<p>This paper demonstrates how the Veneziano partial amplitude of Bosonic string theory admits a generalization to world-(hyper)surfaces of any dimension <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi></math>. In particular, for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi><mo>=</mo><mn>2</mn></math>, by carving up the worldsheet integral according to stipulations imposed on conformal cross ratios, the Virasoro-Shapiro full amplitude can be decomposed into a sum of three partial amplitudes. The amplitudes obtained on generalizing the Veneziano amplitude all contain tachyons. To explore candidate tachyon-free and supersymmetric versions of these amplitudes, a new bootstrap principle is introduced and applied, which demands that towers of residues alternate between all-even and all-odd spin partial waves.</p>

South Korea

Christian Baadsgaard Jepsen

Veneziano amplitude in any dimension and a Virasoro-Shapiro partial amplitude

By numerically solving the general relativistic hydrodynamics (GRH) equations, we investigate quasi-periodic oscillations (QPOs) and accretion dynamics around quantum-corrected black holes (QCBHs). Using the Bondi–Hoyle–Lyttleton (BHL) accretion framework in a quantum-corrected spacetime, we analyze how the black hole spin parameter $\textit{a}$/$\textit{M}$ and the quantum correction parameter $\textit{b}$ influence the shock cone structure, mass accretion rate, and oscillatory behavior of the surrounding plasma. Our results show that although the shock cone forms in every model, its symmetry, geometry, and opening angle are highly sensitive to both parameters. QPO signals extracted from the mass accretion rate at different radial positions reveal the presence of both low-frequency (LFQPOs) and high-frequency QPOs (HFQPOs). In particular, we confirm that oscillation modes such as $$f_{EH}$$ , $$f_{sh}$$ , and $$f_{LT}$$ are trapped inside the cone, with amplitudes and coherence properties that vary systematically with the parameters. While QCBHs share many QPO signatures with classical Kerr black holes, quantum corrections suppress peak amplitudes near the horizon, shift the QPO-generating regions outward, and preserve recognizable resonance patterns such as the 3 : 2 frequency ratio. These results, consistent with both theoretical predictions and observational findings, demonstrate that QCBHs retain key observable features while incorporating quantum gravitational effects. Our findings highlight QPOs as a novel probe of quantum gravity, with implications for future high-resolution observations by the Event Horizon Telescope (EHT) and X-ray binaries (XRBs).

Kuwait

O. Donmez

Accretion dynamics and QPO signatures around quantum-corrected black hole: a comparison with Kerr spacetime

This paper focuses on a conformal block with rank $$ \frac{3}{2} $$ irregular singularity which corresponds to the prepotential of the $$ {\mathcal{H}}_1 $$ Argyres-Douglas theory in Ω background. We derive this irregular conformal block using the generalized holomorphic anomaly recursion relation. This results in an expression which is a power series in Ω-background parameters $\textit{ϵ}$ and exact in coupling. We have verified that in the small coupling regime our result is consistent with previously known expressions.

Armenia

Rubik Poghossian

Hasmik Poghosyan

A note on rank $$ \frac{3}{2} $$ Liouville irregular block

Quantum fluctuations of the spacetime metric induce an uncertainty in the horizon area of a black hole. Working in linearized quantum gravity, we derive the variance in the area of a four-dimensional Schwarzschild black hole from the renormalized graviton propagator. We find that the standard deviation of the horizon area scales as the product of the Schwarzschild radius and the Planck length. For macroscopic black holes, the quantum uncertainty is therefore enormous in Planck units.

United States

Maulik Parikh

Jude Pereira

Quantum uncertainty in the area of a black hole

Multi-particle correlations between azimuthal angle and mean transverse momentum are a powerful tool for probing size and shape correlations in the initial conditions of ultra-relativistic nuclear collisions. These correlations have also been employed to investigate the structure of the colliding nuclei, including potential nuclear shape phase transitions at the energy frontier. However, the direct implementation of these correlations is highly nontrivial, and prior studies have been mostly limited to lower-order correlations, such as the modified Pearson correlation coefficient, $$\rho (v_\textrm{n}^{2}, [p_\textrm{T}])$$ . This paper presents a unified framework that employs a recursive algorithm, enabling the efficient evaluation of arbitrary-order correlations while maintaining computational efficiency. This framework is demonstrated using widely adopted transport models, including AMPT and HIJING. The proposed unified algorithm for multi-particle correlations between azimuthal angle and transverse momentum provides a systematic and efficient approach for multi-particle correlation analyses. Its application in experiments at the Relativistic Heavy Ion Collider and the Large Hadron Collider facilitates the exploration of nuclear structure at ultra-relativistic energies.

Denmark

Emil Nielsen

Nina Nathanson

Kristjan Gulbrandsen

You Zhou

A unified algorithm for multi-particle correlations between azimuthal angle and transverse momentum in ultra-relativistic nuclear collisions

In this work, we reconstruct the $\textit{H}$($\textit{z}$) based on observational Hubble data with Artificial Neural Network, then estimate the cosmological parameters and the Hubble constant. The training data we used are covariance matrix and mock $\textit{H}$($\textit{z}$), which are generated based on the real OHD data and Gaussian process. The use of the covariance matrix propagates the correlated uncertainties and improves training efficiency. Using the reconstructed H(z) data, we first determine the Hubble constant and compare it with CMB-based measurements. To constrain cosmological parameters, we sample on the reconstructed data and calculate the corresponding posterior distributions with Markov chain Monte Carlo. Through comprehensive statistical comparisons, we demonstrate that the parameter estimation using reconstructed samples achieves comparable statistical accuracy to the result derived from real OHD data.

China

Jie-feng Chen

Tong-Jie Zhang

Peng He

Tingting Zhang

Jie Zhang

Estimating cosmological parameters and reconstructing Hubble constant with artificial neural networks: a test with covariance matrix and mock H(z)

We propose a physical scheme of a uniformly accelerated Unruh–DeWitt battery and utilize quantum work extraction as a probe to witness the thermal nature of the Unruh effect induced by the accelerated motion. By employing the open quantum system approach, we analyze the coherent and incoherent components of the ergotropy which is the maximum amount of quantum work extraction of the relativistic battery driven by a coherent field. It has been proved that the steady values of coherent quantum work extraction in the asymptotic condition is only determined by the acceleration-dependent Unruh temperature. The asymptotic behavior of coherent ergotropy can demonstrate the thermal nature of the Unruh effect with respect to the Kubo–Martin–Schwinger condition. Under the circumstance of the Unruh effect, we explore the effect of the phase of the coherent charging field on the dynamics of coherent ergotropy when the battery approaches to the same thermal equilibrium state. The variation in the phase of the coherent driving field can improve the energy storage capacity of a relativistic battery. From viewpoint of energy transfer, the relativistic battery is helpful to examine the Unruh thermality.

Canada

Wei-Wei Zhang

Tian-Xi Ren

Yin-Zhong Wu

Xiang Hao

Coherent quantum work extraction of a relativistic battery as a probe for acceleration-induced Unruh thermality

We present here the first lattice simulation of symplectic quantization, a new functional approach to quantum field theory which allows to define an algorithm to numerically sample the quantum fluctuations of fields directly in Minkowski space-time, at variance with all other present approaches. Symplectic quantization is characterized by a Hamiltonian deterministic dynamics evolving with respect to an additional time parameter $\textit{τ}$ analogous to the fictious time of Parisi-Wu stochastic quantization. The difference between stochastic quantization and the present approach is that the former is well defined only for Euclidean field theories, while the latter allows to sample the causal structure of space-time. In this work we present the numerical study of a real scalar field theory on a 1+1 space-time lattice with a $\textit{λϕ}$ interaction. We find that for $\textit{λ}$ ≪ 1 the two-point correlation function obtained numerically reproduces qualitatively well the shape of the free Feynman propagator. Within symplectic quantization the expectation values over quantum fluctuations are computed as dynamical averages along the dynamics in $\textit{τ}$, in force of a natural ergodic hypothesis connecting Hamiltonian dynamics with a generalized microcanonical ensemble. Analytically, we prove that this $\textit{microcanonical}$ ensemble, in the continuum limit, is equivalent to a $\textit{canonical-like}$ one where the probability density of field configurations is $\textit{P}$ [$\textit{ϕ}$] ∝ exp($\textit{zS}$[$\textit{ϕ}$]/ℏ). The results from our simulations correspond to the value $\textit{z}$ = 1 of the parameter in the canonical weight, which in this case is a well-defined probability density for field configurations in causal space-time, provided that a lower bounded interaction potential is considered. The form proposed for $\textit{P}$ [$\textit{ϕ}$] suggests that our theory can be connected to ordinary quantum field theory by analytic continuation in the complex-$\textit{z}$ plane.

Italy

Martina Giachello

Francesco Scardino

Giacomo Gradenigo

Symplectic quantization: numerical results for the Feynman propagator on a 1+1 lattice and the theoretical relation with quantum field theory

<p>Massless overlap fermions in the real representation of two-dimensional <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>SU</mi><mo stretchy="false">(</mo><msub><mi>N</mi><mi>c</mi></msub><mo stretchy="false">)</mo></math> gauge theories exhibit a mod(2) index due to the rigidity of its spectrum when viewed as a function of the background gauge field—lattice gauge fields on a periodic torus come under two classes: ones that have one set of chirally paired zero modes and ones that do not. Focusing on SU(2) and a single Majorana fermion in an integer representation <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi></math>, we present numerical evidence that shows only one of these classes survives the continuum limit and this depends on the boundary conditions of the fermion and the gauge field. As such, two of the four possible partition functions are zero in the continuum limit. By defining modified partition functions which do not include the zero modes of the overlap fermions in the fermion determinant, we are able to define an expectation value for a fermion bilinear as ratios of two mixed partition functions. This observable is referred to as the topological condensate and has a nonzero expectation value on any finite physical torus and also has a nonzero limit as the size of the torus is taken to infinity. We study the spectral density of fermions and the scaling of the lowest eigenvalue with the size of the torus to show the absence of any spontaneous symmetry breaking but the emergence of zero modes in the infinite volume limit where it is prohibited in finite volume. These results remain the same for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>=</mo><mn>1</mn></math>, 2, 3, and 4. These results motivate us to propose an independent plaquette model which reproduces the correct physics in the infinite volume limit using a single partition function.</p>

Rajamani Narayanan

Ray Romero

Lattice study of two-dimensional SU(2) gauge theories with a single massless Majorana fermion

This work is devoted to examining particle dynamics and thermodynamic behavior of a black hole in the framework of Kalb–Ramond gravity, framing the investigation through the lens of the optical–mechanical analogy. Within this context, we derive a generalized modified dispersion relation, which inherently depends on the underlying spacetime geometry through its metric components. The analysis begins by exploring some physical quantities influenced by the geometry, including the effective index of refraction, the group velocity, and the time delay experienced by particle modes. We then investigate the interparticle potential, considering both massive and massless cases. The thermodynamic properties of the system are subsequently addressed using ensemble theory. In this treatment, we compute the pressure, internal energy, entropy, and heat capacity across three distinct regions: in the immediate vicinity of the event horizon, at the photon sphere, and in the asymptotic region. Notably, all calculations presented throughout this paper admit closed-form $\textit{analytical}$ solutions.

Brazil

A. Filho

Particle motion and thermal effects around a Kalb–Ramond black hole