculation of S-matrix elements and illustrate it in a simple shell model

Signatures of chaos and non-integrability in two-dimensional gravity with dynamical boundary

We propose a model of two-dimensional dilaton gravity with a boundary. In the bulk our model coincides with the classically integrable CGHS model; the dynamical boundary cuts of the CGHS strong-coupling region. As a result, classical dynamics in our model reminds that in the spherically-symmetric gravity: wave packets of matter fields either reflect from the boundary or form black holes. We find large integrable sector of multisoliton solutions in this model. At the same time, we argue that the model is globally non-integrable because solutions at the verge of black hole formation display chaotic properties

Exact solutions and critical chaos in dilaton gravity with a boundary

Abstract We consider (1 + 1)-dimensional dilaton gravity with a reflecting dynamical boundary. The boundary cuts off the region of strong coupling and makes our model causally similar to the spherically-symmetric sector of multidimensional gravity. We demonstrate that this model is exactly solvable at the classical level and possesses an on-shell SL(2, ℝ) symmetry. After introducing general classical solution of the model, we study a large subset of soliton solutions. The latter describe reflection of matter waves off the boundary at low energies and formation of black holes at energies above critical. They can be related to the eigenstates of the auxiliary integrable system, the Gaudin spin chain. We argue that despite being exactly solvable, the model in the critical regime, i.e. at the verge of black hole formation, displays dynamical instabilities specific to chaotic systems. We believe that this model will be useful for studying black holes and gravitational scattering

Preface: “Quarks-2016”, 19th International Seminar on High Energy Physics

The highlights of the most recent CMS results with 13 TeV data will be presented in this overview. The Standard Model precision measurements, including the top quark production, will be shown first. This will be followed by the presentation of Higgs boson studies with the early 13 TeV data. Then the focus will shift to searches for physics beyond the Standard Model, including the searches for several Supersymmetric scenarios, using different analysis techniques. The talk will conclude with searches for the exotic resonances, with an emphasis on studies of the high-mass diphoton production