We develop a covariant formulation of Andreev reflection at a normal-metal–superconductor (N-S) interface embedded in a static curved spacetime and specialize to the Schwarzschild exterior. The construction rests on the Bogoliubov–de Gennes (BdG) equations formulated intrinsically on a static hypersurface Σ <inf><italic>t</italic></inf>, with the superconducting gap &#916; treated as a local order parameter and quasiparticle transport encoded in a conserved probability current whose hypersurface flux defines the conductance for an observer at infinity. Using the timelike Killing field to relate proper and asymptotic observables, we derive a gravitationally redshifted Blonder&#8211;Tinkham&#8211;Klapwijk (BTK) formula in which the asymptotic differential conductance depends on the ratio <italic>E</italic> <inf>&#8734;</inf>/&#916; <inf>&#8734;</inf>, where &#916; <inf>&#8734;</inf>&#8239;&#8801;&#8239; <italic>&#945;</italic>&#8201;&#916; <inf>proper</inf> and <math altimg='si37.svg'><mrow><mi>&#945;</mi><mrow><mo>(</mo><mi>r</mi><mo>)</mo></mrow><mo linebreak='goodbreak'>=</mo><msqrt><mrow><mn>1</mn><mo linebreak='badbreak'>&#8722;</mo><msub><mi>r</mi><mi>s</mi></msub><mo linebreak='badbreak'>/</mo><mi>r</mi></mrow></msqrt></mrow></math> is the Schwarzschild lapse. For a transparent interface, the zero-bias conductance doubling that signals Andreev processes survives at all radii, but the energy window over which it operates is compressed by the lapse. Under asymptotic voltage bias, the conductance spectrum retains its flat-space form when expressed in redshifted variables; under local proper bias, the spectrum is reshaped by <italic>&#945;</italic>. In the near-horizon (Rindler) limit, the effective gap seen at infinity vanishes linearly with proper distance, &#916; <inf>&#8734;</inf>&#8733; <italic>&#954;&#961;</italic>, producing a gapless conductance profile reminiscent of a normal-metal junction&#8212;gravity mimics gap suppression. We analyze the excess current, the thermal conductance, the shot noise Fano factor, and the Wiedemann&#8211;Franz ratio, showing that each acquires a definite <italic>&#945;</italic>-scaling that disentangles local constitutive physics from kinematic redshift. Dimensionless transport ratios&#8212;the normalized conductance, the Fano factor, and the Wiedemann&#8211;Franz number&#8212;are shown to be redshift-invariant. The results are gauge- and coordinate-invariant, operationally stated for both proper and asymptotic observers, and remain analytic from the weak-field regime to the near-horizon limit.

Türkiye

İzzet Sakallı

Andreev reflection and the BTK conductance in schwarzschild spacetime

We extend the celestial Roiban-Spradlin-Volovich-Witten (RSVW) formalism developed in our previous work to minitwistor superspace. Using the Drummond-Henn formula for all tree-level amplitudes in <math altimg='si37.svg'><mrow><mi mathvariant='script'>N</mi><mo linebreak='goodbreak'>=</mo><mn>4</mn></mrow></math> supersymmetric Yang-Mills (SYM) theory, we construct tree-level N <italic>k</italic>-MHV celestial leaf amplitudes and show that their minitwistor-Fourier transforms are given by integrals over moduli spaces of families of minitwistor lines. We also adapt the Korchemsky-Sokatchev twistor-transform techniques for gluon amplitudes to the minitwistor-Fourier transforms of leaf amplitudes. We then describe two dynamical formulations of these celestial amplitudes. First, we show that semiclassical correlators of Wilson operators supported on algebraic cycles in minitwistor superspace act as generating functionals for tree-level N <italic>k</italic>-MHV leaf-gluon amplitudes. Second, we analyse a semiclassical minitwistor sigma model, identify its vertex operators, and construct from them celestial gluon operators that close on the <italic>S</italic>-algebra in the semiclassical approximation; their leading-trace semiclassical correlators again reproduce the tree-level N <italic>k</italic>-MHV leaf amplitudes. A companion paper extends this construction beyond tree level, in particular to one-loop amplitudes via a celestial version of the Brandhuber-Spence-Travaglini formalism.

Brazil

Igor Mol

A celestial description of planar super-Yang-Mills theory

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

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

<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

Spin-3/2 Δ baryon resonances are investigated within AdS/QCD, using Rarita–Schwinger fields. The differential configurational entropy (DCE) and differential configurational complexity (DCC) associated with their bulk energy densities are computed. It yields Regge-like trajectories relating configurational information measures to the radial excitation number and the experimental mass spectrum of the Δ baryons. We then extrapolate the spectrum of heavier Δ baryon resonances beyond currently established states in the PDG, also comparing them with states in PDG omitted from the summary table. Our results support a relevant interplay among holographic QCD dynamics, configurational information entropy, and baryon spectroscopy in strongly coupled QCD.

H. Almeida

R. da Rocha

P.H.O. Silva

B. Toniato

Holographic information measures for spin-3/2 Δ baryons in AdS/QCD

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.

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