We investigate the thermodynamics and phase structure of the deformed AdS-Schwarzschild black hole, generated via the gravitational decoupling (GD) method. In the bulk canonical ensemble, our results exhibit a van der Waals-type first-order phase transition in addition to the Hawking-Page transition, in the suitable parameter regime. Further, we compute the critical exponents characterising the bulk transition, confirming their consistency with mean-field theory predictions. Exploiting the exact holographic dictionary between extended black hole thermodynamics and the dual conformal field theory (CFT), we extend this analysis to the boundary and uncover a rich array of phase transitions and critical phenomena across three distinct thermodynamic ensembles. In particular, in the fixed <math altimg='si78.svg'><mrow><mo>(</mo><mi mathvariant='script'>V</mi><mo>,</mo><mi>C</mi><mo>)</mo></mrow></math> ensemble, the dual CFT exhibits a Hawking-Page-type transition. However, in the fixed ( <italic>p, C</italic>) ensemble, the deformation parameter leads to a distinct thermodynamic behaviour in which multiple branches become unstable, leaving a single thermodynamically stable phase, thus marking a clear departure from the standard van der Waals scenario. Throughout, we emphasise the pivotal influence of the GD deformation parameter on the thermodynamic behaviour, and we elucidate its role in the confinement-deconfinement transitions characteristic of the deformed AdS-Schwarzschild geometry.

India

Kamal L. Panigrahi

Balbeer Singh

Holographic extended thermodynamics of deformed AdS-Schwarzschild black hole

<list id='lst0001'><list-item id='lstitem0001'><label>&#8226;</label><para id='p0001'><italic>f</italic>(<italic>G</italic>) Gravity.</para></list-item><list-item id='lstitem0002'><label>&#8226;</label><para id='p0002'>Bulk viscous cosmological model.</para></list-item><list-item id='lstitem0003'><label>&#8226;</label><para id='p0003'>Bianchi type III cosmological model.</para></list-item></list>

Nihir Basumatary

Mukunda Dewri

Derphungshar Basumatary

Investigating accelerating bulk viscous cosmological model universe in <italic>f</italic>( <italic>G</italic>) gravity

A representation of the <math altimg='si1.svg'><mrow><mi mathvariant='fraktur'>so</mi><mo>(</mo><mn>2</mn><mo>,</mo><mn>5</mn><mo>)</mo></mrow></math> algebra corresponding to the continuous spin field in <bold>AdS<inf>6</inf></bold> is considered. The algebra is realized using the Lie-Lorentz derivative, which naturally incorporates <bold>AdS<inf>6</inf></bold> geometry and spin degrees of freedom. Within this framework, we derive explicit expressions for the Casimir operators in terms of both the covariant derivative and spin invariants. The continuous spin representation under consideration is defined by a system of operator constraints that generalize those known for six-dimensional Minkowski space. We demonstrate that these constraints completely fix all Casimir operators of the <math altimg='si1.svg'><mrow><mi mathvariant='fraktur'>so</mi><mo>(</mo><mn>2</mn><mo>,</mo><mn>5</mn><mo>)</mo></mrow></math> algebra with eigenvalues determined by the dimensional real parameter <bold><italic>&#956;</italic></bold> and the positive (half-)integer <italic>s</italic>.

Russia

Anastasia A. Golubtsova

Mikhail A. Podoinitsyn

Continuous spin field in the <bold>AdS<inf>6</inf></bold> space

We investigate the quantum nature of naked curvature singularities in Einstein-Yang-Mills (EYM) theory using the Horowitz-Marolf (HM) criterion, which assesses quantum singularities via the evolution of quantum scalar fields. Focusing on timelike singularities in spacetime dimension <italic>D</italic>&#8239;&#8805;&#8239;5, we analyze both pure Yang-Mills and Einstein-Maxwell-Yang-Mills (EMYM) solutions. We then incorporate higher curvature corrections through Gauss-Bonnet (GB) terms. From positivity requirement the expression under square root that arises in GB may create a secondary singularity that shall be scrutinized carefully. Our analysis reveals that while EYM and EMYM spacetimes remain quantum mechanically singular, the inclusion of GB corrections can, in general, render the singularity quantum mechanically regular for specific values of the mass parameter <italic>m</italic>, which is related to the YM charge <italic>Q</italic> in <math altimg='si1.svg'><mrow><mi>D</mi><mo linebreak='goodbreak'>=</mo><mn>5</mn></mrow></math> space-time dimensions. Contrary, for space-time dimension <italic>D</italic>&#8239;&#8805;&#8239;6, although the outer (secondary) singularity may be healed quantum mechanically for certain values of the mass parameter <italic>m</italic>, the central singularity remains quantum mechanically singular.

Türkiye

Mert Mangut

Özay Gürtuğ

Mustafa Halilsoy

Quantum probe to the higher dimensional Yang-Mills singularity

In this work, we explore wave optics in four-dimensional static traversable wormhole spacetimes, considering both vacuum and non-vacuum configurations embedded with topological features such as a cosmic string and a point-like global monopole. We begin by examining the influence of a cosmic string on wave propagation, focusing on the scalar Helmholtz wave equation, and show that the resulting modified potential is purely repulsive. We analyze the characteristics of this potential, demonstrating its dependence on the wormhole throat radius and the cosmic string parameter. Using this potential, we derive an expression for the effective refractive index, illustrating how it is influenced by these geometrical and topological factors. We then extend our study to a non-vacuum traversable wormhole spacetime incorporating a point-like global monopole. A similar wave-optical analysis is performed, yielding the corresponding effective potential and refractive index. We show that both the wormhole throat radius and the global monopole parameter significantly affect these optical properties. Finally, we investigate wave optics in a three-dimensional static vacuum traversable wormhole with disclinations. By solving the Helmholtz wave equation, we derive the effective potential and refractive index, showing how these quantities are modified by the presence of disclinations and the wormhole throat. Our results demonstrate that the wormhole throat radius, along with embedded topological features-cosmic string, global monopole, and disclinations-plays a significant role in determining the optical properties of these curved spacetime backgrounds.

Faizuddin Ahmed

Azerbaijan

Algeria

Abdelmalek Bouzenada

Wave optical analysis of traversable wormholes with topological features

We investigate the mutual information harvesting of two circularly accelerated detectors that interact with the massless scalar fields near a reflecting boundary. We consider that the two detectors share a common rotational axis with the same acceleration and trajectory radius. As the interdetector separation increases, the mutual information may exhibit oscillatory behavior at large acceleration and small radius. For a fixed radius, a larger acceleration leads to a larger peak value of the mutual information. Near the boundary, the mutual information may oscillate and the maximum can be obtained. As the acceleration increases, the mutual information in a small interdetector separation first increases and then decreases. For an intermediate interdetector separation, the mutual information may oscillate with the increase of acceleration. For a not large interdetector separation, when we take large acceleration and small radius, as the energy gap increases, the mutual information first decreases, then oscillates, and finally goes to zero. The combination of large acceleration and small radius corresponds to the fast rotation, which significantly modifies the vacuum fluctuations of the field, leading to the oscillatory behavior. Furthermore, the oscillation intensifies near the boundary, which indicates that it is related to the coherent superposition of boundary reflections.

China

Mingkun Quan

Runhu Li

Zixu Zhao

Mutual information harvesting for circularly accelerated detectors

In this work, we construct the color <math altimg='si45.svg'><mrow><mover accent='true'><mn mathvariant='bold'>3</mn><mo>&#175;</mo></mover><mover accent='true'><mn mathvariant='bold'>3</mn><mo>&#175;</mo></mover><mover accent='true'><mn mathvariant='bold'>3</mn><mo>&#175;</mo></mover></mrow></math> type local five-quark currents with the light quarks <italic>qss</italic> in the flavor octet, and study the <math altimg='si46.svg'><mrow><mi>q</mi><mi>s</mi><mi>s</mi><mi>c</mi><mover accent='true'><mi>c</mi><mo>&#175;</mo></mover></mrow></math> pentaquark states via the QCD sum rules in a comprehensive way, and we emphasize that we achieve two light-flavor octets. We obtain the mass spectrum of the hidden-charm-doubly-strange pentaquark states with the isospin-spin-parity <math altimg='si47.svg'><mrow><mi>I</mi><msup><mi>J</mi><mi>P</mi></msup><mo linebreak='goodbreak'>=</mo><mfrac><mn>1</mn><mn>2</mn></mfrac><msup><mrow><mfrac><mn>1</mn><mn>2</mn></mfrac></mrow><mo>&#8722;</mo></msup></mrow></math>, <math altimg='si48.svg'><mrow><mfrac><mn>1</mn><mn>2</mn></mfrac><msup><mrow><mfrac><mn>3</mn><mn>2</mn></mfrac></mrow><mo>&#8722;</mo></msup></mrow></math> and <math altimg='si49.svg'><mrow><mfrac><mn>1</mn><mn>2</mn></mfrac><msup><mrow><mfrac><mn>5</mn><mn>2</mn></mfrac></mrow><mo>&#8722;</mo></msup></mrow></math>, which can be confronted to the experimental data in the future, especially in the process <math altimg='si50.svg'><mrow><msubsup><mstyle mathvariant='normal'><mi>&#926;</mi></mstyle><mi>b</mi><mo>&#8722;</mo></msubsup><mo>&#8594;</mo><msubsup><mi>P</mi><mrow><mi>c</mi><mi>s</mi><mi>s</mi></mrow><mo>&#8722;</mo></msubsup><mi>&#981;</mi><mo>&#8594;</mo><mi>J</mi><mo linebreak='goodbreak'>/</mo><mi>&#968;</mi><msup><mstyle mathvariant='normal'><mi>&#926;</mi></mstyle><mo>&#8722;</mo></msup><mi>&#981;</mi></mrow></math>. As a byproduct, we observe that the lowest hidden-charm pentaquark states are not of the scalar-diquark-scalar-diquark-antiquark type, it is not suitable to refer to the scalar and axialvector diquarks as the &#8220;good&#8221; and &#8220;bad&#8221; diquarks, respectively.

Zhi-Gang Wang

Yang Liu

Analysis of the hidden-charm pentaquark candidates in the <italic>J</italic>/ <italic>&#968;</italic>&#926; mass spectrum via the QCD sum rules

Modern radio interferometers are increasingly challenged by fast transient events, complex radio-frequency interference (RFI), and observing conditions in which near-field and far-field emitters may coexist. Although classical direction-of-arrival (DOA) techniques can achieve high angular resolution, they are often developed for specific array geometries, tend to focus on single-source settings, and usually provide little information about uncertainty. Imaging-based methods, while powerful, are computationally demanding and can introduce delays that are not well suited to real-time transient astronomy.

Halim Zeghdoudi

Fatih Tank

Bayesian polarimetric multi-source direction-of-arrival estimation for transient astronomy with sparse radio interferometric subarrays

In this work, we present the refinement of axion double level crossings within the context of multi-axion mass mixing, specifically focusing on cases where the number of axions exceeds two. Our investigation reveals that double level crossings are a common phenomenon in the mass mixing of the <math altimg='si15.svg'><msub><mi>Z</mi><mi mathvariant='script'>N</mi></msub></math> axion and axion-like particles. Physically, these double level crossings involve a first level crossing at high temperatures followed by a second level crossing induced by the <math altimg='si15.svg'><msub><mi>Z</mi><mi mathvariant='script'>N</mi></msub></math> axion mass transition at <italic>T</italic> <inf>QCD</inf>. We introduce the general model for double level crossings, along with several toy examples, and redefine the light and heavy axion scenarios. In the light axion scenario, double level crossings can occur multiple times in the large <math altimg='si12.svg'><mi mathvariant='script'>N</mi></math> limit. However, excessively large values of <math altimg='si12.svg'><mi mathvariant='script'>N</mi></math> may also prevent the occurrence of double level crossings. Conversely, in the heavy axion scenario, excessively small <math altimg='si12.svg'><mi mathvariant='script'>N</mi></math> may similarly prevent their occurrence. Our findings also have some intriguing implications for axion cosmology.

Hai-Jun Li

Wei Chao

Huai-Ke Guo

Yu-Feng Zhou

Completing axion double level crossings

We investigate the phase-space dynamics of the Barrow Holographic Dark Energy (BHDE) model in a flat Friedmann-Lemaître-Robertson-Walker (FLRW) Universe, considering the non-interacting scenario between dark energy and dark matter. By expressing the cosmological evolution as a dynamical system using suitable dimensionless variables, we identify the critical points and analyze their stability. The phase-line and stream plots illustrate the trajectories of the system, revealing that the Universe evolves naturally from an early-time matter-dominated epoch to a late-time dark energy-dominated accelerated expansion. The stable attractor corresponding to the dark energy-dominated phase confirms the viability of the BHDE model in describing the observed cosmic acceleration without requiring interaction between dark sectors. In addition to the dynamical investigation, we perform an observational analysis using the latest Cosmic Chronometer, DESI DR2, and Pantheon+ datasets to constrain the model parameters and examine the consistency of the non-interacting BHDE model with current cosmological observations. These results highlight the robustness of the non-interacting BHDE framework as a candidate for explaining late-time cosmological dynamics.

L. Sudharani

C.S. Varsha

V. Venkatesha

Phase space analysis of barrow holographic dark energy