December 4 (Wed.)
- Yoonbai Kim
Title : Inhomogeneous Field Theories
Abstract : Inhomogeneous field theories with impurity terms are discussed in both relativistic and nonrelativistic regimes. The models of consideration include scalar field theory, abelian Higgs, Chern-Simons Higgs, and Maxwell Chern-Simons Higgs. Even when some couplings depend on spatial coordinates, supersymmetry and BPS structure are preserved. First, we find a new minimum energy configuration depending on spatial coordinates with non-zero energy density, magnetic field, and sometimes angular momentum density. Nevertheless, all the corresponding charges of the obtained vacuum are shown to have zero value, zero energy, zero magnetic flux, and zero spin. Next, variety of solitons, e.g., kinks, vortices, Q-balls, and their hybrids, are also supported in spite of inhomogeneity of arbitrary shape. Noteworthy characters including noninteracting behavior are reported. Finally, non-BPS inhomogeneous vacuum and the effect of impurity to non-BPS solitons are also explained. We conclude this talk with possible field theoretic description of condensed matter systems contaminated by impurity.
- Jeongwon Ho
Title : Quantum Inhomogeneous Field Theory: Unruh-Like Effects and Bubble Wall Friction
Abstract : In this paper, we study a free scalar field in a specific (1+1)-dimensional curve spacetime. Byintroducing an algebraic state that is locally Hadamard, we derive the renormalized Wightman function and explicitly calculate the covariantly conserved quantum energy-momentum tensor up to a relevant order. From this result, we show that the Hadamard renormalization scheme, which has been effective in traditional quantum field theory in curved spacetime, is also applicable in the quantum inhomogeneous field theory. As applications of this framework, we show the existence of an Unruh-like effect for an observer slightly out of the right asymptotic region, as well as a quantum frictional effect on the bubble wall expansion during the electroweak phase transition in the early universe. Consequently, this study validates the consistency of our method for constructing meaningful physical quantities in quantuminhomogeneous field theory.
- Marc Casals
Title : Quantum effects inside rotating black holes
Abstract : Semiclassical gravity, whereby matter fields are quantized and the gravitational field is kept classical, leads to well-known important effects outside black holes such as the emission of quantum (Hawking) radiation. Recently, interesting semiclassical gravity effects inside black holes have also been unveiled. In this talk, we will present some of these effects, including the abrupt expansion, contraction and twisting that observers may experience when approaching the inner Cauchy horizon of rotating black holes, as well as the irregularity of this Cauchy horizon, with consequences for Penrose’s strong Cosmic Censorship hypothesis and the predictability of Einstein’s equations of General Relativity.
December 5 (Thur.)
- Stefan Scopel
Title :
Abstract :
- Shinji Mukohyama
Title : Extending EFT of inflation/dark energy to arbitrary background with timelike scalar profile
Abstract : I extend EFT of inflation/dark energy to arbitrary background with timelike scalar profile. In this framework a set of consistency relations among EFT coefficients ensures the spatial diffeo invariance. Some applications to black holes in the presence of dark energy will also be discussed.
- Temple He
Title : From ’t Hooft to BMS: Connecting Shockwaves and Memories
Abstract : We study the infrared on-shell action of Einstein gravity in asymptotically flat spacetimes, obtaining an effective, gauge-invariant boundary action for memory and shockwave spacetimes. We show that the phase space is in both cases parameterized by the leading soft variables in asymptotically flat spacetimes, thereby obtaining an equivalence between shockwave and soft commutators. We then demonstrate that our on-shell action is equal to three quantities studied separately in the literature: (i) the soft supertranslation charge; (ii) the shockwave effective action; and (iii) the soft effective action.
- Changhyun Ahn
Title : The (extended) supergravity, the supersymmetric $w_{1+\infty}$ symmetry and the celestial holography
Abstract : I will discuss about the three subjects, the (extended) supergraviy, the supersymmetric $w_{1+\infty}$ symmetry and the celestial holography. After introducing the basic ideas for these three different subjects, I will describe the main results on the recent paper(2407.05601).
- Kyung Kiu Kim
Title : Black Hole Chemistry Knows Extra Dimensions
Abstract : In this work, we study the black hole chemistry with extra dimensions. Our primary system is an Einstein-Yang-Mills-Maxwell theory in 8 dimensions, including four extra ones. We demonstrate how the extra-dimension size affects the black hole size distribution in the 4-dimensional Einstein frame via the black hole chemistry. Therefore, the size data of black holes can be utilized to infer the extra-dimension size. In addition, we discuss the zeroth-order phase transition in the 4-dimensional Kerr-AdS black hole.
- Martti Jarvinen
Title : Phases and Phase transitions of U(1)xSU(2) symmetric holographic matter
Abstract : Holographic CFTs with U(1)xSU(2) symmetry are relevant both for condensed matter and QCD applications. It is known that theories with an SU(2) symmetry and an "isospin" chemical potential may exhibit phases where a p-wave condensate forms spontaneously, breaking the remaining symmetries partially or completely. We carry out a systematic classification and analysis of such phases in the U(1)xSU(2) symmetric case with both the U(1) and the isospin chemical potential in 2+1 and 3+1 boundary dimensions, by using the simplest holographic action, namely Einstein-Yang-Mills (YM) theory with a negative cosmological constant.
- Gong-Show
1. Pavan Dharanipragada (IIT Madras) :
“Holographic RG from Exact RG”
2. Theodoros Nakas (IBS-CTPU-CGA) :
“Black holes with primary scalar hair”
3. Hyeonmo Koo (UOS) :
“Dynamical Friction on Circular Orbit in Self-Interacting Ultra-Light Dark Matter and Fornax Globular Clusters”
4. Toshali Mitra (APCTP) :
“Gubser flow in holographic conformal field theory.”
5. Krzysztof Jodlowski (IBS-CTPU-PTC) :
“Clockwork-inspired extra dimension with general warping”
6. Stephen Angus (CQUeST) :
“Perturbations in O(D,D) string cosmology from double field theory”
December 6 (Fri.)
- Yun Soo Myung
Title : Scalarized black holes
Abstract : We review scalarized black holes obtained from spontaneous to non-linear scalarization in the Einstein-Maxwell-scalar theory with a non-minimal coupling function. These scalarized black holes are obtained by evading no-hair and noble no-hair theorems. Infinite branches of scalarized black holes are found from spontaneous scalarization when the tachyonic instability plays the role of the onset for spontaneous scalarization, while few branches of scalarized black holes are obtained from non-linear scalarization for fixed coupling parameter when the tachyonic instability is absent. Finally, we discuss scalarization of Schwarzschild black hole which violates the weak energy condition in the Einstein-Klein-Gordon theory with a negative potential.
- Shuang-Yong Zhou
Title : Positivity bounds moment problems and UV reconstruction
Abstract : Positivity bounds in effective field theories (EFTs) can be extracted through the moment problem approach, utilizing well-established results from the mathematical literature. We generalize this formalism using the matrix moment approach to derive positivity bounds for theories with multiple field components. The sufficient conditions for obtaining optimal bounds are identified and applied to several example field theories, yielding results that match precisely the numerical bounds computed using other methods. The upper unitarity bounds can also be easily harnessed in the matrix case. Furthermore, the moment problem formulation also provides a means to reverse engineer the UV spectrum from the EFT coefficients, often uniquely, as explicitly demonstrated in examples such as string amplitudes and the stu kink theory.
- Miok Park
Title : Hairy Black Holes by Spontaneous Symmetry Breaking
Abstract : We study hairy black hole solutions in Einstein(-Maxwell)-scalar-Gauss Bonnet theory. The scalar coupling function includes quadratic and quartic terms, so the gravitational action has a U(1) symmetry. We argued that when the effective mass of the scalar field is at the critical value, hairy black holes are generated in a symmetry-broken vacuum via spontaneous symmetry breaking. These hairy black holes are stable under scalar perturbations (quasi-normal modes), and the Goldstone bosons are trivial. Moreover, we found that the spontaneous symmetry breaking (SSB) associated with local U(1) is unlikely to occur within this theory.
- David Kubiznak
Title : Regular black holes: from non-linear electrodynamics to pure gravity models
Abstract : It is well known that (static) regular black hole spacetimes can be sourced by appropriately chosen theories of non-linear electrodynamics. More recently, it was shown that many such models can also be obtained as solutions of vacuum gravity equations, upon considering an infinite series of quasi-topological higher-curvature corrections. After reviewing both these approaches, I will show that the latter construction can be upgraded to yield regular black holes with vanishing inner horizon surface gravity -- a necessary condition for the absence of classical instabilities associated with mass inflation on the inner horizon.
- Hideki Maeda
Title : Fake Schwarzschild and Kerr black holes
Abstract : We present exact solutions describing a fake Schwarzschild black hole that cannot be distinguished from the Schwarzschild black hole by observations. They are constructed by attaching a spherically symmetric dynamical interior solution with a matter field to the Schwarzschild exterior solution at the event horizon without a lightlike thin shell. The dynamical region inside a Killing horizon of a static spherically symmetric perfect-fluid solution obeying an equation of state $p=\chi\rho$ for $\chi\in[-1/3,0)$ can be the interior of a fake Schwarzschild black hole. The matter field inside such a black hole is an anisotropic fluid that violates at least the weak energy condition and can be interpreted as a spacelike (tachyonic) perfect fluid. We also present a model of fake Kerr black holes whose interior is filled with a different matter field violating only the dominant energy condition near the event horizon.
- Roman Konopolya
Title : The sound of the event horizon
Abstract : During the ringdown phase of a gravitational signal emitted by a black hole, the least damped quasinormal frequency dominates. If modifications to Einstein’s theory induce noticeable deformations of the black-hole geometry only near the event horizon, the fundamental mode remains largely unaffected. However, even a small change near the event horizon can significantly impact the first few overtones, providing a means to probe the geometry of the event horizon. Overtones are stable against small deformations of spacetime at a distance from the black hole, allowing the event horizon to be distinguished from the surrounding environment. In contrast to echoes, overtones make a much larger energy contribution. These findings open up new avenues for future observations.
- Special Session : “Prof. Myung Yun Soo”
December 7 (Sat.)
- Gungwon Kang
Title : Close black hole encounters, non-merging ringdowns and test of strong gravitational interactions
Abstract : A perturbed black hole produces characteristic radiations whose frequencies possess some physical information of the black hole such as its mass and angular momentum. We have investigated close hyperbolic encounters of two black holes. In addition to the single burst signal associated with the hyperbolic passage, a non-merging ringdown gravitational radiation has been found for the first time. This new type of gravitational waveforms turns out to be due to the tidal deformations of individual constituent black holes through strong gravitational interactions. We briefly report the main results of this phenomenon, and discuss implications on astrophysical observability and testing horizon dynamics in black hole scattering.
- Hyun Seok Yang
Title : On the Number of Gravitons Radiated from Inspiral Blackhole Binary
Abstract : We discuss the dynamics and gravitational wave emission of compact binary systems during the nonrelativistic inspiral of two black holes or point masses. The understanding of how eccentricity influences graviton emission can help predict the gravitational wave signatures from blackhole or neutron star mergers, which are crucial for multi-messenger astronomy, and improve the accuracy of gravitational wave event predictions.
- Rinku Maji
Title : Topological Defects in Beyond the Standard Models, Gravitational Waves and Pulsar Timing Data
Abstract : Topological defects such as monopoles, cosmic strings, domain walls, and various composite structures can be produced during phase transitions in the early Universe in Beyond the Standard Model (BSM) theories. Composite structures such as monopoles connected by strings and walls bounded by strings (WBS) can be formed in BSM theories such as the grand unified theories (GUTs) depending on the symmetry breaking patterns. We will discuss the formation of a network of `quasi-stable' strings (QSS) in the former case. The gravitational radiation emitted in the early universe by QSS with a dimensionless string tension $G\mu\sim 10^{-6}$, is compatible with the exciting evidence of low-frequency (nanoHz) gravitational background in PTA data, as well as the recent LIGO-VIRGO constraints, provided the superheavy strings and monopoles experience a certain amount of inflation. Finally, we discuss an SO(10) model where a dimension five operator induces kinetic mixing between the abelian subgroups at the unification scale. We discuss gauge coupling unification and proton decay in this model, as well as the appearance of superheavy quasistable strings, which can explain the PTA data.
- Mu-In Park
Title : Discovering Rotating Black Hole Solutions in a Viable Lorentz-Violating Gravity
Abstract : I will explain our recent work on the exact solutions for rotating black holes in a viable Lorentz-Violating Gravity which is a low-energy limit of Horava Gravity.
