Charged black holes arise as solutions of General Relativity (GR) coupled to Maxwell theory. As functions of the mass and charge, they can exhibit extremal behavior, in which case they are stable against thermal decay. (Quantum) corrections to GR are expected to alter the classical features of these objects, especially near extremality. To capture such effects in a model-independent way, we extend the Effective Metric Description (EMD) previously introduced in (Del Piano et al. in Phys Rev D 109(2):024045, 2024, , [gr-qc]; Eur Phys J C 84(12):1273, 2024, , [gr-qc]) for spherically symmetric and static black holes. The EMD parametrizes deformations of the metric in terms of physical quantities, such as the radial spatial distance to the event horizon. While the latter is still viable for non-extremal charged black holes, we argue that the proper time of a free-falling observer is better suited in the extremal case: we derive the necessary conditions for the parameters of such an EMD for constructing a consistent space-time in the vicinity of the (extremal) horizon. Finally, we illustrate our framework through a concrete example, and mention implications of the Weak Gravity Conjecture on the effective metric parameters.

Denmark

Mattia Damia Paciarini

Italy

Manuel Piano

France

Stefan Hohenegger

Francesco Sannino

Effective metric description of charged black holes

We unveil the impact of the $\textit{θ}$-angle on the QCD phase diagram at nonzero isospin and strangeness chemical potentials for three light flavors and different quark mass ratios. We establish the phase boundaries as well as the nature of the associated phase transitions. The order parameters and the physical spectrum in the different phases are determined. We further elucidate the physics around $\textit{θ}$ = $\textit{π}$ where we discover a novel parity-preserving superfluid phase. Finally, we comment on Dashen’s phenomenon in the superfluid phases when varying the number of light flavors.

Japan

Jahmall Bersini

Alessandra D’Alise

Clelia Gambardella

On the $\textit{θ}$-angle physics of QCD under pressure: the strange and isospin phase diagram

Gravitational wave observation has provided numerous insights into the merger of astrophysical black holes. In contrast to other violent events ( <italic>e.g.</italic> supernovae), they are, however, not expected to lead to significant emissions of photons and neutrinos. In this paper we discuss a scenario that would lead to characteristic observable gamma ray bursts, which would provide numerous hints to physics beyond General Relativity. Starting from the hypothesis that micro-black holes (called <italic>morsels</italic>) are formed during the merger process, we show that it is possible to observe their Hawking radiation, which takes the form of gamma ray bursts of a uniquely characteristic form: with energies in the TeV range, their temporal structure is unlike that stemming from any other astrophysical event. Notably, the time delay from the gravitational wave event is correlated to the mass distribution of the morsels. The integrated mass of the morsels, allowed by the unaccounted merger mass, leads to a Hawking radiation in photons that is above the sensitivity of atmospheric Cherenkov telescopes such as HESS, LHAASO and HAWC, and gamma ray space telescopes, such as Fermi-LAT. This renders the hypothesis of morsel creation experimentally testable, and we provide the first concrete bounds on the total mass of morsels formed in specific events.

Giacomo Cacciapaglia

Looking for black hole morsels in astrophysical mergers via Hawking radiation

We develop an effective metric description of 2+1 dimensional black holes describing deviations from the classical Ban̈ados–Teitelboim–Zanelli (BTZ) black hole. The latter is a classical 2+1 dimensional rotating black hole with constant negative curvature. The effective metric is constrained by imposing the black hole symmetries and asymptotic classical behavior. The deformed metric is parametrized in terms of a physical quantity that we choose to be a physical distance. The latter can be solved for in three main regions of interest, the one around the horizon, origin, and spatial infinity. The finiteness of physical quantities at the horizon, such as the Ricci and Kretschmann scalars, leads to universal constraints on the physical parameters of the metric around the horizon. This allows us to further derive the general form of the corrected Hawking temperature in terms of the physical parameters of the effective metric. Assuming that the approach can be generalized to the interior of the black hole, we further develop an effective metric description near the origin. To illustrate the approach, we show how to recast the information encoded in a specific model of quantum BTZ known as quBTZ black hole in terms of the effective metric coefficients.

Mikołaj Myszkowski

Effective metric description of 2+1 dimensional quantum black holes

<p>We determine the scaling dimension <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Δ</mi><mi>n</mi></msub></math> for the class of composite operators <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>ϕ</mi><mi>n</mi></msup></math> in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>λ</mi><msup><mi>ϕ</mi><mn>4</mn></msup></math> theory in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi><mo>=</mo><mn>4</mn><mo>−</mo><mi>ε</mi></math> taking the double scaling limit <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>n</mi><mo stretchy="false">→</mo><mi>∞</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>λ</mi><mo stretchy="false">→</mo><mn>0</mn></math> with fixed <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>λ</mi><mi>n</mi></math> via a semiclassical approach. Our results resum the leading power of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>n</mi></math> at any loop order. In the small <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>λ</mi><mi>n</mi></math> regime we reproduce the known diagrammatic results and predict the infinite series of higher-order terms. For intermediate values of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>λ</mi><mi>n</mi></math> we find that <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Δ</mi><mi>n</mi></msub><mo>/</mo><mi>n</mi></math> increases monotonically approaching a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">(</mo><mi>λ</mi><mi>n</mi><msup><mo stretchy="false">)</mo><mrow><mn>1</mn><mo>/</mo><mn>3</mn></mrow></msup></math> behavior in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>λ</mi><mi>n</mi><mo stretchy="false">→</mo><mi>∞</mi></math> limit. We further generalize our results to neutral operators in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>ϕ</mi><mn>4</mn></msup></math> in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi><mo>=</mo><mn>4</mn><mo>−</mo><mi>ε</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>ϕ</mi><mn>3</mn></msup></math> in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi><mo>=</mo><mn>6</mn><mo>−</mo><mi>ε</mi></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>ϕ</mi><mn>6</mn></msup></math> in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi><mo>=</mo><mn>3</mn><mo>−</mo><mi>ε</mi></math> theories with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>O</mi><mo stretchy="false">(</mo><mi>N</mi><mo stretchy="false">)</mo></math> symmetry.</p>

Croatia

Oleg Antipin

Exact results for scaling dimensions of neutral operators in scalar conformal field theories

<p>We investigate high and low energy implications of a gauge dual description of the Standard Model. The high energy electric theory features gauge dynamics involving only fermionic matter fields, while the low energy magnetic description features a quasisupersymmetric spectrum testable at colliders. The flavor theory is constructed via operators generated at the Planck scale, possibly by gravitational global symmetry breaking interactions. We further show that duality opens novel avenues for theories of grand unification.</p>

Charting standard model duality and its signatures

In a recent work (Del Piano et al. in Phys Rev D 109(2):024045, 2024), we have described spherically symmetric and static quantum black holes as deformations of the classical Schwarzschild metric that depend on the physical distance to the horizon. We have developed a framework that allows us to compute the latter in a self-consistent fashion from the deformed geometry, in the vicinity of the horizon. However, in this formalism, the distance can be replaced by other physical quantities, e.g. curvature invariants such as the Ricci- or Kretschmann scalar. Here, we, therefore, define a more general framework, which we call an (EMD), that captures the deformed geometry based on a generic physical quantity. We develop in detail the Ricci- and Kretschmann scalar EMD, in particular demonstrating how to compute the geometry in a self-consistent manner. Moreover, we provide explicit relations that allow us to express one EMD in terms of the others, thus demonstrating their equivalence.

Effective metric descriptions of quantum black holes

We systematically analyze the impact of dilatonic dynamics on Skyrme spheres, crystals, and branes. The effects of the dilatonic model parameters, encompassing different underlying near-conformal dynamics, on the macroscopic properties of skyrmions such as their mass and radius are discussed. For spheres and crystals we identify special values of the ratio of the decay constants for which the second order differential equations reduce to a solvable first order system. Additionally, in the case of the crystals, the dilaton presence spatially separates the baryon and isospin charge distributions. For branes, we show how the dilaton smooths out their configurations. Our results are expected to have wide implications from the study of near-conformal dynamics stemming from QCD-like theories to phenomenological investigations of nuclear matter in extreme regimes.

Belgium

Matías Torres

Dilatonic dynamics of baryonic crystals, branes, and spheres

Upon introducing a heavy quark in the perturbative regime of the QCD conformal window we precisely determine the associated heavy meson spectrum and wave functions in terms of the number of light flavors and mass. We then compute the conformal Isgur-Wise function which is a central quantity in heavy quark physics. We further determine the impact of the residual low energy confining dynamics on the heavy meson spectrum. As a working framework, we adapt the heavy quark effective theory to the perturbative conformal window dynamics. Our work lays the foundations to systematically go beyond the infinite mass defect approximation in conformal field theories.

Vigilante Di Risi

Davide Iacobacci

Defect induced heavy meson dynamics in the QCD conformal window

We re-consider recent measures of <math><msub><mrow><mi>R</mi></mrow><mrow><mi>K</mi></mrow></msub></math> and <math><msub><mrow><mi>R</mi></mrow><mrow><msup><mrow><mi>K</mi></mrow><mrow><mo>⁎</mo></mrow></msup></mrow></msub></math>, now compatible with the Standard Model expectations, as well as the results for the process <math><mtext>BR</mtext><mo>(</mo><msub><mrow><mi>B</mi></mrow><mrow><mi>s</mi></mrow></msub><mo>→</mo><msup><mrow><mi>μ</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>μ</mi></mrow><mrow><mo>−</mo></mrow></msup><mo>)</mo></math> alongside earlier determinations of <math><msub><mrow><mi>R</mi></mrow><mrow><msup><mrow><mi>D</mi></mrow><mrow><mo>(</mo><mo>⁎</mo><mo>)</mo></mrow></msup></mrow></msub></math> and <math><mtext>BR</mtext><mo>(</mo><msub><mrow><mi>B</mi></mrow><mrow><mi>c</mi></mrow></msub><mo>→</mo><mi>τ</mi><mi>ν</mi><mo>)</mo></math>. We provide analytic constraints on the associated Wilson coefficients in both the <math><mi>b</mi><mo>→</mo><mi>s</mi></math> and the <math><mi>b</mi><mo>→</mo><mi>c</mi></math> sectors. These allow us to estimate the scale of potential New Physics for generic extensions of the Standard Model. We then use the results to constrain the leptoquark landscape.